— \u5f71\u54cd\u6027\u80fd\u7684\u56e0\u7d20;
\n1.\u73af\u5883\u95ee\u9898,MySQL\u7684\u6027\u80fd\u53d7\u4e3b\u673a\u7684\u6027\u80fd\u7279\u5f81\u5f71\u54cd:
\n 1.CPU\u901f\u5ea6\u548c\u6570\u91cf;
\n 2.\u78c1\u76d8I\/O;
\n 3.\u7f51\u7edc\u6027\u80fd;
\n 4.\u64cd\u4f5c\u7cfb\u7edf\u4e89\u7528;
\n2.MySQL\u914d\u7f6e:
\n 1.\u6570\u636e\u5e93\u8bbe\u8ba1:\u7d22\u5f15,\u6570\u636e\u7c7b\u578b(\u5408\u9002\u4e14\u5c3d\u53ef\u80fd\u5c0f),\u6807\u51c6\u5316;
\n 2.\u5e94\u7528\u7a0b\u5e8f\u6027\u80fd:\u7279\u5b9a\u8bf7\u6c42(\u4ec5\u8bf7\u6c42\u7279\u5b9a\u7684\u884c\u548c\u5217),\u77ed\u65f6\u4e8b\u52a1(\u6839\u636e\u4e3b\u952e\u8bbf\u95ee\u7684\u77ed\u4e8b\u52a1);
\n 3.\u914d\u7f6e\u53d8\u91cf:\u8c03\u6574\u7f13\u51b2\u533a,\u9ad8\u901f\u7f13\u5b58,InnoDB\u8bbe\u7f6e;<\/p>\n
— \u76d1\u89c6;
\n1.\u8981\u8c03\u8282\u670d\u52a1\u5668\u7684\u6027\u80fd,\u5fc5\u987b\u4e86\u89e3\u5176\u6027\u80fd\u7279\u5f81;\u53ef\u4ee5\u9488\u5bf9\u6574\u4f53\u6027\u80fd\u8fdb\u884c\u57fa\u51c6\u6d4b\u8bd5,\u4e5f\u53ef\u4ee5\u4f7f\u7528\u65e5\u5fd7\u548cEXPLAIN\u9010\u4e2a\u5206\u6790\u4e8b\u4ef6\u6216\u8005\u4f7f\u7528ERFORMANCE_SCHEMA\u6309\u7ec4\u5206\u6790\u4e8b\u4ef6;
\n2.\u57fa\u51c6\u6d4b\u8bd5:
\n 1.mysqlslap:\u662f\u6807\u51c6MySQL\u5206\u53d1\u7684\u4e00\u90e8\u5206,\u662f\u4e00\u4e2a\u57fa\u51c6\u6d4b\u8bd5\u5de5\u5177,\u7528\u6765\u6a21\u62dfMySQL\u670d\u52a1\u5668\u5b9e\u4f8b\u4e0a\u5ba2\u6237\u673a\u8d1f\u8f7d,\u5e76\u663e\u793a\u6bcf\u4e2a\u9636\u6bb5\u7684\u8ba1\u65f6\u4fe1\u606f;
\n 2.sql-bench:\u662fMySQL\u6e90\u7801\u5206\u53d1\u7684\u4e00\u90e8\u5206,\u5b83\u662f\u4e00\u7cfb\u5217Perl\u811a\u6b65,\u7528\u4e8e\u6267\u884c\u591a\u4e2a\u8bed\u53e5\u548c\u624b\u673a\u72b6\u6001\u8ba1\u65f6\u6570\u636e;
\n3.\u5206\u6790:
\n 1.\u65e5\u5fd7:
\n 1.\u4e00\u822c\u67e5\u8be2\u65e5\u5fd7;
\n 2.\u6162\u67e5\u8be2\u65e5\u5fd7;
\n 2.\u8bed\u53e5:
\n 1.EXPLAIN;
\n 2.PROCEDURE ANALYSE;
\n 3.SHOW STATUS:\u8fd8\u53ef\u4ee5\u4f7f\u7528mysqladmin extended-status\u67e5\u770b;
\n 4.PERFORMANCE_SCHEMA\u6570\u636e\u5e93;<\/p>\n
— \u6027\u80fd\u6a21\u5f0f;
\n\u201c\u6027\u80fd\u6a21\u5f0f\u201d\u662f\u5728\u8f83\u4f4e\u7ea7\u522b\u76d1\u89c6MySQL\u670d\u52a1\u5668\u6267\u884c\u60c5\u51b5\u7684\u529f\u80fd:
\n1.\u8be5\u529f\u80fd\u662f\u4f7f\u7528PERFORMANCE_SCHEMA\u5b58\u50a8\u5f15\u64ce\u548cperformance_schema\u6570\u636e\u5e93\u5b9e\u73b0\u7684;
\n2.\u6027\u80fd\u6a21\u5f0f\u76d1\u89c6\u5e76\u5141\u8bb8\u60a8\u68c0\u67e5MySQL\u670d\u52a1\u5668\u4e2d\u7684\u88ab\u68c0\u6d4b\u4ee3\u7801\u7684\u6027\u80fd\u7279\u5f81:
\n 1.\u5f00\u53d1\u8005\u5c06\u68c0\u6d4b\u51fd\u6570\u548c\u5176\u4ed6\u7f16\u7801\u4e8b\u4ef6\u4ee5\u6536\u96c6\u8ba1\u65f6\u4fe1\u606f;
\n 2.\u516c\u5f00\u7684\u6027\u80fd\u6570\u636e\u5bf9\u4ee5\u4e0b\u4eba\u5458\u6216\u4efb\u52a1\u5f88\u6709\u5e2e\u52a9:
\n 1.MySQL\u4ee3\u7801\u5e93\u7684\u8d21\u732e\u8005;
\n 2.\u63d2\u4ef6\u5f00\u53d1\u8005;
\n 3.\u8bc6\u522b\u4f4e\u7ea7\u522b\u7684\u6027\u80fd\u74f6\u9888,\u5982\u65e5\u5fd7\u6587\u4ef6I\/O\u7b49\u5f85\u6216\u7f13\u51b2\u6c60\u4e92\u65a5;
\n3.\u4eceOracle\u4e0b\u8f7d\u7684\u6240\u6709\u4e8c\u8fdb\u5236\u7248\u672c\u7684MySQL\u4e2d\u90fd\u63d0\u4f9b\u4e86\u6027\u80fd\u6a21\u5f0f;\u9ed8\u8ba4\u60c5\u51b5\u4e0b,\u5c06\u542f\u7528\u6027\u80fd\u6a21\u5f0f,\u5e76\u5728\u670d\u52a1\u5668\u542f\u52a8\u65f6\u4f7f\u7528performance_schema\u53d8\u91cf\u5bf9\u5176\u8fdb\u884c\u63a7\u5236;
\nmysql> SHOW VARIABLES LIKE ‘performance_schema’;
\nmysql> SHOW TABLE STATUS FROM performance_schema\\G<\/p>\n
— \u68c0\u6d4b,\u5b9e\u4f8b,\u4e8b\u4ef6\u548c\u4f7f\u7528\u8005;
\n\u6027\u80fd\u6a21\u5f0f\u6570\u636e\u5e93\u5305\u542b\u914d\u7f6e\u548c\u4e8b\u4ef6\u4fe1\u606f:
\n1.\u6027\u80fd\u6a21\u5f0f\u4e2d\u7684\u201c\u68c0\u6d4b\u201d\u662f\u670d\u52a1\u5668\u4ee3\u7801\u4e2d\u5f15\u53d1\u8981\u76d1\u89c6\u7684\u4e8b\u4ef6\u7684\u70b9;
\n 1.\u6bcf\u4e2a\u68c0\u6d4b\u7531\u5176\u7c7b\u578b\/\u6240\u5c5e\u7684\u6a21\u5757\/\u8be5\u7279\u5b9a\u68c0\u6d4b\u7684\u53d8\u91cf\u6216\u7c7b\u7ec4\u6210,\u901a\u8fc7\u67e5performance_schema.setup_instruments\u8868\u53ef\u67e5\u770b\u6240\u6709\u53ef\u7528\u7684\u68c0\u6d4b;
\n 2.\u6027\u80fd\u6a21\u5f0f\u5c06\u8bb0\u5f55\u5b9e\u4f8b\u8868\u4e2d\u7684\u6bcf\u4e2a\u68c0\u6d4b\u5b9e\u4f8b;\u4f8b\u5982,\u4ee5\u4e0b\u67e5\u8be2\u663e\u793a\u68c0\u6d4bwait\/io\/file\/sql\/FRM\u8bb0\u5f55\u6587\u4ef6\u5b9e\u4f8b\/var\/lib\/mysql\/mem\/tags.frm\u4e0a\u7684\u4e8b\u4ef6;
\n mysql> SELECT file_name, event_name FROM file_instances LIMIT 1\\G *************************** 1. row ***************************
\n FILE_NAME: \/var\/lib\/mysql\/mem\/tags.frm
\n EVENT_NAME: wait\/io\/file\/sql\/FRM
\n2.\u6bcf\u4e2a\u88ab\u68c0\u6d4b\u7684\u5bf9\u8c61\u90fd\u662f\u8be5\u68c0\u6d4b\u7684\u4e00\u4e2a\u201c\u5b9e\u4f8b\u201d,\u8bb0\u5f55\u5728\u4e00\u7cfb\u5217\u5b9e\u4f8b\u8868\u4e2d;
\n3.\u5f53\u7ebf\u7a0b\u6267\u884c\u68c0\u6d4b\u5b9e\u4f8b\u4e2d\u7684\u4ee3\u7801\u65f6,MySQL\u5c06\u8bc6\u522b\u6240\u53d1\u751f\u7684\u201c\u4e8b\u4ef6\u201d,\u5c06\u5176\u8bb0\u5f55\u5728\u4e8b\u4ef6\u548c\u6c47\u603b\u8868\u4e2d;
\n4.\u6bcf\u4e2a\u201c\u4f7f\u7528\u8005\u201d\u90fd\u662f\u6027\u80fd\u6a21\u5f0f\u4e2d\u8868\u7684\u540d\u79f0,\u7528\u4e8e\u8bb0\u5f55\u548c\u67e5\u8be2\u4e8b\u4ef6\u4ee5\u53ca\u4e8b\u4ef6\u7684\u6458\u8981,\u5728SETUP_CONSUMERS\u8868\u4e2d\u8fdb\u884c\u914d\u7f6e;\u6bcf\u4e2a\u4f7f\u7528\u8005\u7684NAME\u662f\u6027\u80fd\u6a21\u5f0f\u4e2d\u7528\u4e8e\u67e5\u8be2\u4e8b\u4ef6\u548c\u6458\u8981\u7684\u8868\u7684\u540d\u79f0,\u88ab\u7981\u7528\u7684\u4f7f\u7528\u8005\u4e0d\u8bb0\u5f55\u4fe1\u606f,\u4ece\u800c\u8282\u7701\u4e86\u7cfb\u7edf\u8d44\u6e90;
\n mysql> SELECT * FROM setup_consumers;
\n5.\u5f53MySQL\u8bc6\u522b\u4e86\u53d1\u751f\u5728\u68c0\u6d4b\u5b9e\u4f8b\u4e2d\u7684\u4e8b\u4ef6\u540e,\u4f1a\u5c06\u5176\u8bb0\u5f55\u5728\u4e8b\u4ef6\u8868\u4e2d:
\n 1.\u4e3b\u4e8b\u4ef6\u8868\u4e3aevents_waits_current,\u8be5\u8868\u4e2d\u5b58\u50a8\u4e86\u6bcf\u4e2a\u7ebf\u7a0b\u6700\u8fd1\u7684\u4e8b\u4ef6;
\n 2.events_waits_history\u5b58\u50a8\u6bcf\u4e2a\u7ebf\u7a0b\u7684\u6700\u8fd110\u4e2a\u4e8b\u4ef6;
\n 3.events_waits_history_long\u5171\u5b58\u50a810,000\u4e2a\u6700\u8fd1\u4e8b\u4ef6;
\n6.\u5f53\u4f7f\u7528\u6027\u80fd\u6a21\u5f0f\u8bc6\u522b\u74f6\u9888\u6216\u5176\u4ed6\u95ee\u9898\u65f6,\u8bf7\u6267\u884c\u4ee5\u4e0b\u64cd\u4f5c:
\n 1.\u786e\u4fdd\u5df2\u9488\u5bf9\u9002\u7528\u4e8e\u60a8\u6240\u9047\u5230\u7684\u95ee\u9898\u7c7b\u578b\u7684\u4e00\u7cfb\u5217\u68c0\u6d4b\u548c\u4f7f\u7528\u8005\u542f\u7528\u4e86\u6027\u80fd\u6a21\u5f0f;\u4f8b\u5982,\u5982\u679c\u60a8\u786e\u5b9a\u95ee\u9898\u51fa\u5728I\/O\u9650\u5236\u4e0a,\u8bf7\u4f7f\u7528wait\/io\/file\/*\u68c0\u6d4b;\u5982\u679c\u4e0d\u786e\u5b9a\u6839\u672c\u539f\u56e0,\u8bf7\u4f7f\u7528\u66f4\u5e7f\u8303\u56f4\u7684\u68c0\u6d4b;
\n 2.\u8fd0\u884c\u7528\u4e8e\u4ea7\u751f\u8be5\u95ee\u9898\u7684\u6d4b\u8bd5\u7528\u4f8b;
\n 3.\u67e5\u8be2events_waits_*\u8868\u7b49\u4f7f\u7528\u8005,\u5c24\u5176\u662f\u4f7f\u7528\u9002\u7528\u7684WHERE\u5b50\u53e5\u8fc7\u6ee4\u5668\u67e5\u8be2events_waits_history_long,\u4ee5\u4fbf\u8fdb\u4e00\u6b65\u7f29\u5c0f\u95ee\u9898\u539f\u56e0\u7684\u8303\u56f4;
\n 4.\u7981\u7528\u90a3\u4e9b\u7528\u4e8e\u8bc4\u4f30\u5df2\u6392\u9664\u7684\u95ee\u9898\u7684\u68c0\u6d4b;
\n 5.\u91cd\u8bd5\u8be5\u6d4b\u8bd5\u7528\u4f8b;<\/p>\n
— \u4e00\u822c\u6570\u636e\u5e93\u4f18\u5316;
\n1.\u5bf9\u6570\u636e\u8fdb\u884c\u6807\u51c6\u5316\u53ef\u4ee5:
\n 1.\u6807\u51c6\u5316\u662f\u79fb\u9664\u6570\u636e\u5e93\u4e2d\u7684\u5197\u4f59\u548c\u4e0d\u5f53\u4f9d\u8d56\u5173\u7cfb(\u4ee5\u907f\u514d\u5c06\u76f8\u540c\u7684\u6570\u636e\u5b58\u50a8\u5728\u591a\u4e2a\u5730\u65b9\u4ee5\u53ca\u51fa\u73b0\u5f02\u5e38\u7684\u98ce\u9669)\u7684\u884c\u4e3a;
\n 2.\u6807\u51c6\u5316\u901a\u5e38\u4f1a\u4ea7\u751f\u4ee5\u4e0b\u7ed3\u679c:\u8bb8\u591a\u8868\u7684\u5217\u53d8\u5c11,\u6574\u4f53\u5b58\u50a8\u8981\u6c42\u964d\u4f4e,I\/O\u9700\u6c42\u964d\u4f4e\u4ee5\u53ca\u5355\u6b21\u63d2\u5165,\u66f4\u65b0\u548c\u5220\u9664\u64cd\u4f5c\u52a0\u5feb;
\n 3.\u8fd9\u63d0\u9ad8\u4e86\u9891\u7e41\u6267\u884c\u5c0f\u66f4\u65b0\u7684\u4e8b\u52a1\u6027\u5de5\u4f5c\u8d1f\u8377\u7684\u6027\u80fd,\u4f46\u4f1a\u4f7f\u68c0\u7d22\u5927\u91cf\u6570\u636e\u7684\u67e5\u8be2\u53d8\u5f97\u590d\u6742;
\n2.\u9009\u62e9\u6b63\u786e\u7684\u6570\u636e\u7c7b\u578b\u548c\u5927\u5c0f\u53ef\u4ee5:
\n 1.\u9009\u62e9\u6b63\u786e\u7684\u6570\u636e\u7c7b\u578b\u662f\u8868\u8bbe\u8ba1\u4e2d\u4e00\u4e2a\u5f88\u91cd\u8981\u5374\u5e38\u5e38\u88ab\u5ffd\u89c6\u7684\u90e8\u5206,\u6570\u636e\u7c7b\u578b\u7684\u5927\u5c0f\u53ef\u80fd\u4f1a\u5bf9\u8868\u64cd\u4f5c\u4ea7\u751f\u8f83\u5927\u7684\u5f71\u54cd;\u4f8b\u5982,\u9009\u62e9\u5c06SMALLINT\u6570\u5b57\u5b58\u50a8\u4e3aINT\u4f1a\u4f7f\u8be5\u5217\u6240\u9700\u7684\u7a7a \u95f4\u7ffb\u500d,\u5728\u5305\u542b\u4e00\u767e\u4e07\u4e2a\u884c\u7684\u8868\u4e2d,\u8be5\u51b3\u7b56\u5c06\u5bfc\u81f4\u6d6a\u8d39\u989d\u5916\u76842MB\u5b58\u50a8\u7a7a\u95f4,\u5e76\u4e14\u78c1\u76d8\u64cd\u4f5c\u901f\u5ea6\u4f1a\u53d8\u6162,\u7f13\u51b2\u533a\u548c\u9ad8\u901f\u7f13\u5b58\u5c06\u9700\u8981\u4f7f\u7528\u66f4\u591a\u5185\u5b58;
\n 2.\u4f7f\u7528INSERT…COMPRESS(field_name)…\u548cSELECT…UNCOMPRESS(column_name)…\u53ef\u4ee5\u5728\u5b58\u50a8\u548c\u68c0\u7d22\u5b57\u7b26\u4e32\u6570\u636e\u65f6\u5bf9\u5176\u8fdb\u884c\u538b\u7f29\u548c\u89e3\u538b\u7f29;\u5c3d\u7ba1\u4e5f\u53ef\u4ee5\u4f7f\u7528CHAR\u6216VARCHAR\u5b57\u6bb5\u6765\u5b9e\u73b0\u6b64\u76ee\u7684,\u4f46\u662f\u901a\u8fc7\u4f7f\u7528VARBINARY\u6216BLOB\u5217\u5b58\u50a8\u538b\u7f29\u6570\u636e\u53ef\u4ee5\u907f\u514d\u5b57\u7b26\u96c6\u8f6c\u6362\u51fa\u73b0\u95ee\u9898;
\n3.\u521b\u5efa\u6700\u4f73\u7d22\u5f15\u53ef\u4ee5:
\n 1.\u5982\u679c\u60a8\u901a\u8fc7\u5728WHERE\u5b50\u53e5\u4e2d\u6307\u5b9a\u4e00\u4e2a\u5b57\u6bb5\u6765\u67e5\u8be2\u8868\u4e2d\u7684\u7279\u5b9a\u884c,\u5e76\u4e14\u8be5\u8868\u6ca1\u6709\u4e3a\u8be5\u5b57\u6bb5\u521b\u5efa\u7d22\u5f15,MySQL\u5c06\u8bfb\u53d6\u8be5\u8868\u4e2d\u7684\u6bcf\u4e00\u884c\u4ee5\u627e\u5230\u6bcf\u4e2a\u5339\u914d\u7684\u884c;\u8fd9\u5c06\u5bfc\u81f4\u5f88\u591a\u4e0d\u5fc5\u8981\u7684\u78c1\u76d8\u8bbf\u95ee,\u5e76\u4e14\u5bf9\u4e8e\u5927\u578b\u8868\u6027\u80fd\u5c06\u663e\u8457\u964d\u4f4e;
\n 2.\u7d22\u5f15\u662f\u6709\u5e8f\u7684\u6210\u7ec4\u6570\u636e,\u901a\u8fc7\u7d22\u5f15,MySQL\u53ef\u4ee5\u66f4\u5bb9\u6613\u5730\u627e\u5230\u67e5\u8be2\u884c\u7684\u6b63\u786e\u4f4d\u7f6e;\u9ed8\u8ba4\u60c5\u51b5\u4e0b,InnoDB\u5c06\u6309\u4e3b\u952e\u6392\u5217\u8868\u7684\u987a\u5e8f,\u8be5\u6709\u5e8f\u8868\u79f0\u4e3a\u7fa4\u96c6\u7d22\u5f15;
\n 3.InnoDB\u8868\u4e0a\u7684\u6bcf\u4e2a\u9644\u52a0\u7d22\u5f15\u6216\u8f85\u52a9\u7d22\u5f15\u4f1a\u5728\u6587\u4ef6\u7cfb\u7edf\u4e2d\u5360\u7528\u989d\u5916\u7684\u7a7a\u95f4,\u56e0\u4e3a\u7d22\u5f15\u5305\u542b\u7d22\u5f15\u5b57\u6bb5\u7684\u989d\u5916\u526f\u672c\u4ee5\u53ca\u4e3b\u952e\u7684\u526f\u672c;
\n 4.\u6bcf\u6b21\u4f7f\u7528INSERT\/UPDATE\/REPLACE\/DELETE\u64cd\u4f5c\u4fee\u6539\u6570\u636e\u65f6,MySQL\u4e5f\u5fc5\u987b\u66f4\u65b0\u6240\u6709\u5305\u542b\u4fee\u6539\u5b57\u6bb5\u7684\u7d22\u5f15,\u56e0\u6b64,\u5411\u8868\u4e2d\u6dfb\u52a0\u591a\u4e2a\u7d22\u5f15\u4f1a\u964d\u4f4e\u5f71\u54cd\u8be5\u8868\u7684\u6570\u636e\u4fee\u6539\u64cd\u4f5c\u7684\u6027\u80fd;
\n 5.\u4e0d\u8fc7,\u5982\u679c\u5bf9\u7d22\u5f15\u8fdb\u884c\u4e86\u9002\u5f53\u8bbe\u8ba1,\u4f9d\u8d56\u4e8e\u7d22\u5f15\u5b57\u6bb5\u7684\u67e5\u8be2\u4fbf\u4f1a\u5728\u6027\u80fd\u4e0a\u6709\u8f83\u5927\u7684\u83b7\u76ca;\u5982\u679c\u67e5\u8be2\u65e0\u6cd5\u4f7f\u7528\u7d22\u5f15\u627e\u5230\u7279\u5b9a\u884c,\u5219\u5fc5\u987b\u6267\u884c\u5168\u8868\u626b\u63cf;\u5373,\u5fc5\u987b\u8bfb\u53d6\u6574\u4e2a\u8868\u6765\u627e\u5230\u8be5\u884c;<\/p>\n
— PROCEDURE ANALYSE;
\n1.PROCEDURE ANALYSE\u5206\u6790\u7ed9\u5b9a\u67e5\u8be2\u4e2d\u7684\u5217,\u5e76\u63d0\u4f9b\u5bf9\u6bcf\u4e2a\u5b57\u6bb5\u7684\u8c03\u8282\u53cd\u9988:mysql> SELECT CountryCode, District, Population FROM City PROCEDURE ANALYSE(250,1024)\\G
\n2.\u63d0\u4f9b\u53c2\u6570\u6765\u8c03\u8282\u5982\u4f55\u5efa\u8baeENUM\u503c:
\n 1.\u5904\u7406\u5217\u65f6\u6240\u4f7f\u7528\u7684\u6700\u5927\u5143\u7d20\u6570\u548c\u6700\u5927\u5185\u5b58;
\n 2.\u793a\u4f8b:…PROCEDURE ANALYSE(100,256);
\n3.\u7528\u4e8e\u6700\u5927\u7a0b\u5ea6\u5730\u51cf\u5c0f\u5b57\u6bb5\u5927\u5c0f:
\n 1.MySQL\u901a\u5e38\u6309\u6700\u5927\u7684\u5b57\u6bb5\u5927\u5c0f\u5206\u914d\u5185\u5b58;
\n 2.\u9690\u5f0fMEMORY\u4e34\u65f6\u8868,\u6392\u5e8f\u7f13\u51b2\u533a\u7b49;
\n4.\u7528\u4e8e\u786e\u5b9a\u5b57\u6bb5\u662f\u5426\u5141\u8bb8NULL;<\/p>\n
\u8865\u5145:
\n1.\u9ed8\u8ba4\u8bbe\u7f6e\u901a\u5e38\u5efa\u8bae\u4f7f\u7528ENUM\u7c7b\u578b\u6765\u4f18\u5316\u8868\u7684\u8bbe\u8ba1,\u5982\u679c\u786e\u5b9a\u4e0d\u60f3\u5728\u5206\u6790\u5217\u65f6\u4f7f\u7528PROCEDURE ANALYSE()\u6240\u5efa\u8bae\u7684ENUM\u503c,\u8bf7\u4f7f\u7528\u975e\u9ed8\u8ba4\u53c2\u6570:
\n 1.\u7b2c\u4e00\u4e2a\u53c2\u6570\u662f\u5206\u6790ENUM\u503c\u662f\u5426\u9002\u5f53\u65f6\u8981\u8003\u8651\u7684\u4e0d\u540c\u5143\u7d20\u6570,\u6b64\u53c2\u6570\u7684\u9ed8\u8ba4\u503c\u4e3a256;
\n 2.\u7b2c\u4e8c\u4e2a\u53c2\u6570\u662f\u7528\u4e8e\u6536\u96c6\u4e0d\u540c\u7684\u503c\u4ee5\u4f9b\u5206\u6790\u7684\u6700\u5927\u5185\u5b58\u91cf,\u6b64\u53c2\u6570\u7684\u9ed8\u8ba4\u503c\u4e3a8192,\u8868\u793a8KB;\u5982\u679c\u4e3a\u6b64\u53c2\u6570\u8bbe\u7f6e\u503c0,\u5219PROCEDURE ANALYSE()\u65e0\u6cd5\u68c0\u67e5\u4e0d\u540c\u7684\u503c\u4ee5\u5efa\u8bae\u4f7f\u7528ENUM\u7c7b\u578b;
\n2.\u5982\u679cPROCEDURE ANALYSE()\u65e0\u6cd5\u5b58\u50a8\u53ef\u63a5\u53d7\u8303\u56f4\u5185\u7684\u5019\u9009ENUM\u503c(\u5728\u53c2\u6570\u8bbe\u7f6e\u7684\u9650\u5236\u5185),\u5219\u4e0d\u4f1a\u5efa\u8bae\u5bf9\u8be5\u5217\u4f7f\u7528ENUM\u7c7b\u578b;
\n3.\u672c\u5e7b\u706f\u7247\u4e2d\u7684\u793a\u4f8b\u5efa\u8bae\u5bf9City.CountryCode\u5217\u4f7f\u7528CHAR(3)\u7c7b\u578b;\u53e6\u4e00\u65b9\u9762,\u5982\u679c\u4f7f\u7528\u9ed8\u8ba4\u53c2\u6570,\u5219PROCEDURE ANALYSE()\u5c06\u5efa\u8baeENUM(‘ABW’,’AFG’,…,’ZMB’,’ZWE’),\u8fd9\u662f\u4e00\u79cd\u5305\u542b\u8d85\u8fc7200\u4e2a\u5143\u7d20\u7684ENUM\u7c7b\u578b,\u5176\u4e2d\u9488\u5bf9\u6bcf\u4e2a\u76f8\u5e94\u7684CountryCode\u503c\u90fd\u5305\u542b\u4e00\u4e2a\u4e0d\u540c\u503c;<\/p>\n
— EXPLAIN;
\n1.EXPLAIN\u547d\u4ee4:
\n 1.\u63cf\u8ff0MySQL\u6253\u7b97\u5982\u4f55\u6267\u884c\u7279\u5b9a\u7684SQL\u8bed\u53e5;
\n 2.\u4e0d\u8fd4\u56de\u6570\u636e\u96c6\u7684\u4efb\u4f55\u6570\u636e;
\n 3.\u63d0\u4f9b\u6709\u5173MySQL\u6253\u7b97\u5982\u4f55\u6267\u884c\u8be5\u8bed\u53e5\u7684\u4fe1\u606f;
\n2.\u4f7f\u7528EXPLAIN\u53ef\u68c0\u67e5SELECT\/INSERT\/REPLACE\/UPDATE\/DELETE\u8bed\u53e5;
\n3.\u5c06EXPLAIN\u7f6e\u4e8e\u8bed\u53e5\u4e4b\u524d:
\n 1.EXPLAIN SELECT …;
\n 2.EXPLAIN UPDATE…;<\/p>\n
\u8865\u5145: select_type\u5217: type\u5217:\u8bbf\u95ee\u8def\u5f84(\u6548\u7387\u4f9d\u6b21\u964d\u4f4e): — \u68c0\u67e5\u670d\u52a1\u5668\u72b6\u6001; — \u4e3b\u8981\u72b6\u6001\u53d8\u91cf; — \u8c03\u8282\u7cfb\u7edf\u53d8\u91cf; — \u4e3b\u8981\u670d\u52a1\u5668\u7cfb\u7edf\u53d8\u91cf; — \u51c6\u5907\u8c03\u8282\u73af\u5883; — \u7ec3\u4e60\u8c03\u8282; — \u8c03\u8282\u793a\u4f8b:\u6392\u5e8f\u7f13\u51b2\u533a\u5927\u5c0f; — \u8bfe\u540e\u7ec3\u4e60;<\/p>\n — \u8865\u5145:Extra\u5176\u5b83\u4fe1\u606f; — \u5f71\u54cd\u6027\u80fd\u7684\u56e0\u7d20; 1.\u73af\u5883\u95ee\u9898,MySQL\u7684\u6027\u80fd\u53d7\u4e3b\u673a\u7684\u6027\u80fd\u7279\u5f81\u5f71\u54cd: 1.CPU\u901f\u5ea6\u548c\u6570\u91cf; […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[21],"tags":[27,31],"class_list":["post-1323","post","type-post","status-publish","format-standard","hentry","category-mysql","tag-mysql","tag-mysql_ocp"],"_links":{"self":[{"href":"http:\/\/www.royalwzy.com\/index.php?rest_route=\/wp\/v2\/posts\/1323","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.royalwzy.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.royalwzy.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.royalwzy.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.royalwzy.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1323"}],"version-history":[{"count":1,"href":"http:\/\/www.royalwzy.com\/index.php?rest_route=\/wp\/v2\/posts\/1323\/revisions"}],"predecessor-version":[{"id":1324,"href":"http:\/\/www.royalwzy.com\/index.php?rest_route=\/wp\/v2\/posts\/1323\/revisions\/1324"}],"wp:attachment":[{"href":"http:\/\/www.royalwzy.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1323"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.royalwzy.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1323"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.royalwzy.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1323"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\n1.EXPLAIN\u5c06\u4e3a\u8bed\u53e5\u4e2d\u4f7f\u7528\u7684\u6bcf\u4e2a\u8868\u751f\u6210\u4e00\u884c\u8f93\u51fa,\u8be5\u8f93\u51fa\u5305\u542b\u4ee5\u4e0b\u5217:
\n 1.id:\u7f16\u53f7;\u82e5\u6ca1\u6709\u5b50\u67e5\u8be2\u548c\u8054\u5408\u67e5\u8be2,id\u5219\u90fd\u662f1;MySQL\u4f1a\u6309\u7167id\u4ece\u5927\u5230\u5c0f\u7684\u987a\u5e8f\u6267\u884cquery,\u5728id\u76f8\u540c\u7684\u60c5\u51b5\u4e0b,\u5219\u4ece\u4e0a\u5230\u4e0b\u6267\u884c;
\n 2.select_type:\u67e5\u8be2\u4e2d\u4f7f\u7528\u7684\u9009\u62e9\u7c7b\u578b;
\n 3.table:\u8f93\u51fa\u7684\u884c\u6240\u5f15\u7528\u7684\u8868;\u6709\u65f6\u770b\u5230\u7684\u662f
\n 4.partitions:\u8f93\u51fa\u884c\u6240\u5bf9\u5e94\u7684\u8868\u5206\u533a;
\n 5.type:\u8bbf\u95ee\u7c7b\u578b,\u8fde\u63a5\u7684\u65b9\u5f0f;
\n 6.possible_keys:\u5728\u67e5\u8be2\u8fc7\u7a0b\u4e2d\u53ef\u80fd\u7528\u5230\u7684\u7d22\u5f15;\u5728\u4f18\u5316\u521d\u671f\u521b\u5efa\u8be5\u5217,\u4f46\u5728\u4ee5\u540e\u7684\u4f18\u5316\u8fc7\u7a0b\u4e2d\u4f1a\u6839\u636e\u5b9e\u9645\u60c5\u51b5\u8fdb\u884c\u9009\u62e9,\u6240\u4ee5\u5728\u8be5\u5217\u5217\u51fa\u7684\u7d22\u5f15\u5728\u540e\u7eed\u8fc7\u7a0b\u4e2d\u53ef\u80fd\u6ca1\u7528;\u8be5\u5217\u4e3aNULL\u610f\u5473\u7740\u6ca1\u6709\u76f8\u5173\u7d22\u5f15,\u53ef\u4ee5\u6839\u636e\u5b9e\u9645\u60c5\u51b5\u770b\u662f\u5426\u9700\u8981\u52a0\u7d22\u5f15;
\n 7.key:\u8bbf\u95ee\u8fc7\u7a0b\u4e2d\u5b9e\u9645\u7528\u5230\u7684\u7d22\u5f15;\u6709\u53ef\u80fd\u4e0d\u4f1a\u51fa\u73b0\u5728possible_keys\u4e2d(\u8fd9\u65f6\u53ef\u80fd\u7528\u7684\u662f\u8986\u76d6\u7d22\u5f15,\u5373\u4f7fquery\u4e2d\u6ca1\u6709where);possible_keys\u63ed\u793a\u54ea\u4e2a\u7d22\u5f15\u66f4\u6709\u6548,key\u662f\u4f18\u5316\u5668\u51b3\u5b9a\u54ea\u4e2a\u7d22\u5f15\u53ef\u80fd\u6700\u5c0f\u5316\u67e5\u8be2\u6210\u672c,\u67e5\u8be2\u6210\u672c\u57fa\u4e8e\u7cfb\u7edf\u5f00\u9500\u7b49\u603b\u548c\u56e0\u7d20,\u6709\u53ef\u80fd\u662f\u201c\u6267\u884c\u65f6\u95f4\u201d\u77db\u76fe;\u5982\u679c\u5f3a\u5236mysql\u4f7f\u7528\u6216\u8005\u5ffd\u7565possible_keys\u4e2d\u7684\u7d22\u5f15,\u9700\u8981\u5728query\u4e2d\u4f7f\u7528FORCE INDEX,USE INDEX\u6216\u8005IGNORE INDEX;
\n 8.key_len:\u663e\u793a\u4f7f\u7528\u7d22\u5f15\u7684\u5b57\u8282\u6570;\u7531\u6839\u636e\u8868\u7ed3\u6784\u8ba1\u7b97\u5f97\u51fa,\u800c\u4e0d\u662f\u5b9e\u9645\u6570\u636e\u7684\u5b57\u8282\u6570;\u5982ColumnA(char(3)) ColumnB(int(11)),\u5728utf-8\u7684\u5b57\u7b26\u96c6\u4e0b,key_len=3*3+4=13;\u8ba1\u7b97\u8be5\u503c\u65f6\u9700\u8981\u8003\u8651\u5b57\u7b26\u5217\u5bf9\u5e94\u7684\u5b57\u7b26\u96c6,\u4e0d\u540c\u5b57\u7b26\u96c6\u5bf9\u5e94\u4e0d\u540c\u7684\u5b57\u8282\u6570;
\n 9.ref:\u663e\u793a\u4e86\u54ea\u4e9b\u5b57\u6bb5\u6216\u8005\u5e38\u91cf\u88ab\u7528\u6765\u548ckey\u914d\u5408\u4ece\u8868\u4e2d\u67e5\u8be2\u8bb0\u5f55\u51fa\u6765;\u663e\u793a\u90a3\u4e9b\u5728index\u67e5\u8be2\u4e2d\u88ab\u5f53\u4f5c\u503c\u4f7f\u7528\u7684\u5728\u5176\u4ed6\u8868\u91cc\u7684\u5b57\u6bb5\u6216\u8005constants
\n 10.rows:\u4f30\u8ba1\u4e3a\u8fd4\u56de\u7ed3\u679c\u96c6\u800c\u9700\u8981\u626b\u63cf\u7684\u884c;\u4e0d\u662f\u6700\u7ec8\u7ed3\u679c\u96c6\u7684\u51fd\u6570,\u628a\u6240\u6709\u7684rows\u4e58\u8d77\u6765\u53ef\u4f30\u7b97\u51fa\u6574\u4e2aquery\u9700\u8981\u68c0\u67e5\u7684\u884c\u6570,\u6709limit\u65f6\u4f1a\u4e0d\u51c6\u786e;
\n 11.filtered:\u6839\u636e\u6761\u4ef6\u8fc7\u6ee4\u7684\u884c\u767e\u5206\u6bd4;
\n 12.Extra:\u4f18\u5316\u7a0b\u5e8f\u63d0\u4f9b\u7684\u6bcf\u4e2a\u67e5\u8be2\u7684\u9644\u52a0\u4fe1\u606f;
\n2.\u6709\u5173\u8f93\u51fa\u5217\u7684\u5b8c\u6574\u8bba\u8ff0:http:\/\/dev.mysql.com\/doc\/refman\/5.6\/en\/explain-output.html;
\n3.\u4f7f\u7528EXPLAIN EXTENDED…\u53ef\u67e5\u770b\u4f18\u5316\u7a0b\u5e8f\u63d0\u4f9b\u7684\u5176\u4ed6\u4fe1\u606f:http:\/\/dev.mysql.com\/doc\/refman\/5.6\/en\/explain-extended.html;<\/p>\n
\n1.SIMPLE:\u7b80\u5355\u67e5\u8be2,\u6ca1\u6709\u4f7f\u7528UNION\u548c\u5b50\u67e5\u8be2;
\n EXPLAIN SELECT * FROM actor WHERE actor_id = 1;
\n2.PRIMARY:\u5305\u542b\u5b50\u67e5\u8be2\u6216\u8054\u5408\u67e5\u8be2\u7684query\u4e2d,\u6700\u5916\u5c42\u7684select\u67e5\u8be2;
\n3.UNION:\u5728\u8054\u5408\u67e5\u8be2\u4e2d\u7b2c\u4e8c\u4e2a\u53ca\u5176\u4ee5\u540e\u7684select\u5bf9\u5e94\u7684\u7c7b\u578b;
\n EXPLAIN SELECT actor_id, last_update FROM film_actor UNION ALL SELECT actor_id, last_update FROM actor;
\n4.DEPENDENT UNION:\u5b50\u67e5\u8be2\u4e2d\u7684union,\u4e14\u4e3aunion\u4e2d\u7b2c\u4e8c\u4e2aselect\u5f00\u59cb\u7684\u540e\u9762\u6240\u6709select,\u540c\u6837\u4f9d\u8d56\u4e8e\u5916\u90e8\u67e5\u8be2\u7684\u7ed3\u679c\u96c6;
\n EXPLAIN SELECT * FROM actor WHERE actor_id IN (SELECT actor_id FROM film_actor UNION ALL SELECT actor_id FROM film_actor);
\n5.UNION RESULT:\u4eceUNION\u4e34\u65f6\u8868\u83b7\u53d6\u7ed3\u679c\u96c6\u5408;
\n6.SUBQUERY:\u5b50\u67e5\u8be2\u5728SELECT\u7684\u76ee\u6807\u91cc,\u4e0d\u5728FROM\u4e2d,\u5b50\u67e5\u8be2\u4e2d\u7684\u7b2c\u4e00\u4e2aSELECT;
\n EXPLAIN SELECT (SELECT actor_id FROM actor) FROM film_actor;
\n7.DEPENDENT SUBQUERY:\u5b50\u67e5\u8be2\u4e2d\u7684\u7b2c\u4e00\u4e2a\u67e5\u8be2,\u4f9d\u8d56\u4e8e\u5916\u90e8\u67e5\u8be2\u7684\u7ed3\u679c\u96c6;
\n8.DERIVED:\u5b50\u67e5\u8be2\u5728from\u5b50\u53e5\u4e2d,\u6267\u884c\u67e5\u8be2\u7684\u65f6\u5019\u4f1a\u628a\u5b50\u67e5\u8be2\u7684\u7ed3\u679c\u96c6\u653e\u5230\u4e34\u65f6\u8868(\u884d\u751f\u8868);
\n EXPLAIN SELECT * FROM (SELECT * FROM actor) AS a;
\n9.MATERIALIZED:\u7269\u5316\u5b50\u67e5\u8be2;
\n10.UNCACHEABLE SUBQUERY:\u8868\u793a\u5b50\u67e5\u8be2,\u4f46\u8fd4\u56de\u7ed3\u679c\u4e0d\u80fd\u88abcache,\u5fc5\u987b\u4f9d\u636e\u5916\u5c42\u67e5\u8be2\u91cd\u65b0\u8ba1\u7b97;
\n11.UNCACHEABLE UNION:\u8868\u793aunion\u7b2c\u4e8c\u4e2a\u6216\u4ee5\u540e\u7684select,\u4f46\u7ed3\u679c\u4e0d\u80fd\u88abcache,\u5fc5\u987b\u4f9d\u636e\u5916\u5c42\u67e5\u8be2\u91cd\u65b0\u8ba1\u7b97;<\/p>\n
\n0.NULL:\u5728\u4f18\u5316\u8fc7\u7a0b\u4e2d\u5c31\u5df2\u5f97\u5230\u7ed3\u679c,\u4e0d\u7528\u518d\u8bbf\u95ee\u8868\u6216\u7d22\u5f15;
\n EXPLAIN SELECT * FROM actor WHERE actor_id = -1;
\n1.system:\u5f53\u8868\u53ea\u6709\u4e00\u884c\u65f6\u5c31\u4f1a\u51fa\u73b0system\u7c7b\u578b;\u662fconst join\u7c7b\u578b\u7684\u7279\u4f8b;\u5728\u6ca1\u6709\u4efb\u4f55\u7d22\u5f15\u7684\u60c5\u51b5\u4e0b,\u53ea\u6709\u4e00\u6761\u6570\u636e,MyISAM\u4f1a\u663e\u793asystem,InnoDB\u4f1a\u663e\u793aALL;
\n use test;
\n CREATE TABLE t_sys1(id INT) ENGINE = InnoDB;
\n CREATE TABLE t_sys2(id INT) ENGINE = MyISAM;
\n INSERT INTO t_sys1 VALUES(1);
\n COMMIT;
\n INSERT INTO t_sys2 VALUES(1);
\n EXPLAIN SELECT * FROM t_sys1;
\n EXPLAIN SELECT * FROM t_sys2;
\n2.const:\u6700\u591a\u4f1a\u6709\u4e00\u6761\u8bb0\u5f55\u5339\u914d,\u56e0\u4e3a\u4ec5\u6709\u4e00\u884c,\u5728\u8fd9\u884c\u7684\u5217\u503c\u53ef\u88ab\u4f18\u5316\u5668\u5269\u4f59\u90e8\u5206\u8ba4\u4e3a\u662f\u5e38\u6570;const\u8868\u5f88\u5feb,\u56e0\u4e3a\u5b83\u4eec\u53ea\u8bfb\u53d6\u4e00\u6b21,\u53d1\u751f\u5728\u6709\u4e00\u4e2aunique key\u6216\u8005\u4e3b\u952e,\u5e76\u4e14where\u5b50\u53e5\u7ed9\u5b83\u8bbe\u5b9a\u4e86\u4e00\u4e2a\u6bd4\u8f83\u503c;
\n eg:EXPLAIN SELECT * FROM actor WHERE actor_id = 1;
\n3.eq_ref:\u5728\u505a\u5173\u8054\u67e5\u8be2\u4e2d,\u524d\u4e00\u4e2a\u8868\u8fd4\u56de\u7684\u503c\u5728\u6b64\u8868\u4e2d\u53ea\u6709\u4e00\u6761\u8bb0\u5f55\u5bf9\u5e94,\u8fd9\u662f\u5173\u8054\u67e5\u8be2\u7684\u6700\u597d\u9009\u62e9;\u6240\u4ee5,\u552f\u4e00\u6027\u7d22\u5f15(Primary or UNIQUE NOT NULL)\u624d\u4f1a\u51fa\u73b0eq_ref(\u975e\u552f\u4e00\u6027\u7d22\u5f15\u4f1a\u51fa\u73b0ref),\u56e0\u4e3a\u552f\u4e00,\u6240\u4ee5\u6700\u591a\u53ea\u8fd4\u56de\u4e00\u6761\u8bb0\u5f55,\u627e\u5230\u540e\u65e0\u9700\u7ee7\u7eed\u67e5\u627e,\u56e0\u6b64\u6bd4ref\u66f4\u5feb;
\n CREATE TABLE t_eq_ref(actor_id SMALLINT(5) PRIMARY KEY);
\n INSERT INTO t_eq_ref VALUES(1);
\n COMMIT;
\n EXPLAIN SELECT * FROM actor, t_eq_ref WHERE actor.actor_id = t_eq_ref.actor_id;
\n4.ref:\u8fd9\u662f\u4e00\u79cd\u7d22\u5f15\u8bbf\u95ee;\u53ea\u6709\u5f53\u4f7f\u7528\u4e00\u4e2a\u975e\u552f\u4e00\u6027\u7d22\u5f15\u6216\u8005\u552f\u4e00\u6027\u7d22\u5f15\u7684\u975e\u552f\u4e00\u6027\u524d\u7f00(\u6362\u53e5\u8bdd\u8bf4,\u5c31\u662f\u65e0\u6cd5\u6839\u636e\u8be5\u503c\u53ea\u53d6\u5f97\u4e00\u6761\u8bb0\u5f55)\u65f6\u624d\u4f1a\u53d1\u751f,\u5c06\u7d22\u5f15\u548c\u67d0\u4e2a\u503c\u76f8\u6bd4\u8f83,\u8fd9\u4e2a\u503c\u53ef\u80fd\u662f\u4e00\u4e2a\u5e38\u6570,\u4e5f\u53ef\u80fd\u662f\u6765\u81ea\u524d\u4e00\u4e2a\u8868\u91cc\u7684\u591a\u8868\u67e5\u8be2\u7684\u7ed3\u679c\u503c;\u5982\u679c\u4f7f\u7528\u7684\u952e\u4ec5\u4ec5\u5339\u914d\u5c11\u91cf\u884c,\u8be5\u8054\u63a5\u7c7b\u578b\u662f\u4e0d\u9519\u7684;
\n EXPLAIN SELECT * FROM film_actor, actor WHERE film_actor.actor_id=actor.actor_id AND film_actor.actor_id = 1;
\n5.ref_or_null:\u7c7b\u4f3cref,\u4e0d\u540c\u7684\u662fMySQL\u4f1a\u5728\u68c0\u7d22\u7684\u65f6\u5019\u989d\u5916\u7684\u641c\u7d22\u5305\u542bNULL\u503c\u7684\u8bb0\u5f55,\u4ed6\u610f\u5473\u7740MySQL\u5fc5\u987b\u8fdb\u884c\u4e8c\u6b21\u67e5\u627e,\u5728\u521d\u6b21\u67e5\u627e\u7684\u7ed3\u679c\u4e2d\u627e\u51faNULL\u6761\u76ee;
\n6.index_merge:\u67e5\u8be2\u4e2d\u4f7f\u7528\u4e24\u4e2a\u6216\u591a\u4e2a\u7d22\u5f15,\u7136\u540e\u5bf9\u7d22\u5f15\u7ed3\u679c\u8fdb\u884c\u5408\u5e76;\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b,key\u5217\u5305\u542b\u6240\u6709\u4f7f\u7528\u7684\u7d22\u5f15,key_len\u5305\u542b\u8fd9\u4e9b\u7d22\u5f15\u7684\u6700\u957f\u7684\u5173\u952e\u5143\u7d20;
\n7.unique_subquery:\u7528\u6765\u4f18\u5316\u6709\u5b50\u67e5\u8be2\u7684in,\u5e76\u4e14\u8be5\u5b50\u67e5\u8be2\u662f\u901a\u8fc7\u4e00\u4e2aunique key\u9009\u62e9\u7684,\u5b50\u67e5\u8be2\u8fd4\u56de\u7684\u5b57\u6bb5\u7ec4\u5408\u662f\u4e3b\u952e\u6216\u8005\u552f\u4e00\u7d22\u5f15;
\n value IN (SELECT primary_key FROM single_table WHERE some_expr)
\n EXPLAIN SELECT * FROM actor WHERE actor_id IN (SELECT actor_id FROM actor);
\n8.index_subquery:\u4e0eunique_subquery\u7c7b\u4f3c,\u5b50\u67e5\u8be2\u4e2d\u7684\u8fd4\u56de\u7ed3\u679c\u5b57\u6bb5\u7ec4\u5408\u662f\u4e00\u4e2a\u7d22\u5f15\u6216\u7d22\u5f15\u7ec4\u5408,\u4f46\u4e0d\u662f\u4e00\u4e2a\u4e3b\u952e\u6216\u8005\u552f\u4e00\u7d22\u5f15;
\n value IN (SELECT key_column FROM single_table WHERE some_expr)
\n EXPLAIN SELECT * FROM film_actor WHERE film_id IN (SELECT film_id FROM film_actor);
\n9.range:\u4f7f\u7528\u7d22\u5f15\u626b\u63cf,\u53ea\u67e5\u8be2\u7ed9\u5b9a\u8303\u56f4\u7684\u8bb0\u5f55;\u6bd4\u5982\u51fa\u73b0=, <>, >, >=, < , <=, IS NULL, <=>, BETWEEN, or IN()\u64cd\u4f5c\u7b26\u65f6:
\n EXPLAIN SELECT * FROM actor WHERE id < 10;\n10.index:\u6309\u7d22\u5f15\u6b21\u5e8f\u626b\u63cf\u6570\u636e,\u56e0\u4e3a\u6309\u7167\u7d22\u5f15\u626b\u63cf\u6240\u4ee5\u4f1a\u907f\u514d\u6392\u5e8f,\u4f46\u4e5f\u4f1a\u626b\u63cf\u6574\u8868\u6570\u636e,\u82e5\u968f\u673a\u8bfb\u53d6\u5f00\u9500\u4f1a\u66f4\u5927;\u5982\u679cextra\u5217\u663e\u793ausing index,\u8bf4\u660e\u4f7f\u7528\u7684\u662f\u8986\u76d6\u7d22\u5f15(\u8986\u76d6\u7d22\u5f15:\u5305\u542b\u6240\u6709\u6ee1\u8db3\u67e5\u8be2\u9700\u8981\u7684\u6570\u636e\u5217\u7684\u7d22\u5f15);\u5bf9\u4e8eInnoDB\u8868\u7279\u522b\u6709\u7528,\u6b64\u65f6\u53ea\u8bbf\u95ee\u7d22\u5f15\u6570\u636e\u5373\u53ef,\u4e0d\u7528\u518d\u6839\u636e\u4e3b\u952e\u4fe1\u606f\u83b7\u53d6\u539f\u6570\u636e\u884c,\u907f\u514d\u4e86\u4e8c\u6b21\u67e5\u8be2;\u800cMyISAM\u8868\u4f18\u5316\u6548\u679c\u76f8\u5bf9InnoDB\u6765\u8bf4\u6ca1\u6709\u90a3\u4e48\u7684\u660e\u663e;\n11.ALL:\u5168\u8868\u626b\u63cf;\u4e00\u822c\u60c5\u51b5\u4e0b,\u5e94\u8be5\u6dfb\u52a0\u7d22\u5f15\u6765\u907f\u514d\u5168\u8868\u626b\u63cf;\u51fa\u4e86\u4f7f\u7528limit\u5b50\u53e5\u6216\u8005Extra\u5217\u6709distinct\u4fe1\u606f;\n\nExtra\u5217:\n1.Using index:\u6b64\u67e5\u8be2\u4f7f\u7528\u4e86\u8986\u76d6\u7d22\u5f15(Covering Index),\u5373\u901a\u8fc7\u7d22\u5f15\u5c31\u80fd\u8fd4\u56de\u7ed3\u679c,\u65e0\u9700\u8bbf\u95ee\u8868;\u82e5\u6ca1\u663e\u793a\"Using index\"\u8868\u793a\u8bfb\u53d6\u4e86\u8868\u6570\u636e;\n EXPLAIN SELECT id FROM City WHERE id = 1890;\n2.Using where:\u8868\u793aMySQL\u670d\u52a1\u5668\u4ece\u5b58\u50a8\u5f15\u64ce\u6536\u5230\u884c\u540e\u518d\u8fdb\u884c\u201c\u540e\u8fc7\u6ee4\u201d(Post-filter);\u6240\u8c13\u201c\u540e\u8fc7\u6ee4\u201d,\u5c31\u662f\u5148\u8bfb\u53d6\u6574\u884c\u6570\u636e,\u518d\u68c0\u67e5\u6b64\u884c\u662f\u5426\u7b26\u5408where\u53e5\u7684\u6761\u4ef6,\u7b26\u5408\u5c31\u7559\u4e0b,\u4e0d\u7b26\u5408\u4fbf\u4e22\u5f03;\u56e0\u4e3a\u68c0\u67e5\u662f\u5728\u8bfb\u53d6\u884c\u540e\u624d\u8fdb\u884c\u7684,\u6240\u4ee5\u79f0\u4e3a\u201c\u540e\u8fc7\u6ee4\u201d;\n EXPLAIN SELECT id FROM City WHERE id < 10;\n3.Using temporary:\u4f7f\u7528\u5230\u4e34\u65f6\u8868\n EXPLAIN SELECT DISTINCT Continent FROM Country;\n4.Using filesort:\u82e5\u67e5\u8be2\u6240\u9700\u7684\u6392\u5e8f\u4e0e\u4f7f\u7528\u7684\u7d22\u5f15\u7684\u6392\u5e8f\u4e00\u81f4,\u56e0\u4e3a\u7d22\u5f15\u662f\u5df2\u6392\u5e8f\u7684,\u56e0\u6b64\u6309\u7d22\u5f15\u7684\u987a\u5e8f\u8bfb\u53d6\u7ed3\u679c\u8fd4\u56de;\u5426\u5219,\u5728\u53d6\u5f97\u7ed3\u679c\u540e,\u8fd8\u9700\u8981\u6309\u67e5\u8be2\u6240\u9700\u7684\u987a\u5e8f\u5bf9\u7ed3\u679c\u8fdb\u884c\u6392\u5e8f,\u8fd9\u65f6\u5c31\u4f1a\u51fa\u73b0Using filesort;\n EXPLAIN SELECT id, CountryCode FROM City WHERE id < 10 ORDER BY CountryCode;\n\nlatin1\/utf8\/gbk\u5b57\u7b26\u6570\/\u5b57\u8282\u6570\/\u6c49\u5b57\u7684\u5bf9\u5e94\u5173\u7cfb:\nlatin1:1character=1byte,1\u6c49\u5b57=2character;\u4e00\u4e2a\u5b57\u6bb5\u5b9a\u4e49\u6210varchar(200),\u53ef\u4ee5\u5b58\u50a8100\u4e2a\u6c49\u5b57\u6216\u8005200\u4e2a\u5b57\u7b26,\u5360\u7528200\u4e2a\u5b57\u8282;\u5c24\u5176\u662f\u5f53\u5b57\u6bb5\u5185\u5bb9\u662f\u5b57\u6bcd\u548c\u6c49\u5b57\u7ec4\u6210\u65f6,\u5c3d\u91cf\u5047\u8bbe\u5b57\u6bb5\u5185\u5bb9\u90fd\u662f\u7531\u6c49\u5b57\u7ec4\u6210,\u636e\u6b64\u6765\u8bbe\u7f6e\u5b57\u6bb5\u957f\u5ea6;\nutf8:1character=3bytes,1\u6c49\u5b57=1character;\u4e00\u4e2a\u5b57\u6bb5\u5b9a\u4e49\u6210varchar(200),\u5219\u5b83\u53ef\u4ee5\u5b58\u50a8200\u4e2a\u6c49\u5b57\u6216\u8005200\u4e2a\u5b57\u6bcd,\u5360\u7528600\u4e2a\u5b57\u8282;\ngbk:1character=2bytes,1\u6c49\u5b57=1character\u4e00\u4e2a\u5b57\u6bb5\u5b9a\u4e49\u6210varchar(200),\u5219\u5b83\u53ef\u4ee5\u5b58\u50a8200\u4e2a\u6c49\u5b57\u6216\u8005200\u4e2a\u5b57\u6bcd,\u5360\u7528400\u4e2a\u5b57\u8282;\n\n-- EXPLAIN\u683c\u5f0f;\nEXPLAIN\u8f93\u51fa\u4e5f\u63d0\u4f9b\u5176\u4ed6\u683c\u5f0f:\n1.\u53ef\u89c6\u5316EXPLAIN:\u5728MySQL Workbench\u4e2d\u63d0\u4f9b\u56fe\u5f62\u683c\u5f0f\u7684\u8f93\u51fa;\n2.EXPLAIN FORMAT=JSON:\n 1.JSON\u683c\u5f0f\u7684\u8f93\u51fa;JSON(JavaScript Object Notation,JavaScript\u5bf9\u8c61\u8868\u793a\u6cd5)\u662f\u4e00\u79cd\u7b80\u5355\u7684\u6570\u636e\u4ea4\u6362\u683c\u5f0f;\n 2.\u5f53\u8981\u5c06EXPLAIN\u8f93\u51fa\u4f20\u9012\u7ed9\u7a0b\u5e8f\u4ee5\u4f9b\u8fdb\u4e00\u6b65\u5904\u7406\/\u5206\u6790\u65f6\u5341\u5206\u6709\u7528;\n mysql> EXPLAIN FORMAT=JSON SELECT * FROM City\\G<\/p>\n
\nMySQL\u63d0\u4f9b\u4e86\u591a\u79cd\u67e5\u770b\u670d\u52a1\u5668\u72b6\u6001\u53d8\u91cf\u7684\u65b9\u6cd5:
\n1.\u5728mysql\u63d0\u793a\u7b26\u4e0b:
\n 1.STATUS;
\n 2.SHOW STATUS;
\n2.\u5728\u7ec8\u7aef\u4e0a:
\n 1.mysqladmin –login-path=login-path status
\n 2.mysqladmin -u user -p extended-status
\n3.\u5bf9mysqladmin\u4f7f\u7528\u9009\u9879\u53ef\u63d0\u4f9b\u9644\u52a0\u529f\u80fd;\u4f8b\u5982,–sleep(\u6216-i)\u9009\u9879\u53ef\u6307\u5b9a\u5728\u8fed\u4ee3\u4e4b\u95f4\u7b49\u5f85\u7684\u79d2\u6570,\u5e76\u5728\u7b49\u5f85\u8be5\u65f6\u95f4\u540e\u81ea\u52a8\u91cd\u65b0\u6267\u884c\u547d\u4ee4;–relative(\u6216-r)\u9009\u9879\u663e\u793a\u81ea\u4e0a\u6b21\u8fed\u4ee3\u540e\u6bcf\u4e2a\u53d8\u91cf\u7684\u5dee\u5f02,\u800c\u4e0d\u662f\u53d8\u91cf\u503c;
\n shell> mysqladmin -i 5 -r status<\/p>\n
\n1.Created_tmp_disk_tables:\u663e\u793a\u78c1\u76d8\u4e0a\u7684\u5185\u90e8\u4e34\u65f6\u8868\u7684\u6570\u91cf;\u83b7\u53d6\u6267\u884c\u8bed\u53e5\u65f6\u670d\u52a1\u5668\u6240\u521b\u5efa\u7684\u4e34\u65f6\u8868\u6570;\u5982\u679c\u8be5\u6570\u503c\u8f83\u9ad8,\u5219\u670d\u52a1\u5668\u5df2\u5728\u78c1\u76d8\u4e0a(\u800c\u4e0d\u662f\u5728\u5185\u5b58\u4e2d)\u521b\u5efa\u591a\u4e2a\u4e34\u65f6\u8868,\u4ece\u800c\u5bfc\u81f4\u67e5\u8be2\u6267\u884c\u8f83\u6162;
\n2.Handler_read_first:\u663e\u793a\u7d22\u5f15\u4e2d\u7b2c\u4e00\u4e2a\u6761\u76ee\u7684\u8bfb\u53d6\u6b21\u6570;\u5982\u679c\u8be5\u6570\u503c\u8f83\u9ad8,\u5219\u670d\u52a1\u5668\u5df2\u6267\u884c\u591a\u6b21\u5b8c\u6574\u7d22\u5f15\u626b\u63cf\u4ee5\u5b8c\u6210\u67e5\u8be2\u8bf7\u6c42;
\n3.Innodb_buffer_pool_wait_free:\u663e\u793a\u670d\u52a1\u5668\u7b49\u5f85\u5e72\u51c0\u9875\u9762\u7684\u6b21\u6570;\u7b49\u5f85InnoDB\u7f13\u51b2\u6c60\u4e2d\u7684\u9875\u9762\u5237\u65b0\u540e\u624d\u53ef\u4ee5\u5b8c\u6210\u67e5\u8be2\u8bf7\u6c42;\u5982\u679c\u8be5\u6570\u503c\u8f83\u9ad8,\u5219\u672a\u6b63\u786e\u8bbe\u7f6eInnoDB\u7f13\u51b2\u6c60\u7684\u5927\u5c0f,\u56e0\u800c\u67e5\u8be2\u6027\u80fd\u53d7\u5230\u5f71\u54cd;
\n4.Max_used_connections:\u663e\u793a\u81ea\u670d\u52a1\u5668\u542f\u52a8\u4ee5\u6765\u7684\u6700\u5927\u5e76\u53d1\u8fde\u63a5\u6570;\u6b64\u53d8\u91cf\u63d0\u4f9b\u975e\u5e38\u6709\u7528\u7684\u4fe1\u606f\u6765\u786e\u5b9a\u670d\u52a1\u5668\u5fc5\u987b\u652f\u6301\u7684\u5e76\u53d1\u8fde\u63a5\u6570;
\n5.Open_tables:\u663e\u793a\u7ed9\u5b9a\u65f6\u95f4\u5185\u6253\u5f00\u7684\u8868\u7684\u6570\u91cf;\u5c06\u6b64\u53d8\u91cf\u4e0e\u670d\u52a1\u5668\u7cfb\u7edf\u53d8\u91cftable_cache\u6bd4\u8f83,\u53ef\u63d0\u4f9b\u6709\u5173\u5e94\u8be5\u4e3a\u8868\u9ad8\u901f\u7f13\u5b58\u9884\u7559\u591a\u5c11\u5185\u5b58\u91cf\u7684\u6709\u7528\u4fe1\u606f;\u5982\u679cOpen_tables\u72b6\u6001\u53d8\u91cf\u7684\u503c\u901a\u5e38\u5f88\u4f4e,\u8bf7\u51cf\u5c0f\u670d\u52a1\u5668\u7cfb\u7edf\u53d8\u91cftable_cache\u7684\u5927\u5c0f;\u5982\u679c\u8be5\u503c\u5f88\u9ad8(\u63a5\u8fd1\u670d\u52a1\u5668\u7cfb\u7edf\u53d8\u91cftable_cache\u7684\u503c),\u8bf7\u589e\u52a0\u5206\u914d\u7ed9\u8868\u9ad8\u901f\u7f13\u5b58\u7684\u5185\u5b58\u91cf\u6765\u7f29\u77ed\u67e5\u8be2\u54cd\u5e94\u65f6\u95f4;
\n6.Select_full_join:\u663e\u793a\u6267\u884c\u8868\u626b\u63cf\u800c\u4e0d\u662f\u4f7f\u7528\u7d22\u5f15\u7684\u8054\u63a5\u6570\u91cf;\u5982\u679c\u8be5\u503c\u4e0d\u662f0,\u5219\u5e94\u8be5\u4ed4\u7ec6\u68c0\u67e5\u8868\u7684\u7d22\u5f15;
\n7.Slow_queries:\u663e\u793a\u7528\u65f6\u6bd4long_query_time\u7cfb\u7edf\u53d8\u91cf\u6240\u6307\u5b9a\u7684\u79d2\u6570\u957f\u7684\u67e5\u8be2\u6570;\u6b64\u72b6\u6001\u53d8\u91cf\u53d6\u51b3\u4e8e\u5bf9long_query_time\u53d8\u91cf(\u9ed8\u8ba4\u503c\u4e3a10\u79d2)\u8bbe\u7f6e\u7684\u4e86\u89e3;\u5982\u679cSlow_queries\u72b6\u6001\u53d8\u91cf\u4e0d\u662f0,\u8bf7\u68c0\u67e5long_query_time\u7684\u503c\u548c\u6162\u901f\u67e5\u8be2\u65e5\u5fd7,\u5e76\u6539\u8fdb\u6240\u6355\u83b7\u7684\u67e5\u8be2;
\n8.Sort_merge_passes:\u663e\u793a\u6392\u5e8f\u7b97\u6cd5\u6240\u6267\u884c\u7684\u5408\u5e76\u4f20\u9012\u6b21\u6570,\u6392\u5e8f\u64cd\u4f5c\u9700\u8981\u5185\u5b58\u4e2d\u7684\u7f13\u51b2\u533a;\u6b64\u72b6\u6001\u53d8\u91cf\u8ba1\u7b97\u6392\u5e8f\u64cd\u4f5c\u6240\u9700\u7684\u7ecf\u8fc7\u6392\u5e8f\u7f13\u51b2\u533a\u7684\u4f20\u9012\u6b21\u6570;\u5982\u679c\u8be5\u503c\u8f83\u9ad8,\u5219\u53ef\u80fd\u8868\u660e\u6392\u5e8f\u7f13\u51b2\u533a\u5927\u5c0f\u4e0d\u8db3\u4ee5\u6267\u884c\u67e5\u8be2\u7684\u4e00\u6b21\u901a\u8fc7\u6392\u5e8f;\u8bf7\u8003\u8651\u589e\u5927sort_buffer_size\u7cfb\u7edf\u53d8\u91cf\u7684\u503c;
\n9.Threads_connected:\u663e\u793a\u5f53\u524d\u6253\u5f00\u7684\u8fde\u63a5\u6570;\u5b9a\u671f\u6355\u83b7\u8be5\u503c\u53ef\u63d0\u4f9b\u6709\u5173\u670d\u52a1\u5668\u4f55\u65f6\u6700\u6d3b\u8dc3\u7684\u6709\u7528\u4fe1\u606f,\u4f7f \u7528\u6b64\u53d8\u91cf\u53ef\u786e\u5b9a\u6267\u884c\u670d\u52a1\u5668\u7ef4\u62a4\u7684\u6700\u4f73\u65f6\u95f4,\u6216\u8005\u53ef\u5c06\u5176\u4f5c\u4e3a\u4e3a\u670d\u52a1\u5668\u5206\u914d\u66f4\u591a\u8d44\u6e90\u7684\u4f9d\u636e;
\n10.Uptime:\u663e\u793a\u670d\u52a1\u5668\u6301\u7eed\u8fd0\u884c\u7684\u79d2\u6570;\u8be5\u503c\u53ef\u4ee5\u63d0\u4f9b\u6709\u5173\u670d\u52a1\u5668\u8fd0\u884c\u72b6\u51b5\u7684\u6709\u7528\u4fe1\u606f,\u4f8b\u5982\u670d\u52a1\u5668\u9700\u8981\u91cd\u65b0\u542f\u52a8\u7684\u9891\u7387;<\/p>\n
\n1.\u9996\u5148\u8c03\u8282\u67e5\u8be2,\u6a21\u5f0f\u548c\u7d22\u5f15:
\n 1.\u4e00\u4e2a\u5e38\u89c1\u7684\u8bef\u533a\u662f\u8ba4\u4e3a\u670d\u52a1\u5668\u53d8\u91cf\u914d\u7f6e\u662f\u670d\u52a1\u5668\u8c03\u8282\u4e2d\u6700\u91cd\u8981\u7684\u90e8\u5206;
\n 2.\u4e8b\u5b9e\u4e0a,\u4f18\u5316\u6a21\u5f0f,\u5e38\u89c1\u67e5\u8be2\u548c\u5178\u578b\u6570\u636e\u5e93\u7684\u7d22\u5f15\u53ef\u83b7\u5f97\u6bd4\u8c03\u8282\u53d8\u91cf\u66f4\u591a\u7684\u597d\u5904;
\n2.\u9488\u5bf9\u670d\u52a1\u5668\u5927\u5c0f\u8fdb\u884c\u8c03\u8282\u5185\u5b58\u548cI\/O:
\n 1.Oracle\u7684MySQL\u5de5\u7a0b\u5e08\u9009\u62e9\u9ed8\u8ba4\u8bbe\u7f6e\u6765\u9002\u5e94\u5927\u591a\u6570\u751f\u4ea7\u7cfb\u7edf,\u8fd9\u4e9b\u7cfb\u7edf\u5e38\u5e38\u8981\u5904\u7406\u9891\u7e41\u7684\u5c0f\u4e8b\u52a1,\u8bb8\u591a\u66f4\u65b0\u548c\u5c11\u6570\u5927\u578b\u6162\u901f\u67e5\u8be2(\u5982\u7528\u4e8e\u751f\u6210\u62a5\u544a\u7684\u67e5\u8be2);
\n 2.\u7136\u800c,\u7531\u4e8eMySQL\u5728\u4ece\u5c0f\u578b\u8bbe\u5907(\u5982\u9500\u552e\u70b9\u7cfb\u7edf\u548c\u8def\u7531\u5668)\u5230\u5177\u6709\u5927\u91cf\u5185\u5b58\u548c\u5feb\u901f\u78c1\u76d8\u9635\u5217\u7684\u5927\u578bWeb\u670d\u52a1\u5668\u7b49\u5404\u79cd\u7cfb\u7edf\u4e0a\u90fd\u5728\u4f7f\u7528,\u53ef\u80fd\u4f1a\u53d1\u73b0,\u5bf9\u4e8e\u60a8\u7684\u7279\u5b9a\u73af\u5883\u548c\u5de5\u4f5c\u8d1f\u8377,\u53ef\u4ee5\u4ece\u66f4\u6539\u670d\u52a1\u5668\u7684\u67d0\u4e9b\u9ed8\u8ba4\u8bbe\u7f6e\u4e2d\u83b7\u76ca;
\n3.\u9488\u5bf9\u5e94\u7528\u7a0b\u5e8f\u914d\u7f6e\u8fdb\u884c\u8c03\u8282:\u5b58\u50a8\u5f15\u64ce\u8bbe\u7f6e
\n 1.\u5c06\u7269\u7406RAM\u768470%\u201385%\u63d0\u4f9b\u7ed9InnoDB\u7f13\u51b2\u6c60;\u5728\u4ec5\u4f7f\u7528InnoDB\u7528\u6237\u8868\u7684MySQL\u4e13\u7528\u670d\u52a1\u5668\u4e0a,\u53ef\u4ee5\u5c06innodb_buffer_pool_size\u7684\u503c\u589e\u5927\u5230\u5360\u670d\u52a1\u5668\u603b\u5185\u5b58\u7684\u8f83\u5927\u6bd4\u4f8b(70%\u201385%),\u540c\u65f6\u8981\u8bb0\u4f4f\u64cd\u4f5c\u7cfb\u7edf\u7684\u9700\u8981,\u5982cron\u4f5c\u4e1a,\u5907\u4efd,\u75c5\u6bd2\u626b\u63cf\u4ee5\u53ca\u7ba1\u7406\u8fde\u63a5\u548c\u4efb\u52a1;\u5982\u679c\u6709\u51e0GB\u7684RAM,\u5219\u8fd8\u53ef\u4ee5\u901a\u8fc7\u4f7f\u7528\u591a\u4e2ainnodb_buffer_pool_instances\u800c\u83b7\u76ca,\u8be5\u8bbe\u7f6e\u53ef\u542f\u7528\u591a\u4e2a\u7f13\u51b2\u6c60,\u4ece\u800c\u907f\u514d\u4e89\u7528;
\n 2.\u6700\u5c0f\u5316MyISAM\u9ad8\u901f\u7f13\u5b58\u548c\u7f13\u51b2\u533a;\u5728\u4e0d\u5c06MyISAM\u7528\u4f5c\u7528\u6237\u8868\u7684\u7cfb\u7edf\u4e0a,\u51cf\u5c0f\u4ec5\u9002\u7528\u4e8eMyISAM\u7684\u9009\u9879\u7684\u503c(\u4f8b\u5982\u5c06key_buffer_size\u7684\u503c\u51cf\u5c0f\u4e3a16MB\u7b49\u8f83\u5c0f\u503c),\u540c\u65f6\u8981\u8bb0\u4f4f\u67d0\u4e9b\u5185\u90e8MySQL\u64cd\u4f5c\u5c06\u4f7f\u7528MyISAM;
\n4.\u8c03\u8282\u5de5\u4f5c\u8d1f\u8377\u7c7b\u578b:
\n 1.\u8fde\u63a5\u6570;
\n 1.\u5f53\u4e3a\u6bcf\u4e2a\u67e5\u8be2\u6216\u6bcf\u4e2a\u8fde\u63a5\u7684\u9ad8\u901f\u7f13\u5b58\u548c\u7f13\u51b2\u533a\u8bbe\u7f6e\u8f83\u5927\u7684\u503c\u65f6,\u4f1a\u51cf\u5c11\u7f13\u51b2\u6c60\u7684\u53ef\u7528\u5927\u5c0f;
\n 2.\u8c03\u8282\u670d\u52a1\u5668\u7684\u914d\u7f6e\u53d8\u91cf\u662f\u4e00\u4e2a\u5e73\u8861\u8fc7\u7a0b,\u9700\u8981\u4ece\u9ed8\u8ba4\u503c\u5f00\u59cb,\u63d0\u4f9b\u5c3d\u53ef\u80fd\u591a\u7684\u5185\u5b58\u7ed9\u7f13\u51b2\u6c60,\u7136\u540e\u8c03\u8282\u4e0e\u4ee5\u4e0b\u9879\u6700\u7d27\u5bc6\u76f8\u5173\u7684\u53d8\u91cf:\u8c03\u8282\u76ee\u6807,\u901a\u8fc7\u68c0\u67e5\u670d\u52a1\u5668\u72b6\u6001\u8bc6\u522b\u51fa\u7684\u95ee\u9898\u4ee5\u53ca\u901a\u8fc7\u67e5\u8be2\u6027\u80fd\u6a21\u5f0f\u8bc6\u522b\u51fa\u7684\u74f6\u9888;
\n 2.\u4e8b\u52a1\u670d\u52a1\u5668:
\n 1.\u5728\u7528\u4e8e\u652f\u6301\u8bb8\u591a\u53cd\u590d\u65ad\u5f00\u5e76\u91cd\u65b0\u8fde\u63a5\u7684\u5feb\u901f\u5e76\u53d1\u4e8b\u52a1\u7684\u670d\u52a1\u5668\u4e0a,\u8bf7\u5c06thread_cache_size\u7684\u503c\u8bbe\u7f6e\u4e3a\u8db3\u591f\u5927\u7684\u503c,\u4ee5\u4fbf\u5927\u591a\u6570\u65b0\u8fde\u63a5\u53ef\u4ee5\u4f7f\u7528\u9ad8\u901f\u7f13\u5b58\u7684\u7ebf\u7a0b;
\n 2.\u8fd9\u53ef\u907f\u514d\u521b\u5efa\u548c\u65ad\u5f00\u6bcf\u4e2a\u8fde\u63a5\u7684\u7ebf\u7a0b\u65f6\u7684\u670d\u52a1\u5668\u5f00\u9500;\u5728\u652f\u6301\u591a\u5199\u5165\u64cd\u4f5c\u7684\u670d\u52a1\u5668\u4e0a,\u8bf7\u63d0\u9ad8innodb_log_file_size\u548cinnodb_log_buffer_size\u7b49\u65e5\u5fd7\u8bbe\u7f6e,\u56e0\u4e3a\u6570\u636e\u4fee\u6539\u64cd\u4f5c\u7684\u6027\u80fd\u5728\u5f88\u5927\u7a0b\u5ea6\u4e0a\u4f9d\u8d56 \u4e8eInnoDB\u65e5\u5fd7\u7684\u6027\u80fd;
\n 3.\u8bf7\u8003\u8651\u66f4\u6539innodb_flush_log_at_trx_commit\u7684\u503c\u4ee5\u63d0\u9ad8\u6bcf\u6b21\u63d0\u4ea4\u7684\u6027\u80fd,\u4f46\u98ce\u9669\u662f:\u5982\u679c\u670d\u52a1\u5668\u51fa\u73b0\u6545\u969c,\u53ef\u80fd\u4f1a\u4e22\u5931\u67d0\u4e9b\u6570\u636e;
\n 4.\u5982\u679c\u60a8\u7684\u5e94\u7528\u7a0b\u5e8f\u53cd\u590d\u6267\u884c\u76f8\u540c\u7684\u67e5\u8be2(\u6216\u591a\u4e2a\u76f8\u540c\u7684\u67e5\u8be2),\u8bf7\u8003\u8651\u542f\u7528\u67e5\u8be2\u9ad8\u901f\u7f13 \u5b58,\u5e76\u6839\u636e\u5e38\u89c1\u67e5\u8be2\u7684\u7ed3\u679c\u8c03\u8282\u5176\u5927\u5c0f,\u65b9\u6cd5\u662f\u4e3aquery_cache_type\u548cquery_cache_size\u8bbe\u7f6e\u9002\u5f53\u7684\u503c;
\n 3.\u62a5\u8868\u670d\u52a1\u5668:\u5728\u7528\u4e8e\u8fd0\u884c\u5c11\u6570\u5927\u578b\u6162\u901f\u67e5\u8be2(\u4f8b\u5982\u7528\u4e8e\u4e1a\u52a1\u667a\u80fd\u62a5\u8868\u7684\u67e5\u8be2)\u7684\u670d\u52a1\u5668\u4e0a,\u4f7f\u7528join_buffer_size\u548csort_buffer_size\u7b49\u8bbe\u7f6e\u589e\u52a0\u4e13\u7528\u4e8e\u7f13\u51b2\u533a\u7684\u5185\u5b58\u91cf;\u867d\u7136\u9ed8\u8ba4\u670d\u52a1\u5668\u8bbe\u7f6e\u66f4\u9002\u5408\u4e8b\u52a1\u7cfb\u7edf,\u4f46\u9ed8\u8ba4\u7684my.cnf\u6587\u4ef6\u5305\u542b\u8fd9\u4e9b\u53d8\u91cf\u9002\u7528\u4e8e\u62a5\u8868\u670d\u52a1\u5668\u7684\u66ff\u4ee3\u503c;<\/p>\n
\n1.innodb_buffer_pool_size:\u5b9a\u4e49InnoDB\u7528\u4e8e\u7f13\u5b58\u8868\u6570\u636e\u548c\u7d22\u5f15\u7684\u5185\u5b58\u7f13\u51b2\u533a\u5927\u5c0f;\u8981\u83b7\u5f97\u6700\u4f73\u6027\u80fd,\u8bf7\u5c06\u6b64\u503c\u8bbe\u7f6e\u4e3a\u5c3d\u53ef\u80fd\u5927,\u540c\u65f6\u8981\u8bb0\u4f4f\u503c\u8fc7\u9ad8\u4f1a\u5bfc\u81f4\u64cd\u4f5c\u7cfb\u7edf\u4ea4\u6362\u9875\u9762,\u4ece\u800c\u5927\u5927\u964d\u4f4e\u6027\u80fd;\u5982\u679c\u5728\u4e13\u7528\u6570\u636e\u5e93\u670d\u52a1 \u5668\u4e0a\u4ec5\u4f7f\u7528\u4e86InnoDB\u7528\u6237\u8868,\u8bf7\u8003\u8651\u5c06\u6b64\u53d8\u91cf\u8bbe\u7f6e\u4e3a\u4ecb\u4e8e\u7269\u7406RAM\u768470%\u523085%\u4e4b\u95f4\u7684\u503c;
\n2.innodb_flush_log_at_trx_commit:\u5b9a\u4e49InnoDB\u5c06\u65e5\u5fd7\u7f13\u51b2\u533a\u5199\u5165\u65e5\u5fd7\u6587\u4ef6\u7684\u9891\u7387,\u4ee5\u53ca\u5bf9\u65e5\u5fd7\u6587\u4ef6\u6267\u884c\u5237\u65b0\u5230\u78c1\u76d8\u64cd\u4f5c\u7684\u9891\u7387;\u6b64\u53d8\u91cf\u6709\u4e09\u79cd\u53ef\u80fd\u7684\u8bbe\u7f6e:
\n 1.0:\u6bcf\u79d2\u5c06\u65e5\u5fd7\u7f13\u51b2\u533a\u5199\u5165\u78c1\u76d8\u4e00\u6b21;
\n 2.1:\u6bcf\u6b21\u63d0\u4ea4\u65f6\u5c06\u65e5\u5fd7\u5237\u65b0\u5230\u78c1\u76d8;\u5982\u679c\u672a\u53d1\u751f\u63d0\u4ea4,\u5219\u6bcf\u79d2\u5237\u65b0\u4e00\u6b21;
\n 3.2:\u5c06\u65e5\u5fd7\u5237\u65b0\u5230\u64cd\u4f5c\u7cfb\u7edf\u9ad8\u901f\u7f13\u5b58\u4e2d,\u5e76\u4e14\u6bcf\u9694innodb_flush_log_at_timeout\u79d2(\u9ed8\u8ba4\u4e3a\u4e00\u79d2)\u5237\u65b0\u5230\u78c1\u76d8\u4e00\u6b21;
\n3.innodb_log_buffer_size:\u5b9a\u4e49InnoDB\u7528\u4e8e\u5199\u5165\u78c1\u76d8\u4e0a\u7684\u65e5\u5fd7\u6587\u4ef6\u7684\u7f13\u51b2\u533a\u7684\u5927\u5c0f;\u6b64\u53d8\u91cf\u7684\u9ed8\u8ba4\u503c\u4e3a8MB;\u4e8b\u52a1\u8d85\u8fc7\u6b64\u5927\u5c0f\u4f1a\u5bfc\u81f4InnoDB\u5728\u4e8b\u52a1\u63d0\u4ea4\u4e4b\u524d\u5c06\u65e5\u5fd7\u5237\u65b0\u5230\u78c1\u76d8,\u4ece\u800c\u964d\u4f4e\u6027\u80fd;\u5bf9\u4e8e\u4f7f\u7528\u5927\u91cfBLOB\u6216\u8005\u5728\u66f4\u65b0\u6d3b\u52a8\u4e2d\u5177\u6709\u8f83\u5927\u5cf0\u503c\u7684\u5e94\u7528\u7a0b\u5e8f,\u53ef\u901a\u8fc7\u589e\u5927\u8be5\u503c\u63d0\u9ad8\u4e8b\u52a1\u6027\u80fd;
\n4.innodb_log_file_size:\u5b9a\u4e49\u65e5\u5fd7\u7ec4\u4e2d\u6bcf\u4e2a\u65e5\u5fd7\u6587\u4ef6\u7684\u5927\u5c0f;\u5bf9\u4e8e\u5927\u578b\u6570\u636e\u96c6\u4e0a\u7684\u5199\u5165\u5bc6\u96c6\u578b\u5de5\u4f5c\u8d1f\u8377,\u8bf7\u8bbe\u7f6e\u6b64\u53d8 \u91cf\u4ee5\u4fbf\u6240\u6709\u65e5\u5fd7\u6587\u4ef6\u7684\u6700\u5927\u603b\u5927\u5c0f(\u901a\u8fc7innodb_log_files_in_group\u8bbe\u7f6e)\u5c0f\u4e8e\u6216\u7b49\u4e8e\u7f13\u51b2\u6c60\u7684\u5927\u5c0f;\u5927\u578b\u65e5\u5fd7\u6587\u4ef6\u4f1a\u51cf\u7f13\u6545\u969c\u6062\u590d,\u4f46\u53ef\u4ee5\u901a\u8fc7\u51cf\u5c11\u68c0\u67e5\u70b9\u5237\u65b0\u6d3b\u52a8\u6765\u63d0\u9ad8\u6574\u4f53\u6027\u80fd;
\n5.join_buffer_size:\u5b9a\u4e49\u7528\u4e8e\u4f7f\u7528\u8868\u626b\u63cf\u7684\u8054\u63a5\u7684\u6700\u5c0f\u7f13\u51b2\u533a\u5927\u5c0f;\u5bf9\u4e8e\u5305\u542b\u65e0\u6cd5\u4f7f\u7528\u7d22\u5f15\u7684\u8054\u63a5\u7684\u67e5\u8be2,\u8bf7\u4ee5\u9ed8\u8ba4\u503c(256 KB)\u4e3a\u8d77\u70b9\u589e\u5927\u8be5\u503c;\u8fd0\u884c\u6b64\u7c7b\u67e5\u8be2\u65f6\u8bf7\u66f4\u6539\u6bcf\u4e2a\u4f1a\u8bdd\u7684\u503c,\u4ee5\u907f\u514d\u8bbe\u7f6e\u5168\u5c40\u8bbe\u7f6e\u800c\u4f7f\u65e0\u9700\u8fd9\u4e48\u5927\u503c\u7684\u67e5\u8be2\u6d6a\u8d39\u5185\u5b58;
\n6.query_cache_size:\u5b9a\u4e49\u4e3a\u7f13\u5b58\u67e5\u8be2\u7ed3\u679c\u800c\u5206\u914d\u7684\u5185\u5b58\u91cf;\u901a\u8fc7\u4f7f\u7528\u67e5\u8be2\u9ad8\u901f\u7f13\u5b58,\u63d0\u9ad8\u9488\u5bf9\u6781\u5c11\u66f4\u6539\u7684\u6570\u636e\u53d1\u51fa\u91cd\u590d\u67e5\u8be2\u7684\u5e94\u7528\u7a0b\u5e8f\u7684\u6027\u80fd;\u4f5c\u4e3a\u57fa\u7ebf,\u8bf7\u6839\u636e\u91cd\u590d\u67e5\u8be2\u7684\u6570\u91cf\u548c\u6240\u8fd4\u56de\u6570\u636e\u7684\u5927\u5c0f\u5c06\u6b64\u53d8\u91cf\u8bbe\u7f6e\u4e3a\u4ecb\u4e8e32MB\u548c512MB\u4e4b\u95f4\u7684\u503c,\u8bf7\u76d1\u89c6\u9ad8\u901f\u7f13\u5b58\u547d\u4e2d\u7387\u4ee5\u786e\u5b9a\u6b64\u53d8\u91cf\u7684\u6709\u6548\u6027,\u5e76\u6839\u636e\u60a8\u7684\u89c2\u5bdf\u8c03\u8282\u5176\u503c;
\n7.sort_buffer_size:\u5b9a\u4e49\u5206\u914d\u7ed9\u9700\u8981\u8fdb\u884c\u6392\u5e8f\u7684\u4f1a\u8bdd\u7684\u6700\u5927\u5185\u5b58\u91cf;\u5982\u679cSort_merge_passes\u72b6\u6001\u53d8\u91cf\u7684\u503c\u5f88\u9ad8,\u8bf7\u589e\u5927\u8be5\u503c\u4ee5\u63d0\u9ad8ORDER BY\u548cGROUP BY\u64cd\u4f5c\u7684\u6027\u80fd;
\n8.table_open_cache:\u5b9a\u4e49\u6240\u6709\u7ebf\u7a0b\u6253\u5f00\u7684\u8868\u7684\u6570\u91cf;\u8bf7\u8bbe\u7f6e\u8be5\u503c\u4ee5\u4f7f\u5176\u5927\u4e8eN * max_connections,\u5176\u4e2d,N\u662f\u5728\u5e94\u7528\u7a0b\u5e8f\u7684\u6240\u6709\u67e5\u8be2\u4e2d\u6240\u4f7f\u7528\u7684\u6700\u5927\u8868\u6570\u91cf;\u8be5\u503c\u8fc7\u9ad8\u4f1a\u5bfc\u81f4\u51fa\u73b0\u9519\u8bef\u201cToo many open files(\u6253\u5f00\u7684\u6587\u4ef6\u592a\u591a)\u201d;Open_tables\u72b6\u6001\u53d8\u91cf\u7684\u503c\u8f83\u9ad8\u8868\u793aMySQL\u9891\u7e41\u6253\u5f00\u548c\u5173\u95ed\u8868,\u56e0\u6b64\u5e94\u8be5\u589e\u5927table_open_cache;
\n9.thread_cache_size:\u4e49\u670d\u52a1\u5668\u5e94\u7f13\u5b58\u4ee5\u4f9b\u91cd\u7528\u7684\u7ebf\u7a0b\u6570;\u9ed8\u8ba4\u60c5\u51b5\u4e0b,\u6b64\u53d8\u91cf\u5c06\u81ea\u52a8\u8c03\u8282\u5927\u5c0f;\u8bc4\u4f30Threads_created\u72b6\u6001\u53d8\u91cf\u53ef\u786e\u5b9a\u662f\u5426\u9700\u8981\u66f4\u6539thread_cache_size\u7684\u503c;<\/p>\n
\n1.\u5c3d\u53ef\u80fd\u5730\u590d\u5236\u751f\u4ea7\u7cfb\u7edf;
\n 1.\u8981\u51cf\u5c0f\u4e0e\u6b63\u5728\u8c03\u8282\u7684\u53d8\u91cf\u65e0\u5173\u7684\u5df2\u66f4\u6539\u56e0\u7d20\u7684\u5f71\u54cd;
\n 2.\u8bf7\u5728\u505c\u673a\u671f\u95f4\u5bf9\u751f\u4ea7\u670d\u52a1\u5668\u6267\u884c\u8c03\u8282,\u6216\u8005\u6700\u597d\u5728\u590d\u5236\u7684\u7cfb\u7edf\u4e0a\u8fdb\u884c\u8c03\u8282;
\n2.\u51b3\u5b9a\u8c03\u8282\u76ee\u6807:
\n 1.\u6bcf\u79d2\u5904\u7406\u66f4\u591a\u4e8b\u52a1;
\n 2.\u66f4\u5feb\u751f\u6210\u590d\u6742\u62a5\u8868;
\n 3.\u901a\u8fc7\u5e76\u53d1\u8fde\u63a5\u7684\u5cf0\u503c\u63d0\u9ad8\u6027\u80fd;
\n3.\u9009\u62e9\u9002\u5f53\u7684\u53d8\u91cf\u8fdb\u884c\u8c03\u8282:\u7f13\u51b2\u533a,\u9ad8\u901f\u7f13\u5b58,\u65e5\u5fd7\u8bbe\u7f6e;
\n4.\u4e3a\u4e86\u6700\u51c6\u786e\u5730\u6a21\u62df\u6b63\u5728\u9488\u5bf9\u5176\u8fdb\u884c\u8c03\u8282\u7684\u5de5\u4f5c\u8d1f\u8377,\u9700\u8981\u6536\u96c6\u4e00\u7ec4\u6709\u4ee3\u8868\u6027\u7684\u8bed\u53e5:
\n 1.\u4ece\u5e94\u7528\u7a0b\u5e8f\u4e2d\u9009\u62e9\u67e5\u8be2\u548c\u4fee\u6539\u64cd\u4f5c\u6bd4\u4f8b\u6b63\u786e\u7684\u8bed\u53e5\u5e8f\u5217;
\n 2.\u5728\u8981\u4f18\u5316\u7684\u6bcf\u5929\u6216\u6bcf\u5468\u671f\u95f4\u5185,\u4f7f\u7528\u4e00\u822c\u67e5\u8be2\u65e5\u5fd7\u4ece\u751f\u4ea7\u670d\u52a1\u5668\u6536\u96c6\u5b9e\u9645\u8bed\u53e5;<\/p>\n
\n1.\u67e5\u627e\u6bcf\u4e2a\u53d8\u91cf\u7684\u6700\u4f73\u503c\u7684\u57fa\u51c6\u6d4b\u8bd5:
\n 1.mysqlslap\u6216mysql\u6765\u8fd0\u884c\u5de5\u4f5c\u8d1f\u8377\u5e76\u83b7\u53d6\u5e73\u5747\u6267\u884c\u65f6\u95f4;
\n 2.sql-bench\u6765\u8fd0\u884c\u66f4\u4e00\u822c\u7684\u57fa\u51c6\u6d4b\u8bd5;
\n 3.mysqladmin extended-status\u6765\u83b7\u53d6\u5de5\u4f5c\u8d1f\u8377\u524d\u540e\u7684\u72b6\u6001\u53d8\u91cf\u7684\u503c;
\n 4.top\u7b49\u64cd\u4f5c\u7cfb\u7edf\u5de5\u5177\u6216\/proc\u6587\u4ef6\u7cfb\u7edf\u6765\u8bbf\u95ee\u8fc7\u7a0b\u5ea6\u91cf;
\n2.\u5c06\u53d8\u91cf\u8bbe\u7f6e\u4e3a\u4f4e\u4e8e\u5176\u9ed8\u8ba4\u503c\u7684\u8bbe\u7f6e;
\n3.\u8fdb\u884c\u57fa\u51c6\u6d4b\u8bd5,\u6d4b\u91cf\u76f8\u5173\u5ea6\u91cf:
\n 1.\u865a\u62df\u5185\u5b58\u4f7f\u7528;
\n 2.\u6240\u82b1\u8d39\u7684\u5e73\u5747\u65f6\u95f4;
\n 3.\u76f8\u5173\u72b6\u6001\u53d8\u91cf;
\n4.\u589e\u5927\u53d8\u91cf\u503c\u5e76\u91cd\u590d\u57fa\u51c6\u6d4b\u8bd5:\u5982\u679c\u9700\u8981,\u5237\u65b0\u72b6\u6001\u53d8\u91cf;
\n5.\u5c06\u7ed3\u679c\u7ed8\u5236\u6210\u56fe:
\n 1.\u67e5\u627e\u6536\u76ca\u7684\u4e0b\u964d\u70b9\u548c\u6027\u80fd\u7684\u9ad8\u5cf0;
\n 2.\u6839\u636e\u6240\u7528\u8d44\u6e90\u548c\u6027\u80fd\u4e4b\u95f4\u7684\u6700\u4f73\u5e73\u8861\u6765\u51b3\u5b9a\u6700\u7ec8\u53d8\u91cf\u503c;
\n6.\u5982\u679c\u8981\u9488\u5bf9\u7279\u5b9a\u53d8\u91cf\u4f7f\u7528\u591a\u4e2a\u4e0d\u540c\u503c\u8fd0\u884c\u5fae\u8c03\u57fa\u51c6\u6d4b\u8bd5,\u6216\u8005\u5982\u679c\u8981\u5728\u5f88\u957f\u4e00\u6bb5\u65f6\u95f4\u5185\u53cd\u590d\u8fd0\u884c\u76f8\u540c\u7684\u57fa\u51c6\u6d4b\u8bd5,\u8bf7\u8003\u8651\u4f7f\u7528\u811a\u672c\u8bed\u8a00\u6765\u81ea\u52a8\u5316\u57fa\u51c6\u6d4b\u8bd5\u4e2d\u6240\u4f7f\u7528\u7684\u6b65\u9aa4;<\/p>\n
\n1.\u672c\u5e7b\u706f\u7247\u4e2d\u7684\u793a\u4f8b\u663e\u793a\u4e86\u4e00\u7cfb\u5217\u9488\u5bf9\u5177\u6709\u7e41\u91cd\u6392\u5e8f\u5de5\u4f5c\u8d1f\u8377\u7684\u6570\u636e\u5e93\u7684\u6d4b\u8bd5\u7ed3\u679c,\u5176\u4e2d,\u8fd0\u884c\u6d4b\u8bd5\u65f6\u66f4\u6539\u4e86sort_buffer_size\u53d8\u91cf;
\n2.\u56fe\u8868\u663e\u793a:
\n 1.\u5728sort_buffer_size\u4ece32KB\u589e\u5927\u5230512KB\u65f6,Sort_merge_passes\u72b6\u6001\u53d8\u91cf\u7684\u503c(\u53ef\u4f7f\u7528mysqladmin extended_status-r\u67e5\u770b)\u6025\u5267\u4e0b\u964d,\u5728\u6b64\u4e4b\u540e\u53c8\u7f13\u6162\u964d\u4f4e;
\n 2.\u6d4b\u8bd5\u5de5\u4f5c\u8d1f\u8377\u6240\u82b1\u7684\u5e73\u5747\u65f6\u95f4(\u53ef\u4f7f\u7528mysqlslap\u67e5\u770b)\u5728sort_buffer_size\u4e3a512KB\u65f6\u964d\u4f4e,\u57284MB\u65f6\u8fbe\u5230\u6781\u5927\u5cf0\u503c,\u7136\u540e\u57288MB\u65f6\u4e0b\u964d,\u6700\u7ec8\u572832MB\u65f6\u8fbe\u5230\u6700\u4f73\u6027\u80fd;
\n 3.mysqld\u8fdb\u7a0b\u7684\u603b\u865a\u62df\u5185\u5b58(\u53ef\u4f7f\u7528top\u67e5\u770b)\u5728sort_buffer_size\u4e3a512KB\u65f6\u6700\u5c0f,\u6b64\u540e\u4e00\u76f4\u523016MB\u90fd\u7a33\u6b65\u4e0a\u5347,\u572832MB\u65f6\u6025\u5267\u4e0a\u5347;
\n3.\u67e5\u8be2\u7684\u5e73\u5747\u65f6\u95f4\u6700\u77ed\u65f6,sort_buffer_size\u4e3a32MB,\u8be5\u8bbe\u7f6e\u4f7f\u7528\u4e86\u5927\u91cf\u5185\u5b58,\u800c\u7f13\u51b2\u6c60\u672c\u6765\u53ef\u4ee5\u66f4\u597d\u5730\u5229\u7528\u8fd9\u4e9b\u5185\u5b58;\u5728\u672c\u793a\u4f8b\u4e2d,\u9488\u5bf9\u6d4b\u8bd5\u4e2d\u6240\u4f7f\u7528\u7684\u5de5\u4f5c\u8d1f\u8377,\u670d\u52a1\u5668\u548c\u6570\u636e\u5e93\u7684\u7279\u5b9a\u7ec4\u5408,512KB\u8bbe\u7f6e\u53ef\u5728\u6027\u80fd\u548c\u6240\u7528\u5185\u5b58\u4e4b\u95f4\u63d0\u4f9b\u6700\u4f73\u5e73\u8861;<\/p>\n
\n1.distinct:\u5f53MySQL\u627e\u5230\u7b2c\u4e00\u6761\u5339\u914d\u7684\u7ed3\u679c\u503c\u65f6,\u5c31\u505c\u6b62\u8be5\u503c\u7684\u67e5\u8be2,\u7136\u540e\u7ee7\u7eed\u8be5\u5217\u5176\u4ed6\u503c\u7684\u67e5\u8be2;
\n2.not exists:\u5728\u5de6\u8fde\u63a5\u4e2d,\u4f18\u5316\u5668\u53ef\u4ee5\u901a\u8fc7\u6539\u53d8\u539f\u6709\u7684\u67e5\u8be2\u7ec4\u5408\u800c\u4f7f\u7528\u7684\u4f18\u5316\u65b9\u6cd5;\u5f53\u53d1\u73b0\u4e00\u4e2a\u5339\u914d\u7684\u884c\u4e4b\u540e,\u4e0d\u518d\u4e3a\u524d\u9762\u7684\u884c\u7ee7\u7eed\u68c0\u7d22,\u53ef\u4ee5\u90e8\u5206\u51cf\u5c11\u6570\u636e\u8bbf\u95ee\u7684\u6b21\u6570;
\n3.const row not found:\u6d89\u53ca\u5230\u7684\u8868\u4e3a\u7a7a\u8868,\u91cc\u9762\u6ca1\u6709\u6570\u636e;
\n4.Full scan on NULL key:\u662f\u4f18\u5316\u5668\u5bf9\u5b50\u67e5\u8be2\u7684\u4e00\u79cd\u4f18\u5316\u65b9\u5f0f,\u65e0\u6cd5\u901a\u8fc7\u7d22\u5f15\u8bbf\u95eeNULL\u503c\u7684\u65f6\u5019\u4f1a\u505a\u6b64\u4f18\u5316;
\n5.Impossible Having:Having\u5b50\u53e5\u603b\u662ffalse\u800c\u4e0d\u80fd\u9009\u62e9\u4efb\u4f55\u5217;\u4f8b\u5982having 1=0;
\n6.Impossible WHERE:Where\u5b50\u53e5\u603b\u662ffalse\u800c\u4e0d\u80fd\u9009\u62e9\u4efb\u4f55\u5217;\u4f8b\u5982where 1=0;
\n7.Impossible WHERE noticed after reading const tables:MySQL\u901a\u8fc7\u8bfb\u53d6\u201cconst\/system tables\u201d,\u53d1\u73b0Where\u5b50\u53e5\u4e3afalse;\u4e5f\u5c31\u662f\u8bf4:\u5728where\u5b50\u53e5\u4e2dfalse\u6761\u4ef6\u5bf9\u5e94\u7684\u8868\u5e94\u8be5\u662fconst\/system tables;\u8fd9\u4e2a\u5e76\u4e0d\u662fMySQL\u901a\u8fc7\u7edf\u8ba1\u4fe1\u606f\u505a\u51fa\u7684,\u800c\u662f\u771f\u7684\u53bb\u5b9e\u9645\u8bbf\u95ee\u4e00\u904d\u6570\u636e\u540e\u624d\u5f97\u51fa\u7684\u7ed3\u8bba;\u5f53\u5bf9\u67d0\u4e2a\u8868\u6307\u5b9a\u4e86\u4e3b\u952e\u6216\u8005\u975e\u7a7a\u552f\u4e00\u7d22\u5f15\u4e0a\u7684\u7b49\u503c\u6761\u4ef6,\u4e00\u4e2aquery\u6700\u591a\u53ea\u53ef\u80fd\u547d\u4e2d\u4e00\u4e2a\u7ed3\u679c,MySQL\u5728explain\u4e4b\u524d\u4f1a\u4f18\u5148\u6839\u636e\u8fd9\u4e00\u6761\u4ef6\u67e5\u627e\u5bf9\u5e94\u8bb0\u5f55,\u5e76\u7528\u8bb0\u5f55\u7684\u5b9e\u9645\u503c\u66ff\u6362query\u4e2d\u6240\u6709\u7528\u5230\u6765\u81ea\u8be5\u8868\u5c5e\u6027\u7684\u5730\u65b9;
\n8.No matching min\/max row:\u6ca1\u6709\u884c\u6ee1\u8db3\u5982\u4e0b\u7684\u67e5\u8be2\u6761\u4ef6;
\n9.no matching row in const table:\u5bf9\u4e00\u4e2a\u6709join\u7684\u67e5\u8be2,\u5305\u542b\u4e00\u4e2a\u7a7a\u8868\u6216\u8005\u6ca1\u6709\u6570\u636e\u6ee1\u8db3\u4e00\u4e2a\u552f\u4e00\u7d22\u5f15\u6761\u4ef6;
\n10.No tables used:\u67e5\u8be2\u6ca1\u6709From\u5b50\u53e5,\u6216\u8005\u6709\u4e00\u4e2aFrom Dual(dual:\u865a\u62df\u8868,\u662f\u4e3a\u4e86\u6ee1\u8db3select…from…\u4e60\u60ef)\u5b50\u53e5;
\n EXPLAIN SELECT VERSION()
\n11.Range checked for each record (index map: N):MySQL\u53d1\u73b0\u6ca1\u6709\u597d\u7684index,\u4f46\u53d1\u73b0\u5982\u679c\u8fdb\u4e00\u6b65\u83b7\u53d6\u4e0b\u4e00\u5f20join\u8868\u7684\u5217\u7684\u503c\u540e,\u67d0\u4e9bindex\u53ef\u4ee5\u901a\u8fc7range\u7b49\u4f7f\u7528;MySQL\u6ca1\u627e\u5230\u5408\u9002\u7684\u53ef\u7528\u7684\u7d22\u5f15;\u53d6\u4ee3\u7684\u529e\u6cd5\u662f,\u5bf9\u4e8e\u524d\u4e00\u4e2a\u8868\u7684\u6bcf\u4e00\u4e2a\u884c\u8fde\u63a5,\u5b83\u4f1a\u505a\u4e00\u4e2a\u68c0\u9a8c\u4ee5\u51b3\u5b9a\u8be5\u4f7f\u7528\u54ea\u4e2a\u7d22\u5f15\uff08\u5982\u679c\u6709\u7684\u8bdd\uff09,\u5e76\u4e14\u4f7f\u7528\u8fd9\u4e2a\u7d22\u5f15\u6765\u4ece\u8868\u91cc\u53d6\u5f97\u8bb0\u5f55;\u8fd9\u4e2a\u8fc7\u7a0b\u4e0d\u4f1a\u5f88\u5feb,\u4f46\u603b\u6bd4\u6ca1\u6709\u4efb\u4f55\u7d22\u5f15\u65f6\u505a\u8868\u8fde\u63a5\u6765\u5f97\u5feb;
\n12.Select tables optimized away:\u5f53\u6211\u4eec\u4f7f\u7528\u67d0\u4e9b\u805a\u5408\u51fd\u6570\u6765\u8bbf\u95ee\u5b58\u5728\u7d22\u5f15\u7684\u67d0\u4e2a\u5b57\u6bb5\u65f6,\u4f18\u5316\u5668\u4f1a\u901a\u8fc7\u7d22\u5f15\u76f4\u63a5\u4e00\u6b21\u5b9a\u4f4d\u5230\u6240\u9700\u8981\u7684\u6570\u636e\u884c\u5b8c\u6210\u6574\u4e2a\u67e5\u8be2;\u5728\u4f7f\u7528\u67d0\u4e9b\u805a\u5408\u51fd\u6570\u5982min, max\u7684query,\u76f4\u63a5\u8bbf\u95ee\u5b58\u50a8\u7ed3\u6784(B\u6811\u6216\u8005B+\u6811)\u7684\u6700\u5de6\u4fa7\u53f6\u5b50\u8282\u70b9\u6216\u8005\u6700\u53f3\u4fa7\u53f6\u5b50\u8282\u70b9\u5373\u53ef,\u8fd9\u4e9b\u53ef\u4ee5\u901a\u8fc7index\u89e3\u51b3;Select count(*) from table(\u4e0d\u5305\u542bwhere\u7b49\u5b50\u53e5),MyISAM\u4fdd\u5b58\u4e86\u8bb0\u5f55\u7684\u603b\u6570,\u53ef\u4ee5\u76f4\u63a5\u8fd4\u56de\u7ed3\u679c,\u800cInnodb\u9700\u8981\u5168\u8868\u626b\u63cf;Query\u4e2d\u4e0d\u80fd\u6709group by\u64cd\u4f5c;
\n13.unique row not found:\u5bf9\u4e8eSELECT \u2026 FROM tbl_name,\u6ca1\u6709\u884c\u6ee1\u8db3unique index\u6216\u8005primary key;\u4ece\u8868\u4e2d\u67e5\u8be2id\u4e0d\u5b58\u5728\u7684\u4e00\u4e2a\u503c\u4f1a\u663e\u793aImpossible WHERE noticed after reading const tables;
\n14.Using filesort:\u6307MySQL\u5c06\u7528\u5916\u90e8\u6392\u5e8f\u800c\u4e0d\u662f\u6309\u7167index\u987a\u5e8f\u6392\u5217\u7ed3\u679c;\u6570\u636e\u8f83\u5c11\u65f6\u4ece\u5185\u5b58\u6392\u5e8f,\u5426\u5219\u4ece\u78c1\u76d8\u6392\u5e8f;Explain\u4e0d\u4f1a\u663e\u793a\u7684\u544a\u8bc9\u5ba2\u6237\u7aef\u7528\u54ea\u79cd\u6392\u5e8f;
\n15.Using index:\u8868\u793aMySQL\u4f7f\u7528\u8986\u76d6\u7d22\u5f15\u907f\u514d\u5168\u8868\u626b\u63cf,\u4e0d\u9700\u8981\u518d\u5230\u8868\u4e2d\u8fdb\u884c\u4e8c\u6b21\u67e5\u627e\u6570\u636e;\u6ce8\u610f\u4e0d\u8981\u548ctype\u4e2d\u7684index\u7c7b\u578b\u6df7\u6dc6;
\n16.Using index for group-by:\u7c7b\u4f3cUsing index,\u6240\u9700\u6570\u636e\u53ea\u9700\u8981\u8bfb\u53d6\u7d22\u5f15,\u5f53query\u4e2d\u6709group by\u6216distinct\u5b50\u53e5\u65f6,\u5982\u679c\u5206\u7ec4\u5b57\u6bb5\u4e5f\u5728\u7d22\u5f15\u4e2d,extra\u5c31\u4f1a\u663e\u793a\u8be5\u503c;
\n17.Using temporary:MySQL\u5c06\u521b\u5efa\u4e00\u4e2a\u4e34\u65f6\u8868\u6765\u5bb9\u7eb3\u4e2d\u95f4\u7ed3\u679c;\u5728group by\u548corder by\u7684\u65f6,\u5982\u679c\u6709\u5fc5\u8981\u7684\u8bdd;\u4f8b\u5982group by\u4e00\u4e2a\u975e\u952e\u5217,\u4f18\u5316\u5668\u4f1a\u521b\u5efa\u4e00\u4e2a\u4e34\u65f6\u8868,\u6709\u4e2a\u6309\u7167group by\u6761\u4ef6\u6784\u5efa\u7684unique key,\u7136\u540e\u5bf9\u4e8e\u6bcf\u6761\u67e5\u8be2\u7ed3\u679c\uff08\u5ffd\u7565group by\uff09,\u5c1d\u8bd5insert\u5230\u4e34\u65f6\u8868\u4e2d,\u5982\u679c\u7531\u4e8eunique key\u5bfc\u81f4insert\u5931\u8d25,\u5219\u5df2\u6709\u7684\u8bb0\u5f55\u5c31\u76f8\u5e94\u7684updated;\u4f8b\u5982,name\u4e0a\u6ca1\u6709\u7d22\u5f15,SELECT name,COUNT(*) FROM product GROUP BY name,\u4e3a\u4e86\u6392\u5e8f,MySQL\u5c31\u9700\u8981\u521b\u5efa\u4e34\u65f6\u8868;\u6b64\u65f6\u4e00\u822c\u8fd8\u4f1a\u663e\u793ausing filesort;
\n18.Using where:\u8868\u793aMySQL\u5c06\u5bf9storage engine\u63d0\u53d6\u7684\u7ed3\u679c\u8fdb\u884c\u8fc7\u6ee4;\u4f8b\u5982,price\u6ca1\u6709index,SELECT * FROM product WHERE price=1300.00;\u6709\u8bb8\u591awhere\u7684\u6761\u4ef6\u7531\u4e8e\u5305\u542b\u4e86index\u4e2d\u7684\u5217,\u5728\u67e5\u627e\u7684\u65f6\u5019\u5c31\u53ef\u4ee5\u8fc7\u6ee4,\u6240\u4ee5\u4e0d\u662f\u6240\u6709\u5e26where\u5b50\u53e5\u7684\u67e5\u8be2\u4f1a\u663e\u793aUsing where;
\n19.Using join buffer:5.1.18\u7248\u672c\u4ee5\u540e\u624d\u6709\u7684\u503c;join\u7684\u8fd4\u56de\u5217\u53ef\u4ee5\u4ecebuffer\u4e2d\u83b7\u53d6,\u4e0e\u5f53\u524d\u8868join;
\n\u4f8b\u5982:explain select * from t1,t2 where t1.col < 10 and t2.col < 10\n20.Scanned N databases:\u6307\u5728\u5904\u7406information_schema\u67e5\u8be2\u65f6,\u6709\u591a\u5c11\u76ee\u5f55\u9700\u8981\u626b\u63cf;\n EXPLAIN SELECT TABLE_NAME, ROW_FORMAT FROM INFORMATION_SCHEMA.TABLES\n21.Open_full_table:\u6307\u793a\u4eceinformation_schema\u67e5\u8be2\u4fe1\u606f\u65f6\u6709\u5173\u6587\u4ef6\u5f00\u542f\u7684\u4f18\u5316; Skip_open_table:\u8868\u4fe1\u606f\u5df2\u7ecf\u83b7\u5f97,\u4e0d\u9700\u8981\u6253\u5f00;\n22.Open_frm_only:\u53ea\u6253\u5f00.frm\u6587\u4ef6; Open_trigger_only:\u53ea\u6253\u5f00.trg\u6587\u4ef6; Open_full_table:\u6ca1\u6709\u4f18\u5316;.frm,.myd\u548c.myi\u6587\u4ef6\u90fd\u6253\u5f00;\n23.Using sort_union(\u2026), Using union(\u2026), Using intersect(\u2026):\u90fd\u51fa\u73b0\u5728index_merge\u8bfb\u53d6\u7c7b\u578b\u4e2d;\n 1.Using sort_union:\u7528\u4e24\u4e2a\u6216\u8005\u4e24\u4e2a\u4ee5\u4e0a\u7684key\u63d0\u53d6\u6570\u636e,\u4f46\u4f18\u5316\u5668\u65e0\u6cd5\u786e\u4fdd\u6bcf\u4e2akey\u4f1a\u63d0\u53d6\u5230\u4e00\u4e2a\u81ea\u7136\u6392\u597d\u5e8f\u7684\u7ed3\u679c,\u6240\u4ee5\u4e3a\u4e86\u6392\u9664\u591a\u4f59\u7684\u6570\u636e,\u9700\u8981\u989d\u5916\u7684\u5904\u7406;\n 2.\u4f8b\u5982,customer\u7684state,\uff08lname,fname\uff09\u662fkey,\u4f46lname\u4e0d\u662fkey,SELECT COUNT(*) FROM customer WHERE (lname = \u2018Jones') OR (state = \u2018UT'),\u7531\u4e8elname\u4e0a\u9762\u6ca1\u6709key,\u6240\u4ee5\u4f7f\u7528\uff08lname,fname\uff09,\u4f7f\u5f97\u7ed3\u679c\u53ef\u80fd\u4e0d\u6309\u7167\u987a\u5e8f,\u4f18\u5316\u5668\u9700\u8981\u989d\u5916\u7684\u4e00\u4e9b\u5de5\u4f5c;\n 3.Using union:\u7528\u4e24\u4e2a\u6216\u8005\u4e24\u4e2a\u4ee5\u4e0a\u7684key\u63d0\u53d6\u6570\u636e,\u5206\u522b\u53d6\u5f97\u7ed3\u679c\u662f\u5df2\u6392\u5e8f,\u901a\u8fc7\u5408\u5e76\u5c31\u53ef\u4ee5\u83b7\u5f97\u6b63\u786e\u7ed3\u679c;\u4f8b\u5982,customer\u4e2d\u7684state\u548c\uff08lname,fname\uff09\u662fkey,SELECT COUNT(state) FROM customer WHERE (lname = \u2018Jones' AND fname='John') OR (state = \u2018UT'); Using intersect:\u7528\u4e24\u4e2a\u6216\u8005\u4e24\u4e2a\u4ee5\u4e0a\u7684key\u63d0\u53d6\u6570\u636e,\u5206\u522b\u53d6\u5f97\u7ed3\u679c\u662f\u5df2\u6392\u5e8f,\u901a\u8fc7\u6c42\u4ea4\u5c31\u53ef\u4ee5\u83b7\u5f97\u6b63\u786e\u7ed3\u679c;\n 4.\u4f8b\u5982,customer\u4e2d\u7684state\u548c\uff08lname,fname\uff09\u662fkey,SELECT COUNT(state) FROM customer WHERE (lname = \u2018Jones' AND fname='John') AND (state = \u2018UT');\n24.Using where with pushed condition:\u4ec5\u7528\u5728ndb\u4e0a;MySQL Cluster\u7528Condition Pushdown\u4f18\u5316\u6539\u5584\u975e\u7d22\u5f15\u5b57\u6bb5\u548c\u5e38\u91cf\u4e4b\u95f4\u7684\u76f4\u63a5\u6bd4\u8f83;condition\u88abpushed down\u5230cluster\u7684\u6570\u636e\u8282\u70b9,\u5e76\u5728\u6240\u6709\u6570\u636e\u8282\u70b9\u540c\u65f6\u4f30\u7b97,\u628a\u4e0d\u5408\u6761\u4ef6\u7684\u5217\u5254\u9664\u907f\u514d\u7f51\u7edc\u4f20\u8f93;<\/derivedn><\/derivedn><\/p>\n","protected":false},"excerpt":{"rendered":"