10.3 \u4f7f\u4f60\u7684\u6570\u636e\u5c3d\u53ef\u80fd\u5c0f<\/p>\n
\u6700\u57fa\u672c\u7684\u4f18\u5316\u4e4b\u4e00\u662f\u4f7f\u4f60\u7684\u6570\u636e(\u548c\u7d22\u5f15)\u5728\u78c1\u76d8\u4e0a(\u5e76\u4e14\u5728\u5185\u5b58\u4e2d)\u5360\u636e\u7684\u7a7a\u95f4\u5c3d\u53ef\u80fd\u5c0f\u3002\u8fd9\u80fd\u7ed9\u51fa\u5de8\u5927\u7684\u6539\u8fdb\uff0c\u56e0\u4e3a\u78c1\u76d8\u8bfb\u5165\u8f83\u5feb\u5e76\u4e14\u901a\u5e38\u4e5f\u7528\u8f83\u5c11\u7684\u4e3b\u5b58\u50a8\u5668\u3002\u5982\u679c\u5728\u66f4\u5c0f\u7684\u5217\u4e0a\u505a\u7d22\u5f15\uff0c\u7d22\u5f15\u4e5f\u5360\u636e\u8f83\u5c11\u7684\u8d44\u6e90\u3002 <\/p>\n
\u4f60\u80fd\u7528\u4e0b\u9762\u7684\u6280\u672f\u4f7f\u8868\u7684\u6027\u80fd\u66f4\u597d\u5e76\u4e14\u4f7f\u5b58\u50a8\u7a7a\u95f4\u6700\u5c0f\uff1a <\/p>\n
\u5c3d\u53ef\u80fd\u5730\u4f7f\u7528\u6700\u6709\u6548(\u6700\u5c0f)\u7684\u7c7b\u578b\u3002MySQL\u6709\u5f88\u591a\u8282\u7701\u78c1\u76d8\u7a7a\u95f4\u548c\u5185\u5b58\u7684\u4e13\u4e1a\u5316\u7c7b\u578b\u3002 <\/p>\n
\u5982\u679c\u53ef\u80fd\u4f7f\u8868\u66f4\u5c0f\uff0c\u4f7f\u7528\u8f83\u5c0f\u7684\u6574\u6570\u7c7b\u578b\u3002\u4f8b\u5982\uff0cMEDIUMINT\u7ecf\u5e38\u6bd4INT\u597d\u4e00\u4e9b\u3002 <\/p>\n
\u5982\u679c\u53ef\u80fd\uff0c\u58f0\u660e\u5217\u4e3aNOT NULL\u3002\u5b83\u4f7f\u4efb\u4f55\u4e8b\u60c5\u66f4\u5feb\u800c\u4e14\u4f60\u4e3a\u6bcf\u5217\u8282\u7701\u4e00\u4f4d\u3002\u6ce8\u610f\u5982\u679c\u5728\u4f60\u7684\u5e94\u7528\u5e8f\u4e2d\u4f60\u786e\u5b9e\u9700\u8981NULL\uff0c\u4f60\u5e94\u8be5\u6beb\u65e0\u7591\u95ee\u4f7f\u7528\u5b83\uff0c\u53ea\u662f\u907f\u514d\u7f3a\u7701\u5730\u5728\u6240\u6709\u5217\u4e0a\u6709\u5b83\u3002 <\/p>\n
\u5982\u679c\u4f60\u6ca1\u6709\u4efb\u4f55\u53d8\u957f\u5217(VARCHAR\u3001TEXT\u6216BLOB\u5217)\uff0c\u4f7f\u7528\u56fa\u5b9a\u5c3a\u5bf8\u7684\u8bb0\u5f55\u683c\u5f0f\u3002\u8fd9\u6bd4\u8f83\u5feb\u4f46\u662f\u4e0d\u5e78\u5730\u53ef\u80fd\u4f1a\u6d6a\u8d39\u4e00\u4e9b\u7a7a\u95f4\u3002\u89c110.6 \u9009\u62e9\u4e00\u79cd\u8868\u7c7b\u578b\u3002 <\/p>\n
\u6bcf\u5f20\u684c\u5b50\u5e94\u8be5\u6709\u5c3d\u53ef\u80fd\u77ed\u7684\u4e3b\u7d22\u5f15\u3002\u8fd9\u4f7f\u4e00\u884c\u7684\u8fa8\u8ba4\u5bb9\u6613\u800c\u6709\u6548\u3002 <\/p>\n
\u5bf9\u6bcf\u4e2a\u8868\uff0c\u4f60\u5fc5\u987b\u51b3\u5b9a\u4f7f\u7528\u54ea\u79cd\u5b58\u50a8\/\u7d22\u5f15\u65b9\u6cd5\u3002\u89c19.4 MySQL\u8868\u7c7b\u578b\u3002\u4e5f\u53ef\u53c2\u89c110.6 \u9009\u62e9\u4e00\u79cd\u8868\u7c7b\u578b\u3002 <\/p>\n
\u53ea\u521b\u5efa\u4f60\u786e\u5b9e\u9700\u8981\u7684\u7d22\u5f15\u3002\u7d22\u5f15\u5bf9\u68c0\u7d22\u6709\u597d\u5904\u4f46\u662f\u5f53\u4f60\u9700\u8981\u5feb\u901f\u5b58\u50a8\u4e1c\u897f\u65f6\u5c31\u53d8\u5f97\u7cdf\u7cd5\u3002\u5982\u679c\u4f60\u4e3b\u8981\u901a\u8fc7\u641c\u7d22\u5217\u7684\u7ec4\u5408\u6765\u5b58\u53d6\u4e00\u4e2a\u8868\uff0c\u4ee5\u5b83\u4eec\u505a\u4e00\u4e2a\u7d22\u5f15\u3002\u7b2c\u4e00\u4e2a\u7d22\u5f15\u90e8\u5206\u5e94\u8be5\u662f\u6700\u5e38\u7528\u7684\u5217\u3002\u5982\u679c<\/p>\n
\u4f60\u603b\u662f\u4f7f\u7528\u8bb8\u591a\u5217\uff0c\u4f60\u5e94\u8be5\u9996\u5148\u4ee5\u66f4\u591a\u7684\u526f\u672c\u4f7f\u7528\u5217\u4ee5\u83b7\u5f97\u66f4\u597d\u7684\u5217\u7d22\u5f15\u538b\u7f29\u3002 <\/p>\n
\u5982\u679c\u5f88\u53ef\u80fd\u4e00\u4e2a\u7d22\u5f15\u5728\u5934\u51e0\u4e2a\u5b57\u7b26\u4e0a\u6709\u552f\u4e00\u7684\u524d\u7f00\uff0c\u4ec5\u4ec5\u7d22\u5f15\u8be5\u524d\u7f00\u6bd4\u8f83\u597d\u3002MySQL\u652f\u6301\u5728\u4e00\u4e2a\u5b57\u7b26\u5217\u7684\u4e00\u90e8\u5206\u4e0a\u7684\u7d22\u5f15\u3002\u66f4\u77ed\u7684\u7d22\u5f15\u66f4\u5feb\uff0c\u4e0d\u4ec5\u56e0\u4e3a\u4ed6\u4eec\u5360\u8f83\u5c11\u7684\u78c1\u76d8\u7a7a\u95f4\u800c\u4e14\u56e0\u4e3a\u4ed6\u4eec\u5c06\u5728\u7d22\u5f15\u7f13\u5b58\u4e2d\u7ed9\u4f60\u66f4\u591a\u7684\u547d\u4e2d\u7387\u5e76\u4e14\u56e0\u6b64\u6709\u66f4\u5c11\u78c1\u76d8\u5bfb\u9053\u3002\u89c110.2.3 \u8c03\u8282\u670d\u52a1\u5668\u53c2\u6570\u3002 <\/p>\n
\u5728\u4e00\u4e9b\u60c5\u5f62\u4e0b\uff0c\u5206\u5272\u4e00\u4e2a\u7ecf\u5e38\u88ab\u626b\u63cf\u8fdb2\u4e2a\u8868\u7684\u8868\u662f\u6709\u76ca\u7684\u3002\u7279\u522b\u662f\u5982\u679c\u5b83\u662f\u4e00\u4e2a\u52a8\u6001\u683c\u5f0f\u7684\u8868\u5e76\u4e14\u5b83\u53ef\u80fd\u4f7f\u4e00\u4e2a\u80fd\u7528\u6765\u626b\u63cf\u540e\u627e\u51fa\u76f8\u5173\u884c\u7684\u8f83\u5c0f\u9759\u6001\u683c\u5f0f\u7684\u8868\u3002 <\/p>\n
10.4 MySQL\u7d22\u5f15\u7684\u4f7f\u7528<\/p>\n
\u7d22\u5f15\u88ab\u7528\u6765\u5feb\u901f\u627e\u51fa\u5728\u4e00\u4e2a\u5217\u4e0a\u7528\u4e00\u7279\u5b9a\u503c\u7684\u884c\u3002\u6ca1\u6709\u7d22\u5f15\uff0cMySQL\u4e0d\u5f97\u4e0d\u9996\u5148\u4ee5\u7b2c\u4e00\u6761\u8bb0\u5f55\u5f00\u59cb\u5e76\u7136\u540e\u8bfb\u5b8c\u6574\u4e2a\u8868\u76f4\u5230\u5b83\u627e\u51fa\u76f8\u5173\u7684\u884c\u3002\u8868\u8d8a\u5927\uff0c\u82b1\u8d39\u65f6\u95f4\u8d8a\u591a\u3002\u5982\u679c\u8868\u5bf9\u4e8e\u67e5\u8be2\u7684\u5217\u6709\u4e00\u4e2a\u7d22\u5f15\uff0cMySQL\u80fd\u5feb\u901f\u5230\u8fbe\u4e00\u4e2a\u4f4d\u7f6e\u53bb\u641c\u5bfb\u5230\u6570\u636e\u6587\u4ef6\u7684\u4e2d\u95f4\uff0c\u6ca1\u6709\u5fc5\u8981\u8003\u8651\u6240\u6709\u6570\u636e\u3002\u5982\u679c\u4e00\u4e2a\u8868\u67091000\u884c\uff0c\u8fd9\u6bd4\u987a\u5e8f\u8bfb\u53d6\u81f3\u5c11\u5feb100\u500d\u3002\u6ce8\u610f\u4f60\u9700\u8981\u5b58\u53d6\u51e0\u4e4e\u6240\u67091000\u884c\uff0c\u5b83\u8f83\u5feb\u7684\u987a\u5e8f\u8bfb\u53d6\uff0c\u56e0\u4e3a\u6b64\u65f6\u6211\u4eec\u907f\u514d\u78c1\u76d8\u5bfb\u9053\u3002 <\/p>\n
\u6240\u6709\u7684MySQL\u7d22\u5f15(PRIMARY\u3001UNIQUE\u548cINDEX)\u5728B\u6811\u4e2d\u5b58\u50a8\u3002\u5b57\u7b26\u4e32\u662f\u81ea\u52a8\u5730\u538b\u7f29\u524d\u7f00\u548c\u7ed3\u5c3e\u7a7a\u95f4\u3002\u89c17.27 CREATE INDEX\u53e5\u6cd5\u3002 <\/p>\n
\u7d22\u5f15\u7528\u4e8e\uff1a <\/p>\n
\u5feb\u901f\u627e\u51fa\u5339\u914d\u4e00\u4e2aWHERE\u5b50\u53e5\u7684\u884c\u3002
\u5f53\u6267\u884c\u8054\u7ed3\u65f6\uff0c\u4ece\u5176\u4ed6\u8868\u68c0\u7d22\u884c\u3002
\u5bf9\u7279\u5b9a\u7684\u7d22\u5f15\u5217\u627e\u51faMAX()\u6216MIN()\u503c\u3002
\u5982\u679c\u6392\u5e8f\u6216\u5206\u7ec4\u5728\u4e00\u4e2a\u53ef\u7528\u952e\u7684\u6700\u5de6\u9762\u524d\u7f00\u4e0a\u8fdb\u884c(\u4f8b\u5982\uff0cORDER BY key_part_1,key_part_2)\uff0c\u6392\u5e8f\u6216\u5206\u7ec4\u4e00\u4e2a\u8868\u3002\u5982\u679c\u6240\u6709\u952e\u503c\u90e8\u5206\u8ddf\u968fDESC\uff0c\u952e\u4ee5\u5012\u5e8f\u88ab\u8bfb\u53d6\u3002
\u5728\u4e00\u4e9b\u60c5\u51b5\u4e2d\uff0c\u4e00\u4e2a\u67e5\u8be2\u80fd\u88ab\u4f18\u5316\u6765\u68c0\u7d22\u503c\uff0c\u4e0d\u7528\u54a8\u8be2\u6570\u636e\u6587\u4ef6\u3002\u5982\u679c\u5bf9\u67d0\u4e9b\u8868\u7684\u6240\u6709\u4f7f\u7528\u7684\u5217\u662f\u6570\u5b57\u578b\u7684\u5e76\u4e14\u6784\u6210\u67d0\u4e9b\u952e\u7684\u6700\u5de6\u9762\u524d\u7f00\uff0c\u4e3a\u4e86\u66f4\u5feb\uff0c\u503c\u53ef\u4ee5\u4ece\u7d22\u5f15\u6811\u88ab\u68c0\u7d22\u51fa\u6765\u3002
\u5047\u5b9a\u4f60\u53d1\u51fa\u4e0b\u5217SELECT\u8bed\u53e5\uff1a <\/p>\n
mysql>; SELECT * FROM tbl_name WHERE col1=val1 AND col2=val2;<\/p>\n
\u5982\u679c\u4e00\u4e2a\u591a\u5217\u7d22\u5f15\u5b58\u5728\u4e8ecol1\u548ccol2\u4e0a\uff0c\u9002\u5f53\u7684\u884c\u53ef\u4ee5\u76f4\u63a5\u88ab\u53d6\u51fa\u3002\u5982\u679c\u5206\u5f00\u7684\u5355\u884c\u5217\u7d22\u5f15\u5b58\u5728\u4e8ecol1\u548ccol2\u4e0a\uff0c\u4f18\u5316\u5668\u8bd5\u56fe\u901a\u8fc7\u51b3\u5b9a\u54ea\u4e2a\u7d22\u5f15\u5c06\u627e\u5230\u66f4\u5c11\u7684\u884c\u5e76\u6765\u627e\u51fa\u66f4\u5177\u9650\u5236\u6027\u7684\u7d22\u5f15\u5e76\u4e14\u4f7f\u7528\u8be5\u7d22\u5f15\u53d6\u884c\u3002 <\/p>\n
\u5982\u679c\u8868\u6709\u4e00\u4e2a\u591a\u5217\u7d22\u5f15\uff0c\u4efb\u4f55\u6700\u5de6\u9762\u7684\u7d22\u5f15\u524d\u7f00\u80fd\u88ab\u4f18\u5316\u5668\u4f7f\u7528\u4ee5\u627e\u51fa\u884c\u3002\u4f8b\u5982\uff0c\u5982\u679c\u4f60\u6709\u4e00\u4e2a3\u884c\u5217\u7d22\u5f15(col1,col2,col3)\uff0c\u4f60\u5df2\u7ecf\u7d22\u5f15\u4e86\u5728(col1)\u3001(col1,col2)\u548c(col1,col2,col3)\u4e0a\u7684\u641c\u7d22\u80fd\u529b\u3002 <\/p>\n
\u5982\u679c\u5217\u4e0d\u6784\u6210\u7d22\u5f15\u7684\u6700\u5de6\u9762\u524d\u7f00\uff0cMySQL\u4e0d\u80fd\u4f7f\u7528\u4e00\u4e2a\u90e8\u5206\u7684\u7d22\u5f15\u3002\u5047\u5b9a\u4f60\u4e0b\u9762\u663e\u793a\u7684SELECT\u8bed\u53e5\uff1a <\/p>\n
mysql>; SELECT * FROM tbl_name WHERE col1=val1;
mysql>; SELECT * FROM tbl_name WHERE col2=val2;
mysql>; SELECT * FROM tbl_name WHERE col2=val2 AND col3=val3;<\/p>\n
\u5982\u679c\u4e00\u4e2a\u7d22\u5f15\u5b58\u5728\u4e8e(col1\u3001col2\u3001col3)\u4e0a\uff0c\u53ea\u6709\u4e0a\u9762\u663e\u793a\u7684\u7b2c\u4e00\u4e2a\u67e5\u8be2\u4f7f\u7528\u7d22\u5f15\u3002\u7b2c\u4e8c\u4e2a\u548c\u7b2c\u4e09\u4e2a\u67e5\u8be2\u786e\u5b9e\u5305\u542b\u7d22\u5f15\u7684\u5217\uff0c\u4f46\u662f(col2)\u548c(col2\u3001col3)\u4e0d\u662f(col1\u3001col2\u3001col3)\u7684\u6700\u5de6\u9762\u524d\u7f00\u3002 <\/p>\n
\u5982\u679cLIKE\u53c2\u6570\u662f\u4e00\u4e2a\u4e0d\u4ee5\u4e00\u4e2a\u901a\u914d\u7b26\u5b57\u7b26\u8d77\u59cb\u7684\u4e00\u4e2a\u5e38\u6570\u5b57\u7b26\u4e32\uff0cMySQL\u4e5f\u4e3aLIKE\u6bd4\u8f83\u4f7f\u7528\u7d22\u5f15\u3002\u4f8b\u5982\uff0c\u4e0b\u5217SELECT\u8bed\u53e5\u4f7f\u7528\u7d22\u5f15\uff1a <\/p>\n
mysql>; select * from tbl_name where key_col LIKE “atrick%”;
mysql>; select * from tbl_name where key_col LIKE “at%_ck%”;<\/p>\n
\u5728\u7b2c\u4e00\u6761\u8bed\u53e5\u4e2d\uff0c\u53ea\u8003\u8651\u6709”atrick” <= key_col < \"atricl\"\u7684\u884c\u3002\u5728\u7b2c\u4e8c\u6761\u8bed\u53e5\u4e2d\uff0c\u53ea\u8003\u8651\u6709\"at\" <= key_col < \"au\"\u7684\u884c\u3002 \n\n\u4e0b\u5217SELECT\u8bed\u53e5\u5c06\u4e0d\u4f7f\u7528\u7d22\u5f15\uff1a \n\nmysql>; select * from tbl_name where key_col LIKE “%Patrick%”;
mysql>; select * from tbl_name where key_col LIKE other_col;<\/p>\n
\u5728\u7b2c\u4e00\u6761\u8bed\u53e5\u4e2d\uff0cLIKE\u503c\u4ee5\u4e00\u4e2a\u901a\u914d\u7b26\u5b57\u7b26\u5f00\u59cb\u3002\u5728\u7b2c\u4e8c\u6761\u8bed\u53e5\u4e2d\uff0cLIKE\u503c\u4e0d\u662f\u4e00\u4e2a\u5e38\u6570\u3002 <\/p>\n
\u5982\u679c column_name \u662f\u4e00\u4e2a\u7d22\u5f15\uff0c\u4f7f\u7528column_name IS NULL\u7684\u641c\u7d22\u5c06\u4f7f\u7528\u7d22\u5f15\u3002 <\/p>\n
MySQL\u901a\u5e38\u4f7f\u7528\u627e\u51fa\u6700\u5c11\u6570\u91cf\u7684\u884c\u7684\u7d22\u5f15\u3002\u4e00\u4e2a\u7d22\u5f15\u88ab\u7528\u4e8e\u4f60\u4e0e\u4e0b\u5217\u64cd\u4f5c\u7b26\u4f5c\u6bd4\u8f83\u7684\u5217\uff1a=\u3001>;\u3001>;=\u3001<\u3001<=\u3001BETWEEN\u548c\u4e00\u4e2a\u6709\u4e00\u4e2a\u975e\u901a\u914d\u7b26\u524d\u7f00\u8c61'something%'\u7684LIKE\u7684\u5217\u3002 \n\n\u4efb\u4f55\u4e0d\u8de8\u8d8a\u7684\u5728WHERE\u5b50\u53e5\u7684\u6240\u6709AND\u5c42\u6b21\u7684\u7d22\u5f15\u4e0d\u7528\u6765\u4f18\u5316\u8be2\u95ee\u3002 \n\n\u4e0b\u5217WHERE\u5b50\u53e5\u4f7f\u7528\u7d22\u5f15\uff1a\n\n… WHERE index_part1=1 AND index_part2=2
… WHERE index=1 OR A=10 AND index=2 \/* index = 1 OR index = 2 *\/
… WHERE index_part1='hello' AND index_part_3=5
\/* optimized like “index_part1='hello'” *\/<\/p>\n
\u8fd9\u4e9bWHERE\u5b50\u53e5\u4e0d\u4f7f\u7528\u7d22\u5f15\uff1a <\/p>\n
… WHERE index_part2=1 AND index_part3=2 \/* index_part_1 is not used *\/
… WHERE index=1 OR A=10 \/* No index *\/
… WHERE index_part1=1 OR index_part2=10 \/* No index spans all rows *\/<\/p>\n
10.5 \u5b58\u53d6\u6216\u66f4\u65b0\u6570\u636e\u7684\u67e5\u8be2\u901f\u5ea6<\/p>\n
\u9996\u5148\uff0c\u4e00\u4ef6\u4e8b\u60c5\u5f71\u54cd\u6240\u6709\u7684\u8be2\u95ee\u3002\u4f60\u6709\u7684\u8bb8\u53ef\u7cfb\u7edf\u8bbe\u7f6e\u8d8a\u590d\u6742\uff0c\u4f60\u5f97\u5230\u66f4\u591a\u7684\u5f00\u9500\u3002<\/p>\n
\u5982\u679c\u4f60\u4e0d\u8ba9\u4efb\u4f55GRANT\u8bed\u53e5\u6267\u884c\uff0cMySQL\u5c06\u7a0d\u5fae\u4f18\u5316\u8bb8\u53ef\u68c0\u67e5\u3002\u56e0\u6b64\u5982\u679c\u4f60\u6709\u5f88\u5927\u91cf\uff0c\u503c\u5f97\u82b1\u65f6\u95f4\u6765\u907f\u514d\u6388\u6743\uff0c\u5426\u5219\u66f4\u591a\u7684\u8bb8\u53ef\u68c0\u67e5\u6709\u66f4\u5927\u7684\u5f00\u9500\u3002 <\/p>\n
\u5982\u679c\u4f60\u7684\u95ee\u9898\u662f\u4e0e\u4e00\u4e9b\u660e\u663e\u7684MySQL\u51fd\u6570\u6709\u5173\uff0c\u4f60\u603b\u80fd\u5728MySQL\u5ba2\u6237\u4e2d\u8ba1\u7b97\u5176\u65f6\u95f4\uff1a<\/p>\n
mysql>; select benchmark(1000000,1+1);
+————————+
| benchmark(1000000,1+1) |
+————————+
| 0 |
+————————+
1 row in set (0.32 sec)<\/p>\n
\u4e0a\u9762\u663e\u793aMySQL\u80fd\u5728PentiumII 400MHz\u4e0a\u4ee50.32\u79d2\u6267\u884c1,000,000\u4e2a+\u8868\u8fbe\u5f0f\u3002 <\/p>\n
\u6240\u6709MySQL\u51fd\u6570\u5e94\u8be5\u88ab\u9ad8\u5ea6\u4f18\u5316\uff0c\u4f46\u662f\u4ee5\u53ef\u80fd\u6709\u4e00\u4e9b\u4f8b\u5916\u5e76\u4e14benchmark(loop_count,expression)\u662f\u627e\u51fa\u662f\u5426\u4f60\u7684\u67e5\u8be2\u6709\u95ee\u9898\u7684\u4e00\u4e2a\u6781\u597d\u5de5\u5177\u3002<\/p>\n
10.5.1 \u4f30\u8ba1\u67e5\u8be2\u6027\u80fd
\u5728\u5927\u591a\u6570\u60c5\u51b5\u4e0b\uff0c\u4f60\u80fd\u901a\u8fc7\u8ba1\u7b97\u78c1\u76d8\u5bfb\u9053\u4f30\u8ba1\u6027\u80fd\u3002\u5bf9\u5c0f\u7684\u8868\uff0c\u4f60\u901a\u5e38\u80fd\u57281\u6b21\u78c1\u76d8\u5bfb\u9053\u4e2d\u627e\u5230\u884c(\u56e0\u4e3a\u8fd9\u4e2a\u7d22\u5f15\u53ef\u80fd\u88ab\u7f13\u51b2)\u3002\u5bf9\u66f4\u5927\u7684\u8868\uff0c\u4f60\u80fd\u4f30\u8ba1\u5b83(\u4f7f\u7528 B++ \u6811\u7d22\u5f15)\uff0c\u4f60\u5c06\u9700\u8981\uff1alog(row_count)\/log(index_block_length\/3*2\/(index_length + data_pointer_length))+1\u6b21\u5bfb\u9053\u627e\u5230\u884c\u3002 <\/p>\n
\u5728MySQL\u4e2d\uff0c\u7d22\u5f15\u5757\u901a\u5e38\u662f1024\u4e2a\u5b57\u8282\u4e14\u6570\u636e\u6307\u9488\u901a\u5e38\u662f4\u4e2a\u5b57\u8282\uff0c\u8fd9\u5bf9\u4e00\u4e2a\u6709\u4e00\u4e2a\u7d22\u5f15\u957f\u5ea6\u4e3a3(\u4e2d\u7b49\u6574\u6570)\u7684 500,000 \u884c\u7684\u8868\u7ed9\u4f60\uff1alog(500,000)\/log(1024\/3*2\/(3+4)) + 1= 4 \u6b21\u5bfb\u9053\u3002 <\/p>\n
\u8c61\u4e0a\u9762\u7684\u7d22\u5f15\u5c06\u8981\u6c42\u5927\u7ea6 500,000 * 7 * 3\/2 = 5.2M\uff0c(\u5047\u8bbe\u7d22\u5f15\u7f13\u51b2\u533a\u88ab\u5145\u6ee1\u52302\/3(\u5b83\u662f\u5178\u578b\u7684))\uff0c\u4f60\u5c06\u53ef\u80fd\u5728\u5185\u5b58\u4e2d\u6709\u7d22\u5f15\u7684\u5927\u90e8\u5206\u5e76\u4e14\u4f60\u5c06\u53ef\u80fd\u4ec5\u9700\u89811-2\u8c03\u7528\u4eceOS\u8bfb\u6570\u636e\u6765\u627e\u51fa\u884c\u3002 <\/p>\n
\u7136\u800c\u5bf9\u4e8e\u5199\uff0c\u4f60\u5c06\u9700\u8981 4 \u6b21\u5bfb\u9053\u8bf7\u6c42(\u5982\u4e0a)\u6765\u627e\u5230\u5728\u54ea\u513f\u5b58\u653e\u65b0\u7d22\u5f15\u5e76\u4e14\u901a\u5e38\u97002\u6b21\u5bfb\u9053\u66f4\u65b0\u8fd9\u4e2a\u7d22\u5f15\u5e76\u4e14\u5199\u5165\u884c\u3002 <\/p>\n
\u6ce8\u610f\uff0c\u4e0a\u8ff0\u4e0d\u5473\u7740\u4f60\u7684\u5e94\u7528\u7a0b\u5e8f\u5c06\u7f13\u6162\u5730\u4ee5 N log N \u9000\u5316\uff01\u5f53\u8868\u683c\u53d8\u5f97\u66f4\u5927\u65f6\uff0c\u53ea\u8981\u4e00\u5207\u88abOS\u6216SQL\u670d\u52a1\u5668\u7f13\u51b2\uff0c\u4e8b\u60c5\u5c06\u4ec5\u4ec5\u6216\u591a\u6216\u5c11\u5730\u66f4\u6162\u3002\u5728\u6570\u636e\u53d8\u5f97\u592a\u5927\u4e0d\u80fd\u88ab\u7f13\u51b2\u540e\uff0c\u4e8b\u60c5\u5c06\u5f00\u59cb\u53d8\u5f97\u66f4\u6162\u76f4\u5230\u4f60\u7684\u5e94\u7528\u7a0b\u5e8f\u4ec5\u4ec5\u53d7\u78c1\u76d8\u5bfb\u9053\u9650\u5236(\u5b83\u4ee5N log N\u589e\u52a0)\u3002\u4e3a\u4e86\u907f\u514d\u8fd9\u4e2a\u589e\u52a0\uff0c\u7d22\u5f15\u7f13\u51b2\u968f\u6570\u636e\u589e\u52a0\u800c\u589e\u52a0\u3002\u89c110.2.3 \u8c03\u8282\u670d\u52a1\u5668\u53c2\u6570\u3002<\/p>\n
10.5.2 SELECT\u67e5\u8be2\u7684\u901f\u5ea6
\u603b\u7684\u6765\u8bf4\uff0c\u5f53\u4f60\u60f3\u8981\u4f7f\u4e00\u4e2a\u8f83\u6162\u7684SELECT … WHERE\u66f4\u5feb\uff0c\u68c0\u67e5\u7684\u7b2c\u4e00\u4ef6\u4e8b\u60c5\u662f\u4f60\u662f\u5426\u80fd\u589e\u52a0\u4e00\u4e2a\u7d22\u5f15\u3002\u89c110.4 MySQL \u7d22\u5f15\u7684\u4f7f\u7528\u3002\u5728\u4e0d\u540c\u8868\u4e4b\u95f4\u7684\u6240\u6709\u5f15\u7528\u901a\u5e38\u5e94\u8be5\u7528\u7d22\u5f15\u5b8c\u6210\u3002\u4f60\u53ef\u4ee5\u4f7f\u7528EXPLAIN\u6765\u786e\u5b9a\u54ea\u4e2a\u7d22\u5f15\u7528\u4e8e\u4e00\u6761SELECT\u8bed\u53e5\u3002\u89c17.22 EXPLAIN\u53e5\u6cd5(\u5f97\u5230\u5173\u4e8e\u4e00\u6761SELECT\u7684\u4fe1\u606f)\u3002 <\/p>\n
\u4e00\u4e9b\u4e00\u822c\u7684\u5efa\u8bae\uff1a <\/p>\n
\u4e3a\u4e86\u5e2e\u52a9MySQL\u66f4\u597d\u5730\u4f18\u5316\u67e5\u8be2\uff0c\u5728\u5b83\u5df2\u7ecf\u88c5\u8f7d\u4e86\u76f8\u5173\u6570\u636e\u540e\uff0c\u5728\u4e00\u4e2a\u8868\u4e0a\u8fd0\u884cmyisamchk –analyze\u3002\u8fd9\u4e3a\u6bcf\u4e00\u4e2a\u66f4\u65b0\u4e00\u4e2a\u503c\uff0c\u6307\u51fa\u6709\u76f8\u540c\u503c\u5730\u5e73\u5747\u884c\u6570\uff08\u5f53\u7136\uff0c\u5bf9\u552f\u4e00\u7d22\u5f15\uff0c\u8fd9\u603b\u662f1\u3002\uff09
\u4e3a\u4e86\u6839\u636e\u4e00\u4e2a\u7d22\u5f15\u6392\u5e8f\u4e00\u4e2a\u7d22\u5f15\u548c\u6570\u636e\uff0c\u4f7f\u7528myisamchk –sort-index –sort-records=1\uff08\u5982\u679c\u4f60\u60f3\u8981\u5728\u7d22\u5f151\u4e0a\u6392\u5e8f)\u3002\u5982\u679c\u4f60\u6709\u4e00\u4e2a\u552f\u4e00\u7d22\u5f15\uff0c\u4f60\u60f3\u8981\u6839\u636e\u8be5\u7d22\u5f15\u5730\u6b21\u5e8f\u8bfb\u53d6\u6240\u6709\u7684\u8bb0\u5f55\uff0c\u8fd9\u662f\u4f7f\u5b83\u66f4\u5feb\u7684\u4e00\u4e2a\u597d\u65b9\u6cd5\u3002\u7136\u800c\u6ce8\u610f\uff0c\u8fd9\u4e2a\u6392\u5e8f\u6ca1\u6709\u88ab\u6700\u4f73\u5730\u7f16\u5199\uff0c\u5e76\u4e14\u5bf9\u4e00\u4e2a\u5927\u8868\u5c06\u82b1\u5f88\u957f\u65f6\u95f4\uff01
10.5.3 MySQL\u600e\u6837\u4f18\u5316WHERE\u5b50\u53e5
where\u4f18\u5316\u88ab\u653e\u5728SELECT\u4e2d\uff0c\u56e0\u4e3a\u4ed6\u4eec\u6700\u4e3b\u8981\u5728\u90a3\u91cc\u4f7f\u7528\u91cc\uff0c\u4f46\u662f\u540c\u6837\u7684\u4f18\u5316\u88ab\u7528\u4e8eDELETE\u548cUPDATE\u8bed\u53e5\u3002<\/p>\n
\u4e5f\u8981\u6ce8\u610f\uff0c\u672c\u8282\u662f\u4e0d\u5b8c\u5168\u7684\u3002MySQL\u786e\u5b9e\u4f5c\u4e86\u8bb8\u591a\u4f18\u5316\u800c\u6211\u4eec\u6ca1\u6709\u65f6\u95f4\u5168\u90e8\u8bb0\u5f55\u4ed6\u4eec\u3002 <\/p>\n
\u7531MySQL\u5b9e\u65bd\u7684\u4e00\u4e9b\u4f18\u5316\u5217\u5728\u4e0b\u9762\uff1a <\/p>\n
\u5220\u9664\u4e0d\u5fc5\u8981\u7684\u62ec\u53f7\uff1a
((a AND b) AND c OR (((a AND b) AND (c AND d))))
->; (a AND b AND c) OR (a AND b AND c AND d)<\/p>\n
\u5e38\u6570\u8c03\u5165\uff1a
(a->; b>;5 AND b=c AND a=5<\/p>\n
\u5220\u9664\u5e38\u6570\u6761\u4ef6(\u56e0\u5e38\u6570\u8c03\u5165\u6240\u9700)\uff1a
(B>;=5 AND B=5) OR (B=6 AND 5=5) OR (B=7 AND 5=6)
->; B=5 OR B=6<\/p>\n
\u7d22\u5f15\u4f7f\u7528\u7684\u5e38\u6570\u8868\u8fbe\u5f0f\u4ec5\u8ba1\u7b97\u4e00\u6b21\u3002
\u5728\u4e00\u4e2a\u5355\u4e2a\u8868\u4e0a\u7684\u6ca1\u6709\u4e00\u4e2aWHERE\u7684COUNT(*)\u76f4\u63a5\u4ece\u8868\u4e2d\u68c0\u7d22\u4fe1\u606f\u3002\u5f53\u4ec5\u4f7f\u7528\u4e00\u4e2a\u8868\u65f6\uff0c\u5bf9\u4efb\u4f55NOT NULL\u8868\u8fbe\u5f0f\u4e5f\u8fd9\u6837\u505a\u3002
\u65e0\u6548\u5e38\u6570\u8868\u8fbe\u5f0f\u7684\u65e9\u671f\u68c0\u6d4b\u3002MySQL\u5feb\u901f\u68c0\u6d4b\u67d0\u4e9bSELECT\u8bed\u53e5\u662f\u4e0d\u53ef\u80fd\u7684\u5e76\u4e14\u4e0d\u8fd4\u56de\u884c\u3002
\u5982\u679c\u4f60\u4e0d\u4f7f\u7528GROUP BY\u6216\u5206\u7ec4\u51fd\u6570(COUNT()\u3001MIN()\u2026\u2026)\uff0cHAVING\u4e0eWHERE\u5408\u5e76\u3002
\u4e3a\u6bcf\u4e2a\u5b50\u8054\u7ed3(sub join)\uff0c\u6784\u9020\u4e00\u4e2a\u66f4\u7b80\u5355\u7684WHERE\u4ee5\u5f97\u5230\u4e00\u4e2a\u66f4\u5feb\u7684WHERE\u8ba1\u7b97\u5e76\u4e14\u4e5f\u5c3d\u5feb\u8df3\u8fc7\u8bb0\u5f55\u3002
\u6240\u6709\u5e38\u6570\u7684\u8868\u5728\u67e5\u8be2\u4e2d\u7684\u4efb\u4f55\u5176\u4ed6\u8868\u524d\u88ab\u9996\u5148\u8bfb\u51fa\u3002\u4e00\u4e2a\u5e38\u6570\u7684\u8868\u662f\uff1a
\u4e00\u4e2a\u7a7a\u8868\u6216\u4e00\u4e2a\u67091\u884c\u7684\u8868\u3002
\u4e0e\u5728\u4e00\u4e2aUNIQUE\u7d22\u5f15\u3001\u6216\u4e00\u4e2aPRIMARY KEY\u7684WHERE\u5b50\u53e5\u4e00\u8d77\u4f7f\u7528\u7684\u8868\uff0c\u8fd9\u91cc\u6240\u6709\u7684\u7d22\u5f15\u90e8\u5206\u4f7f\u7528\u4e00\u4e2a\u5e38\u6570\u8868\u8fbe\u5f0f\u5e76\u4e14\u7d22\u5f15\u90e8\u5206\u88ab\u5b9a\u4e49\u4e3aNOT NULL\u3002
\u6240\u6709\u4e0b\u5217\u7684\u8868\u7528\u4f5c\u5e38\u6570\u8868\uff1a <\/p>\n
mysql>; SELECT * FROM t WHERE primary_key=1;
mysql>; SELECT * FROM t1,t2
WHERE t1.primary_key=1 AND t2.primary_key=t1.id;<\/p>\n
\u5bf9\u8054\u7ed3\u8868\u7684\u6700\u597d\u8054\u7ed3\u7ec4\u5408\u662f\u901a\u8fc7\u5c1d\u8bd5\u6240\u6709\u53ef\u80fd\u6027\u6765\u627e\u5230\u3002\u5982\u679c\u6240\u6709\u5728ORDER BY\u548cGROUP BY\u7684\u5217\u6765\u81ea\u540c\u4e00\u4e2a\u8868\uff0c\u90a3\u4e48\u5f53\u5ec9\u6d01\u65f6\uff0c\u8be5\u8868\u9996\u5148\u88ab\u9009\u4e2d\u3002
\u5982\u679c\u6709\u4e00\u4e2aORDER BY\u5b50\u53e5\u548c\u4e00\u4e2a\u4e0d\u540c\u7684GROUP BY\u5b50\u53e5\uff0c\u6216\u5982\u679cORDER BY\u6216GROUP BY\u5305\u542b\u4e0d\u662f\u6765\u81ea\u8054\u7ed3\u961f\u5217\u4e2d\u7684\u7b2c\u4e00\u4e2a\u8868\u7684\u5176\u4ed6\u8868\u7684\u5217\uff0c\u521b\u5efa\u4e00\u4e2a\u4e34\u65f6\u8868\u3002
\u5982\u679c\u4f60\u4f7f\u7528SQL_SMALL_RESULT\uff0cMySQL\u5c06\u4f7f\u7528\u4e00\u4e2a\u5728\u5185\u5b58\u4e2d\u7684\u8868\u3002
\u56e0\u4e3aDISTINCT\u88ab\u53d8\u6362\u5230\u5728\u6240\u6709\u7684\u5217\u4e0a\u7684\u4e00\u4e2aGROUP BY\uff0cDISTINCT\u4e0eORDER BY\u7ed3\u5408\u4e5f\u5c06\u5728\u8bb8\u591a\u60c5\u51b5\u4e0b\u9700\u8981\u4e00\u5f20\u4e34\u65f6\u8868\u3002
\u6bcf\u4e2a\u8868\u7684\u7d22\u5f15\u88ab\u67e5\u8be2\u5e76\u4e14\u4f7f\u7528\u8de8\u8d8a\u5c11\u4e8e30% \u7684\u884c\u7684\u7d22\u5f15\u3002\u5982\u679c\u8fd9\u6837\u7684\u7d22\u5f15\u6ca1\u80fd\u627e\u5230\uff0c\u4f7f\u7528\u4e00\u4e2a\u5feb\u901f\u7684\u8868\u626b\u63cf\u3002
\u5728\u4e00\u4e9b\u60c5\u51b5\uff0cMySQL\u80fd\u4ece\u7d22\u5f15\u4e2d\u8bfb\u51fa\u884c\uff0c\u751a\u81f3\u4e0d\u54a8\u8be2\u6570\u636e\u6587\u4ef6\u3002\u5982\u679c\u7d22\u5f15\u4f7f\u7528\u7684\u6240\u6709\u5217\u662f\u6570\u5b57\u7684\uff0c\u90a3\u4e48\u53ea\u6709\u7d22\u5f15\u6811\u88ab\u7528\u6765\u89e3\u7b54\u67e5\u8be2\u3002
\u5728\u6bcf\u4e2a\u8bb0\u5f55\u88ab\u8f93\u51fa\u524d\uff0c\u90a3\u4e9b\u4e0d\u5339\u914dHAVING\u5b50\u53e5\u7684\u884c\u88ab\u8df3\u8fc7\u3002
\u4e0b\u9762\u662f\u4e00\u4e9b\u5f88\u5feb\u7684\u67e5\u8be2\u4f8b\u5b50\uff1a <\/p>\n
mysql>; SELECT COUNT(*) FROM tbl_name;
mysql>; SELECT MIN(key_part1),MAX(key_part1) FROM tbl_name;
mysql>; SELECT MAX(key_part2) FROM tbl_name
WHERE key_part_1=constant;
mysql>; SELECT … FROM tbl_name
ORDER BY key_part1,key_part2,… LIMIT 10;
mysql>; SELECT … FROM tbl_name
ORDER BY key_part1 DESC,key_part2 DESC,… LIMIT 10;<\/p>\n
\u4e0b\u5217\u67e5\u8be2\u4ec5\u4f7f\u7528\u7d22\u5f15\u6811\u5c31\u53ef\u89e3\u51b3(\u5047\u8bbe\u7d22\u5f15\u5217\u662f\u6570\u5b57\u7684)\uff1a <\/p>\n
mysql>; SELECT key_part1,key_part2 FROM tbl_name WHERE key_part1=val;
mysql>; SELECT COUNT(*) FROM tbl_name
WHERE key_part1=val1 AND key_part2=val2;
mysql>; SELECT key_part2 FROM tbl_name GROUP BY key_part1;<\/p>\n
\u4e0b\u5217\u67e5\u8be2\u4f7f\u7528\u7d22\u5f15\u4ee5\u6392\u5e8f\u987a\u5e8f\u68c0\u7d22\uff0c\u4e0d\u7528\u4e00\u6b21\u53e6\u5916\u7684\u6392\u5e8f\uff1a <\/p>\n
mysql>; SELECT … FROM tbl_name ORDER BY key_part1,key_part2,…
mysql>; SELECT … FROM tbl_name ORDER BY key_part1 DESC,key_part2 DESC,…<\/p>\n
10.5.4 MySQL\u600e\u6837\u4f18\u5316LEFT JOIN
\u5728MySQL\u4e2d\uff0cA LEFT JOIN B\u5b9e\u73b0\u5982\u4e0b\uff1a <\/p>\n
\u8868B\u88ab\u8bbe\u7f6e\u4e3a\u4f9d\u8d56\u4e8e\u8868A\u3002
\u8868A\u88ab\u8bbe\u7f6e\u4e3a\u4f9d\u8d56\u4e8e\u6240\u6709\u7528\u5728LEFT JOIN\u6761\u4ef6\u7684\u8868(\u9664B\u5916)\u3002
\u6240\u6709LEFT JOIN\u6761\u4ef6\u88ab\u79fb\u5230WHERE\u5b50\u53e5\u4e2d\u3002
\u8fdb\u884c\u6240\u6709\u6807\u51c6\u7684\u8054\u7ed3\u4f18\u5316\uff0c\u9664\u4e86\u4e00\u4e2a\u8868\u603b\u662f\u5728\u6240\u6709\u5b83\u4f9d\u8d56\u7684\u8868\u4e4b\u540e\u88ab\u8bfb\u53d6\u3002\u5982\u679c\u6709\u4e00\u4e2a\u5faa\u73af\u4f9d\u8d56\uff0cMySQL\u5c06\u53d1\u51fa\u4e00\u4e2a\u9519\u8bef\u3002
\u8fdb\u884c\u6240\u6709\u6807\u51c6\u7684WHERE\u4f18\u5316\u3002
\u5982\u679c\u5728A\u4e2d\u6709\u4e00\u884c\u5339\u914dWHERE\u5b50\u53e5\uff0c\u4f46\u662f\u5728B\u4e2d\u6ca1\u6709\u4efb\u4f55\u884c\u5339\u914dLEFT JOIN\u6761\u4ef6\uff0c\u90a3\u4e48\u5728B\u4e2d\u751f\u6210\u6240\u6709\u5217\u8bbe\u7f6e\u4e3aNULL\u7684\u4e00\u884c\u3002
\u5982\u679c\u4f60\u4f7f\u7528LEFT JOIN\u6765\u627e\u51fa\u5728\u67d0\u4e9b\u8868\u4e2d\u4e0d\u5b58\u5728\u7684\u884c\u5e76\u4e14\u5728WHERE\u90e8\u5206\u4f60\u6709\u4e0b\u5217\u6d4b\u8bd5\uff1acolumn_name IS NULL\uff0c\u8fd9\u91cccolumn_name \u88ab\u58f0\u660e\u4e3aNOT NULL\u7684\u5217\uff0c\u90a3\u4e48MySQL\u5728\u5b83\u5df2\u7ecf\u627e\u5230\u4e86\u5339\u914dLEFT JOIN\u6761\u4ef6\u7684\u4e00\u884c\u540e\uff0c\u5c06\u505c\u6b62\u5728\u66f4\u591a\u7684\u884c\u540e\u5bfb\u627e(\u5bf9\u4e00\u7279\u5b9a\u7684\u952e\u7ec4\u5408)\u3002
10.5.5 MySQL\u600e\u6837\u4f18\u5316LIMIT
\u5728\u4e00\u4e9b\u60c5\u51b5\u4e2d\uff0c\u5f53\u4f60\u4f7f\u7528LIMIT #\u800c\u4e0d\u4f7f\u7528HAVING\u65f6\uff0cMySQL\u5c06\u4ee5\u4e0d\u540c\u65b9\u5f0f\u5904\u7406\u67e5\u8be2\u3002 <\/p>\n
\u5982\u679c\u4f60\u7528LIMIT\u53ea\u9009\u62e9\u4e00\u4e9b\u884c\uff0c\u5f53MySQL\u4e00\u822c\u6bd4\u8f83\u559c\u6b22\u505a\u5b8c\u6574\u7684\u8868\u626b\u63cf\u65f6\uff0c\u5b83\u5c06\u5728\u4e00\u4e9b\u60c5\u51b5\u4e0b\u4f7f\u7528\u7d22\u5f15\u3002
\u5982\u679c\u4f60\u4f7f\u7528LIMIT #\u4e0eORDER BY\uff0cMySQL\u4e00\u65e6\u627e\u5230\u4e86\u7b2c\u4e00\u4e2a # \u884c\uff0c\u5c06\u7ed3\u675f\u6392\u5e8f\u800c\u4e0d\u662f\u6392\u5e8f\u6574\u4e2a\u8868\u3002
\u5f53\u7ed3\u5408LIMIT #\u548cDISTINCT\u65f6\uff0cMySQL\u4e00\u65e6\u627e\u5230#\u4e2a\u552f\u4e00\u7684\u884c\uff0c\u5b83\u5c06\u505c\u6b62\u3002
\u5728\u4e00\u4e9b\u60c5\u51b5\u4e0b\uff0c\u4e00\u4e2aGROUP BY\u80fd\u901a\u8fc7\u987a\u5e8f\u8bfb\u53d6\u952e(\u6216\u5728\u952e\u4e0a\u505a\u6392\u5e8f)\u6765\u89e3\u51b3\uff0c\u5e76\u7136\u540e\u8ba1\u7b97\u6458\u8981\u76f4\u5230\u952e\u503c\u6539\u53d8\u3002\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0cLIMIT #\u5c06\u4e0d\u8ba1\u7b97\u4efb\u4f55\u4e0d\u5fc5\u8981\u7684GROUP\u3002
\u53ea\u8981MySQL\u5df2\u7ecf\u53d1\u9001\u4e86\u7b2c\u4e00\u4e2a#\u884c\u5230\u5ba2\u6237\uff0c\u5b83\u5c06\u653e\u5f03\u67e5\u8be2\u3002
LIMIT 0\u5c06\u603b\u662f\u5feb\u901f\u8fd4\u56de\u4e00\u4e2a\u7a7a\u96c6\u5408\u3002\u8fd9\u5bf9\u68c0\u67e5\u67e5\u8be2\u5e76\u4e14\u5f97\u5230\u7ed3\u679c\u5217\u7684\u5217\u7c7b\u578b\u662f\u6709\u7528\u7684\u3002
\u4e34\u65f6\u8868\u7684\u5927\u5c0f\u4f7f\u7528LIMIT #\u8ba1\u7b97\u9700\u8981\u591a\u5c11\u7a7a\u95f4\u6765\u89e3\u51b3\u67e5\u8be2\u3002
10.5.6 INSERT\u67e5\u8be2\u7684\u901f\u5ea6
\u63d2\u5165\u4e00\u4e2a\u8bb0\u5f55\u7684\u65f6\u95f4\u7531\u4e0b\u5217\u7ec4\u6210\uff1a <\/p>\n
\u8fde\u63a5\uff1a(3)
\u53d1\u9001\u67e5\u8be2\u7ed9\u670d\u52a1\u5668\uff1a(2)
\u5206\u6790\u67e5\u8be2\uff1a(2)
\u63d2\u5165\u8bb0\u5f55\uff1a\uff081 x \u8bb0\u5f55\u5927\u5c0f\uff09
\u63d2\u5165\u7d22\u5f15\uff1a\uff081 x \u7d22\u5f15\uff09
\u5173\u95ed\uff1a(1)
\u8fd9\u91cc\u7684\u6570\u5b57\u6709\u70b9\u4e0e\u603b\u4f53\u65f6\u95f4\u6210\u6b63\u6bd4\u3002\u8fd9\u4e0d\u8003\u8651\u6253\u5f00\u8868\u7684\u521d\u59cb\u5f00\u9500(\u5b83\u4e3a\u6bcf\u4e2a\u5e76\u53d1\u8fd0\u884c\u7684\u67e5\u8be2\u505a\u4e00\u6b21)\u3002 <\/p>\n
\u8868\u7684\u5927\u5c0f\u4ee5N log N (B \u6811)\u7684\u901f\u5ea6\u51cf\u6162\u7d22\u5f15\u7684\u63d2\u5165\u3002 <\/p>\n
\u52a0\u5feb\u63d2\u5165\u7684\u4e00\u4e9b\u65b9\u6cd5\uff1a <\/p>\n
\u5982\u679c\u4f60\u540c\u65f6\u4ece\u540c\u4e00\u5ba2\u6237\u63d2\u5165\u5f88\u591a\u884c\uff0c\u4f7f\u7528\u591a\u4e2a\u503c\u8868\u7684INSERT\u8bed\u53e5\u3002\u8fd9\u6bd4\u4f7f\u7528\u5206\u5f00INSERT\u8bed\u53e5\u5feb(\u5728\u4e00\u4e9b\u60c5\u51b5\u4e2d\u51e0\u500d)\u3002
\u5982\u679c\u4f60\u4ece\u4e0d\u540c\u5ba2\u6237\u63d2\u5165\u5f88\u591a\u884c\uff0c\u4f60\u80fd\u901a\u8fc7\u7528INSERT DELAYED\u8bed\u53e5\u5f97\u5230\u66f4\u9ad8\u7684\u901f\u5ea6\u3002\u89c17.14 INSERT\u53e5\u6cd5\u3002
\u6ce8\u610f\uff0c\u7528MyISAM\uff0c\u5982\u679c\u5728\u8868\u4e2d\u6ca1\u6709\u5220\u9664\u7684\u884c\uff0c\u80fd\u5728SELECT:s\u6b63\u5728\u8fd0\u884c\u7684\u540c\u65f6\u63d2\u5165\u884c\u3002
\u5f53\u4ece\u4e00\u4e2a\u6587\u672c\u6587\u4ef6\u88c5\u8f7d\u4e00\u4e2a\u8868\u65f6\uff0c\u4f7f\u7528LOAD DATA INFILE\u3002\u8fd9\u901a\u5e38\u6bd4\u4f7f\u7528\u5f88\u591aINSERT\u8bed\u53e5\u5feb20\u500d\u3002\u89c17.16 LOAD DATA INFILE\u53e5\u6cd5\u3002
\u5f53\u8868\u6709\u5f88\u591a\u7d22\u5f15\u65f6\uff0c\u6709\u53ef\u80fd\u591a\u505a\u4e9b\u5de5\u4f5c\u4f7f\u5f97LOAD DATA INFILE\u66f4\u5feb\u4e9b\u3002\u4f7f\u7528\u4e0b\u5217\u8fc7\u7a0b\uff1a
\u6709\u9009\u62e9\u5730\u7528CREATE TABLE\u521b\u5efa\u8868\u3002\u4f8b\u5982\u4f7f\u7528mysql\u6216Perl-DBI\u3002
\u6267\u884cFLUSH TABLES\uff0c\u6216\u5916\u58f3\u547d\u4ee4mysqladmin flush-tables\u3002
\u4f7f\u7528myisamchk –keys-used=0 -rq \/path\/to\/db\/tbl_name\u3002\u8fd9\u5c06\u4ece\u8868\u4e2d\u5220\u9664\u6240\u6709\u7d22\u5f15\u7684\u4f7f\u7528\u3002
\u7528LOAD DATA INFILE\u628a\u6570\u636e\u63d2\u5165\u5230\u8868\u4e2d\uff0c\u8fd9\u5c06\u4e0d\u66f4\u65b0\u4efb\u4f55\u7d22\u5f15\uff0c\u56e0\u6b64\u5f88\u5feb\u3002
\u5982\u679c\u4f60\u6709myisampack\u5e76\u4e14\u60f3\u8981\u538b\u7f29\u8868\uff0c\u5728\u5b83\u4e0a\u9762\u8fd0\u884cmyisampack\u3002\u89c110.6.3 \u538b\u7f29\u8868\u7684\u7279\u5f81\u3002
\u7528myisamchk -r -q \/path\/to\/db\/tbl_name\u518d\u521b\u5efa\u7d22\u5f15\u3002\u8fd9\u5c06\u5728\u5c06\u5b83\u5199\u5165\u78c1\u76d8\u524d\u5728\u5185\u5b58\u4e2d\u521b\u5efa\u7d22\u5f15\u6811\uff0c\u5e76\u4e14\u5b83\u66f4\u5feb\uff0c\u56e0\u4e3a\u907f\u514d\u5927\u91cf\u78c1\u76d8\u5bfb\u9053\u3002\u7ed3\u679c\u7d22\u5f15\u6811\u4e5f\u88ab\u5b8c\u7f8e\u5730\u5e73\u8861\u3002
\u6267\u884cFLUSH TABLES\uff0c\u6216\u5916\u58f3\u547d\u4ee4mysqladmin flush-tables\u3002
\u8fd9\u4e2a\u8fc7\u7a0b\u5c06\u88ab\u6784\u9020\u8fdb\u5728MySQL\u7684\u67d0\u4e2a\u672a\u6765\u7248\u672c\u7684LOAD DATA INFILE\u3002<\/p>\n
\u4f60\u53ef\u4ee5\u9501\u5b9a\u4f60\u7684\u8868\u4ee5\u52a0\u901f\u63d2\u5165\u3002
mysql>; LOCK TABLES a WRITE;
mysql>; INSERT INTO a VALUES (1,23),(2,34),(4,33);
mysql>; INSERT INTO a VALUES (8,26),(6,29);
mysql>; UNLOCK TABLES;<\/p>\n
\u4e3b\u8981\u7684\u901f\u5ea6\u5dee\u522b\u662f\u7d22\u5f15\u7f13\u51b2\u533a\u4ec5\u88ab\u6e05\u6d17\u5230\u78c1\u76d8\u4e0a\u4e00\u6b21\uff0c\u5728\u6240\u6709INSERT\u8bed\u53e5\u5b8c\u6210\u540e\u3002\u4e00\u822c\u6709\u4e0e\u6709\u4e0d\u540c\u7684INSERT\u8bed\u53e5\u90a3\u6837\u593a\u7684\u7d22\u5f15\u7f13\u51b2\u533a\u6e05\u6d17\u3002\u5982\u679c\u4f60\u80fd\u7528\u4e00\u4e2a\u5355\u4e2a\u8bed\u53e5\u63d2\u5165\u6240\u6709\u7684\u884c\uff0c\u9501\u5b9a\u5c31\u4e0d\u9700\u8981\u3002\u9501\u5b9a\u4e5f\u5c06\u964d\u4f4e\u591a\u8fde\u63a5\u6d4b\u8bd5\u7684\u6574\u4f53\u65f6\u95f4\uff0c\u4f46\u662f\u5bf9\u67d0\u4e9b\u7ebf\u7a0b\u6700\u5927\u7b49\u5f85\u65f6\u95f4\u5c06\u4e0a\u5347(\u56e0\u4e3a\u4ed6\u4eec\u7b49\u5f85\u9501)\u3002\u4f8b\u5982\uff1a<\/p>\n
thread 1 does 1000 inserts
thread 2, 3, and 4 does 1 insert
thread 5 does 1000 inserts<\/p>\n
\u5982\u679c\u4f60\u4e0d\u4f7f\u7528\u9501\u5b9a\uff0c2\u30013\u548c4\u5c06\u57281\u548c5\u524d\u5b8c\u6210\u3002\u5982\u679c\u4f60\u4f7f\u7528\u9501\u5b9a\uff0c2\u30013\u548c4\u5c06\u53ef\u80fd\u4e0d\u57281\u62165\u524d\u5b8c\u6210\uff0c\u4f46\u662f\u6574\u4f53\u65f6\u95f4\u5e94\u8be5\u5feb\u5927\u7ea640%\u3002\u56e0\u4e3aINSERT, UPDATE\u548cDELETE\u64cd\u4f5c\u5728MySQL\u4e2d\u662f\u5f88\u5feb\u7684\uff0c\u901a\u8fc7\u4e3a\u591a\u4e8e\u5927\u7ea65\u6b21\u8fde\u7eed\u4e0d\u65ad\u5730\u63d2\u5165\u6216\u66f4\u65b0\u4e00\u884c\u7684\u4e1c\u897f\u52a0\u9501\uff0c\u4f60\u5c06\u83b7\u5f97\u66f4\u597d\u7684\u6574\u4f53\u6027\u80fd\u3002\u5982\u679c\u4f60\u505a\u5f88\u591a\u4e00\u884c\u7684\u63d2\u5165\uff0c\u4f60\u53ef\u4ee5\u505a\u4e00\u4e2aLOCK TABLES\uff0c\u5076\u5c14\u968f\u540e\u505a\u4e00\u4e2aUNLOCK TABLES(\u5927\u7ea6\u6bcf1000\u884c)\u4ee5\u5141\u8bb8\u53e6\u5916\u7684\u7ebf\u7a0b\u5b58\u53d6\u8868\u3002\u8fd9\u4ecd\u7136\u5c06\u5bfc\u81f4\u83b7\u5f97\u597d\u7684\u6027\u80fd\u3002\u5f53\u7136\uff0cLOAD DATA INFILE\u5bf9\u88c5\u8f7d\u6570\u636e\u4ecd\u7136\u662f\u66f4\u5feb\u7684\u3002 <\/p>\n
\u4e3a\u4e86\u5bf9LOAD DATA INFILE\u548cINSERT\u5f97\u5230\u4e00\u4e9b\u66f4\u5feb\u7684\u901f\u5ea6\uff0c\u6269\u5927\u5173\u952e\u5b57\u7f13\u51b2\u533a\u3002\u89c110.2.3 \u8c03\u8282\u670d\u52a1\u5668\u53c2\u6570\u3002<\/p>\n
10.5.7 UPDATE\u67e5\u8be2\u7684\u901f\u5ea6
\u66f4\u6539\u67e5\u8be2\u88ab\u4f18\u5316\u4e3a\u6709\u4e00\u4e2a\u5199\u5f00\u9500\u7684\u4e00\u4e2aSELECT\u67e5\u8be2\u3002\u5199\u901f\u5ea6\u4f9d\u8d56\u4e8e\u88ab\u66f4\u65b0\u6570\u636e\u5927\u5c0f\u548c\u88ab\u66f4\u65b0\u7d22\u5f15\u7684\u6570\u91cf\u3002 <\/p>\n
\u4f7f\u66f4\u6539\u66f4\u5feb\u7684\u53e6\u4e00\u4e2a\u65b9\u6cd5\u662f\u63a8\u8fdf\u66f4\u6539\u5e76\u4e14\u7136\u540e\u4e00\u884c\u4e00\u884c\u5730\u505a\u5f88\u591a\u66f4\u6539\u3002\u5982\u679c\u4f60\u9501\u5b9a\u8868\uff0c\u505a\u4e00\u884c\u4e00\u884c\u5730\u5f88\u591a\u66f4\u6539\u6bd4\u4e00\u6b21\u505a\u4e00\u4e2a\u5feb\u3002 <\/p>\n
\u6ce8\u610f\uff0c\u52a8\u6001\u8bb0\u5f55\u683c\u5f0f\u7684\u66f4\u6539\u4e00\u4e2a\u8f83\u957f\u603b\u957f\u7684\u8bb0\u5f55\uff0c\u53ef\u80fd\u5207\u5f00\u8bb0\u5f55\u3002\u56e0\u6b64\u5982\u679c\u4f60\u7ecf\u5e38\u8fd9\u6837\u505a\uff0c\u65f6\u4e0d\u65f6\u5730OPTIMIZE TABLE\u662f\u975e\u5e38\u91cd\u8981\u7684\u3002\u89c17.9 OPTIMIZE TABLE\u53e5\u6cd5\u3002 <\/p>\n
10.5.8 DELETE\u67e5\u8be2\u7684\u901f\u5ea6
\u5220\u9664\u4e00\u4e2a\u8bb0\u5f55\u7684\u65f6\u95f4\u7cbe\u786e\u5730\u4e0e\u7d22\u5f15\u6570\u91cf\u6210\u6b63\u6bd4\u3002\u4e3a\u4e86\u66f4\u5feb\u901f\u5730\u5220\u9664\u8bb0\u5f55\uff0c\u4f60\u53ef\u4ee5\u589e\u52a0\u7d22\u5f15\u7f13\u5b58\u7684\u5927\u5c0f\u3002\u89c110.2.3 \u8c03\u8282\u670d\u52a1\u5668\u53c2\u6570\u3002 <\/p>\n
\u4ece\u4e00\u4e2a\u8868\u5220\u9664\u6240\u6709\u884c\u6bd4\u5220\u9664\u884c\u7684\u4e00\u5927\u90e8\u5206\u4e5f\u8981\u5f97\u591a\u3002 <\/p>\n","protected":false},"excerpt":{"rendered":"
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