Chapter聽9.聽Language Structure - MySQL 5.1参考手册中文版

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'a string'

"another string"

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[_charset_name]'string' [COLLATE collation_name]

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SELECT _latin1'string';

SELECT _latin1'string' COLLATE latin1_danish_ci;

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mysql> SELECT 'hello', '"hello"', '""hello""', 'hel''lo', '\'hello';

+-------+---------+-----------+--------+--------+

| hello | "hello" | ""hello"" | hel'lo | 'hello |

+-------+---------+-----------+--------+--------+

mysql> SELECT "hello", "'hello'", "''hello''", "hel""lo", "\"hello";

+-------+---------+-----------+--------+--------+

| hello | 'hello' | ''hello'' | hel"lo | "hello |

+-------+---------+-----------+--------+--------+

mysql> SELECT 'This\nIs\nFour\nLines';

+--------------------+

| This

Is

Four

Lines |

+--------------------+

mysql> SELECT 'disappearing\ backslash';

+------------------------+

| disappearing backslash |

+------------------------+

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mysql> CREATE TABLE t (b BIT(8));

mysql> INSERT INTO t SET b = b'11111111';

mysql> INSERT INTO t SET b = b'1010';

+------+----------+----------+----------+

| b+0  | BIN(b+0) | OCT(b+0) | HEX(b+0) |

+------+----------+----------+----------+

|  255 | 11111111 | 377      | FF       |

|   10 | 1010     | 12       | A        |

+------+----------+----------+----------+

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    -> WHERE a.col_name = 1 OR A.col_name = 2;

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璇锋敞鎰忓湪Unix涓�灏�lower_case_tables_name璁剧疆涓�1涔嬪墠锛岄噸鍚�mysqld涔嬪墠锛屽繀椤诲厛灏嗘棫鐨勬暟鎹�搴撳悕鍜岃〃鍚嶈浆鎹�涓哄皬鍐欍��

缁撴瀯寮忓彉閲忓湪涓や釜鏂归潰涓嶅悓浜庡父瑙勭郴缁熷彉閲忥細

路         鍏跺�兼槸涓�涓�鍚�缁勪欢鐨勭粨鏋勶紝鍙�浠ユ寚瀹氭湇鍔″櫒鍙傛暟锛屼竴鑸�绱у瘑鐩稿叧銆�

路         鍙�鑳芥槸缁欏畾绫诲瀷鐨勭粨鏋勫紡鍙橀噺鐨勫嚑涓�瀹炰緥銆傛瘡涓�瀹炰緥鏈変竴涓�涓嶅悓鐨勫悕锛屾寚鍚戞湇鍔″櫒缁存姢鐨勪笉鍚岀殑璧勬簮銆�

MySQL 5.1鏀�鎸佺粨鏋勫紡鍙橀噺绫诲瀷锛屽彲浠ユ寚瀹氱洃鎺ч敭鍊肩紦瀛樻搷浣滅殑鍙傛暟銆傞敭鍊肩紦瀛樼粨鏋勫紡鍙橀噺鏈変互涓嬬粍浠讹細

路         key_buffer_size

路         key_cache_block_size

路         key_cache_division_limit

路         key_cache_age_threshold

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瑕佸紩鐢ㄧ粨鏋勫紡鍙橀噺瀹炰緥鐨勭粍浠讹紝鍙�浠ヤ娇鐢�instance_name.component_name鏍煎紡鐨勫�嶅悎鍚嶃�備緥濡傦細

hot_cache.key_buffer_size

hot_cache.key_cache_block_size

cold_cache.key_cache_block_size

瀵逛簬姣忎釜缁撴瀯寮忕郴缁熷彉閲忥紝鎬绘槸棰勫畾涔夊悕涓�default鐨勪竴涓�瀹炰緥銆傚�傛灉涓嶄娇鐢ㄤ换浣曞疄渚嬪悕寮曠敤缁撴瀯寮忓彉閲忕殑涓�涓�缁勪欢锛�default瀹炰緥琚�浣跨敤銆傝繖鏍凤紝default.key_buffer_size鍜�key_buffer_sizeboth鍧囨寚鍚戝悓涓�绯荤粺鍙橀噺銆�

缁撴瀯寮忓彉閲忓疄渚嬪拰缁勪欢鐨勫懡鍚嶈�勫垯涓猴��

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路         姣忎釜缁撴瀯寮忓彉閲忕被鍨嬬殑缁勪欢鍚嶅湪鎵�鏈夌郴缁熷彉閲忓悕涓�蹇呴』鏄�鍞�涓�鐨勩�傚�傛灉涓嶆槸杩欐��(涔熷氨鏄�璇达紝濡傛灉涓や釜涓嶅悓绫诲瀷鐨勭粨鏋勫紡鍙橀噺鑳藉�熷叡浜�缁勪欢鎴愬憳鍚�)锛屽皢涓嶆竻妤氫娇鐢ㄥ摢涓�榛樿�ょ粨鏋勫紡鍙橀噺鏉ョ敤浣滄病鏈変娇鐢ㄥ疄渚嬪悕闄愬畾鐨勬垚鍛樺悕銆�

路         濡傛灉缁撴瀯寮忓彉閲忓疄渚嬪悕浣滀负鏈�寮曡捣鏉ョ殑璇嗗埆绗︿笉鍚堟硶锛屽皢瀹冪敤鍙嶅嬀鍙峰紩璧锋潵浣滀负璇嗗埆绗︺�備緥濡傦紝hot-cache涓嶅悎娉曪紝浣�`hot-cache` 鍚堟硶銆�

路         global銆�session鍜�local涓嶆槸鍚堟硶瀹炰緥鍚嶃�傝繖鏍峰彲浠ラ伩鍏嶄笌寮曠敤闈炵粨鏋勫紡绯荤粺鍙橀噺鐨勭�﹀彿鐨勫啿绐侊紝渚嬪��@@global.var_name銆�

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涓�涓�渚嬪�栨槸锛屽彲浠ュ湪鍙�鑳藉嚭鐜扮畝鍗曞彉閲忓悕鐨勪笂涓嬫枃涓�浣跨敤澶嶅悎鍚嶅紩鐢ㄧ粨鏋勫紡鍙橀噺缁勪欢銆備緥濡傦紝鍙�浠ヤ娇鐢ㄤ竴涓�鍛戒护琛岄�夐」鏈�鏌愪釜缁撴瀯寮忓彉閲忓垎閰嶄竴涓�鍊硷細

shell> mysqld --hot_cache.key_buffer_size=64K

鍦ㄩ�夐」鏂囦欢涓�锛屼娇鐢�锛�

[mysqld]

hot_cache.key_buffer_size=64K

濡傛灉鐢ㄨ�ラ�夐」鍚�鍔ㄦ湇鍔″櫒锛岄櫎浜嗛粯璁ゅぇ灏忎��8MB鐨勯粯璁ら敭鍊肩紦瀛橈紝杩樺垱寤轰竴涓�鍚嶄��hot_cache鐨勯敭鍊肩紦瀛橈紝澶у皬涓�64KB銆�

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shell> mysqld --key_buffer_size=256K \

         --extra_cache.key_buffer_size=128K \

         --extra_cache.key_cache_block_size=2048

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鍦ㄤ笅闈㈢殑渚嬪瓙涓�锛岀��3涓�涓嶅悓鐨勯敭鍊肩紦瀛橈紙澶у皬姣斾緥涓�3:1:1锛夊惎鍔ㄦ湇鍔″櫒锛�

shell> mysqld --key_buffer_size=6M \

         --hot_cache.key_buffer_size=2M \

         --cold_cache.key_buffer_size=2M

涔熷彲浠ュ湪杩愯�屾椂璁剧疆鍜屾��绱㈢粨鏋勫紡鍙橀噺鍊笺�備緥濡傦紝瑕佹兂灏嗗悕涓�hot_cache鐨勪竴涓�閿�鍊肩紦瀛樼殑澶у皬璁剧疆涓�10MB锛屼娇鐢ㄤ笅闈�浠讳綍涓�涓�璇�鍙ワ細

mysql> SET GLOBAL hot_cache.key_buffer_size = 10*1024*1024;

mysql> SET @@global.hot_cache.key_buffer_size = 10*1024*1024;

瑕佹兂妫�绱㈢紦瀛樺ぇ灏忥紝鎵ц�岋��

mysql> SELECT @@global.hot_cache.key_buffer_size;

浣嗘槸锛屼笅闈㈢殑璇�鍙ヤ笉宸ヤ綔銆傚彉閲忎笉瑙ｉ噴涓轰竴涓�澶嶅悎鍚嶏紝鑰屾槸瑙ｉ噴涓�LIKE妯″紡鍖归厤鎿嶄綔鐨勭畝鍗曞瓧绗︿覆锛�

mysql> SHOW GLOBAL VARIABLES LIKE 'hot_cache.key_buffer_size';

杩欐槸涓�涓�鍦ㄥ彲鑳藉嚭鐜扮畝鍗曠殑鍙橀噺鍚嶆椂浣跨敤缁撴瀯寮忓彉閲忓悕鐨勪緥瀛愩��