Chapter聽8.聽Client and Utility Programs

Chapter聽8.聽Client and Utility Programs
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8.1.聽Overview of Client and Utility Programs

The following list briefly describes the MySQL client programs and utilities:

my_print_defaults
A utility that are present in option groups of option files. See Section聽8.2, 鈥�my_print_defaults 鈥� Display Options from Option Files鈥�.
myisam_ftdump
A utility that displays information about full-text indexes in MyISAM tables. See Section聽8.3, 鈥�myisam_ftdump 鈥� Display Full-Text Index information鈥�.
myisamchk, isamchk
A utility to describe, check, optimize, and repair MyISAM tables. isamchk is a similar program for ISAM tables. See Section聽8.4, 鈥�myisamchk 鈥� MyISAM Table-Maintenance Utility鈥�.
myisamlog, isamlog
Utilities that process the contents of a MyISAM or ISAM log file. See Section聽8.5, 鈥�myisamlog 鈥� Display MyISAM Log File Contents鈥�.
myisampack, pack_isam
Utilities that compress MyISAM or ISAM tables to produce smaller read-only tables. See Section聽8.6, 鈥�myisampack 鈥� Generate Compressed, Read-Only MyISAM Tables鈥�.
mysql
The command-line tool for interactively entering SQL statements or executing them from a file in batch mode. See Section聽8.7, 鈥�mysql 鈥� The MySQL Command-Line Tool鈥�.
mysqlaccess
A script that checks the access privileges for a hostname, username, and database combination. See Section聽8.8, 鈥�mysqlaccess 鈥� Client for Checking Access Privileges鈥�.
mysqladmin
A client that performs administrative operations, such as creating or dropping databases, reloading the grant tables, flushing tables to disk, and reopening log files. mysqladmin can also be used to retrieve version, process, and status information from the server. See Section聽8.9, 鈥�mysqladmin 鈥� Client for Administering a MySQL Server鈥�.
mysqlbinlog
A utility for reading statements from a binary log. The log of executed statements contained in the binary log files can be used to help recover from a crash. See Section聽8.10, 鈥�mysqlbinlog 鈥� Utility for Processing Binary Log Files鈥�.
mysqlcheck
A table-maintenance client that checks, repairs, analyzes, and optimizes tables. See Section聽8.11, 鈥�mysqlcheck 鈥� A Table Maintenance and Repair Program鈥�.
mysqldump
A client that dumps a MySQL database into a file as SQL, text, or XML. See Section聽8.12, 鈥�mysqldump 鈥� A Database Backup Program鈥�.
mysqlhotcopy
A utility that quickly makes backups of MyISAM or ISAM tables while the server is running. See Section聽8.13, 鈥�mysqlhotcopy 鈥� A Database Backup Program鈥�.
mysqlimport
A client that imports text files into their respective tables using LOAD DATA INFILE. See Section聽8.14, 鈥�mysqlimport 鈥� A Data Import Program鈥�.
mysqlshow
A client that displays information about databases, tables, columns, and indexes. See Section聽8.17, 鈥�mysqlshow 鈥� Display Database, Table, and Column Information鈥�.
mysql_convert_table_format
A utility that converts tables in a database to use a given storage engine. See Section聽8.18, 鈥�mysql_convert_table_format 鈥� Convert Tables to Use a Given Storage Engine鈥�.
mysql_explain_log
A utility that analyzes queries in the MySQL query log using EXPLAIN See Section聽8.19, 鈥�mysql_explain_log 鈥� Use EXPLAIN on Statements in Query Log鈥�.
mysql_find_rows
A utility that reads update log files and extracts queries that match a given regular expression. See Section聽8.20, 鈥�mysql_find_rows 鈥� Extract Queries from Update Log鈥�.
mysql_fix_extensions
A utility that converts the extensions for MyISAM (or ISAM) table files to lowercase. This can be useful after transferring the files from a system with case-insensitive filenames to a system with case-sensitive filenames. See Section聽8.21, 鈥�mysql_fix_extensions 鈥� Make Table Filename Extensions Lowercase鈥�.
mysql_setpermission
A utility for interactively setting permissions in the MySQL grant tables. See Section聽8.22, 鈥�mysql_setpermission 鈥� Interactively Set Permissions in Grant Tables鈥�.
mysql_tableinfo
A utility that generates database metadata. Section聽8.23, 鈥�mysql_tableinfo 鈥� Generate Database Metadata鈥�.
mysql_waitpid
A utility that kills the process with a given process ID. See Section聽8.24, 鈥�mysql_waitpid 鈥� Kill Process and Wait for Its Termination鈥�.
mysql_zap
A utility that kills processes that match a pattern. See Section聽8.25, 鈥�mysql_zap 鈥� Kill Processes That Match a Pattern鈥�.
perror
A utility that displays the meaning of system or MySQL error codes. See Section聽8.26, 鈥�perror 鈥� Explain Error Codes鈥�.
replace
A utility program that performs string replacement in the input text. See Section聽8.27, 鈥�replace 鈥� A String-Replacement Utility鈥�.
resolveip
A utility program that resolves a hostname to an IP address or vice versa. See Section聽8.28, 鈥�resolveip 鈥� Resolve Hostname to IP Address or Vice Versa鈥�.
resolve_stack_dump
A utility program that resolves a numeric stack trace dump to symbols. See Section聽8.29, 鈥�resolve_stack_dump 鈥� Resolve Numeric Stack Trace Dump to Symbols鈥�.

MySQL AB also provides a number of GUI tools for administering and otherwise working with MySQL servers. For basic information about these, see Chapter聽4, Using MySQL Programs.

Each MySQL program takes many different options. Most programs provide a --help option that you can use to get a full description of the program's different options. For example, try mysql --help.

MySQL client programs that communicate with the server using the MySQL client/server library use the following environment variables:

`MYSQL_UNIX_PORT`	The default Unix socket file; used for connections to `localhost`
`MYSQL_TCP_PORT`	The default port number; used for TCP/IP connections
`MYSQL_PWD`	The default password
`MYSQL_DEBUG`	Debug trace options when debugging
`TMPDIR`	The directory where temporary tables and files are created

Use of MYSQL_PWD is insecure. See Section聽5.8.6, 鈥淜eeping Your Password Secure鈥�.

You can override the default option values or values specified in environment variables for all standard programs by specifying options in an option file or on the command line. See Section聽4.3, 鈥淪pecifying Program Options鈥�.

8.2.聽my_print_defaults 鈥� Display Options from Option Files

my_print_defaults displays the options that are present in option groups of option files. The output indicates what options will be used by programs that read the specified option groups. For example, the mysqlcheck program reads the [mysqlcheck] and [client] option groups. To see what options are present in those groups in the standard option files, invoke my_print_defaults like this:

shell> my_print_defaults mysqlcheck client
--user=myusername
--password=secret
--host=localhost

The output consists of options, one per line, in the form that they would be specified on the command line.

my_print_defaults understands the following options:

--help, -?
Display a help message and exit.
--config-file=file_name, --defaults-file=file_name, -c file_name
Read only the given option file.
--debug=debug_options, -# debug_options
Write a debugging log. The debug_options string often is 'd:t:o,file_name'. The default is 'd:t:o,/tmp/my_print_defaults.trace'.
--defaults-extra-file=file_name, --extra-file=file_name, -e file_name
Read this option file after the global option file but (on Unix) before the user option file.
--defaults-group-suffix=suffix, -g suffix
In addition to the groups named on the command line, read groups that have the given suffix.
--no-defaults, -n
Return an empty string.
--verbose, -v
Verbose mode. Print more information about what the program does.
--version, -V
Display version information and exit.

8.3.聽myisam_ftdump 鈥� Display Full-Text Index information

myisam_ftdump displays information about FULLTEXT indexes in MyISAM tables. It reads the MyISAM index file directly, so it must be run on the server host where the table is located

Invoke myisam_ftdump like this:

shell> myisam_ftdump [options] tbl_name index_num

The tbl_name argument should be the name of a MyISAM table. You can also specify a table by naming its index file (the file with the .MYI suffix). If you do not invoke myisam_ftdump in the directory where the table files are located, the table or index file name must be preceded by the pathname to the table's database directory. Index numbers begin with 0.

Example: Suppose that the test database contains a table named mytexttablel that has the following definition:

CREATE TABLE mytexttable
(
  id   INT NOT NULL,
  txt  TEXT NOT NULL,
  PRIMARY KEY (id),
  FULLTEXT (txt)
);

The index on id is index 0 and the FULLTEXT index on txt is index 1. If your working directory is the test database directory, invoke myisam_ftdump as follows:

shell> myisam_ftdump mytexttable 1

If the pathname to the test database directory is /usr/local/mysql/data/test, you can also specify the table name argument using that pathname. This is useful if you do not invoke myisam_ftdump in the database directory:

shell> myisam_ftdump /usr/local/mysql/data/test/mytexttable 1

myisam_ftdump understands the following options:

--help, -h -?
Display a help message and exit.
--count, -c
Calculate per-word statistics (counts and global weights).
--dump, -d
Dump the index, including data offsets and word weights.
--length, -l
Report the length distribution.
--stats, -s
Report global index statistics. This is the default operation if no other operation is specified.
--verbose, -v
Verbose mode. Print more output about what the program does.

8.4.聽myisamchk 鈥� MyISAM Table-Maintenance Utility

8.4.1. myisamchk General Options
8.4.2. myisamchk Check Options
8.4.3. myisamchk Repair Options
8.4.4. Other myisamchk Options
8.4.5. myisamchk Memory Usage

The myisamchk utility gets information about your database tables or checks, repairs, or optimizes them. myisamchk works with MyISAM tables (tables that have .MYD and .MYI files for storing data and indexes). A related utility, isamchk, works with ISAM tables (tables that have .ISD and .ISM files for storing data and indexes).

Caution

It is best to make a backup of a table before performing a table repair operation; under some circumstances the operation might cause data loss. Possible causes include but are not limited to filesystem errors.

Invoke myisamchk like this:

shell> myisamchk [options] tbl_name ...

The options specify what you want myisamchk to do. They are described in the following sections. You can also get a list of options by invoking myisamchk --help.

With no options, myisamchk simply checks your table as the default operation. To get more information or to tell myisamchk to take corrective action, specify options as described in the following discussion.

tbl_name is the database table you want to check or repair. If you run myisamchk somewhere other than in the database directory, you must specify the path to the database directory, because myisamchk has no idea where the database is located. In fact, myisamchk does not actually care whether the files you are working on are located in a database directory. You can copy the files that correspond to a database table into some other location and perform recovery operations on them there.

You can name several tables on the myisamchk command line if you wish. You can also specify a table by naming its index file (the file with the .MYI suffix). This allows you to specify all tables in a directory by using the pattern *.MYI. For example, if you are in a database directory, you can check all the MyISAM tables in that directory like this:

shell> myisamchk *.MYI

If you are not in the database directory, you can check all the tables there by specifying the path to the directory:

shell> myisamchk /path/to/database_dir/*.MYI

You can even check all tables in all databases by specifying a wildcard with the path to the MySQL data directory:

shell> myisamchk /path/to/datadir/*/*.MYI

The recommended way to quickly check all MyISAM and ISAM tables is:

shell> myisamchk --silent --fast /path/to/datadir/*/*.MYI
shell> isamchk --silent /path/to/datadir/*/*.ISM

If you want to check all MyISAM and ISAM tables and repair any that are corrupted, you can use the following commands:

shell> myisamchk --silent --force --fast --update-state \
          --key_buffer_size=64M --sort_buffer_size=64M \
          --read_buffer_size=1M --write_buffer_size=1M \
          /path/to/datadir/*/*.MYI
shell> isamchk --silent --force --key_buffer_size=64M \
          --sort_buffer_size=64M --read_buffer_size=1M --write_buffer_size=1M \
          /path/to/datadir/*/*.ISM

These commands assume that you have more than 64MB free. For more information about memory allocation with myisamchk, see Section聽8.4.5, 鈥�myisamchk Memory Usage鈥�.

MySQL Enterprise For expert advice on checking and repairing tables, subscribe to the MySQL Network Monitoring and Advisory. For more information see http://www.mysql.com/products/enterprise/advisors.html.

Important

You must ensure that no other program is using the tables while you are running myisamchk. The most effective means of doing so is to shut down the MySQL server while running myisamchk, or to lock all tables that myisamchk is being used on.

Otherwise, when you run myisamchk, it may display the following error message:

warning: clients are using or haven't closed the table properly

This means that you are trying to check a table that has been updated by another program (such as the mysqld server) that hasn't yet closed the file or that has died without closing the file properly, which can sometimes lead to the corruption of one or more MyISAM tables.

If mysqld is running, you must force it to flush any table modifications that are still buffered in memory by using FLUSH TABLES. You should then ensure that no one is using the tables while you are running myisamchk

However, the easiest way to avoid this problem is to use CHECK TABLE instead of myisamchk to check tables. See Section聽13.5.2.3, 鈥�CHECK TABLE Syntax鈥�.

8.4.1.聽myisamchk General Options

The options described in this section can be used for any type of table maintenance operation performed by myisamchk. The sections following this one describe options that pertain only to specific operations, such as table checking or repairing.

--help, -?
Display a help message and exit.
--debug=debug_options, -# debug_options
Write a debugging log. The debug_options string often is 'd:t:o,file_name'.
--silent, -s
Silent mode. Write output only when errors occur. You can use -s twice (-ss) to make myisamchk very silent.
--verbose, -v
Verbose mode. Print more information about what the program does. This can be used with -d and -e. Use -v multiple times (-vv, -vvv) for even more output.
--version, -V
Display version information and exit.
--wait, -w
Instead of terminating with an error if the table is locked, wait until the table is unlocked before continuing. If you are running mysqld with external locking disabled, the table can be locked only by another myisamchk command.

You can also set the following variables by using --var_name=value syntax:

Variable	Default Value
`decode_bits`	9
`ft_max_word_len`	version-dependent
`ft_min_word_len`	4
`ft_stopword_file`	built-in list
`key_buffer_size`	523264
`myisam_block_size`	1024
`read_buffer_size`	262136
`sort_buffer_size`	2097144
`sort_key_blocks`	16
`stats_method`	nulls_unequal
`write_buffer_size`	262136

It is also possible to set variables by using --set-variable=var_name=value or -O var_name=value syntax. However, this syntax is deprecated as of MySQL 4.0.

The possible myisamchk variables and their default values can be examined with myisamchk --help:

sort_buffer_size is used when the keys are repaired by sorting keys, which is the normal case when you use --recover.

key_buffer_size is used when you are checking the table with --extend-check or when the keys are repaired by inserting keys row by row into the table (like when doing normal inserts). Repairing through the key buffer is used in the following cases:

You use --safe-recover.
The temporary files needed to sort the keys would be more than twice as big as when creating the key file directly. This is often the case when you have large key values for CHAR, VARCHAR, or TEXT columns, because the sort operation needs to store the complete key values as it proceeds. If you have lots of temporary space and you can force myisamchk to repair by sorting, you can use the --sort-recover option.

Repairing through the key buffer takes much less disk space than using sorting, but is also much slower.

If you want a faster repair, set the key_buffer_size and sort_buffer_size variables to about 25% of your available memory. You can set both variables to large values, because only one of them is used at a time.

myisam_block_size is the size used for index blocks. It is available as of MySQL 4.0.0.

stats_method influences how NULL values are treated for index statistics collection when the --analyze option is given. It acts like the myisam_stats_method system variable. For more information, see the description of myisam_stats_method in Section聽5.2.3, 鈥淪ystem Variables鈥�, and Section聽7.4.7, 鈥�MyISAM Index Statistics Collection鈥�. stats_method was added in MySQL 4.1.15/5.0.14. For older versions, the statistics collection method is equivalent to nulls_equal.

The ft_min_word_len and ft_max_word_len variables are available as of MySQL 4.0.0. ft_stopword_file is available as of MySQL 4.0.19.

ft_min_word_len and ft_max_word_len indicate the minimum and maximum word length for FULLTEXT indexes. ft_stopword_file names the stopword file. These need to be set under the following circumstances.

If you use myisamchk to perform an operation that modifies table indexes (such as repair or analyze), the FULLTEXT indexes are rebuilt using the default full-text parameter values for minimum and maximum word length and the stopword file unless you specify otherwise. This can result in queries failing.

The problem occurs because these parameters are known only by the server. They are not stored in MyISAM index files. To avoid the problem if you have modified the minimum or maximum word length or the stopword file in the server, specify the same ft_min_word_len, ft_max_word_len, and ft_stopword_file values to myisamchk that you use for mysqld. For example, if you have set the minimum word length to 3, you can repair a table with myisamchk like this:

shell> myisamchk --recover --ft_min_word_len=3 tbl_name.MYI

To ensure that myisamchk and the server use the same values for full-text parameters, you can place each one in both the [mysqld] and [myisamchk] sections of an option file:

[mysqld]
ft_min_word_len=3

[myisamchk]
ft_min_word_len=3

An alternative to using myisamchk is to use the REPAIR TABLE, ANALYZE TABLE, OPTIMIZE TABLE, or ALTER TABLE. These statements are performed by the server, which knows the proper full-text parameter values to use.

8.4.2.聽myisamchk Check Options

myisamchk supports the following options for table checking operations:

--check, -c
Check the table for errors. This is the default operation if you specify no option that selects an operation type explicitly.
--check-only-changed, -C
Check only tables that have changed since the last check.
--extend-check, -e
Check the table very thoroughly. This is quite slow if the table has many indexes. This option should only be used in extreme cases. Normally, myisamchk or myisamchk --medium-check should be able to determine whether there are any errors in the table.
If you are using --extend-check and have plenty of memory, setting the key_buffer_size variable to a large value helps the repair operation run faster.
--fast, -F
Check only tables that haven't been closed properly.
--force, -f
Do a repair operation automatically if myisamchk finds any errors in the table. The repair type is the same as that specified with the --recover or -r option.
--information, -i
Print informational statistics about the table that is checked.
--medium-check, -m
Do a check that is faster than an --extend-check operation. This finds only 99.99% of all errors, which should be good enough in most cases.
--read-only, -T
Don't mark the table as checked. This is useful if you use myisamchk to check a table that is in use by some other application that does not use locking, such as mysqld when run with external locking disabled.
--update-state, -U
Store information in the .MYI file to indicate when the table was checked and whether the table crashed. This should be used to get full benefit of the --check-only-changed option, but you shouldn't use this option if the mysqld server is using the table and you are running it with external locking disabled.

8.4.3.聽myisamchk Repair Options

myisamchk supports the following options for table repair operations:

--backup, -B
Make a backup of the .MYD file as file_name-time.BAK
--character-sets-dir=path
The directory where character sets are installed. See Section聽5.10.1, 鈥淭he Character Set Used for Data and Sorting鈥�.
--correct-checksum
Correct the checksum information for the table.
--data-file-length=len, -D len
Maximum length of the data file (when re-creating data file when it is 鈥�full鈥�).
--extend-check, -e
Do a repair that tries to recover every possible row from the data file. Normally, this also finds a lot of garbage rows. Don't use this option unless you are totally desperate.
--force, -f
Overwrite old intermediate files (files with names like tbl_name.TMD) instead of aborting.
--keys-used=val, -k val
For myisamchk, the option value is a bit-value that indicates which indexes to update. Each binary bit of the option value corresponds to a table index, where the first index is bit 0. For isamchk, the option value indicates that only the first val of the table indexes should be updated. In either case, an option value of 0 disables updates to all indexes, which can be used to get faster inserts. Deactivated indexes can be reactivated by using myisamchk -r or (isamchk -r).
--no-symlinks, -l
Do not follow symbolic links. Normally myisamchk repairs the table that a symlink points to. This option does not exist as of MySQL 4.0 because versions from 4.0 on do not remove symlinks during repair operations.
--max-record-length=len
Skip rows larger than the given length if myisamchk cannot allocate memory to hold them. This option was added in MySQL 4.1.1.
--parallel-recover, -p
Uses the same technique as -r and -n, but creates all the keys in parallel, using different threads. This option was added in MySQL 4.0.2. This is beta-quality code; use at your own risk!.
--quick, -q
Achieve a faster repair by not modifying the data file. You can specify this option twice to force myisamchk to modify the original data file in case of duplicate keys.
--recover, -r
Do a repair that can fix almost any problem except unique keys that are not unique (which is an extremely unlikely error with ISAM/MyISAM tables). If you want to recover a table, this is the option to try first. You should try --safe-recover only if myisamchk reports that the table cannot be recovered by --recover. (In the unlikely case that --recover fails, the data file remains intact.)
If you have lots of memory, you should increase the value of sort_buffer_size.
--safe-recover, -o
Do a repair using an old recovery method that reads through all rows in order and updates all index trees based on the rows found. This is an order of magnitude slower than --recover, but can handle a couple of very unlikely cases that --recover cannot. This recovery method also uses much less disk space than --recover. Normally, you should repair first using --recover, and then with --safe-recover only if --recover fails.
If you have lots of memory, you should increase the value of key_buffer_size.
--set-character-set=name
Change the character set used by the table indexes. This option was replaced by --set-collation in MySQL 4.1.1.
--set-collation=name
Specify the collation to use for sorting table indexes. The character set name is implied by the first part of the collation name. This option was added in MySQL 4.1.11.
--sort-recover, -n
Force myisamchk to use sorting to resolve the keys even if the temporary files should be very big.
--tmpdir=path, -t path
Path of the directory to be used for storing temporary files. If this is not set, myisamchk uses the value of the TMPDIR environment variable. Starting from MySQL 4.1, tmpdir can be set to a list of directory paths that are used successively in round-robin fashion for creating temporary files. The separator character between directory names should be colon (鈥�:鈥�) on Unix and semicolon (鈥�;鈥�) on Windows, NetWare, and OS/2.
--unpack, -u
Unpack a table that was packed with myisampack.

8.4.4.聽Other `myisamchk` Options

myisamchk supports the following options for actions other than table checks and repairs:

--analyze, -a
Analyze the distribution of key values. This improves join performance by enabling the join optimizer to better choose the order in which to join the tables and which indexes it should use. To obtain information about the key distribution, use a myisamchk --description --verbose tbl_name command or the SHOW INDEX FROM tbl_name statement.
MySQL Enterprise For expert advice on optimizing tables, subscribe to the MySQL Network Monitoring and Advisory. For more information see http://www.mysql.com/products/enterprise/advisors.html.
--block-search=offset, -b offset
Find the record that a block at the given offset belongs to.
--description, -d
Print some descriptive information about the table.
--set-auto-increment[=value], -A[value]
Force AUTO_INCREMENT numbering for new records to start at the given value (or higher, if there are existing records with AUTO_INCREMENT values this large). If value is not specified, AUTO_INCREMENT numbers for new records begin with the largest value currently in the table, plus one.
--sort-index, -S
Sort the index tree blocks in high-low order. This optimizes seeks and makes table scans that use indexes faster.
--sort-records=N, -R N
Sort records according to a particular index. This makes your data much more localized and may speed up range-based SELECT and ORDER BY operations that use this index. (The first time you use this option to sort a table, it may be very slow.) To determine a table's index numbers, use SHOW INDEX, which displays a table's indexes in the same order that myisamchk sees them. Indexes are numbered beginning with 1.
If keys are not packed (PACK_KEYS=0), they have the same length, so when myisamchk sorts and moves records, it just overwrites record offsets in the index. If keys are packed (PACK_KEYS=1), myisamchk must unpack key blocks first, then re-create indexes and pack the key blocks again. (In this case, re-creating indexes is faster than updating offsets for each index.)

8.4.5.聽myisamchk Memory Usage

Memory allocation is important when you run myisamchk. myisamchk uses no more memory than its memory-related variables are set to. If you are going to use myisamchk on very large tables, you should first decide how much memory you want it to use. The default is to use only about 3MB to perform repairs. By using larger values, you can get myisamchk to operate faster. For example, if you have more than 32MB RAM, you could use options such as these (in addition to any other options you might specify):

shell> myisamchk --sort_buffer_size=16M --key_buffer_size=16M \
           --read_buffer_size=1M --write_buffer_size=1M ...

Using --sort_buffer_size=16M should probably be enough for most cases.

Be aware that myisamchk uses temporary files in TMPDIR. If TMPDIR points to a memory filesystem, you may easily get out of memory errors. If this happens, run myisamchk with the --tmpdir=path option to specify some directory located on a filesystem that has more space.

When repairing, myisamchk also needs a lot of disk space:

Double the size of the data file (the original file and a copy). This space is not needed if you do a repair with --quick; in this case, only the index file is re-created. This space must be available on the same filesystem as the original data file, as the copy is created in the same directory as the original.
Space for the new index file that replaces the old one. The old index file is truncated at the start of the repair operation, so you usually ignore this space. This space must be available on the same filesystem as the original data file.
When using --recover or --sort-recover (but not when using --safe-recover), you need space for a sort buffer. The following formula yields the amount of space required:
```
(largest_key + row_pointer_length) 脳 number_of_rows 脳 2
```
You can check the length of the keys and the row_pointer_length with myisamchk -dv tbl_name. This space is allocated in the temporary directory (specified by TMPDIR or --tmpdir=path).

If you have a problem with disk space during repair, you can try --safe-recover instead of --recover.

8.5.聽myisamlog 鈥� Display MyISAM Log File Contents

myisamlog processes the contents of a MyISAM log file. isamlog is similar, but is used with ISAM log files.

Invoke myisamlog or isamloglike this:

shell> myisamlog [options] [log_file [tbl_name] ...]
shell> isamlog [options] [log_file [tbl_name] ...]

The default operation is update (-u). If a recovery is done (-r), all writes and possibly updates and deletes are done and errors are only counted. The default log file name is myisam.log for myisamlog and isam.log for isamlog if no log_file argument is given. If tables are named on the command line, only those tables are updated.

myisamlog and isamlog understand the following options:

-?, -I
Display a help message and exit.
-c N
Execute only N commands.
-f N
Specify the maximum number of open files.
-i
Display extra information before exiting.
-o offset
Specify the starting offset.
-p N
Remove N components from path.
-r
Perform a recovery operation.
-R record_pos_file record_pos
Specify record position file and record position.
-u
Perform an update operation.
-v
Verbose mode. Print more output about what the program does. This option can be given multiple times to produce more and more output.
-w write_file
Specify the write file.
-V
Display version information.

8.6.聽myisampack 鈥� Generate Compressed, Read-Only MyISAM Tables

The myisampack utility compresses MyISAM tables. myisampack works by compressing each column in the table separately. Usually, myisampack packs the data file 40%-70%.

When the table is used later, the server reads into memory the information needed to decompress columns. This results in much better performance when accessing individual rows, because you only have to uncompress exactly one row.

MySQL uses mmap() when possible to perform memory mapping on compressed tables. If mmap() does not work, MySQL falls back to normal read/write file operations.

A similar utility, pack_isam, compresses ISAM tables. Because ISAM tables are deprecated, this section discusses only myisampack, but the general procedures for using myisampack are also true for pack_isam unless otherwise specified. References to myisamchk should be read as references to isamchk if you are using pack_isam.

Please note the following:

If the mysqld server was invoked with external locking disabled, it is not a good idea to invoke myisampack if the table might be updated by the server during the packing process. It is safest to compress tables with the server stopped.
After packing a table, it becomes read-only. This is generally intended (such as when accessing packed tables on a CD). Allowing writes to a packed table is on our TODO list, but with low priority.
myisampack can pack BLOB or TEXT columns. (The older pack_isam program for ISAM tables does not have this capability.)

Invoke myisampack like this:

shell> myisampack [options] file_name ...

Each filename argument should be the name of an index (.MYI) file. If you are not in the database directory, you should specify the pathname to the file. It is permissible to omit the .MYI extension.

After you compress a table with myisampack, you should use myisamchk -rq to rebuild its indexes. Section聽8.4, 鈥�myisamchk 鈥� MyISAM Table-Maintenance Utility鈥�.

myisampack supports the following options:

--help, -?
Display a help message and exit.
--backup, -b
Make a backup of each table's data file using the name tbl_name.OLD.
--character-sets-dir=path
The directory where character sets are installed. See Section聽5.10.1, 鈥淭he Character Set Used for Data and Sorting鈥�.
--debug[=debug_options], -# [debug_options]
Write a debugging log. The debug_options string often is 'd:t:o,file_name'.
--force, -f
Produce a packed table even if it becomes larger than the original or if the intermediate file from an earlier invocation of myisampack exists. (myisampack creates an intermediate file named tbl_name.TMD in the database directory while it compresses the table. If you kill myisampack, the .TMD file might not be deleted.) Normally, myisampack exits with an error if it finds that tbl_name.TMD exists. With --force, myisampack packs the table anyway.
--join=big_tbl_name, -j big_tbl_name
Join all tables named on the command line into a single table big_tbl_name. All tables that are to be combined must have identical structure (same column names and types, same indexes, and so forth).
--packlength=len, -p len
Specify the row length storage size, in bytes. The value should be 1, 2, or 3. myisampack stores all rows with length pointers of 1, 2, or 3 bytes. In most normal cases, myisampack can determine the correct length value before it begins packing the file, but it may notice during the packing process that it could have used a shorter length. In this case, myisampack prints a note that you could use a shorter row length the next time you pack the same file.
--silent, -s
Silent mode. Write output only when errors occur.
--test, -t
Do not actually pack the table, just test packing it.
--tmpdir=path, -T path
Use the named directory as the location where myisampack creates temporary files.
--verbose, -v
Verbose mode. Write information about the progress of the packing operation and its result.
--version, -V
Display version information and exit.
--wait, -w
Wait and retry if the table is in use. If the mysqld server was invoked with external locking disabled, it is not a good idea to invoke myisampack if the table might be updated by the server during the packing process.

The following sequence of commands illustrates a typical table compression session:

shell> ls -l station.*
-rw-rw-r--   1 monty    my         994128 Apr 17 19:00 station.MYD
-rw-rw-r--   1 monty    my          53248 Apr 17 19:00 station.MYI
-rw-rw-r--   1 monty    my           5767 Apr 17 19:00 station.frm

shell> myisamchk -dvv station

MyISAM file:     station
Isam-version:  2
Creation time: 1996-03-13 10:08:58
Recover time:  1997-02-02  3:06:43
Data records:              1192  Deleted blocks:              0
Datafile parts:            1192  Deleted data:                0
Datafile pointer (bytes):     2  Keyfile pointer (bytes):     2
Max datafile length:   54657023  Max keyfile length:   33554431
Recordlength:               834
Record format: Fixed length

table description:
Key Start Len Index   Type                 Root  Blocksize    Rec/key
1   2     4   unique  unsigned long        1024       1024          1
2   32    30  multip. text                10240       1024          1

Field Start Length Type
1     1     1
2     2     4
3     6     4
4     10    1
5     11    20
6     31    1
7     32    30
8     62    35
9     97    35
10    132   35
11    167   4
12    171   16
13    187   35
14    222   4
15    226   16
16    242   20
17    262   20
18    282   20
19    302   30
20    332   4
21    336   4
22    340   1
23    341   8
24    349   8
25    357   8
26    365   2
27    367   2
28    369   4
29    373   4
30    377   1
31    378   2
32    380   8
33    388   4
34    392   4
35    396   4
36    400   4
37    404   1
38    405   4
39    409   4
40    413   4
41    417   4
42    421   4
43    425   4
44    429   20
45    449   30
46    479   1
47    480   1
48    481   79
49    560   79
50    639   79
51    718   79
52    797   8
53    805   1
54    806   1
55    807   20
56    827   4
57    831   4

shell> myisampack station.MYI
Compressing station.MYI: (1192 records)
- Calculating statistics

normal:     20  empty-space:   16  empty-zero:     12  empty-fill:  11
pre-space:   0  end-space:     12  table-lookups:   5  zero:         7
Original trees:  57  After join: 17
- Compressing file
87.14%
Remember to run myisamchk -rq on compressed tables

shell> ls -l station.*
-rw-rw-r--   1 monty    my         127874 Apr 17 19:00 station.MYD
-rw-rw-r--   1 monty    my          55296 Apr 17 19:04 station.MYI
-rw-rw-r--   1 monty    my           5767 Apr 17 19:00 station.frm

shell> myisamchk -dvv station

MyISAM file:     station
Isam-version:  2
Creation time: 1996-03-13 10:08:58
Recover time:  1997-04-17 19:04:26
Data records:               1192  Deleted blocks:              0
Datafile parts:             1192  Deleted data:                0
Datafile pointer (bytes):      3  Keyfile pointer (bytes):     1
Max datafile length:    16777215  Max keyfile length:     131071
Recordlength:                834
Record format: Compressed

table description:
Key Start Len Index   Type                 Root  Blocksize    Rec/key
1   2     4   unique  unsigned long       10240       1024          1
2   32    30  multip. text                54272       1024          1

Field Start Length Type                         Huff tree  Bits
1     1     1      constant                             1     0
2     2     4      zerofill(1)                          2     9
3     6     4      no zeros, zerofill(1)                2     9
4     10    1                                           3     9
5     11    20     table-lookup                         4     0
6     31    1                                           3     9
7     32    30     no endspace, not_always              5     9
8     62    35     no endspace, not_always, no empty    6     9
9     97    35     no empty                             7     9
10    132   35     no endspace, not_always, no empty    6     9
11    167   4      zerofill(1)                          2     9
12    171   16     no endspace, not_always, no empty    5     9
13    187   35     no endspace, not_always, no empty    6     9
14    222   4      zerofill(1)                          2     9
15    226   16     no endspace, not_always, no empty    5     9
16    242   20     no endspace, not_always              8     9
17    262   20     no endspace, no empty                8     9
18    282   20     no endspace, no empty                5     9
19    302   30     no endspace, no empty                6     9
20    332   4      always zero                          2     9
21    336   4      always zero                          2     9
22    340   1                                           3     9
23    341   8      table-lookup                         9     0
24    349   8      table-lookup                        10     0
25    357   8      always zero                          2     9
26    365   2                                           2     9
27    367   2      no zeros, zerofill(1)                2     9
28    369   4      no zeros, zerofill(1)                2     9
29    373   4      table-lookup                        11     0
30    377   1                                           3     9
31    378   2      no zeros, zerofill(1)                2     9
32    380   8      no zeros                             2     9
33    388   4      always zero                          2     9
34    392   4      table-lookup                        12     0
35    396   4      no zeros, zerofill(1)               13     9
36    400   4      no zeros, zerofill(1)                2     9
37    404   1                                           2     9
38    405   4      no zeros                             2     9
39    409   4      always zero                          2     9
40    413   4      no zeros                             2     9
41    417   4      always zero                          2     9
42    421   4      no zeros                             2     9
43    425   4      always zero                          2     9
44    429   20     no empty                             3     9
45    449   30     no empty                             3     9
46    479   1                                          14     4
47    480   1                                          14     4
48    481   79     no endspace, no empty               15     9
49    560   79     no empty                             2     9
50    639   79     no empty                             2     9
51    718   79     no endspace                         16     9
52    797   8      no empty                             2     9
53    805   1                                          17     1
54    806   1                                           3     9
55    807   20     no empty                             3     9
56    827   4      no zeros, zerofill(2)                2     9
57    831   4      no zeros, zerofill(1)                2     9

myisampack displays the following kinds of information:

normal
The number of columns for which no extra packing is used.
empty-space
The number of columns containing values that are only spaces. These occupy one bit.
empty-zero
The number of columns containing values that are only binary zeros. These occupy one bit.
empty-fill
The number of integer columns that do not occupy the full byte range of their type. These are changed to a smaller type. For example, a BIGINT column (eight bytes) can be stored as a TINYINT column (one byte) if all its values are in the range from -128 to 127.
pre-space
The number of decimal columns that are stored with leading spaces. In this case, each value contains a count for the number of leading spaces.
end-space
The number of columns that have a lot of trailing spaces. In this case, each value contains a count for the number of trailing spaces.
table-lookup
The column had only a small number of different values, which were converted to an ENUM before Huffman compression.
zero
The number of columns for which all values are zero.
Original trees
The initial number of Huffman trees.
After join
The number of distinct Huffman trees left after joining trees to save some header space.

After a table has been compressed, myisamchk -dvv prints additional information about each column:

Type
The data type. The value may contain any of the following descriptors:
- constant
  All rows have the same value.
- no endspace
  Do not store endspace.
- no endspace, not_always
  Do not store endspace and do not do endspace compression for all values.
- no endspace, no empty
  Do not store endspace. Do not store empty values.
- table-lookup
  The column was converted to an ENUM.
- zerofill(N)
  The most significant N bytes in the value are always 0 and are not stored.
- no zeros
  Do not store zeros.
- always zero
  Zero values are stored using one bit.
Huff tree
The number of the Huffman tree associated with the column.
Bits
The number of bits used in the Huffman tree.

After you run myisampack, you must run myisamchk to re-create any indexes. At this time, you can also sort the index blocks and create statistics needed for the MySQL optimizer to work more efficiently:

shell> myisamchk -rq --sort-index --analyze tbl_name.MYI

A similar procedure applies for ISAM tables. After using pack_isam, use isamchk to re-create the indexes:

shell> isamchk -rq --sort-index --analyze tbl_name.ISM

After you have installed the packed table into the MySQL database directory, you should execute mysqladmin flush-tables to force mysqld to start using the new table.

To unpack a packed table, use the --unpack option to myisamchk or isamchk.

8.7.聽mysql 鈥� The MySQL Command-Line Tool

8.7.1. mysql Options
8.7.2. mysql Commands
8.7.3. mysql Server-Side Help
8.7.4. Executing SQL Statements from a Text File
8.7.5. mysql Tips

mysql is a simple SQL shell (with GNU readline capabilities). It supports interactive and non-interactive use. When used interactively, query results are presented in an ASCII-table format. When used non-interactively (for example, as a filter), the result is presented in tab-separated format. The output format can be changed using command options.

If you have problems due to insufficient memory for large result sets, use the --quick option. This forces mysql to retrieve results from the server a row at a time rather than retrieving the entire result set and buffering it in memory before displaying it. This is done by returning the result set using the mysql_use_result() C API function in the client/server library rather than mysql_store_result().

Using mysql is very easy. Invoke it from the prompt of your command interpreter as follows:

shell> mysql db_name

Or:

shell> mysql --user=user_name --password=your_password db_name

Then type an SQL statement, end it with 鈥�;鈥�, \g, or \G and press Enter.

You can execute SQL statements in a script file (batch file) like this:

shell> mysql db_name < script.sql > output.tab

8.7.1.聽mysql Options

mysql supports the following options:

--help, -?
Display a help message and exit.
--auto-rehash
Enable automatic rehashing. This option is on by default, which enables table and column name completion. Use --skip-auto-rehash to disable rehashing. That causes mysql to start faster, but you must issue the rehash command if you want to use table and column name completion.
--batch, -B
Print results using tab as the column separator, with each row on a new line. With this option, mysql does not use the history file.
--character-sets-dir=path
The directory where character sets are installed. See Section聽5.10.1, 鈥淭he Character Set Used for Data and Sorting鈥�.
--column-names
Write column names in results.
--compress, -C
Compress all information sent between the client and the server if both support compression.
--database=db_name, -D db_name
The database to use. This is useful primarily in an option file.
--debug[=debug_options], -# [debug_options]
Write a debugging log. The debug_options string often is 'd:t:o,file_name'. The default is 'd:t:o,/tmp/mysql.trace'.
--debug-info, -T
Print some debugging information when the program exits.
--default-character-set=charset_name
Use charset_name as the default character set. See Section聽5.10.1, 鈥淭he Character Set Used for Data and Sorting鈥�.
--delimiter=str
Set the statement delimiter. The default is the semicolon character (鈥�;鈥�).
--execute=statement, -e statement
Execute the statement and quit. The default output format is like that produced with --batch. See Section聽4.3.1, 鈥淯sing Options on the Command Line鈥�, for some examples.
--force, -f
Continue even if an SQL error occurs.
--host=host_name, -h host_name
Connect to the MySQL server on the given host.
--html, -H
Produce HTML output.
--ignore-spaces, -i
Ignore spaces after function names. The effect of this is described in the discussion for the IGNORE_SPACE SQL mode (see Section聽5.2.6, 鈥淪QL Modes鈥�).
--line-numbers
Write line numbers for errors. Disable this with --skip-line-numbers.
--local-infile[={0|1}]
Enable or disable LOCAL capability for LOAD DATA INFILE. With no value, the option enables LOCAL. The option may be given as --local-infile=0 or --local-infile=1 to explicitly disable or enable LOCAL. Enabling LOCAL has no effect if the server does not also support it.
MySQL Enterprise For expert advice on the security implications of enabling LOCAL, subscribe to the MySQL Network Monitoring and Advisory. For more information see http://www.mysql.com/products/enterprise/advisors.html.
--named-commands, -G
Enable named mysql commands. Long-format commands are allowed, not just short-format commands. For example, quit and \q both are recognized. Use --skip-named-commands to disable named commands. See Section聽8.7.2, 鈥�mysql Commands鈥�.
--no-auto-rehash, -A
Deprecated form of -skip-auto-rehash. See the description for --auto-rehash.
--no-beep, -b
Do not beep when errors occur.
--no-named-commands, -g
Disable named commands. Use the \* form only, or use named commands only at the beginning of a line ending with a semicolon (鈥�;鈥�). As of MySQL 3.23.22, mysql starts with this option enabled by default. However, even with this option, long-format commands still work from the first line. See Section聽8.7.2, 鈥�mysql Commands鈥�.
--no-pager
Deprecated form of --skip-pager. See the --pager option.
--no-tee
Do not copy output to a file. Section聽8.7.2, 鈥�mysql Commands鈥�, discusses tee files further.
--one-database, -o
Ignore statements except those for the default database named on the command line. This is useful for skipping updates to other databases in the binary log.
--pager[=command]
Use the given command for paging query output. If the command is omitted, the default pager is the value of your PAGER environment variable. Valid pagers are less, more, cat [> filename], and so forth. This option works only on Unix. It does not work in batch mode. To disable paging, use --skip-pager. Section聽8.7.2, 鈥�mysql Commands鈥�, discusses output paging further.
--password[=password], -p[password]
The password to use when connecting to the server. If you use the short option form (-p), you cannot have a space between the option and the password. If you omit the password value following the --password or -p option on the command line, you are prompted for one.
Specifying a password on the command line should be considered insecure. See Section聽5.8.6, 鈥淜eeping Your Password Secure鈥�.
--port=port_num, -P port_num
The TCP/IP port number to use for the connection.
--prompt=format_str
Set the prompt to the specified format. The default is mysql>. The special sequences that the prompt can contain are described in Section聽8.7.2, 鈥�mysql Commands鈥�.
--protocol={TCP|SOCKET|PIPE|MEMORY}
The connection protocol to use. Added in MySQL 4.1.
--quick, -q
Do not cache each query result, print each row as it is received. This may slow down the server if the output is suspended. With this option, mysql does not use the history file.
--raw, -r
Write column values without escape conversion. Often used with the --batch option.
--reconnect
If the connection to the server is lost, automatically try to reconnect. A single reconnect attempt is made each time the connection is lost. To suppress reconnection behavior, use --skip-reconnect. Added in MySQL 4.1.0.
--safe-updates, --i-am-a-dummy, -U
Allow only those UPDATE and DELETE statements that specify which rows to modify by using key values. If you have set this option in an option file, you can override it by using --safe-updates on the command line. See Section聽8.7.5, 鈥�mysql Tips鈥�, for more information about this option.
--secure-auth
Do not send passwords to the server in old (pre-4.1.1) format. This prevents connections except for servers that use the newer password format. This option was added in MySQL 4.1.1.
MySQL Enterprise For expert advice on database security, subscribe to the MySQL Network Monitoring and Advisory. For more information see http://www.mysql.com/products/enterprise/advisors.html.
--sigint-ignore
Ignore SIGINT signals (typically the result of typing Control-C). This option was added in MySQL 4.1.6.
--silent, -s
Silent mode. Produce less output. This option can be given multiple times to produce less and less output.
--skip-column-names, -N
Do not write column names in results.
--skip-line-numbers, -L
Do not write line numbers for errors. Useful when you want to compare result files that include error messages.
--socket=path, -S path
For connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.
--ssl*
Options that begin with --ssl specify whether to connect to the server via SSL and indicate where to find SSL keys and certificates. See Section聽5.8.7.3, 鈥淪SL Command Options鈥�.
--table, -t
Display output in table format. This is the default for interactive use, but can be used to produce table output in batch mode.
--tee=file_name
Append a copy of output to the given file. This option does not work in batch mode. in Section聽8.7.2, 鈥�mysql Commands鈥�, discusses tee files further.
--unbuffered, -n
Flush the buffer after each query.
--user=user_name, -u user_name
The MySQL username to use when connecting to the server.
--verbose, -v
Verbose mode. Produce more output about what the program does. This option can be given multiple times to produce more and more output. (For example, -v -v -v produces table output format even in batch mode.)
--version, -V
Display version information and exit.
--vertical, -E
Print query output rows vertically (one line per column value). Without this option, you can specify vertical output for individual statements by terminating them with \G.
--wait, -w
If the connection cannot be established, wait and retry instead of aborting.
--xml, -X
Produce XML output.

You can also set the following variables by using --var_name=value syntax:

connect_timeout
The number of seconds before connection timeout. (Default value is 0.)
max_allowed_packet
The maximum packet length to send to or receive from the server. (Default value is 16MB.)
max_join_size
The automatic limit for rows in a join when using --safe-updates. (Default value is 1,000,000.)
net_buffer_length
The buffer size for TCP/IP and socket communication. (Default value is 16KB.)
select_limit
The automatic limit for SELECT statements when using --safe-updates. (Default value is 1,000.)

It is also possible to set variables by using --set-variable=var_name=value or -O var_name=value syntax. In MySQL 4.1, this syntax is deprecated.

On Unix, the mysql client writes a record of executed statements to a history file. By default, the history file is named .mysql_history and is created in your home directory. To specify a different file, set the value of the MYSQL_HISTFILE environment variable.

If you do not want to maintain a history file, first remove .mysql_history if it exists, and then use either of the following techniques:

Set the MYSQL_HISTFILE variable to /dev/null. To cause this setting to take effect each time you log in, put the setting in one of your shell's startup files.
Create .mysql_history as a symbolic link to /dev/null:
```
shell> ln -s /dev/null $HOME/.mysql_history
```
You need do this only once.

8.7.2.聽mysql Commands

mysql sends each SQL statement that you issue to the server to be executed. There is also a set of commands that mysql itself interprets. For a list of these commands, type help or \h at the mysql> prompt:

mysql> help

MySQL commands:
?         (\?) Synonym for `help'.
clear     (\c) Clear command.
connect   (\r) Reconnect to the server. Optional arguments are db and host.
delimiter (\d) Set statement delimiter. NOTE: Takes the rest of the line as
               new delimiter.
edit      (\e) Edit command with $EDITOR.
ego       (\G) Send command to mysql server, display result vertically.
exit      (\q) Exit mysql. Same as quit.
go        (\g) Send command to mysql server.
help      (\h) Display this help.
nopager   (\n) Disable pager, print to stdout.
notee     (\t) Don't write into outfile.
pager     (\P) Set PAGER [to_pager]. Print the query results via PAGER.
print     (\p) Print current command.
prompt    (\R) Change your mysql prompt.
quit      (\q) Quit mysql.
rehash    (\#) Rebuild completion hash.
source    (\.) Execute an SQL script file. Takes a file name as an argument.
status    (\s) Get status information from the server.
system    (\!) Execute a system shell command.
tee       (\T) Set outfile [to_outfile]. Append everything into given
               outfile.
use       (\u) Use another database. Takes database name as argument.
charset   (\C) Switch to another charset. Might be needed for processing binlog with multi-byte charsets.
warnings  (\W) Show warnings after every statement.
nowarning (\w) Don't show warnings after every statement.

For server side help, type 'help contents'

Each command has both a long and short form. The long form is not case sensitive; the short form is. The long form can be followed by an optional semicolon terminator, but the short form should not.

If you provide an argument to the help command, mysql uses it as a search string to access server-side help from the contents of the MySQL Reference Manual. For more information, see Section聽8.7.3, 鈥�mysql Server-Side Help鈥�.

In the delimiter command, you should avoid the use of the backslash (鈥�\鈥�) character because that is the escape character for MySQL.

The edit, nopager, pager, and system commands work only in Unix.

The status command provides some information about the connection and the server you are using. If you are running in --safe-updates mode, status also prints the values for the mysql variables that affect your queries.

To log queries and their output, use the tee command. All the data displayed on the screen is appended into a given file. This can be very useful for debugging purposes also. You can enable this feature on the command line with the --tee option, or interactively with the tee command. The tee file can be disabled interactively with the notee command. Executing tee again re-enables logging. Without a parameter, the previous file is used. Note that tee flushes query results to the file after each statement, just before mysql prints its next prompt.

By using the --pager option, it is possible to browse or search query results in interactive mode with Unix programs such as less, more, or any other similar program. If you specify no value for the option, mysql checks the value of the PAGER environment variable and sets the pager to that. Output paging can be enabled interactively with the pager command and disabled with nopager. The command takes an optional argument; if given, the paging program is set to that. With no argument, the pager is set to the pager that was set on the command line, or stdout if no pager was specified.

Output paging works only in Unix because it uses the popen() function, which does not exist on Windows. For Windows, the tee option can be used instead to save query output, although this is not as convenient as pager for browsing output in some situations.

Here are a few tips about the pager command:

You can use it to write to a file and the results go only to the file:
```
mysql> pager cat > /tmp/log.txt
```
You can also pass any options for the program that you want to use as your pager:
```
mysql> pager less -n -i -S
```
In the preceding example, note the -S option. You may find it very useful for browsing wide query results. Sometimes a very wide result set is difficult to read on the screen. The -S option to less can make the result set much more readable because you can scroll it horizontally using the left-arrow and right-arrow keys. You can also use -S interactively within less to switch the horizontal-browse mode on and off. For more information, read the less manual page:
```
shell> man less
```
You can specify very complex pager commands for handling query output:
```
mysql> pager cat | tee /dr1/tmp/res.txt \
          | tee /dr2/tmp/res2.txt | less -n -i -S
```
In this example, the command would send query results to two files in two different directories on two different filesystems mounted on /dr1 and /dr2, yet still display the results onscreen via less.

You can also combine the tee and pager functions. Have a tee file enabled and pager set to less, and you are able to browse the results using the less program and still have everything appended into a file the same time. The difference between the Unix tee used with the pager command and the mysql built-in tee command is that the built-in tee works even if you do not have the Unix tee available. The built-in tee also logs everything that is printed on the screen, whereas the Unix tee used with pager does not log quite that much. Additionally, tee file logging can be turned on and off interactively from within mysql. This is useful when you want to log some queries to a file, but not others.

From MySQL 4.0.2 on, the default mysql> prompt can be reconfigured. The string for defining the prompt can contain the following special sequences:

Option	Description
`\v`	The server version
`\d`	The default database
`\h`	The server host
`\p`	The current TCP/IP port or socket file
`\u`	Your username
`\U`	Your full `user_name@host_name` account name
`\\`	A literal 鈥�`\`鈥� backslash character
`\n`	A newline character
`\t`	A tab character
`\聽`	A space (a space follows the backslash)
`\_`	A space
`\R`	The current time, in 24-hour military time (0-23)
`\r`	The current time, standard 12-hour time (1-12)
`\m`	Minutes of the current time
`\y`	The current year, two digits
`\Y`	The current year, four digits
`\D`	The full current date
`\s`	Seconds of the current time
`\w`	The current day of the week in three-letter format (Mon, Tue, 鈥�)
`\P`	am/pm
`\o`	The current month in numeric format
`\O`	The current month in three-letter format (Jan, Feb, 鈥�)
`\c`	A counter that increments for each statement you issue
`\S`	Semicolon
`\'`	Single quote
`\"`	Double quote

鈥�\鈥� followed by any other letter just becomes that letter.

If you specify the prompt command with no argument, mysql resets the prompt to the default of mysql>.

You can set the prompt in several ways:

Use an environment variable. You can set the MYSQL_PS1 environment variable to a prompt string. For example:
```
shell> export MYSQL_PS1="(\u@\h) [\d]> "
```
Use a command-line option. You can set the --prompt option on the command line to mysql. For example:
```
shell> mysql --prompt="(\u@\h) [\d]> "
(user@host) [database]>
```
Use an option file. You can set the prompt option in the [mysql] group of any MySQL option file, such as /etc/my.cnf or the .my.cnf file in your home directory. For example:
```
[mysql]
prompt=(\\u@\\h) [\\d]>\\_
```
In this example, note that the backslashes are doubled. If you set the prompt using the prompt option in an option file, it is advisable to double the backslashes when using the special prompt options. There is some overlap in the set of allowable prompt options and the set of special escape sequences that are recognized in option files. (These sequences are listed in Section聽4.3.2, 鈥淯sing Option Files鈥�.) The overlap may cause you problems if you use single backslashes. For example, \s is interpreted as a space rather than as the current seconds value. The following example shows how to define a prompt within an option file to include the current time in HH:MM:SS> format:
```
[mysql]
prompt="\\r:\\m:\\s> "
```

Set the prompt interactively. You can change your prompt interactively by using the prompt (or \R) command. For example:

mysql> prompt (\u@\h) [\d]>\_
PROMPT set to '(\u@\h) [\d]>\_'
(user@host) [database]>
(user@host) [database]> prompt
Returning to default PROMPT of mysql>
mysql>

8.7.3.聽mysql Server-Side Help

mysql> help search_string

As of MySQL 4.1, if you provide an argument to the help command, mysql uses it as a search string to access server-side help from the contents of the MySQL Reference Manual. The proper operation of this command requires that the help tables in the mysql database be initialized with help topic information (see Section聽5.2.8, 鈥淪erver-Side Help鈥�).

If there is no match for the search string, the search fails:

mysql> help me

Nothing found
Please try to run 'help contents' for a list of all accessible topics

Use help contents to see a list of the help categories:

mysql> help contents
You asked for help about help category: "Contents"
For more information, type 'help <item>', where <item> is one of the
following categories:
   Account Management
   Administration
   Data Definition
   Data Manipulation
   Data Types
   Functions
   Functions and Modifiers for Use with GROUP BY
   Geographic Features
   Language Structure
   Storage Engines
   Table Maintenance
   Transactions

If the search string matches multiple items, mysql shows a list of matching topics:

mysql> help logs
Many help items for your request exist.
To make a more specific request, please type 'help <item>',
where <item> is one of the following topics:
   SHOW
   SHOW BINARY LOGS
   SHOW ENGINE
   SHOW LOGS

Use a topic as the search string to see the help entry for that topic:

mysql> help show binary logs
Name: 'SHOW BINARY LOGS'
Description:
Syntax:
SHOW BINARY LOGS
SHOW MASTER LOGS

Lists the binary log files on the server. This statement is used as
part of the procedure described in [purge-master-logs], that shows how
to determine which logs can be purged.

mysql> SHOW BINARY LOGS;
+---------------+-----------+
| Log_name      | File_size |
+---------------+-----------+
| binlog.000015 |    724935 |
| binlog.000016 |    733481 |
+---------------+-----------+

8.7.4.聽Executing SQL Statements from a Text File

The mysql client typically is used interactively, like this:

shell> mysql db_name

However, it is also possible to put your SQL statements in a file and then tell mysql to read its input from that file. To do so, create a text file text_file that contains the statements you wish to execute. Then invoke mysql as shown here:

shell> mysql db_name < text_file

If you place a USE db_name statement as the first statement in the file, it is unnecessary to specify the database name on the command line:

shell> mysql < text_file

If you are already running mysql, you can execute an SQL script file using the source command or \. command:

mysql> source file_name
mysql> \. file_name

Sometimes you may want your script to display progress information to the user. For this you can insert statements like this:

SELECT '<info_to_display>' AS ' ';

The statement shown outputs <info_to_display>.

For more information about batch mode, see Section聽3.5, 鈥淯sing mysql in Batch Mode鈥�.

8.7.5.聽mysql Tips

8.7.5.1. Displaying Query Results Vertically
8.7.5.2. Using the --safe-updates Option
8.7.5.3. Disabling mysql Auto-Reconnect

This section describes some techniques that can help you use mysql more effectively.

8.7.5.1.聽Displaying Query Results Vertically

Some query results are much more readable when displayed vertically, instead of in the usual horizontal table format. Queries can be displayed vertically by terminating the query with \G instead of a semicolon. For example, longer text values that include newlines often are much easier to read with vertical output:

mysql> SELECT * FROM mails WHERE LENGTH(txt) < 300 LIMIT 300,1\G
*************************** 1. row ***************************
  msg_nro: 3068
     date: 2000-03-01 23:29:50
time_zone: +0200
mail_from: Monty
    reply: monty@no.spam.com
  mail_to: "Thimble Smith" <tim@no.spam.com>
      sbj: UTF-8
      txt: >>>>> "Thimble" == Thimble Smith writes:

Thimble> Hi.  I think this is a good idea.  Is anyone familiar
Thimble> with UTF-8 or Unicode? Otherwise, I'll put this on my
Thimble> TODO list and see what happens.

Yes, please do that.

Regards,
Monty
     file: inbox-jani-1
     hash: 190402944
1 row in set (0.09 sec)

8.7.5.2.聽Using the `--safe-updates` Option

For beginners, a useful startup option is --safe-updates (or --i-am-a-dummy, which has the same effect). This option was introduced in MySQL 3.23.11. It is helpful for cases when you might have issued a DELETE FROM tbl_name statement but forgotten the WHERE clause. Normally, such a statement deletes all rows from the table. With --safe-updates, you can delete rows only by specifying the key values that identify them. This helps prevent accidents.

When you use the --safe-updates option, mysql issues the following statement when it connects to the MySQL server:

SET SQL_SAFE_UPDATES=1,SQL_SELECT_LIMIT=1000, SQL_MAX_JOIN_SIZE=1000000;

See Section聽13.5.3, 鈥�SET Syntax鈥�.

The SET statement has the following effects:

You are not allowed to execute an UPDATE or DELETE statement unless you specify a key constraint in the WHERE clause or provide a LIMIT clause (or both). For example:
```
UPDATE tbl_name SET not_key_column=val WHERE key_column=val;

UPDATE tbl_name SET not_key_column=val LIMIT 1;
```
The server limits all large SELECT results to 1,000 rows unless the statement includes a LIMIT clause.
The server aborts multiple-table SELECT statements that probably need to examine more than 1,000,000 row combinations.

To specify limits different from 1,000 and 1,000,000, you can override the defaults by using the --select_limit and --max_join_size options:

shell> mysql --safe-updates --select_limit=500 --max_join_size=10000

8.7.5.3.聽Disabling mysql Auto-Reconnect

If the mysql client loses its connection to the server while sending a statement, it immediately and automatically tries to reconnect once to the server and send the statement again. However, even if mysql succeeds in reconnecting, your first connection has ended and all your previous session objects and settings are lost: temporary tables, the autocommit mode, and user-defined and session variables. Also, any current transaction rolls back. This behavior may be dangerous for you, as in the following example where the server was shut down and restarted between the first and second statements without you knowing it:

mysql> SET @a=1;
Query OK, 0 rows affected (0.05 sec)

mysql> INSERT INTO t VALUES(@a);
ERROR 2006: MySQL server has gone away
No connection. Trying to reconnect...
Connection id:    1
Current database: test

Query OK, 1 row affected (1.30 sec)

mysql> SELECT * FROM t;
+------+
| a    |
+------+
| NULL |
+------+
1 row in set (0.05 sec)

The @a user variable has been lost with the connection, and after the reconnection it is undefined. If it is important to have mysql terminate with an error if the connection has been lost, you can start the mysql client with the --skip-reconnect option.

For more information about auto-reconnect and its effect on state information when a reconnection occurs, see Section聽17.2.13, 鈥淐ontrolling Automatic Reconnect Behavior鈥�.

8.8.聽mysqlaccess 鈥� Client for Checking Access Privileges

mysqlaccess is a diagnostic tool that Yves Carlier has provided for the MySQL distribution. It checks the access privileges for a hostname, username, and database combination. Note that mysqlaccess checks access using only the user, db, and host tables. It does not check table, column, or routine privileges specified in the tables_priv, columns_priv, or procs_priv tables.

Invoke mysqlaccess like this:

shell> mysqlaccess [host_name [user_name [db_name]]] [options]

mysqlaccess understands the following options:

--help, -?
Display a help message and exit.
--brief, -b
Generate reports in single-line tabular format.
--commit
Copy the new access privileges from the temporary tables to the original grant tables. The grant tables must be flushed for the new privileges to take effect. (For example, execute a mysqladmin reload command.)
--copy
Reload the temporary grant tables from original ones.
--db=db_name, -d db_name
Specify the database name.
--debug=N
Specify the debug level. N can be an integer from 0 to 3.
--host=host_name, -h host_name
The hostname to use in the access privileges.
--howto
Display some examples that show how to use mysqlaccess.
--old_server
Assume that the server is an old MySQL server (before MySQL 3.21) that does not yet know how to handle full WHERE clauses.
--password[=password], -p[password]
The password to use when connecting to the server. If you omit the password value following the --password or -p option on the command line, you are prompted for one.
Specifying a password on the command line should be considered insecure. See Section聽5.8.6, 鈥淜eeping Your Password Secure鈥�.
--plan
Display suggestions and ideas for future releases.
--preview
Show the privilege differences after making changes to the temporary grant tables.
--relnotes
Display the release notes.
--rhost=host_name, -H host_name
Connect to the MySQL server on the given host.
--rollback
Undo the most recent changes to the temporary grant tables.
--spassword[=password], -P[password]
The password to use when connecting to the server as the superuser. If you omit the password value following the --password or -p option on the command line, you are prompted for one.
Specifying a password on the command line should be considered insecure. See Section聽5.8.6, 鈥淜eeping Your Password Secure鈥�.
--superuser=user_name, -U user_name
Specify the username for connecting as the superuser.
--table, -t
Generate reports in table format.
--user=user_name, -u user_name
The username to use in the access privileges.
--version, -v
Display version information and exit.

If your MySQL distribution is installed in some non-standard location, you must change the location where mysqlaccess expects to find the mysql client. Edit the mysqlaccess script at approximately line 18. Search for a line that looks like this:

$MYSQL     = '/usr/local/bin/mysql';    # path to mysql executable

Change the path to reflect the location where mysql actually is stored on your system. If you do not do this, a Broken pipe error will occur when you run mysqlaccess.

8.9.聽mysqladmin 鈥� Client for Administering a MySQL Server

mysqladmin is a client for performing administrative operations. You can use it to check the server's configuration and current status, to create and drop databases, and more.

Invoke mysqladmin like this:

shell> mysqladmin [options] command [command-arg] [command [command-arg]] ...

mysqladmin supports the commands described in the following list. Some of the commands take an argument following the command name.

create db_name
Create a new database named db_name.
debug
Tell the server to write debug information to the error log.
drop db_name
Delete the database named db_name and all its tables.
extended-status
Display the server status variables and their values.
MySQL Enterprise For expert advice on using server system variables, subscribe to the MySQL Network Monitoring and Advisory. For more information see http://www.mysql.com/products/enterprise/advisors.html.
flush-hosts
Flush all information in the host cache.
flush-logs
Flush all logs.
flush-privileges
Reload the grant tables (same as reload).
flush-status
Clear status variables.
flush-tables
Flush all tables.
flush-threads
Flush the thread cache. (Added in MySQL 3.23.16.)
kill id,id,...
Kill server threads. If multiple thread ID values are given, there must be no spaces in the list.
old-password new-password
This is like the password command but stores the password using the old (pre-4.1) password-hashing format. This command was added in MySQL 4.1.0. (See Section聽5.7.9, 鈥淧assword Hashing as of MySQL 4.1鈥�.)
MySQL Enterprise For expert advice on the security implications of using the old-password command, subscribe to the MySQL Network Monitoring and Advisory. For more information see http://www.mysql.com/products/enterprise/advisors.html.
password new-password
Set a new password. This changes the password to new-password for the account that you use with mysqladmin for connecting to the server. Thus, the next time you invoke mysqladmin (or any other client program) using the same account, you will need to specify the new password.
If the new-password value contains spaces or other characters that are special to your command interpreter, you need to enclose it within quotes. On Windows, be sure to use double quotes rather than single quotes; single quotes are not stripped from the password, but rather are interpreted as part of the password. For example:
```
shell> mysqladmin password "my new password"
```
ping
Check whether the server is alive. The return status from mysqladmin is 0 if the server is running, 1 if it is not. Beginning with MySQL 4.0.22, the status is 0 even in case of an error such as Access denied, because that means the server is running but refused the connection, which is different from the server not running.
processlist
Show a list of active server threads. This is like the output of the SHOW PROCESSLIST statement. If the --verbose option is given, the output is like that of SHOW FULL PROCESSLIST.
reload
Reload the grant tables.
refresh
Flush all tables and close and open log files.
shutdown
Stop the server.
start-slave
Start replication on a slave server. (Added in MySQL 3.23.16.)
status
Display a short server status message.
stop-slave
Stop replication on a slave server. (Added in MySQL 3.23.16.)
variables
Display the server system variables and their values.
MySQL Enterprise For expert advice on using server system variables, subscribe to the MySQL Network Monitoring and Advisory. For more information see http://www.mysql.com/products/enterprise/advisors.html.
version
Display version information from the server.

All commands can be shortened to any unique prefix. For example:

shell> mysqladmin proc stat
+----+-------+-----------+----+---------+------+-------+------------------+
| Id | User  | Host      | db | Command | Time | State | Info             |
+----+-------+-----------+----+---------+------+-------+------------------+
| 51 | monty | localhost |    | Query   | 0    |       | show processlist |
+----+-------+-----------+----+---------+------+-------+------------------+
Uptime: 1473624  Threads: 1  Questions: 39487  
Slow queries: 0  Opens: 541  Flush tables: 1  
Open tables: 19  Queries per second avg: 0.0268

The mysqladmin status command result displays the following values:

Uptime
The number of seconds the MySQL server has been running.
Threads
The number of active threads (clients).
Questions
The number of questions (queries) from clients since the server was started.
Slow queries
The number of queries that have taken more than long_query_time seconds. See Section聽5.11.5, 鈥淭he Slow Query Log鈥�.
Opens
The number of tables the server has opened.
Flush tables
The number of flush-*, refresh, and reload commands the server has executed.
Open tables
The number of tables that currently are open.
Memory in use
The amount of memory allocated directly by mysqld. This value is displayed only when MySQL has been compiled with --with-debug=full.
Maximum memory used
The maximum amount of memory allocated directly by mysqld. This value is displayed only when MySQL has been compiled with --with-debug=full.

If you execute mysqladmin shutdown when connecting to a local server using a Unix socket file, mysqladmin waits until the server's process ID file has been removed, to ensure that the server has stopped properly.

mysqladmin supports the following options:

--help, -?
Display a help message and exit.
--character-sets-dir=path
The directory where character sets are installed. See Section聽5.10.1, 鈥淭he Character Set Used for Data and Sorting鈥�.
--compress, -C
Compress all information sent between the client and the server if both support compression.
--count=N, -c N
The number of iterations to make for repeated command execution. This works only with the --sleep option.
--debug[=debug_options], -# [debug_options]
Write a debugging log. The debug_options string often is 'd:t:o,file_name'. The default is 'd:t:o,/tmp/mysqladmin.trace'.
--default-character-set=charset_name
Use charset_name as the default character set. See Section聽5.10.1, 鈥淭he Character Set Used for Data and Sorting鈥�. Added in MySQL 4.1.9.
--force, -f
Do not ask for confirmation for the drop db_name command. With multiple commands, continue even if an error occurs.
--host=host_name, -h host_name
Connect to the MySQL server on the given host.
--password[=password], -p[password]
The password to use when connecting to the server. If you use the short option form (-p), you cannot have a space between the option and the password. If you omit the password value following the --password or -p option on the command line, you are prompted for one.
Specifying a password on the command line should be considered insecure. See Section聽5.8.6, 鈥淜eeping Your Password Secure鈥�.
--port=port_num, -P port_num
The TCP/IP port number to use for the connection.
--protocol={TCP|SOCKET|PIPE|MEMORY}
The connection protocol to use. Added in MySQL 4.1.
--relative, -r
Show the difference between the current and previous values when used with the --sleep option. Currently, this option works only with the extended-status command.
--silent, -s
Exit silently if a connection to the server cannot be established.
--sleep=delay, -i delay
Execute commands repeatedly, sleeping for delay seconds in between. The --count option determines the number of iterations.
--socket=path, -S path
For connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.
--ssl*
Options that begin with --ssl specify whether to connect to the server via SSL and indicate where to find SSL keys and certificates. See Section聽5.8.7.3, 鈥淪SL Command Options鈥�.
--user=user_name, -u user_name
The MySQL username to use when connecting to the server.
--verbose, -v
Verbose mode. Print more information about what the program does.
--version, -V
Display version information and exit.
--vertical, -E
Print output vertically. This is similar to --relative, but prints output vertically.
--wait[=count], -w[count]
If the connection cannot be established, wait and retry instead of aborting. If a count value is given, it indicates the number of times to retry. The default is one time.

You can also set the following variables by using --var_name=value syntax:

connect_timeout
The maximum number of seconds before connection timeout. The default value is 43200 (12 hours).
shutdown_timeout
The maximum number of seconds to wait for server shutdown. The default value is 3600 (1 hour).

It is also possible to set variables by using --set-variable=var_name=value or -O var_name=value syntax. However, this syntax is deprecated as of MySQL 4.0.

8.10.聽mysqlbinlog 鈥� Utility for Processing Binary Log Files

The binary log files that the server generates are written in binary format. To examine these files in text format, use the mysqlbinlog utility. It is available as of MySQL 3.23.14. You can also use mysqlbinlog to read relay log files written by a slave server in a replication setup. Relay logs have the same format as binary log files.

Invoke mysqlbinlog like this:

shell> mysqlbinlog [options] log_file ...

For example, to display the contents of the binary log file named binlog.000003, use this command:

shell> mysqlbinlog binlog.0000003

The output includes all events contained in binlog.000003. Event information includes the statement executed, the time the statement took, the thread ID of the client that issued it, the timestamp when it was executed, and so forth.

The output from mysqlbinlog can be re-executed (for example, by using it as input to mysql) to reapply the statements in the log. This is useful for recovery operations after a server crash. For other usage examples, see the discussion later in this section.

Normally, you use mysqlbinlog to read binary log files directly and apply them to the local MySQL server. It is also possible to read binary logs from a remote server by using the --read-from-remote-server option. When you read remote binary logs, the connection parameter options can be given to indicate how to connect to the server. These options are --host, --password, --port, --protocol, --socket, and --user; they are ignored except when you also use the --read-from-remote-server option.

Binary logs and relay logs are discussed further in Section聽5.11.4, 鈥淭he Binary Log鈥�, and Section聽6.3.4, 鈥淩eplication Relay and Status Files鈥�.

mysqlbinlog supports the following options:

--help, -?
Display a help message and exit.
--character-sets-dir=path
The directory where character sets are installed. See Section聽5.10.1, 鈥淭he Character Set Used for Data and Sorting鈥�.
--database=db_name, -d db_name
List entries for just this database (local log only). You can only specify one database with this option - if you specify multiple --database options, only the last one is used. This option forces mysqlbinlog to output entries from the binary log where the default database (that is, the one selected by USE) is db_name. Note that this does not replicate cross-database statements such as UPDATE some_db.some_table SET foo='bar' while having selected a different database or no database.
--debug[=debug_options], -# [debug_options]
Write a debugging log. A typical debug_options string is often 'd:t:o,file_name'.
--disable-log-bin, -D
Disable binary logging. This is useful for avoiding an endless loop if you use the --to-last-log option and are sending the output to the same MySQL server. This option also is useful when restoring after a crash to avoid duplication of the statements you have logged. This option is available as of MySQL 4.1.8.
This option requires that you have the SUPER privilege. It causes mysqlbinlog to include a SET SQL_LOG_BIN=0 statement in its output to disable binary logging of the remaining output. The SET statement is ineffective unless you have the SUPER privilege.
--force-read, -f
With this option, if mysqlbinlog reads a binary log event that it does not recognize, it prints a warning, ignores the event, and continues. Without this option, mysqlbinlog stops if it reads such an event.
--host=host_name, -h host_name
Get the binary log from the MySQL server on the given host.
--local-load=path, -l path
Prepare local temporary files for LOAD DATA INFILE in the specified directory.
--offset=N, -o N
Skip the first N entries in the log.
--password[=password], -p[password]
The password to use when connecting to the server. If you use the short option form (-p), you cannot have a space between the option and the password. If you omit the password value following the --password or -p option on the command line, you are prompted for one.
Specifying a password on the command line should be considered insecure. See Section聽5.8.6, 鈥淜eeping Your Password Secure鈥�.
--port=port_num, -P port_num
The TCP/IP port number to use for connecting to a remote server.
--position=N, -j N
Deprecated. Use --start-position instead (starting from MySQL 4.1.4).
--protocol={TCP|SOCKET|PIPE|MEMORY}
The connection protocol to use. Added in MySQL 4.1.
--read-from-remote-server, -R
Read the binary log from a MySQL server rather than reading a local log file. Any connection parameter options are ignored unless this option is given as well. These options are --host, --password, --port, --protocol, --socket, and --user.
--result-file=name, -r name
Direct output to the given file.
--set-charset=charset_name
Add a SET NAMES charset_name statement to the output to specify the character set to be used for processing log files. This option was added in MySQL 4.1.21.
--short-form, -s
Display only the statements contained in the log, without any extra information.
--socket=path, -S path
For connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.
--start-datetime=datetime
Start reading the binary log at the first event having a timestamp equal to or later than the datetime argument. The datetime value is relative to the local time zone on the machine where you run mysqlbinlog. The value should be in a format accepted for the DATETIME or TIMESTAMP data types. For example:
```
shell> mysqlbinlog --start-datetime="2005-12-25 11:25:56" binlog.000003
```
This option is available as of MySQL 4.1.4. It is useful for point-in-time recovery. See Section聽5.9.2, 鈥淓xample Backup and Recovery Strategy鈥�.
--stop-datetime=datetime
Stop reading the binary log at the first event having a timestamp equal or posterior to the datetime argument. This option is useful for point-in-time recovery. See the description of the --start-datetime option for information about the datetime value. This option is available as of MySQL 4.1.4.
--start-position=N
Start reading the binary log at the first event having a position equal to the N argument. This option applies to the first log file named on the command line. Available as of MySQL 4.1.4 (previously named --position).
--stop-position=N
Stop reading the binary log at the first event having a position equal or greater than the N argument. This option applies to the last log file named on the command line. Available as of MySQL 4.1.4.
--to-last-log, -t
Do not stop at the end of the requested binary log from a MySQL server, but rather continue printing until the end of the last binary log. If you send the output to the same MySQL server, this may lead to an endless loop. This option requires --read-from-remote-server. Available as of MySQL 4.1.2.
--user=user_name, -u user_name
The MySQL username to use when connecting to a remote server.
--version, -V
Display version information and exit.

You can also set the following variable by using --var_name=value syntax:

open_files_limit
Specify the number of open file descriptors to reserve.

It is also possible to set variables by using --set-variable=var_name=value or -O var_name=value syntax. This syntax is deprecated.

You can pipe the output of mysqlbinlog into the mysql client to execute the statements contained in the binary log. This is used to recover from a crash when you have an old backup (see Section聽5.9.1, 鈥淒atabase Backups鈥�). For example:

shell> mysqlbinlog binlog.000001 | mysql

Or:

shell> mysqlbinlog binlog.[0-9]* | mysql

You can also redirect the output of mysqlbinlog to a text file instead, if you need to modify the statement log first (for example, to remove statements that you do not want to execute for some reason). After editing the file, execute the statements that it contains by using it as input to the mysql program.

mysqlbinlog has the --start-position option, which prints only those statements with an offset in the binary log greater than or equal to a given position (the given position must match the start of one event). It also has options to stop and start when it sees an event with a given date and time. This enables you to perform point-in-time recovery using the --stop-datetime option (to be able to say, for example, 鈥�roll forward my databases to how they were today at 10:30 a.m.鈥�).

If you have more than one binary log to execute on the MySQL server, the safe method is to process them all using a single connection to the server. Here is an example that demonstrates what may be unsafe:

shell> mysqlbinlog binlog.000001 | mysql # DANGER!!
shell> mysqlbinlog binlog.000002 | mysql # DANGER!!

Processing binary logs this way using different connections to the server causes problems if the first log file contains a CREATE TEMPORARY TABLE statement and the second log contains a statement that uses the temporary table. When the first mysql process terminates, the server drops the temporary table. When the second mysql process attempts to use the table, the server reports 鈥�unknown table.鈥�

To avoid problems like this, use a single connection to execute the contents of all binary logs that you want to process. Here is one way to do so:

shell> mysqlbinlog binlog.000001 binlog.000002 | mysql

Another approach is to write all the logs to a single file and then process the file:

shell> mysqlbinlog binlog.000001 >  /tmp/statements.sql
shell> mysqlbinlog binlog.000002 >> /tmp/statements.sql
shell> mysql -e "source /tmp/statements.sql"

In MySQL 3.23, the binary log did not contain the data to load for LOAD DATA INFILE statements. To execute such a statement from a binary log file, the original data file was needed. Starting from MySQL 4.0.14, the binary log does contain the data, so mysqlbinlog can produce output that reproduces the LOAD DATA INFILE operation without the original data file. mysqlbinlog copies the data to a temporary file and writes a LOAD DATA LOCAL INFILE statement that refers to the file. The default location of the directory where these files are written is system-specific. To specify a directory explicitly, use the --local-load option.

Because mysqlbinlog converts LOAD DATA INFILE statements to LOAD DATA LOCAL INFILE statements (that is, it adds LOCAL), both the client and the server that you use to process the statements must be configured to allow LOCAL capability. See Section聽5.6.4, 鈥淪ecurity Issues with LOAD DATA LOCAL鈥�.

MySQL Enterprise For expert advice on the security implications of enabling LOCAL, subscribe to the MySQL Network Monitoring and Advisory. For more information see http://www.mysql.com/products/enterprise/advisors.html.

Warning: The temporary files created for LOAD DATA LOCAL statements are not automatically deleted because they are needed until you actually execute those statements. You should delete the temporary files yourself after you no longer need the statement log. The files can be found in the temporary file directory and have names like original_file_name-#-#.

Before MySQL 4.1, mysqlbinlog could not prepare output suitable for mysql if the binary log contained interlaced statements originating from different clients that used temporary tables of the same name. This is fixed in MySQL 4.1. However, the problem still existed for LOAD DATA INFILE statements until it was fixed in MySQL 4.1.8.

8.11.聽mysqlcheck 鈥� A Table Maintenance and Repair Program

The mysqlcheck client checks, repairs, optimizes, and analyzes tables. mysqlcheck is available as of MySQL 3.23.38.

mysqlcheck is similar in function to myisamchk, but works differently. The main operational difference is that mysqlcheck must be used when the mysqld server is running, whereas myisamchk should be used when it is not. The benefit of using mysqlcheck is that you do not have to stop the server to check or repair your tables.

mysqlcheck uses the SQL statements CHECK TABLE, REPAIR TABLE, ANALYZE TABLE, and OPTIMIZE TABLE in a convenient way for the user. It determines which statements to use for the operation you want to perform, and then sends the statements to the server to be executed. For details about which storage engines each statement works with, see the descriptions for those statements in Chapter聽13, SQL Statement Syntax.

The MyISAM storage engine supports all four statements, so mysqlcheck can be used to perform all four operations on MyISAM tables. Other storage engines do not necessarily support all operations. In such cases, an error message is displayed. For example, if test.t is a MEMORY table, an attempt to check it produces this result:

shell> mysqlcheck test t
test.t
note     : The storage engine for the table doesn't support check

Caution

It is best to make a backup of a table before performing a table repair operation; under some circumstances the operation might cause data loss. Possible causes include but are not limited to filesystem errors.

There are three general ways to invoke mysqlcheck:

shell> mysqlcheck [options] db_name [tables]
shell> mysqlcheck [options] --databases db_name1 [db_name2 db_name3...]
shell> mysqlcheck [options] --all-databases

If you do not name any tables following db_name or if you use the --databases or --all-databases option, entire databases are checked.

mysqlcheck has a special feature compared to other client programs. The default behavior of checking tables (--check) can be changed by renaming the binary. If you want to have a tool that repairs tables by default, you should just make a copy of mysqlcheck named mysqlrepair, or make a symbolic link to mysqlcheck named mysqlrepair. If you invoke mysqlrepair, it repairs tables.

The following names can be used to change mysqlcheck default behavior:

mysqlrepair	The default option is `--repair`
mysqlanalyze	The default option is `--analyze`
mysqloptimize	The default option is `--optimize`

mysqlcheck supports the following options:

--help, -?
Display a help message and exit.
--all-databases, -A
Check all tables in all databases. This is the same as using the --databases option and naming all the databases on the command line.
--all-in-1, -1
Instead of issuing a statement for each table, execute a single statement for each database that names all the tables from that database to be processed.
--analyze, -a
Analyze the tables.
MySQL Enterprise For expert advice on optimizing tables, subscribe to the MySQL Network Monitoring and Advisory. For more information see http://www.mysql.com/products/enterprise/advisors.html.
--auto-repair
If a checked table is corrupted, automatically fix it. Any necessary repairs are done after all tables have been checked.
--character-sets-dir=path
The directory where character sets are installed. See Section聽5.10.1, 鈥淭he Character Set Used for Data and Sorting鈥�.
--check, -c
Check the tables for errors. This is the default operation.
--check-only-changed, -C
Check only tables that have changed since the last check or that have not been closed properly.
--compress
Compress all information sent between the client and the server if both support compression.
--databases, -B
Process all tables in the named databases. Normally, mysqlcheck treats the first name argument on the command line as a database name and following names as table names. With this option, it treats all name arguments as database names.
--debug[=debug_options], -# [debug_options]
Write a debugging log. A typical debug_options string is often 'd:t:o,file_name'.
--default-character-set=charset_name
Use charset_name as the default character set. See Section聽5.10.1, 鈥淭he Character Set Used for Data and Sorting鈥�.
--extended, -e
If you are using this option to check tables, it ensures that they are 100% consistent but takes a long time.
If you are using this option to repair tables, it runs an extended repair that may not only take a long time to execute, but may produce a lot of garbage rows also!
--fast, -F
Check only tables that have not been closed properly.
--force, -f
Continue even if an SQL error occurs.
--host=host_name, -h host_name
Connect to the MySQL server on the given host.
--medium-check, -m
Do a check that is faster than an --extended operation. This finds only 99.99% of all errors, which should be good enough in most cases.
--optimize, -o
Optimize the tables.
--password[=password], -p[password]
The password to use when connecting to the server. If you use the short option form (-p), you cannot have a space between the option and the password. If you omit the password value following the --password or -p option on the command line, you are prompted for one.
Specifying a password on the command line should be considered insecure. See Section聽5.8.6, 鈥淜eeping Your Password Secure鈥�.
--port=port_num, -P port_num
The TCP/IP port number to use for the connection.
--protocol={TCP|SOCKET|PIPE|MEMORY}
The connection protocol to use. This option was added in MySQL 4.1.
--quick, -q
If you are using this option to check tables, it prevents the check from scanning the rows to check for incorrect links. This is the fastest check method.
If you are using this option to repair tables, it tries to repair only the index tree. This is the fastest repair method.
--repair, -r
Perform a repair that can fix almost anything except unique keys that are not unique.
--silent, -s
Silent mode. Print only error messages.
--socket=path, -S path
For connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.
--ssl*
Options that begin with --ssl specify whether to connect to the server via SSL and indicate where to find SSL keys and certificates. See Section聽5.8.7.3, 鈥淪SL Command Options鈥�.
--tables
Overrides the --databases or -B option. All name arguments following the option are regarded as table names.
--use-frm
For repair operations on MyISAM tables, get the table structure from the .frm file so that the table can be repaired even if the .MYI header is corrupted. This option was added in MySQL 4.0.5.
--user=user_name, -u user_name
The MySQL username to use when connecting to the server.
--verbose, -v
Verbose mode. Print information about the various stages of program operation.
--version, -V
Display version information and exit.

8.12.聽mysqldump 鈥� A Database Backup Program

The mysqldump client is a backup program originally written by Igor Romanenko. It can be used to dump a database or a collection of databases for backup or transfer to another SQL server (not necessarily a MySQL server). The dump typically contains SQL statements to create the table, populate it, or both. However, mysqldump can also be used to generate files in CSV, other delimited text, or XML format.

If you are doing a backup on the server and your tables all are MyISAM tables, consider using the mysqlhotcopy instead because it can accomplish faster backups and faster restores. See Section聽8.13, 鈥�mysqlhotcopy 鈥� A Database Backup Program鈥�.

There are three general ways to invoke mysqldump:

shell> mysqldump [options] db_name [tables]
shell> mysqldump [options] --databases db_name1 [db_name2 db_name3...]
shell> mysqldump [options] --all-databases

If you do not name any tables following db_name or if you use the --databases or --all-databases option, entire databases are dumped.

To get a list of the options your version of mysqldump supports, execute mysqldump --help.

Some mysqldump options are shorthand for groups of other options. --opt and --compact fall into this category. For example, use of --opt is the same as specifying --add-drop-table --add-locks --create-options --disable-keys --extended-insert --lock-tables --quick --set-charset. Note that as of MySQL 4.1, all of the options that --opt stands for also are on by default because --opt is on by default.

To reverse the effect of a group option, uses its --skip-xxx form (--skip-opt or --skip-compact). It is also possible to select only part of the effect of a group option by following it with options that enable or disable specific features. Here are some examples:

To select the effect of --opt except for some features, use the --skip option for each feature. For example, to disable extended inserts and memory buffering, use --opt --skip-extended-insert --skip-quick. (As of MySQL 4.1, --skip-extended-insert --skip-quick is sufficient because --opt is on by default.)
To reverse --opt for all features except index disabling and table locking, use --skip-opt --disable-keys --lock-tables.

When you selectively enable or disable the effect of a group option, order is important because options are processed first to last. For example, --disable-keys --lock-tables --skip-opt would not have the intended effect; it is the same as --skip-opt by itself.

mysqldump can retrieve and dump table contents row by row, or it can retrieve the entire content from a table and buffer it in memory before dumping it. Buffering in memory can be a problem if you are dumping large tables. To dump tables row by row, use the --quick option (or --opt, which enables --quick). --opt (and hence --quick) is enabled by default as of MySQL 4.1 to enable memory buffering, use --skip-quick.

If you are using a recent version of mysqldump to generate a dump to be reloaded into a very old MySQL server, you should not use the --opt or --extended-insert option. Use --skip-opt instead.

Before MySQL 4.1.2, out-of-range numeric values such as -inf and inf, as well as NaN (not-a-number) values are dumped by mysqldump as NULL. You can see this using the following sample table:

mysql> CREATE TABLE t (f DOUBLE);
mysql> INSERT INTO t VALUES(1e+111111111111111111111);
mysql> INSERT INTO t VALUES(-1e111111111111111111111);
mysql> SELECT f FROM t;
+------+
| f    |
+------+
|  inf |
| -inf |
+------+

For this table, mysqldump produces the following data output:

--
-- Dumping data for table `t`
--

INSERT INTO t VALUES (NULL);
INSERT INTO t VALUES (NULL);

The significance of this behavior is that if you dump and restore the table, the new table has contents that differ from the original contents. This problem is fixed as of MySQL 4.1.2; you cannot insert inf in the table, so this mysqldump behavior is only relevant when you deal with old servers.

mysqldump supports the following options:

--help, -?
Display a help message and exit.
--add-drop-database
Add a DROP DATABASE statement before each CREATE DATABASE statement. Added in MySQL 4.1.13.
--add-drop-table
Add a DROP TABLE statement before each CREATE TABLE statement.
--add-locks
Surround each table dump with LOCK TABLES and UNLOCK TABLES statements. This results in faster inserts when the dump file is reloaded. See Section聽7.2.13, 鈥淪peed of INSERT Statements鈥�.
--all-databases, -A
Dump all tables in all databases. This is the same as using the --databases option and naming all the databases on the command line.
--allow-keywords
Allow creation of column names that are keywords. This works by prefixing each column name with the table name.
--character-sets-dir=path
The directory where character sets are installed. See Section聽5.10.1, 鈥淭he Character Set Used for Data and Sorting鈥�.
--comments, -i
Write additional information in the dump file such as program version, server version, and host. This option is enabled by default. To suppress this additional information, use --skip-comments. This option was added in MySQL 4.0.17.
--compact
Produce less verbose output. This option suppresses comments and enables the --skip-add-drop-table, --skip-set-charset, --skip-disable-keys, and --skip-add-locks options. Added in MySQL 4.1.2.
--compatible=name
Produce output that is more compatible with other database systems or with older MySQL servers. The value of name can be ansi, mysql323, mysql40, postgresql, oracle, mssql, db2, maxdb, no_key_options, no_table_options, or no_field_options. To use several values, separate them by commas. These values have the same meaning as the corresponding options for setting the server SQL mode. See Section聽5.2.6, 鈥淪QL Modes鈥�.
This option does not guarantee compatibility with other servers. It only enables those SQL mode values that are currently available for making dump output more compatible. For example, --compatible=oracle does not map data types to Oracle types or use Oracle comment syntax.
This option requires a server version of 4.1.0 or higher. With older servers, it does nothing.
--complete-insert, -c
Use complete INSERT statements that include column names.
--compress, -C
Compress all information sent between the client and the server if both support compression.
--create-options
Include all MySQL-specific table options in the CREATE TABLE statements. Before MySQL 4.1.2, use --all instead.
--databases, -B
Dump several databases. Normally, mysqldump treats the first name argument on the command line as a database name and following names as table names. With this option, it treats all name arguments as database names. CREATE DATABASE and USE statements are included in the output before each new database.
--debug[=debug_options], -# [debug_options]
Write a debugging log. The debug_options string is often 'd:t:o,file_name'. The default value is 'd:t:o,/tmp/mysqldump.trace'.
--default-character-set=charset_name
Use charset_name as the default character set. See Section聽5.10.1, 鈥淭he Character Set Used for Data and Sorting鈥�. If no character set is specified, mysqldump from MySQL 4.1.2 or later uses utf8, and earlier versions use latin1.
--delayed-insert
Write INSERT DELAYED statements rather than INSERT statements.
--delete-master-logs
On a master replication server, delete the binary logs after performing the dump operation. This option automatically enables --first-slave before MySQL 4.1.8 and enables --master-data thereafter. It was added in MySQL 3.23.57 (for MySQL 3.23) and MySQL 4.0.13 (for MySQL 4.0).
--disable-keys, -K
For each table, surround the INSERT statements with /*!40000 ALTER TABLE tbl_name DISABLE KEYS */; and /*!40000 ALTER TABLE tbl_name ENABLE KEYS */; statements. This makes loading the dump file into a MySQL 4.0 or newer server faster because the indexes are created after all rows are inserted. This option is effective only for non-unique indexes of MyISAM tables. only.
--extended-insert, -e
Use multiple-row INSERT syntax that include several VALUES lists. This results in a smaller dump file and speeds up inserts when the file is reloaded.
--fields-terminated-by=..., --fields-enclosed-by=..., --fields-optionally-enclosed-by=..., --fields-escaped-by=...
These options are used with the -T option and have the same meaning as the corresponding clauses for LOAD DATA INFILE. See Section聽13.2.5, 鈥�LOAD DATA INFILE Syntax鈥�.
--first-slave, -x
Deprecated. Renamed to --lock-all-tables in MySQL 4.1.8.
--flush-logs, -F
Flush the MySQL server log files before starting the dump. This option requires the RELOAD privilege. Note that if you use this option in combination with the --all-databases (or -A) option, the logs are flushed for each database dumped. The exception is when using --lock-all-tables or --master-data: In this case, the logs are flushed only once, corresponding to the moment that all tables are locked. If you want your dump and the log flush to happen at exactly the same moment, you should use --flush-logs together with either --lock-all-tables or --master-data.
--force, -f
Continue even if an SQL error occurs during a table dump.
--host=host_name, -h host_name
Dump data from the MySQL server on the given host. The default host is localhost.
--hex-blob
Dump binary columns using hexadecimal notation (for example, 'abc' becomes 0x616263). The affected data types are BINARY, VARBINARY, and BLOB in MySQL 4.1 and up, and CHAR BINARY, VARCHAR BINARY, and BLOB in MySQL 4.0. This option was added in MySQL 4.0.23 and 4.1.8.
--ignore-table=db_name.tbl_name
Do not dump the given table, which must be specified using both the database and table names. To ignore multiple tables, use this option multiple times. This option was added in MySQL 4.1.9.
--insert-ignore
Write INSERT statements with the IGNORE option. This option was added in MySQL 4.1.12.
--lines-terminated-by=...
This option is used with the -T option and has the same meaning as the corresponding clause for LOAD DATA INFILE. See Section聽13.2.5, 鈥�LOAD DATA INFILE Syntax鈥�.
--lock-all-tables, -x
Lock all tables across all databases. This is achieved by acquiring a global read lock for the duration of the whole dump. This option automatically turns off --single-transaction and --lock-tables. Added in MySQL 4.1.8.
--lock-tables, -l
Lock all tables before dumping them. The tables are locked with READ LOCAL to allow concurrent inserts in the case of MyISAM tables. For transactional tables such as InnoDB and BDB, --single-transaction is a much better option, because it does not need to lock the tables at all.
Please note that when dumping multiple databases, --lock-tables locks tables for each database separately. Therefore, this option does not guarantee that the tables in the dump file are logically consistent between databases. Tables in different databases may be dumped in completely different states.
--master-data[=value]
Write the binary log filename and position to the output. This option requires the RELOAD privilege and the binary log must be enabled. If the option value is equal to 1, the position and filename are written to the dump output in the form of a CHANGE MASTER statement. If the dump is from a master server and you use it to set up a slave server, the CHANGE MASTER statement causes the slave to start from the correct position in the master's binary logs. If the option value is equal to 2, the CHANGE MASTER statement is written as an SQL comment. (This is the default action if value is omitted.) value may be given as of MySQL 4.1.8; before that, do not specify an option value.
The --master-data option automatically turns off --lock-tables. It also turns on --lock-all-tables, unless --single-transaction also is specified (in which case, a global read lock is acquired only for a short time at the beginning of the dump. See also the description for --single-transaction. In all cases, any action on logs happens at the exact moment of the dump.
--no-autocommit
Enclose the INSERT statements for each dumped table within SET AUTOCOMMIT=0 and COMMIT statements.
--no-create-db, -n
This option suppresses the CREATE DATABASE statements that are otherwise included in the output if the --databases or --all-databases option is given.
--no-create-info, -t
Do not write CREATE TABLE statements that re-create each dumped table.
--no-data, -d
Do not write any table row information (that is, do not dump table contents). This is very useful if you want to dump only the CREATE TABLE statement for the table.
--opt
This option is shorthand; it is the same as specifying --add-drop-table --add-locks --create-options --disable-keys --extended-insert --lock-tables --quick --set-charset. It should give you a fast dump operation and produce a dump file that can be reloaded into a MySQL server quickly.
As of MySQL 4.1, --opt is enabled by default. Use --skip-opt to disable it. See the discussion at the beginning of this section for information about selectively enabling or disabling certain of the options affected by --opt.
--order-by-primary
Sorts each table's rows by its primary key, or by its first unique index, if such an index exists. This is useful when dumping a MyISAM table to be loaded into an InnoDB table, but will make the dump itself take considerably longer. This option was added in MySQL 4.1.8.
--password[=password], -p[password]
The password to use when connecting to the server. If you use the short option form (-p), you cannot have a space between the option and the password. If you omit the password value following the --password or -p option on the command line, you are prompted for one.
Specifying a password on the command line should be considered insecure. See Section聽5.8.6, 鈥淜eeping Your Password Secure鈥�.
--port=port_num, -P port_num
The TCP/IP port number to use for the connection.
--protocol={TCP|SOCKET|PIPE|MEMORY}
The connection protocol to use. Added in MySQL 4.1.
--quick, -q
This option is useful for dumping large tables. It forces mysqldump to retrieve rows for a table from the server a row at a time rather than retrieving the entire row set and buffering it in memory before writing it out.
--quote-names, -Q
Quote database, table, and column names within 鈥�`鈥� characters. If the ANSI_QUOTES SQL mode is enabled, names are quoted within 鈥�"鈥� characters. As of MySQL 4.1.1, --quote-names is enabled by default. It can be disabled with --skip-quote-names, but this option should be given after any option such as --compatible that may enable --quote-names.
--result-file=file, -r file
Direct output to a given file. This option should be used on Windows to prevent newline 鈥�\n鈥� characters from being converted to 鈥�\r\n鈥� carriage return/newline sequences. The result file is created and its contents overwritten, even if an error occurs while generating the dump. The previous contents are lost.
--set-charset
Add SET NAMES default_character_set to the output. This option is enabled by default. To suppress the SET NAMES statement, use --skip-set-charset. This option was added in MySQL 4.1.2.
--single-transaction
This option issues a BEGIN SQL statement before dumping data from the server. It is useful only with transactional tables such as InnoDB and BDB, because then it dumps the consistent state of the database at the time when BEGIN was issued without blocking any applications.
When using this option, you should keep in mind that only InnoDB tables are dumped in a consistent state. For example, any MyISAM or MEMORY tables dumped while using this option may still change state.
The --single-transaction option was added in MySQL 4.0.2. This option is mutually exclusive with the --lock-tables option, because LOCK TABLES causes any pending transactions to be committed implicitly.
This option is not supported for MySQL Cluster tables; the results cannot be guaranteed to be consistent due to the fact that the NDBCluster storage engine supports only the READ_COMMITTED transaction isolation level. You should always use NDB backup and restore instead.
To dump large tables, you should combine this option with --quick.
--skip-opt
See the description for the --opt option.
--socket=path, -S path
For connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.
--skip-comments
See the description for the --comments option.
--ssl*
Options that begin with --ssl specify whether to connect to the server via SSL and indicate where to find SSL keys and certificates. See Section聽5.8.7.3, 鈥淪SL Command Options鈥�.
--tab=path, -T path
Produce tab-separated data files. For each dumped table, mysqldump creates a tbl_name.sql file that contains the CREATE TABLE statement that creates the table, and a tbl_name.txt file that contains its data. The option value is the directory in which to write the files.
By default, the .txt data files are formatted using tab characters between column values and a newline at the end of each line. The format can be specified explicitly using the --fields-xxx and --lines-terminated-by options.
Note: This option should be used only when mysqldump is run on the same machine as the mysqld server. You must have the FILE privilege, and the server must have permission to write files in the directory that you specify.
--tables
Override the --databases or -B option. mysqldump regards all name arguments following the option as table names.
--user=user_name, -u user_name
The MySQL username to use when connecting to the server.
--verbose, -v
Verbose mode. Print more information about what the program does.
--version, -V
Display version information and exit.
--where='where_condition', -w 'where_condition'
Dump only rows selected by the given WHERE condition. Quotes around the condition are mandatory if it contains spaces or other characters that are special to your command interpreter.
Examples:
```
--where="user='jimf'"
-w"userid>1"
-w"userid<1"
```
--xml, -X
Write dump output as well-formed XML.

You can also set the following variables by using --var_name=value syntax:

max_allowed_packet
The maximum size of the buffer for client/server communication. The value of the variable can be up to 16MB before MySQL 4.0, and up to 1GB from MySQL 4.0 on.
net_buffer_length
The initial size of the buffer for client/server communication. When creating multiple-row-insert statements (as with option --extended-insert or --opt), mysqldump creates rows up to net_buffer_length length. If you increase this variable, you should also ensure that the net_buffer_length variable in the MySQL server is at least this large.

It is also possible to set variables by using --set-variable=var_name=value or -O var_name=value syntax. However, this syntax is deprecated as of MySQL 4.0.

The most common use of mysqldump is probably for making a backup of an entire database:

shell> mysqldump db_name > backup-file.sql

You can read the dump file back into the server like this:

shell> mysql db_name < backup-file.sql

Or like this:

shell> mysql -e "source /path-to-backup/backup-file.sql" db_name

mysqldump is also very useful for populating databases by copying data from one MySQL server to another:

shell> mysqldump --opt db_name | mysql --host=remote_host -C db_name

It is possible to dump several databases with one command:

shell> mysqldump --databases db_name1 [db_name2 ...] > my_databases.sql

To dump all databases, use the --all-databases option:

shell> mysqldump --all-databases > all_databases.sql

For InnoDB tables, mysqldump provides a way of making an online backup:

shell> mysqldump --all-databases --single-transaction > all_databases.sql

This backup just needs to acquire a global read lock on all tables (using FLUSH TABLES WITH READ LOCK) at the beginning of the dump. As soon as this lock has been acquired, the binary log coordinates are read and the lock is released. If and only if one long updating statement is running when the FLUSH statement is issued, the MySQL server may get stalled until that long statement finishes, and then the dump becomes lock-free. If the update statements that the MySQL server receives are short (in terms of execution time), the initial lock period should not be noticeable, even with many updates.

For point-in-time recovery (also known as 鈥�roll-forward,鈥� when you need to restore an old backup and replay the changes that happened since that backup), it is often useful to rotate the binary log (see Section聽5.11.4, 鈥淭he Binary Log鈥�) or at least know the binary log coordinates to which the dump corresponds:

shell> mysqldump --all-databases --master-data=2 > all_databases.sql

Or:

shell> mysqldump --all-databases --flush-logs --master-data=2
              > all_databases.sql

The --master-data and --single-transaction options can be used simultaneously as of MySQL 4.1.8, which provides a convenient way to make an online backup suitable for point-in-time recovery if tables are stored using the InnoDB storage engine.

For more information on making backups, see Section聽5.9.1, 鈥淒atabase Backups鈥�, and Section聽5.9.2, 鈥淓xample Backup and Recovery Strategy鈥�.

8.13.聽mysqlhotcopy 鈥� A Database Backup Program

mysqlhotcopy is a Perl script that was originally written and contributed by Tim Bunce. It uses LOCK TABLES, FLUSH TABLES, and cp or scp to make a database backup quickly. It is the fastest way to make a backup of the database or single tables, but it can be run only on the same machine where the database directories are located. mysqlhotcopy works only for backing up MyISAM and ISAM tables, and ARCHIVE tables as of MySQL 4.1. mysqlhotcopy runs on Unix, and also on NetWare as of MySQL 4.0.18.

shell> mysqlhotcopy db_name [/path/to/new_directory]

shell> mysqlhotcopy db_name_1 ... db_name_n /path/to/new_directory

Back up tables in the given database that match a regular expression:

shell> mysqlhotcopy db_name./regex/

The regular expression for the table name can be negated by prefixing it with a tilde (鈥�~鈥�):

shell> mysqlhotcopy db_name./~regex/

mysqlhotcopy supports the following options:

--help, -?
Display a help message and exit.
--addtodest
Do not rename target directory (if it exists); merely add files to it. This option was added in MySQL 4.0.13.
--allowold
Do not abort if a target exists; rename it by adding an _old suffix.
--checkpoint=db_name.tbl_name
Insert checkpoint entries into the specified database db_name and table tbl_name.
--chroot=path
Base directory of the chroot jail in which mysqld operates. The path value should match that of the --chroot option given to mysqld. This option was added in MySQL 4.0.19.
--debug
Enable debug output.
--dryrun, -n
Report actions without performing them.
--flushlog
Flush logs after all tables are locked.
--host=host_name, -h host_name
The hostname of the local host to use for making a TCP/IP connection to the local server. By default, the connection is made to localhost using a Unix socket file.
--keepold
Do not delete previous (renamed) target when done.
--method=command
The method for copying files (cp or scp).
--noindices
Do not include full index files in the backup. This makes the backup smaller and faster. The indexes for reloaded tables can be reconstructed later with myisamchk -rq for MyISAM tables or isamchk -rq for ISAM tables.
--password=password, -ppassword
The password to use when connecting to the server. Note that the password value is not optional for this option, unlike for other MySQL programs. You can use an option file to avoid giving the password on the command line.
Specifying a password on the command line should be considered insecure. See Section聽5.8.6, 鈥淜eeping Your Password Secure鈥�.
--port=port_num, -P port_num
The TCP/IP port number to use when connecting to the local server.
--quiet, -q
Be silent except for errors.
--record_log_pos=db_name.tbl_name
Record master and slave status in the specified database db_name and table tbl_name.
--regexp=expr
Copy all databases with names that match the given regular expression.
--resetmaster
Reset the binary log after locking all the tables.
--resetslave
Reset the master.info file after locking all the tables.
--socket=path, -S path
The Unix socket file to use for the connection.
--suffix=str
The suffix for names of copied databases.
--tmpdir=path
The temporary directory. The default is /tmp.
--user=user_name, -u user_name
The MySQL username to use when connecting to the server.

mysqlhotcopy reads the [client] and [mysqlhotcopy] option groups from option files.

To execute mysqlhotcopy, you must have access to the files for the tables that you are backing up, the SELECT privilege for those tables, the RELOAD privilege (to be able to execute FLUSH TABLES), and the LOCK TABLES privilege (to be able to lock the tables).

Use perldoc for additional mysqlhotcopy documentation, including information about the structure of the tables needed for the --checkpoint and --record_log_pos options:

shell> perldoc mysqlhotcopy

8.14.聽mysqlimport 鈥� A Data Import Program

The mysqlimport client provides a command-line interface to the LOAD DATA INFILE SQL statement. Most options to mysqlimport correspond directly to clauses of LOAD DATA INFILE syntax. See Section聽13.2.5, 鈥�LOAD DATA INFILE Syntax鈥�.

Invoke mysqlimport like this:

shell> mysqlimport [options] db_name textfile1 [textfile2 ...]

For each text file named on the command line, mysqlimport strips any extension from the filename and uses the result to determine the name of the table into which to import the file's contents. For example, files named patient.txt, patient.text, and patient all would be imported into a table named patient.

mysqlimport supports the following options:

--help, -?
Display a help message and exit.
--character-sets-dir=path
The directory where character sets are installed. See Section聽5.10.1, 鈥淭he Character Set Used for Data and Sorting鈥�.
--columns=column_list, -c column_list
This option takes a comma-separated list of column names as its value. The order of the column names indicates how to match data file columns with table columns.
--compress, -C
Compress all information sent between the client and the server if both support compression.
--debug[=debug_options], -# [debug_options]
Write a debugging log. The debug_options string often is 'd:t:o,file_name'.
--default-character-set=charset_name
Use charset_name as the default character set. See Section聽5.10.1, 鈥淭he Character Set Used for Data and Sorting鈥�.
--delete, -D
Empty the table before importing the text file.
--fields-terminated-by=..., --fields-enclosed-by=..., --fields-optionally-enclosed-by=..., --fields-escaped-by=...
These options have the same meaning as the corresponding clauses for LOAD DATA INFILE. See Section聽13.2.5, 鈥�LOAD DATA INFILE Syntax鈥�.
--force, -f
Ignore errors. For example, if a table for a text file does not exist, continue processing any remaining files. Without --force, mysqlimport exits if a table does not exist.
--host=host_name, -h host_name
Import data to the MySQL server on the given host. The default host is localhost.
--ignore, -i
See the description for the --replace option.
--ignore-lines=N
Ignore the first N lines of the data file.
--lines-terminated-by=...
This option has the same meaning as the corresponding clause for LOAD DATA INFILE. For example, to import Windows files that have lines terminated with carriage return/linefeed pairs, use --lines-terminated-by="\r\n". (You might have to double the backslashes, depending on the escaping conventions of your command interpreter.) See Section聽13.2.5, 鈥�LOAD DATA INFILE Syntax鈥�.
--local, -L
Read input files locally from the client host.
MySQL Enterprise For expert advice on the security implications of enabling LOCAL, subscribe to the MySQL Network Monitoring and Advisory. For more information see http://www.mysql.com/products/enterprise/advisors.html.
--lock-tables, -l
Lock all tables for writing before processing any text files. This ensures that all tables are synchronized on the server.
--low-priority
Use LOW_PRIORITY when loading the table. This affects only storage engines that use only table-level locking (MyISAM, MEMORY, MERGE).
--password[=password], -p[password]
The password to use when connecting to the server. If you use the short option form (-p), you cannot have a space between the option and the password. If you omit the password value following the --password or -p option on the command line, you are prompted for one.
Specifying a password on the command line should be considered insecure. See Section聽5.8.6, 鈥淜eeping Your Password Secure鈥�.
--port=port_num, -P port_num
The TCP/IP port number to use for the connection.
--protocol={TCP|SOCKET|PIPE|MEMORY}
The connection protocol to use. Added in MySQL 4.1.
--replace, -r
The --replace and --ignore options control handling of input rows that duplicate existing rows on unique key values. If you specify --replace, new rows replace existing rows that have the same unique key value. If you specify --ignore, input rows that duplicate an existing row on a unique key value are skipped. If you do not specify either option, an error occurs when a duplicate key value is found, and the rest of the text file is ignored.
--silent, -s
Silent mode. Produce output only when errors occur.
--socket=path, -S path
For connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.
--ssl*
Options that begin with --ssl specify whether to connect to the server via SSL and indicate where to find SSL keys and certificates. See Section聽5.8.7.3, 鈥淪SL Command Options鈥�.
--user=user_name, -u user_name
The MySQL username to use when connecting to the server.
--verbose, -v
Verbose mode. Print more information about what the program does.
--version, -V
Display version information and exit.

Here is a sample session that demonstrates use of mysqlimport:

shell> mysql -e 'CREATE TABLE imptest(id INT, n VARCHAR(30))' test
shell> ed
a
100     Max Sydow
101     Count Dracula
.
w imptest.txt
32
q
shell> od -c imptest.txt
0000000   1   0   0  \t   M   a   x       S   y   d   o   w  \n   1   0
0000020   1  \t   C   o   u   n   t       D   r   a   c   u   l   a  \n
0000040
shell> mysqlimport --local test imptest.txt
test.imptest: Records: 2  Deleted: 0  Skipped: 0  Warnings: 0
shell> mysql -e 'SELECT * FROM imptest' test
+------+---------------+
| id   | n             |
+------+---------------+
|  100 | Max Sydow     |
|  101 | Count Dracula |
+------+---------------+

8.15.聽mysqlmanagerc 鈥� Internal Test-Suite Program

This program was used internally for test purposes. As of MySQL 5.0, it is no longer used.

8.16.聽mysqlmanager-pwgen 鈥� Internal Test-Suite Program

This program was used internally for test purposes. As of MySQL 5.0, it is no longer used.

8.17.聽mysqlshow 鈥� Display Database, Table, and Column Information

The mysqlshow client can be used to quickly see which databases exist, their tables, or a table's columns or indexes.

mysqlshow provides a command-line interface to several SQL SHOW statements. See Section聽13.5.4, 鈥�SHOW Syntax鈥�. The same information can be obtained by using those statements directly. For example, you can issue them from the mysql client program.

Invoke mysqlshow like this:

shell> mysqlshow [options] [db_name [tbl_name [col_name]]]

If no database is given, a list of database names is shown.
If no table is given, all matching tables in the database are shown.
If no column is given, all matching columns and column types in the table are shown.

The output displays only the names of those databases, tables, or columns for which you have some privileges.

If the last argument contains shell or SQL wildcard characters (鈥�*鈥�, 鈥�?鈥�, 鈥�%鈥�, or 鈥�_鈥�), only those names that are matched by the wildcard are shown. If a database name contains any underscores, those should be escaped with a backslash (some Unix shells require two) to get a list of the proper tables or columns. 鈥�*鈥� and 鈥�?鈥� characters are converted into SQL 鈥�%鈥� and 鈥�_鈥� wildcard characters. This might cause some confusion when you try to display the columns for a table with a 鈥�_鈥� in the name, because in this case, mysqlshow shows you only the table names that match the pattern. This is easily fixed by adding an extra 鈥�%鈥� last on the command line as a separate argument.

mysqlshow supports the following options:

--help, -?
Display a help message and exit.
--character-sets-dir=path
The directory where character sets are installed. See Section聽5.10.1, 鈥淭he Character Set Used for Data and Sorting鈥�.
--compress, -C
Compress all information sent between the client and the server if both support compression.
--debug[=debug_options], -# [debug_options]
Write a debugging log. The debug_options string often is 'd:t:o,file_name'.
--default-character-set=charset_name
Use charset_name as the default character set. See Section聽5.10.1, 鈥淭he Character Set Used for Data and Sorting鈥�.
--host=host_name, -h host_name
Connect to the MySQL server on the given host.
--keys, -k
Show table indexes.
--password[=password], -p[password]
The password to use when connecting to the server. If you use the short option form (-p), you cannot have a space between the option and the password. If you omit the password value following the --password or -p option on the command line, you are prompted for one.
Specifying a password on the command line should be considered insecure. See Section聽5.8.6, 鈥淜eeping Your Password Secure鈥�.
Specifying a password on the command line should be considered insecure. See Section聽5.8.6, 鈥淜eeping Your Password Secure鈥�.
--port=port_num, -P port_num
The TCP/IP port number to use for the connection.
--protocol={TCP|SOCKET|PIPE|MEMORY}
The connection protocol to use. Added in MySQL 4.1.
--socket=path, -S path
For connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.
--ssl*
Options that begin with --ssl specify whether to connect to the server via SSL and indicate where to find SSL keys and certificates. See Section聽5.8.7.3, 鈥淪SL Command Options鈥�.
--status, -i
Display extra information about each table.
--user=user_name, -u user_name
The MySQL username to use when connecting to the server.
--verbose, -v
Verbose mode. Print more information about what the program does. This option can be used multiple times to increase the amount of information.
--version, -V
Display version information and exit.

8.18.聽mysql_convert_table_format 鈥� Convert Tables to Use a Given Storage Engine

mysql_convert_table_format converts the tables in a database to use a particular storage engine (MyISAM by default). mysql_convert_table_format is written in Perl and requires that the DBI and DBD::mysql Perl modules be installed (see Section聽2.15, 鈥淧erl Installation Notes鈥�).

Invoke mysql_convert_table_format like this:

shell> mysql_convert_table_format [options]db_name

The db_name argument indicates the database containing the tables to be converted.

mysql_convert_table_format understands the options described in the following list.

--help
Display a help message and exit.
--force
Continue even if errors occur.
--host=host_name
Connect to the MySQL server on the given host.
--password=password
The password to use when connecting to the server. Note that the password value is not optional for this option, unlike for other MySQL programs. You can use an option file to avoid giving the password on the command line.
Specifying a password on the command line should be considered insecure. See Section聽5.8.6, 鈥淜eeping Your Password Secure鈥�.
--port=port_num
The TCP/IP port number to use for the connection.
--socket=path
For connections to localhost, the Unix socket file to use.
--type=engine_name
Specify the storage engine that the tables should be converted to use. The default is MyISAM if this option is not given.
MySQL Enterprise For expert advice on choosing the optimum storage engine, subscribe to the MySQL Network Monitoring and Advisory. For more information see http://www.mysql.com/products/enterprise/advisors.html.
--user=user_name
The MySQL username to use when connecting to the server.
--verbose
Verbose mode. Print more information about what the program does.
--version
Display version information and exit.

8.19.聽mysql_explain_log 鈥� Use EXPLAIN on Statements in Query Log

mysql_explain_log reads its standard input for query log contents. It uses EXPLAIN to analyze SELECT statements found in the input. UPDATE statements are rewritten to SELECT statements and also analyzed with EXPLAIN. mysql_explain_log then displays a summary of its results.

The results may assist you in determining which queries result in table scans and where it would be beneficial to add indexes to your tables.

Invoke mysql_explain_log like this, where log_file contains all or part of a MySQL query log:

shell> mysql_explain_log [options] < log_file

mysql_explain_log understands the following options:

--date=YYMMDD, -d YYMMDD
Select entries from the log only for the given date.
--host=host_name, -h host_name
Connect to the MySQL server on the given host.
--password=password, -p password
The password to use when connecting to the server.
Specifying a password on the command line should be considered insecure. See Section聽5.8.6, 鈥淜eeping Your Password Secure鈥�.
--printerror=1, -e 1
Enable error output.
--socket=path, -S path
For connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.
--user=user_name, -u user_name
The MySQL username to use when connecting to the server.

8.20.聽mysql_find_rows 鈥� Extract Queries from Update Log

mysql_find_rows reads update log files and extracts queries that match a given regular expression or that contain USE db_name or SET statements.

Invoke mysql_find_rows like this:

shell> mysql_find_rows [options] [file_name ...]

Each file_name argument should be the name of an updat log file. If no filenames are given, mysql_find_rows reads the standard input.

Examples:

mysql_find_rows --regexp=problem_table --rows=20 < update.log
mysql_find_rows --regexp=problem_table  update-log.1 update-log.2

mysql_find_rows supports the following options:

--help, --Information
Display a help message and exit.
--regexp=pattern
Display queries that match the pattern.
--rows=N
Quit after displaying N queries.
--skip-use-db
Do not include USE db_name statements in the output.
--start_row=N
Start output from this row.

8.21.聽mysql_fix_extensions 鈥� Make Table Filename Extensions Lowercase

mysql_fix_extensions converts the extensions for MyISAM (or ISAM) table files to lowercase. It looks for files with an extension that that matches any lettercase variant of .frm, .myd, .myi, .isd, and .ism and renames them to have extensionsn of .frm, .MYD, .MYI, .ISD, and .ISM, respectively. This can be useful after transferring the files from a system with case-insensitive filenames (such as Windows) to a system with case-sensitive filenames.

Invoke mysql_fix_extensions like this, where data_dir is the pathname to the MySQL data directory.

shell> mysql_fix_extensions data_dir

8.22.聽mysql_setpermission 鈥� Interactively Set Permissions in Grant Tables

mysql_setpermission is a Perl script that was originally written and contributed by Luuk de Boer. It interactively sets permissions in the MySQL grant tables. mysql_setpermission is written in Perl and requires that the DBI and DBD::mysql Perl modules be installed (see Section聽2.15, 鈥淧erl Installation Notes鈥�).

Invoke mysql_setpermission like this:

shell> mysql_setpermission [options]

options should be either --help to display the help message, or options that indicate how to connect to the MySQL server. The account used when you connect determines which permissions you have when attempting to modify existing permissions in the grant tables.

mysql_setpermissions also reads options from the [client] and [perl] groups in the .my.cnf file in your home directory, if the file exists.

mysql_setpermission understands the following options:

--help
Display a help message and exit.
--host=host_name
Connect to the MySQL server on the given host.
--password=password
The password to use when connecting to the server. Note that the password value is not optional for this option, unlike for other MySQL programs. You can use an option file to avoid giving the password on the command line.
Specifying a password on the command line should be considered insecure. See Section聽5.8.6, 鈥淜eeping Your Password Secure鈥�.
--port=port_num
The TCP/IP port number to use for the connection.
--socket=path
For connections to localhost, the Unix socket file to use.
--user=user_name
The MySQL username to use when connecting to the server.

8.23.聽mysql_tableinfo 鈥� Generate Database Metadata

mysql_tableinfo creates tables and populates them with database metadata. It uses SHOW DATABASES, SHOW TABLES, SHOW TABLE STATUS, SHOW COLUMNS, and SHOW INDEX to obtain the metadata.

In MySQL 5.0 and up, the INFORMATION_SCHEMA database contains the same kind of information in the SCHEMATA, TABLES, COLUMNS, and STATISTICS tables. See The INFORMATION_SCHEMA Database.

Invoke mysql_tableinfo like this:

shell> mysql_tableinfo [options] db_name [db_like [tbl_like]]

The db_name argument indicates which database mysql_tableinfo should use as the location for the metadata tables. The database will be created if it does not exist. The tables will be named db, tbl (or tbl_status), col, and idx.

If the db_like or tbl_like arguments are given, they are used as patterns and metadata is generated only for databases or tables that match the patterns. These arguments default to % if not given.

Examples:

mysql_tableinfo info
mysql_tableinfo info world
mysql_tableinfo info mydb tmp%

Each of the commands stores information into tables in the info database. The first stores information for all databases and tables. The second stores information for all tables in the world database. The third stores information for tables in the mydb database that have names matching the pattern tmp%.

mysql_tableinfo supports the following options:

--help
Display a help message and exit.
--clear
Before populating each metadata table, drop it if it exists.
--clear-only
Similar to --clear, but exits after dropping the metadata tables to be populated.
--col
Generate column metadata into the col table.
--host=host_name, -h host_name
Connect to the MySQL server on the given host.
--idx
Generate index metadata into the idx table.
--password=password, -ppassword
The password to use when connecting to the server. Note that the password value is not optional for this option, unlike for other MySQL programs. You can use an option file to avoid giving the password on the command line.
Specifying a password on the command line should be considered insecure. See Section聽5.8.6, 鈥淜eeping Your Password Secure鈥�.
--port=port_num, -P port_num
The TCP/IP port number to use for the connection.
--prefix=prefix_str
Add prefix_str at the beginning of each metadata table name.
--quiet, -q
Be silent except for errors.
--socket=path, -S path
The Unix socket file to use for the connection.
--tbl-status
Use SHOW TABLE STATUS instead of SHOW TABLES. This provides more complete information, but is slower.
--user=user_name, -u user_name
The MySQL username to use when connecting to the server.

8.24.聽mysql_waitpid 鈥� Kill Process and Wait for Its Termination

mysql_waitpid signals a process to terminate and waits for the process to exit. It uses the kill() system call and Unix signals, so it runs on Unix and Unix-like systems.

Invoke mysql_waitpid like this:

shell> mysql_waitpid [options] pid wait_time

mysql_waitpid sends signal 0 to the process identified by pid and waits up to wait_time seconds for the process to terminate. pid and wait_time must be positive integers.

If process termination occurs within the wait time or the process does not exist, mysql_waitpid returns 0. Otherwise, it returns 1.

If the kill() system call cannot handle signal 0, mysql_waitpid() uses signal 1 instead.

mysql_waitpid understands the following options:

--help, -?, -I
Display a help message and exit.
--verbose, -v
Verbose mode. Display a warning if signal 0 could not be used and signal 1 is used instead.
--version, -V
Display version information and exit.

8.25.聽mysql_zap 鈥� Kill Processes That Match a Pattern

mysql_zap kills processes that match a pattern. It uses the ps command and Unix signals, so it runs on Unix and Unix-like systems.

Invoke mysql_zap like this:

shell> mysql_zap [-signal] [-?Ift] pattern

A process matches if its output line from the ps command contains the pattern. By default, mysql_zap asks for confirmation for each process. Respond y to kill the process, or q to exit mysql_zap. For any other response, mysql_zap does not attempt to kill the process.

If the -signal option is given, it specifies the name or number of the signal to send to each process. Otherwise, mysql_zap tries first with TERM (signal 15) and then with KILL (signal 9).

mysql_zap understands the following additional options:

--help, -?, -I
Display a help message and exit.
-f
Force mode. mysql_zap attempts to kill each process without confirmation.
-t
Test mode. Display information about each process but do not kill it.

8.26.聽perror 鈥� Explain Error Codes

For most system errors, MySQL displays, in addition to an internal text message, the system error code in one of the following styles:

message ... (errno: #)
message ... (Errcode: #)

You can find out what the error code means by examining the documentation for your system or by using the perror utility.

perror prints a description for a system error code or for a storage engine (table handler) error code.

Invoke perror like this:

shell> perror [options] errorcode ...

Example:

shell> perror 13 64
Error code  13:  Permission denied
Error code  64:  Machine is not on the network

To obtain the error message for a MySQL Cluster error code, invoke perror with the --ndb option:

shell> perror --ndb errorcode

Note that the meaning of system error messages may be dependent on your operating system. A given error code may mean different things on different operating systems.

perror supports the following options:

--help, --info, -I, -?
Display a help message and exit.
--ndb
Print the error message for a MySQL Cluster error code.
--silent, -s
Silent mode. Print only the error message.
--verbose, -v
Verbose mode. Print error code and message. This is the default behavior.
--version, -V
Display version information and exit.

8.27.聽replace 鈥� A String-Replacement Utility

The replace utility program changes strings in place in files or on the standard input.

Invoke replace in one of the following ways:

shell> replace from to [from to] ... -- file [file] ...
shell> replace from to [from to] ... < file

from represents a string to look for and to represents its replacement. There can be one or more pairs of strings.

Use the -- option to indicate where the string-replacement list ends and the filenames begin. In this case, any file named on the command line is modified in place, so you may want to make a copy of the original before converting it. replace prints a message indicating which of the input files it actually modifies.

If the -- option is not given, replace reads the standard input and writes to the standard output.

replace uses a finite state machine to match longer strings first. It can be used to swap strings. For example, the following command swaps a and b in the given files, file1 and file2:

shell> replace a b b a -- file1 file2 ...

The replace program is used by msql2mysql. See Section聽17.9.1, 鈥�msql2mysql 鈥� Convert mSQL Programs for Use with MySQL鈥�.

replace supports the following options:

-?, -I
Display a help message and exit.
-# debug_options
Write a debugging log. The debug_options string often is 'd:t:o,file_name'.
-s
Silent mode. Print less information what the program does.
-v
Verbose mode. Print more information about what the program does.
-V
Display version information and exit.

8.28.聽resolveip 鈥� Resolve Hostname to IP Address or Vice Versa

The resolveip utility resolves hostnames to IP addresses and vice versa.

Invoke resolveip like this:

shell> resolveip [options] {host_name|ip-addr} ...

resolveip understands the options described in the following list.

--help, -info, -?, -I
Display a help message and exit.
--silent, -s
Silent mode. Produce less output.
--version, -V
Display version information and exit.

8.29.聽resolve_stack_dump 鈥� Resolve Numeric Stack Trace Dump to Symbols

resolve_stack_dump resolves a numeric stack dump to symbols.

Invoke resolve_stack_dump like this:

shell> resolve_stack_dump [options] symbols_file [numeric_dump_file]

The symbols file should include the output from the nm --numeric-sort mysqld command. The numeric dump file should contain a numeric stack track from mysqld. If no numeric dump file is named on the command line, the stack trace is read from the standard input.

resolve_stack_dump understands the options described in the following list.

--help, -h
Display a help message and exit.
--numeric-dump-file=file_name, -n file_name
Read the stack trace from the given file.
--symbols-file=file_name, -s file_name
Use the given symbols file.
--version, -V
Display version information and exit.

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Chapter聽7.聽Optimization聽	Home	聽Chapter聽9.聽Language Structure

Chapter聽8.聽Client and Utility Programs - MySQL 4.1参考手册英文版

8.1.聽Overview of Client and Utility Programs

8.2.聽my_print_defaults 鈥� Display Options from Option Files

8.3.聽myisam_ftdump 鈥� Display Full-Text Index information

8.4.聽myisamchk 鈥� MyISAM Table-Maintenance Utility

Caution

Important

8.4.1.聽myisamchk General Options

8.4.2.聽myisamchk Check Options

8.4.3.聽myisamchk Repair Options

8.4.4.聽Other myisamchk Options

8.4.5.聽myisamchk Memory Usage

8.5.聽myisamlog 鈥� Display MyISAM Log File Contents

8.6.聽myisampack 鈥� Generate Compressed, Read-Only MyISAM Tables

8.7.聽mysql 鈥� The MySQL Command-Line Tool

8.7.1.聽mysql Options

8.7.2.聽mysql Commands

8.7.3.聽mysql Server-Side Help

8.7.4.聽Executing SQL Statements from a Text File

8.7.5.聽mysql Tips

8.7.5.1.聽Displaying Query Results Vertically

8.7.5.2.聽Using the --safe-updates Option

8.7.5.3.聽Disabling mysql Auto-Reconnect

8.8.聽mysqlaccess 鈥� Client for Checking Access Privileges

8.9.聽mysqladmin 鈥� Client for Administering a MySQL Server

8.10.聽mysqlbinlog 鈥� Utility for Processing Binary Log Files

8.11.聽mysqlcheck 鈥� A Table Maintenance and Repair Program

Caution

8.12.聽mysqldump 鈥� A Database Backup Program

8.13.聽mysqlhotcopy 鈥� A Database Backup Program

8.14.聽mysqlimport 鈥� A Data Import Program

8.15.聽mysqlmanagerc 鈥� Internal Test-Suite Program

8.16.聽mysqlmanager-pwgen 鈥� Internal Test-Suite Program

8.17.聽mysqlshow 鈥� Display Database, Table, and Column Information

8.18.聽mysql_convert_table_format 鈥� Convert Tables to Use a Given Storage Engine

8.19.聽mysql_explain_log 鈥� Use EXPLAIN on Statements in Query Log

8.20.聽mysql_find_rows 鈥� Extract Queries from Update Log

8.21.聽mysql_fix_extensions 鈥� Make Table Filename Extensions Lowercase

8.22.聽mysql_setpermission 鈥� Interactively Set Permissions in Grant Tables

8.23.聽mysql_tableinfo 鈥� Generate Database Metadata

8.24.聽mysql_waitpid 鈥� Kill Process and Wait for Its Termination

8.25.聽mysql_zap 鈥� Kill Processes That Match a Pattern

8.26.聽perror 鈥� Explain Error Codes

8.27.聽replace 鈥� A String-Replacement Utility

8.28.聽resolveip 鈥� Resolve Hostname to IP Address or Vice Versa

8.29.聽resolve_stack_dump 鈥� Resolve Numeric Stack Trace Dump to Symbols

8.4.4.聽Other `myisamchk` Options

8.7.5.2.聽Using the `--safe-updates` Option