{"id":8964,"date":"2023-11-28T20:48:52","date_gmt":"2023-11-28T12:48:52","guid":{"rendered":"https:\/\/wx.kaifamiao.info\/?p=8964"},"modified":"2023-11-28T20:49:36","modified_gmt":"2023-11-28T12:49:36","slug":"mysql-wei-shen-me-zhe-me-she-ji","status":"publish","type":"post","link":"http:\/\/wx.kaifamiao.info\/index.php\/2023\/11\/28\/mysql-wei-shen-me-zhe-me-she-ji\/","title":{"rendered":"MySQL\u4e3a\u4ec0\u4e48\u8fd9\u4e48\u8bbe\u8ba1\uff1f"},"content":{"rendered":"

\u5bf9\u5927\u591a\u6570\u5e94\u7528\u6ca1\u6709\u610f\u4e49\uff0c\u53ea\u662f\u89c4\u5b9a\u4e00\u4e9b\u5de5\u5177\u7528\u6765\u663e\u793a\u5b57\u7b26\u7684\u4e2a\u6570\uff1bint(l)\u548cint(20)\u5b58\u50a8\u548c\u8ba1\u7b97\u5747\u4e00\u6837\uff1b
\nMySQL\u4e2d\u5982\u4f55\u5b9a\u4f4d\u53ca\u4f18\u5316SQL\u8bed\u53e5\u7684\u6027\u80fd\u95ee\u9898\uff1f\u521b\u5efa\u7684\u7d22\u5f15\u6709\u6ca1\u6709\u88ab\u4f7f\u7528\u5230\uff1f\u6216\u8005\u8bf4\u600e\u4e48\u624d\u53ef\u4ee5\u77e5\u9053\u8fd9\u6761\u8bed\u53e5\u8fd0\u884c\u5f88\u6162\u7684\u539f\u56e0\uff1f
\n\u5bf9\u4e8e\u4f4e\u6027\u80fd\u7684SQL\u8bed\u53e5\u7684\u5b9a\u4f4d\uff0c\u6700\u91cd\u8981\u4e5f\u662f\u6700\u6709\u6548\u7684\u65b9\u6cd5\u5c31\u662f\u4f7f\u7528\u6267\u884c\u8ba1\u5212\uff0cMySQL\u63d0\u4f9b\u4e86explain\u547d\u4ee4\u6765\u67e5\u770b\u8bed\u53e5\u7684\u6267\u884c\u8ba1\u5212\u3002\u6211\u4eec\u77e5\u9053\uff0c\u4e0d\u7ba1\u662f\u54ea\u79cd\u6570\u636e\u5e93\uff0c\u6216\u8005\u662f\u54ea\u79cd\u6570\u636e\u5e93\u5f15\u64ce\uff0c\u5728\u5bf9\u4e00\u6761SQL\u8bed\u53e5\u8fdb\u884c\u6267\u884c\u7684\u8fc7\u7a0b\u4e2d\u90fd\u4f1a\u505a\u5f88\u591a\u76f8\u5173\u7684\u4f18\u5316\uff0c\u5bf9\u4e8e\u67e5\u8be2\u8bed\u53e5\uff0c\u6700\u91cd\u8981\u7684\u4f18\u5316\u65b9\u5f0f\u5c31\u662f\u4f7f\u7528\u7d22\u5f15\u3002\u800c\u6267\u884c\u8ba1\u5212\uff0c\u5c31\u662f\u663e\u793a\u6570\u636e\u5e93\u5f15\u64ce\u5bf9\u4e8eSQL\u8bed\u53e5\u7684\u6267\u884c\u7684\u8be6\u7ec6\u60c5\u51b5\uff0c\u5176\u4e2d\u5305\u542b\u4e86\u662f\u5426\u4f7f\u7528\u7d22\u5f15\uff0c\u4f7f\u7528\u4ec0\u4e48\u7d22\u5f15\uff0c\u4f7f\u7528\u7684\u7d22\u5f15\u7684\u76f8\u5173\u4fe1\u606f\u7b49\u3002
\n\u6267\u884c\u8ba1\u5212\u5305\u542b\u7684\u4fe1\u606fid\u6709\u4e00\u7ec4\u6570\u5b57\u7ec4\u6210\u3002\u8868\u793a\u4e00\u4e2a\u67e5\u8be2\u4e2d\u5404\u4e2a\u5b50\u67e5\u8be2\u7684\u6267\u884c\u987a\u5e8f\uff1b
\n1\u3001\tid\u76f8\u540c\u6267\u884c\u987a\u5e8f\u7531\u4e0a\u81f3\u4e0b\u3002
\n2\u3001\tid\u4e0d\u540c\uff0cid\u503c\u8d8a\u5927\u4f18\u5148\u7ea7\u8d8a\u9ad8\uff0c\u8d8a\u5148\u88ab\u6267\u884c\u3002
\n3\u3001\tid\u4e3anull\u65f6\u8868\u793a\u4e00\u4e2a\u7ed3\u679c\u96c6\uff0c\u4e0d\u9700\u8981\u4f7f\u7528\u5b83\u67e5\u8be2\uff0c\u5e38\u51fa\u73b0\u5728\u5305\u542bunion\u7b49\u67e5\u8be2\u8bed\u53e5\u4e2d\u3002<\/p>\n

\"\"<\/p>\n

select_type\u6bcf\u4e2a\u5b50\u67e5\u8be2\u7684\u67e5\u8be2\u7c7b\u578b\uff0c\u4e00\u4e9b\u5e38\u89c1\u7684\u67e5\u8be2\u7c7b\u578b\u3002
\nid\tselect_type\tdescription
\n1\tSIMPLE\t\u4e0d\u5305\u542b\u4efb\u4f55\u5b50\u67e5\u8be2\u6216union\u7b49 \u67e5\u8be2
\n2\tPRIMARY\t\u5305\u542b\u5b50\u67e5\u8be2\u6700\u5916\u5c42\u67e5\u8be2\u5c31\u663e\u793a \u4e3a PRIMARY
\n3\tSUBQUERY\t\u5728select\u6216where\u5b57\u53e5\u4e2d\u5305\u542b \u7684\u67e5\u8be2
\n4\tDERIVED\tfrom\u5b57\u53e5\u4e2d\u5305\u542b\u7684\u67e5\u8be2
\n5\tUNION\t\u51fa\u73b0\u5728union\u540e\u7684\u67e5\u8be2\u8bed\u53e5\u4e2d
\n6\tUNION RESULT\t\u4eceUNION\u4e2d\u83b7\u53d6\u7ed3\u679c\u96c6\u4f8b\u5982\u4e0a\u6587\u7684\u7b2c\u4e09\u4e2a\u4f8b\u5b50
\ntable\u67e5\u8be2\u7684\u6570\u636e\u8868\uff0c\t\u5f53\u4ece\u884d\u751f\u8868\u4e2d\u67e5\u6570\u636e\u65f6\u4f1a\u663e\u793aX\t\u8868\u793a\u5bf9\u5e94\u7684\u6267\u884c\u8ba1\u5212id partitions
\n\u8868\u5206\u533a\u3001\u8868\u521b\u5efa\u7684\u65f6\u5019\u53ef\u4ee5\u6307\u5b9a\u901a\u8fc7\u90a3\u4e2a\u5217\u8fdb\u884c\u8868\u5206\u533a\u3002\u4e3e\u4e2a\u4f8b\u5b50:<\/p>\n

id int unsigned not null AUT0_INCREMENT,\nname varchar(255),\nPRIMARY KEY (id)\n)engine = innodb partition by key (id) partitions 5\uff1b\n<\/code><\/pre>\n
type(\u975e\u5e38\u91cd\u8981\uff0c\u53ef\u4ee5\u770b\u5230\u6709\u6ca1\u6709\u8d70\u7d22\u5f15)\u8bbf\u95ee\u7c7b\u578b
\n1\u3001\tALL\u626b\u63cf\u5168\u8868\u6570\u636e
\n2\u3001\tindex\u904d\u5386\u7d22\u5f15
\n3\u3001\trange\u7d22\u5f15\u8303\u56f4\u67e5\u627e
\n4\u3001\tindex_subquery\u5728\u5b50\u67e5\u8be2\u4e2d\u4f7f\u7528ref
\n5\u3001\tunique_subquery \u5728\u5b50\u67e5\u8be2\u4e2d\u4f7f\u7528 eq_ref
\n6\u3001\tref_or_null\u5bf9Null\u8fdb\u884c\u7d22\u5f15\u7684\u4f18\u5316\u7684ref
\n7\u3001\tfulltext\u4f7f\u7528\u5168\u6587\u7d22\u5f15
\n8\u3001\tref\u4f7f\u7528\u975e\u552f\u4e00\u7d22\u5f15\u67e5\u627e\u6570\u636e
\n9\u3001\teq_ref \u5728 join \u67e5\u8be2\u4e2d\u4f7f\u7528 PRIMARY KEYorUNIQUE NOT NULL \u7d22\u5f15\u5173\u8054\u3002
\n10\u3001\tpossible_keys\u53ef\u80fd\u4f7f\u7528\u7684\u7d22\u5f15\uff0c\u6ce8\u610f\u4e0d\u4e00\u5b9a\u4f1a\u4f7f\u7528\u3002\u67e5\u8be2\u6d89\u53ca\u5230\u7684\u5b57\u6bb5\u4e0a\u82e5\u5b58\u5728\u7d22\u5f15\uff0c \u5219\u8be5\u7d22\u5f15\u5c06\u88ab\u5217\u51fa\u6765\u3002\u5f53\u8be5\u5217\u4e3aNULL\u65f6\u5c31\u8981\u8003\u8651\u5f53\u524d\u7684SQL\u662f\u5426\u9700\u8981\u4f18\u5316\u4e86\u3002
\n11\u3001\tkey\u663e\u793aMySQL\u5728\u67e5\u8be2\u4e2d\u5b9e\u9645\u4f7f\u7528\u7684\u7d22\u5f15\uff0c\u82e5\u6ca1\u6709\u4f7f\u7528\u7d22\u5f15\uff0c\u663e\u793a\u4e3aNULL\u3002
\n12\u3001\tTIPS\uff1a\u67e5\u8be2\u4e2d\u82e5\u4f7f\u7528\u4e86\u8986\u76d6\u7d22\u5f15(\u8986\u76d6\u7d22\u5f15\uff1a\u7d22\u5f15\u7684\u6570\u636e\u8986\u76d6\u4e86\u9700\u8981\u67e5\u8be2\u7684\u6240\u6709\u6570\u636e)\uff0c\u5219\u8be5\u7d22\u5f15\u4ec5\u51fa\u73b0\u5728key\u5217\u8868\u4e2d
\n13\u3001\tkey_length \u7d22\u5f15\u957f\u5ea6
\n14\u3001\tref\u8868\u793a\u4e0a\u8ff0\u8868\u7684\u8fde\u63a5\u5339\u914d\u6761\u4ef6\uff0c\u5373\u54ea\u4e9b\u5217\u6216\u5e38\u91cf\u88ab\u7528\u4e8e\u67e5\u627e\u7d22\u5f15\u5217\u4e0a\u7684\u503c
\n15\u3001\trows\u8fd4\u56de\u4f30\u7b97\u7684\u7ed3\u679c\u96c6\u6570\u76ee\uff0c\u5e76\u4e0d\u662f\u4e00\u4e2a\u51c6\u786e\u7684\u503c\u3002
\n16\u3001\textra\u7684\u4fe1\u606f\u975e\u5e38\u4e30\u5bcc\uff0c\u5e38\u89c1\u7684\u6709\uff1a
\n17\u3001\tUsing index\u4f7f\u7528\u8986\u76d6\u7d22\u5f15
\n18\u3001\tUsing where\u4f7f\u7528\u4e86\u7528where\u5b50\u53e5\u6765\u8fc7\u6ee4\u7ed3\u679c\u96c6
\n19\u3001\tUsing filesort\u4f7f\u7528\u6587\u4ef6\u6392\u5e8f\uff0c\u4f7f\u7528\u975e\u7d22\u5f15\u5217\u8fdb\u884c\u6392\u5e8f\u65f6\u51fa\u73b0\uff0c\u975e\u5e38\u6d88\u8017\u6027\u80fd\uff0c\u5c3d\u91cf\u4f18\u5316\u3002
\n20\u3001Using temporary\u4f7f\u7528\u4e86\u4e34\u65f6\u8868sql\u4f18\u5316\u7684\u76ee\u6807\u53ef\u4ee5\u53c2\u8003\u963f\u91cc\u5f00\u53d1\u624b\u518c
\n\u63a8\u8350
\nSQL\u6027\u80fd\u4f18\u5316\u7684\u76ee\u6807\uff1a\u81f3\u5c11\u8981\u8fbe\u5230range\u7ea7\u522b\uff0c\u8981\u6c42\u662fref\u7ea7\u522b\uff0c\u5982\u679c\u53ef\u4ee5\u662fconsts\u6700\u597d
\n\u8bf4\u660e\uff1a
\n1\u3001\tconsts\u5355\u8868\u4e2d\u6700\u591a\u53ea\u6709\u4e00\u4e2a\u5339\u914d\u884c\uff08\u4e3b\u952e\u6216\u8005\u552f\u4e00\u7d22\u5f15\uff09\uff0c\u5728\u4f18\u5316\u9636\u6bb5\u5373\u53ef\u8bfb\u53d6\u5230\u6570\u636e\u3002
\n2\u3001\tref\u6307\u7684\u662f\u4f7f\u7528\u666e\u901a\u7684\u7d22\u5f15\uff08normal index\uff09\u3002
\n3\u3001\trange\u5bf9\u7d22\u5f15\u8fdb\u884c\u8303\u56f4\u68c0\u7d22\u3002
\n\u53cd\u4f8b\uff1a
\nexplain\u8868\u7684\u7ed3\u679c\uff0ctype=index,\u7d22\u5f15\u7269\u7406\u6587\u4ef6\u5168\u626b\u63cf\uff0c\u901f\u5ea6\u975e\u5e38\u6162\uff0c\u8fd9\u4e2aindex\u7ea7\u522b\u6bd4\u8f83range \u8fd8\u4f4e\uff0c\u4e0e\u5168\u8868\u626b\u63cf\u662f\u5c0f\u5deb\u89c1\u5927\u5deb\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u5bf9\u5927\u591a\u6570\u5e94\u7528\u6ca1\u6709\u610f\u4e49\uff0c\u53ea\u662f\u89c4\u5b9a\u4e00\u4e9b\u5de5\u5177\u7528\u6765\u663e\u793a\u5b57\u7b26\u7684\u4e2a\u6570\uff1bint(l)\u548cint(20)\u5b58\u50a8\u548c\u8ba1\u7b97\u5747\u4e00\u6837\uff1b My […]<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[102],"tags":[],"class_list":["post-8964","post","type-post","status-publish","format-standard","hentry","category-db"],"_links":{"self":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/8964","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/comments?post=8964"}],"version-history":[{"count":1,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/8964\/revisions"}],"predecessor-version":[{"id":8965,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/8964\/revisions\/8965"}],"wp:attachment":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/media?parent=8964"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/categories?post=8964"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/tags?post=8964"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}