{"id":4170,"date":"2013-01-29T10:08:09","date_gmt":"2013-01-29T02:08:09","guid":{"rendered":"http:\/\/www.orczhou.com\/?p=4170"},"modified":"2013-01-29T10:08:09","modified_gmt":"2013-01-29T02:08:09","slug":"mysql-source-code-query-optimization-index-merge","status":"publish","type":"post","link":"https:\/\/www.orczhou.com\/index.php\/2013\/01\/mysql-source-code-query-optimization-index-merge\/","title":{"rendered":"MySQL\u4f18\u5316\u5668\uff1aindex merge\u4ecb\u7ecd"},"content":{"rendered":"

\u5728MySQL\u5b98\u65b9\u624b\u518c\u4e0a\uff0c\u5173\u4e8eindex merge\u7684\u4ecb\u7ecd<\/a>\u975e\u5e38\u975e\u5e38\u5c11\u3002\u751a\u81f3\u8fd8\u6709\u4e0d\u5c11\u8bef\u5bfc\u7684\u5730\u65b9\uff0c\u8fd9\u6b21\u628a5.1\u7248\u672c\u5173\u4e8e\u6b64\u7c7b\u4f18\u5316\u5904\u7406\u7684\u4ee3\u7801\u7ec6\u770b\u4e86\u4e00\u904d\uff0c\u4ee5\u6848\u4f8b\u7684\u65b9\u5f0f\u4ecb\u7ecd\u4e86\u5404\u79cd\u5b9e\u7528index merge\u8bbf\u95ee\u7c7b\u578b\u7684SQL\u3002\u540e\u7eed\u7684\u8fd8\u4f1a\u7ee7\u7eed\u4ecb\u7ecdindex merge\u5b9e\u73b0\u7684\u4e3b\u8981\u6570\u636e\u7ed3\u6784\uff0c\u4ee5\u53ca\u6210\u672c\u8bc4\u4f30\u3002<\/p>\n\n

1. \u4ec0\u4e48\u662findex merge<\/h3>\n

MySQL\u4f18\u5316\u5668\u5982\u679c\u53d1\u73b0\u53ef\u4ee5\u4f7f\u7528\u591a\u4e2a\u7d22\u5f15\u67e5\u627e\u540e\u7684\u4ea4\u96c6\/\u5e76\u96c6\u5b9a\u4f4d\u6570\u636e\uff0c\u90a3\u4e48MySQL\u4f18\u5316\u5668\u5c31\u4f1a\u5c1d\u8bd5index merge\u8fd9\u7c7b\u8bbf\u95ee\u65b9\u5f0f\u3002index merge\u4e3b\u8981\u5206\u4e3a\u4e24\u5927\u7c7b\uff0c\u591a\u4e2a\u7d22\u5f15\u4ea4\u96c6\u8bbf\u95ee(intersections)\uff0c\u591a\u4e2a\u7d22\u5f15\u5e76\u96c6\u8bbf\u95ee\uff0c\u5f53\u7136\u8fd9\u4e24\u7c7b\u8fd8\u53ef\u4ee5\u7ec4\u5408\u51fa\u66f4\u4e3a\u590d\u6742\u7684\u65b9\u5f0f\uff0c\u4f8b\u5982\u591a\u4e2a\u4ea4\u96c6\u540e\u505a\u5e76\u96c6\u3002<\/p>\n

1.1 index merge\u7684\u9650\u5236\uff1arange\u4f18\u5148<\/h4>\n

MySQL\u57285.6.7\u4e4b\u524d\uff0c\u4f7f\u7528index merge\u6709\u4e00\u4e2a\u91cd\u8981\u7684\u524d\u63d0\u6761\u4ef6\uff1a\u6ca1\u6709range\u53ef\u4ee5\u4f7f\u7528\u3002\u8fd9\u4e2a\u9650\u5236\u964d\u4f4e\u4e86MySQL index merge\u53ef\u4ee5\u4f7f\u7528\u7684\u573a\u666f\u3002\u7406\u60f3\u72b6\u6001\u662f\u540c\u65f6\u8bc4\u4f30\u6210\u672c\u540e\u7136\u540e\u505a\u51fa\u9009\u62e9\u3002\u56e0\u4e3a\u8fd9\u4e2a\u9650\u5236\uff0c\u5c31\u6709\u4e86\u4e0b\u9762\u8fd9\u4e2a\u5df2\u77e5\u7684bad case(\u53c2\u8003<\/a>)\uff1a<\/p>\n

SELECT * FROM t1 WHERE (goodkey1 < 10 OR goodkey2 < 20) AND badkey < 30;<\/p><\/blockquote>\n

\u4f18\u5316\u5668\u53ef\u4ee5\u9009\u62e9\u4f7f\u7528goodkey1\u548cgoodkey2\u505aindex merge\uff0c\u4e5f\u53ef\u4ee5\u4f7f\u7528badkey\u505arange\u3002\u56e0\u4e3a\u4e0a\u9762\u7684\u539f\u5219\uff0c\u65e0\u8bbagoodkey1\u548cgoodkey2\u7684\u9009\u62e9\u5ea6\u5982\u4f55\uff0cMySQL\u90fd\u53ea\u4f1a\u8003\u8651range\uff0c\u800c\u4e0d\u4f1a\u4f7f\u7528index merge\u7684\u8bbf\u95ee\u65b9\u5f0f\u3002\u8fd9\u662f\u4e00\u4e2a\u60b2\u5267…\uff085.6.7\u7248\u672c\u9488\u5bf9\u6b64\u6709\u4fee\u590d<\/a>)<\/p>\n

2. \u5173\u4e8eindex merge\u7684\u4e00\u4e9b\u6848\u4f8b<\/h3>\n

\u5173\u4e8e\u4ec0\u4e48\u662f\u4ea4\u96c6\/\u5e76\u96c6\u5728\u624b\u518c\u4e2d\u6709\u8be6\u7ec6\u4ecb\u7ecd<\/a>\uff0c\u8fd9\u91cc\u4e0d\u8d58\u8ff0\u3002\u8fd9\u91cc\u901a\u8fc7\u51e0\u4e2a\u6848\u4f8b\u6765\u770b\u770b\uff0c\u54ea\u4e9b\u60c5\u51b5\u4f7f\u7528\u4ea4\u96c6\uff0c\u54ea\u4e9b\u60c5\u51b5\u4f7f\u7528\u5e76\u96c6\uff0c\u54ea\u4e9b\u60c5\u51b5\u4f7f\u7528\u66f4\u590d\u6742\u7684\u7ec4\u5408\u3002<\/p>\n

\u793a\u4f8b\u4e2d\u4f7f\u7528\u7684\u8868\u7ed3\u6784\u548c\u6570\u636e\u53c2\u8003\u672c\u65874.2\u8282\u3002<\/p>\n

2.1 k1_p1 = 2 or k2_p1 = 4<\/h4>\n

\u8fd9\u662f\u6700\u5178\u578b\uff0c\u4e5f\u662f\u6700\u7b80\u5355\u7684\u573a\u666f\u4e86\uff1a<\/p>\n

SELECT * FROM tmp_index_merge where key1_part1 = 2 or key2_part1 = 4<\/p>\n

explain SELECT * FROM tmp_index_merge where key1_part1 = 2 or key2_part1 = 4\\G\r\n            ......\r\n        table: tmp_index_merge\r\n         type: index_merge\r\n          key: ind1,ind2\r\n      key_len: 4,4\r\n        Extra: Using sort_union(ind1,ind2); Using where<\/blockquote><\/pre>\n
2.2 (k1_p1=2 and k1_p2=7) or k2_p1=4\\G<\/h4>\n
\u8fd9\u4e2a\u6848\u4f8b\u7a0d\u5fae\u590d\u6742\u4e00\u4e01\u70b9\uff0c\u7b2c\u4e00\u4e2a\u7d22\u5f15\u4f7f\u7528\u4e86\u4e24\u4e2a\u5b57\u6bb5\uff1a<\/p>\n
explain SELECT * FROM tmp_index_merge \r\nwhere (key1_part1 = 2 and key1_part2 = 7) or key2_part1 = 4\\G\r\n            ......\r\n        table: tmp_index_merge\r\n         type: index_merge\r\n          key: ind1,ind2\r\n      key_len: 8,4\r\n        Extra: Using sort_union(ind1,ind2); Using where<\/blockquote><\/pre>\n
2.3 (k1_p1=2 or k1_p1=7) or k2_p1=4\\G<\/h4>\n
\u8fd9\u4e2a\u6848\u4f8b\u4e5f\u80fd\u591f\u4f7f\u7528index merge\u3002\u5185\u90e8\u7684\u5b9e\u73b0\u6bd4\u5b83\u8868\u9762\u4e0a\u770b\u8d77\u6765\u8981\u590d\u6742\uff0c\u8fd9\u91cc\u7b80\u5355\u89e3\u91ca\u4e00\u4e0b\uff1aMySQL\u5728\u9012\u5f52\u5904\u7406\u8fd9\u4e2aWHERE\u6761\u4ef6\u65f6\uff0c\u5148\u5904\u7406\u524d\u4e00\u90e8\u5206(key1_part1 = 2 or key1_part1 = 7)\u3002\u5bf9\u4e8e\u540c\u4e00\u4e2a\u7d22\u5f15\u7684\u540c\u4e00\u4e2a\u5b57\u6bb5\u8fdb\u884cor\u64cd\u4f5c\uff0cMySQL\u4f1a\u5c06\u5176\u5408\u5e76\u6210\u4e00\u9897SEL_ARG\u6811(\u5177\u4f53\u53c2\u8003<\/a>)\uff0c\u4e24\u4e2a\u6761\u4ef6\u901a\u8fc7SEL_ARG\u7684Next\/prev\u6307\u9488\u8fde\u63a5\u3002MySQL\u7684range\u8bbf\u95ee\u65b9\u5f0f\u53ef\u4ee5\u901a\u8fc7\u904d\u5386\u8fd9\u68f5\u6811(\u4e5f\u53ef\u4ee5\u53c2\u8003\u524d\u9762\u8fd9\u7bc7\u6587\u7ae0<\/a>)\u3002\u63a5\u7740\u4f18\u5316\u5668\u518d\u5904\u7406or\u7684\u53e6\u4e00\u4e2a\u5206\u652f(key2_part1 = 4)\u53d1\u73b0\u53ef\u4ee5\u4f7f\u7528\u7b2c\u4e8c\u4e2a\u7d22\u5f15\uff0c\u4e8e\u662f\u5c06index merge\u52a0\u5165\u53ef\u80fd\u7684\u6267\u884c\u8ba1\u5212\u5217\u8868(\u540e\u7eed\u8bc4\u4f30\u6210\u672c\uff0c\u518d\u51b3\u5b9a\u662f\u5426\u5b9e\u7528\u8be5\u8bbf\u95ee\u65b9\u5f0f)\u3002<\/p>\n
explain SELECT * FROM tmp_index_merge \r\nwhere (key1_part1 = 2 or key1_part1 = 7) or key2_part1 = 4\\G\r\n            ......\r\n        table: tmp_index_merge\r\n         type: index_merge\r\n          key: ind1,ind2\r\n      key_len: 4,4\r\n        Extra: Using sort_union(ind1,ind2); Using where<\/blockquote><\/pre>\n
2.4 (k1_p1=2 or k1_p2=7) or k2_p1=4\\G<\/h4>\n
\u8fd9\u79cd\u60c5\u51b5\u662f\u65e0\u6cd5\u76f4\u63a5\u4f7f\u7528\u4efb\u4f55\u7d22\u5f15\u7684\u3002\u4e0d\u89e3\u91ca\u3002<\/p>\n
explain SELECT * FROM tmp_index_merge \r\nwhere (key1_part1 = 2 or key1_part2 = 7) or key2_part1 = 4\\G\r\n            ......\r\n        table: tmp_index_merge\r\n         type: ALL\r\npossible_keys: ind1,ind2\r\n          key: NULL\r\n        Extra: Using where<\/blockquote><\/pre>\n
2.5 k1_p1=1 or (k1_p1=2 and k1_p2=4 and k2_p1=3)<\/h4>\n
\u5bf9\u4e8e\u8fd9\u6837\u7684\u6761\u4ef6\uff0cMySQL\u4f1a\u53d1\u73b0\u53ef\u4ee5\u4f7f\u7528range\u8bbf\u95ee\u65b9\u5f0f\u3002\u800c\u6839\u636e\u524d\u9762\u7684”range\u4f18\u5148”\u539f\u5219\uff0cMySQL\u4e0d\u518d\u8003\u8651index merge(\u8fd9\u91cck1_p1=1\u548ck2_p1=3\u662f\u53ef\u4ee5\u901a\u8fc7index merge\u8bbf\u95ee\u65b9\u5f0f\u5b9e\u73b0\u7684)\u3002MySQL\u5728\u8003\u8651\u4f7f\u7528key1\u8bbf\u95ee\u7684\u65f6\u5019\uff0c\u770b\u5230\u7684\u6761\u4ef6\u662f\uff1ak1_p1=1 or (k1_p1=2 and k1_p2=4)\u3002\u8fd9\u91ccOR\u4e24\u8fb9\u7684\u6761\u4ef6\u53ef\u4ee5\u6784\u9020\u6210\u4e00\u9897\u72ec\u7acb\u7684SEL_ARG\u3002(\u672c\u6587\u540e\u9762\u5c0f\u7ed3\u201c\u66f4\u591a\u5173\u4e8erange\u4f18\u5148\u539f\u5219\u201d\u6709\u66f4\u591a\u8be6\u7ec6\u4ecb\u7ecd)<\/p>\n
\u6240\u4ee5\uff0cMySQL\u4f1a\u76f4\u63a5\u4f7f\u7528range\uff0c\u800c\u4e0d\u518d\u8003\u8651index merge\u3002(\u600e\u6837\u7684\u6761\u4ef6\u65e0\u6cd5\u591f\u7740\u6210\u4e00\u9897SEL_ARG\u6811\uff0c\u53c2\u8003\uff0c\u5bf9\u4e8e\u4e24\u9897SEL_ARG\u901a\u8fc7or\u5408\u5e76\u7684\u65f6\u5019\uff0c\u8fd8\u6709\u4e00\u4e9b\u66f4\u590d\u6742\u7684\u4e8b\u60c5\uff0c\u8fd9\u91cc\u6682\u65f6\u4e0d\u505a\u4ecb\u7ecd)<\/p>\n
explain SELECT * FROM tmp_sel_tree \r\nwhere key1_part1=1 or (key1_part1=2 and key1_part2=4 and key2_part1=3)\\G\r\n        table: tmp_sel_tree\r\n         type: range\r\n          key: ind1\r\n      key_len: 8\r\n        Extra: Using where<\/blockquote><\/pre>\n
\u5982\u679c\u524d\u9762\u8fd9\u51e0\u4e2a\u6848\u4f8b\u770b\u660e\u767d\u4e86\uff0c\u90a3\u53ef\u4ee5\u7ee7\u7eed\u4e86\uff0c\u4e0b\u9762\u4f1a\u6709\u4e00\u4e9b\u66f4\u590d\u6742\u7684\u6848\u4f8b\uff1a<\/p>\n
2.6 \u5d4c\u5957\u7684\u6848\u4f8b1<\/h4>\n
\u8fd9\u4e2a\u6848\u4f8b\u770b\u8d77\u6765\u5f88\u590d\u6742\uff0c\u4f46\u5176\u672c\u8d28\u8ddf\u6700\u524d\u9762\u63d0\u5230\u7684”\u5df2\u77e5\u7684bad case”\u76f8\u540c\uff0c\u662f\u4e00\u4e2a\u53ef\u4ee5\u4f7f\u7528index merge\uff0c\u4f46\u662f\u88abrange\u4f18\u5148\u6389\u7684\u6848\u4f8b\u3002<\/p>\n
SELECT * FROM tmp_sel_tree where \r\n  ( key1_part1 = 1 or (key1_part2 = 2 and key2_part1 = 3) ) and\r\n  ( key3_part1 = 5 )<\/blockquote><\/pre>\n
2.7 \u5d4c\u5957\u7684\u6848\u4f8b2<\/h4>\n
\u8fd9\u4e2a\u6848\u4f8b\u8ddf\u4e0a\u9762\u7a0d\u6709\u4e0d\u540c\uff0c\u662f\u4e00\u4e2a\u4e09\u4e2a\u7d22\u5f15\u7684index merge\uff0c\u8fd9\u91ccMySQL\u5c06\u8003\u8651\u4f7f\u7528index merge\u3002\u4f46\u662f\u4e00\u822c\u6765\u8bf4\uff0c\u8fd9\u7c7bindex merge\u6210\u672c\u672c\u8eab\u8f83\u5927\uff0c\u5bb9\u6613\u8d85\u8fc7\u5168\u8868\u7684\u6210\u672c\uff1a<\/p>\n
SELECT * FROM tmp_sel_tree where \r\n  ( key1_part1 = 1 or (key1_part2 = 2 and key2_part1 = 3) ) or\r\n  ( key3_part1 = 5 )<\/blockquote><\/pre>\n
\u5982\u679c\u6210\u672c\u8bc4\u4f30\u540e\uff0c\u53d1\u73b0index merge\u6210\u672c\u5c0f\u4e8e\u5168\u8868\uff0c\u5219\u4f1a\u4f7f\u7528\uff1a<\/p>\n
        table: tmp_sel_tree\r\n         type: index_merge\r\n          key: ind1,ind2,ind3\r\n        Extra: Using sort_union(ind1,ind2,ind3); Using where\r\n<\/blockquote><\/pre>\n
3. \u66f4\u591a\u5173\u4e8erange\u4f18\u5148\u539f\u5219<\/h3>\n
\u53ef\u4ee5\u4f7f\u7528range\u7684\u60c5\u51b5<\/h4>\n
\u57285.6.7\u4e4b\u524d\u7684MySQL\u7248\u672c\uff0c\u53ea\u8981\u53ef\u4ee5\u4f7f\u7528Range\u8bbf\u95ee\u65b9\u5f0f\uff0c\u90a3\u5c31\u4e0d\u4f1a\u518d\u4f7f\u7528index merge\u3002\u56e0\u4e3a\u53ef\u4ee5\u4f7f\u7528range\u8bbf\u95ee\u7684WHERE\u6761\u4ef6\u662f\u975e\u5e38\u591a\u7684\uff0c\u9664\u4e86\u6211\u4eec\u5e38\u89c1\u7684(k1_p1=const and k2_p2>const)\uff0c\u5982\u679c\u53c2\u8003Range\u4f18\u5316\u76f8\u5173\u7684\u6570\u636e\u7ed3\u6784<\/a>\uff0c\u8fd8\u4f1a\u770b\u5230\u66f4\u591a\u7684WHERE\u6761\u4ef6\u53ef\u4ee5\u4f7f\u7528range\u3002<\/p>\n
\u8fd9\u91cc\u62ff\u51fa\u5176\u4e2d\u4e00\u4e2a\u8f83\u4e3a\u590d\u6742\u7684\u53ef\u4ee5\u4f7f\u7528range\u8bbf\u95ee\u7684WHERE\u6761\u4ef6\uff0c\u505a\u4e00\u4e2a\u7b80\u5355\u5206\u6790\u3002<\/p>\n
WHERE \r\n  (\r\n    key1_part1 = 3 and key1_part2 > 5 and key2_part1 = 7\r\n  ) \r\n  or ( key1_part1 > 2 )\r\n<\/blockquote><\/pre>\n
\u5bf9\u4e8e\u7d22\u5f15key2\u6765\u8bf4\uff0c\u8fd9\u4e2a\u6761\u4ef6\u53ef\u4ee5\u7b80\u5316\u4e3a\u5982\u4e0b\uff0c\u53ef\u4ee5\u4f7f\u7528index merge\u7684\u8bbf\u95ee\u65b9\u5f0f\uff1a<\/p>\n
(TRUE AND TRUE AND key2_part1 = 7) OR ( key1_part1 < 2 )<\/blockquote><\/pre>\n
\u5bf9\u4e8e\u7d22\u5f15key1\u6765\u8bf4\uff0c\u6761\u4ef6\u7b80\u5316\u4e3a\uff1a<\/p>\n
(key1_part1 = 3 and key1_part2 > 5 and TRUE) or (key1_part1 > 2)<\/blockquote><\/pre>\n
\u5bf9\u4e8e\u7d22\u5f15key1\uff0c\u8fd9\u662f\u4e00\u4e2a\u53ef\u4ee5\u4f7f\u7528range\u8bbf\u95ee\u65b9\u5f0f\u7684\u6761\u4ef6\u3002\u6839\u636e\u524d\u6587Range\u4f18\u5316\u76f8\u5173\u7684\u6570\u636e\u7ed3\u6784<\/a>\u53ef\u4ee5\u6784\u9020\u6210\u4e00\u9897SEL_ARG\u7ed3\u6784\uff0c\u5982\u4e0b\uff1a<\/p>\n
               $                      $   \r\nSEL_ARG[2,∞)   $                      $   \r\n       |^      $                      $   \r\n   next||      $                      $   \r\n       ||prev  $                      $   \r\n       v|      $                      $   \r\nSEL_ARG[3,3] ==$====>  SEL_ARG[5,∞]   $   \r\n               $                      $<\/blockquote><\/pre>\n
range\u8bbf\u95ee\u4f1a\u4f9d\u6b21SEL_ARG\uff0c\u904d\u5386\u8bbf\u95ee\u3002\u56e0\u4e3a\u6709range\u8bbf\u95ee\u65b9\u5f0f\uff0c\u6240\u4ee5\u8fd9\u7c7b\u6761\u4ef6\u4e0d\u4f1a\u518d\u8003\u8651index merge\u3002<\/p>\n
\u4f46\u5982\u679cWHERE\u662f\u5982\u4e0b\u6837\u5b50\uff08OR\u540e\u9762\u6761\u4ef6\u662fkey1_part2\u800c\u4e0d\u662fkey1_part1\uff09\uff1a<\/p>\n
WHERE \r\n  (\r\n    key1_part1 = 3 and key1_part2 > 5 and key2_part1 = 7\r\n  ) \r\n  or ( key1_part2 > 2 )\r\n<\/blockquote><\/pre>\n
 OR\u540e\u9762\u7684key1_part2\u662f\u65e0\u6cd5\u4e0e\u524d\u9762\u7684key1\u6761\u4ef6\u5408\u5e76\u6210\u4e00\u9897SEL_ARG\u6811\uff0c\u6240\u4ee5\u4e5f\u5c31\u65e0\u6cd5\u4f7f\u7528range\u8bbf\u95ee\u3002\u56e0\u4e3aor\u540e\u9762\u6761\u4ef6\u65e0\u6cd5\u72ec\u7acb\u4f7f\u7528\u7d22\u5f15\u8bbf\u95ee\uff0c\u6240\u4ee5\u4e5f\u540c\u6837\u65e0\u6cd5\u505aindex merge\u8bbf\u95ee\u3002<\/p>\n
4. \u5176\u4ed6<\/h3>\n
4.1 type in MySQL Explain<\/h4>\n
\u5728MySQL\u624b\u518c\u4e2d\u628aExplain\u4e2dtype\u5217\u79f0\u4e3a\uff1a”EXPLAIN Join Types”\u3002\u8fd9\u7ed9\u5f88\u591a\u4eba\u4ea7\u751f\u4e86\u8bef\u89e3\uff0c\u8fd9\u91cc\u7684Type\u5b9e\u9645\u662f\u6307\u5728\u6574\u4e2aJOIN\u4e2d\u8fd9\u4e2a\u5355\u8868\u7684\u8bbf\u95ee\u65b9\u5f0f\u3002\u4f8b\u5982\uff1a<\/p>\n
           id: 1\r\n  select_type: SIMPLE\r\n        table: tmp_sel_tree\r\n         type: index_merge<\/span>\r\npossible_keys: ind1,ind2,ind3\r\n          key: ind1,ind2,ind3\r\n      key_len: 4,4,4<\/blockquote><\/pre>\n
\u5e38\u89c1\u7684\u5355\u8868\u8bbf\u95ee\u65b9\u5f0f\u6709\uff1aconst\/ref\/range\/index\/all<\/p>\n
MySQL\u7684\u4f18\u5316\u5668\u4e3b\u8981\u6709\u4e24\u4e2a\u81ea\u7531\u5ea6\uff0c\u4e00\u4e2a\u662f\u786e\u5b9a\u6bcf\u4e2a\u5355\u8868\u7684\u8bbf\u95ee\u65b9\u5f0f\u3002\u53e6\u4e00\u4e2a\u5c31\u662f\u8bbf\u95ee\u987a\u5e8f\u3002\u535a\u5ba2\u4e2d\u5e38\u8bf4\u7684\u4f7f\u7528”range\u4f18\u5316” “index merge\u4f18\u5316”\u4e5f\u662f\u6307MySQL\u5355\u8868\u8bbf\u95ee\u65b9\u5f0f\u9009\u62e9\u4e86”range”\u6216\u8005”index merge”\u3002<\/p>\n
4.2 \u793a\u4f8b\u4e2d\u7684\u8868\u7ed3\u6784\u548c\u6570\u636e<\/h4>\n
CREATE TABLE `tmp_index_merge` (\r\n  `id` int(11) NOT NULL,\r\n  `key1_part1` int(11) NOT NULL,\r\n  `key1_part2` int(11) NOT NULL,\r\n  `key2_part1` int(11) NOT NULL,\r\n  `key2_part2` int(11) NOT NULL,\r\n  `key2_part3` int(11) NOT NULL,\r\n  `key3_part1` int(11) NOT NULL DEFAULT '4',\r\n  KEY `ind1` (`key1_part1`,`key1_part2`),\r\n  KEY `ind2` (`key2_part1`,`key2_part2`,`key2_part3`),\r\n  KEY `ind3` (`key3_part1`)\r\n) ENGINE=InnoDB DEFAULT CHARSET=gbk\r\n1 row in set (0.01 sec)\r\n\r\nroot@test 11:33:22>select * from tmp_index_merge;\r\n+----+------------+------------+------------+------------+------------+------------+\r\n| id | key1_part1 | key1_part2 | key2_part1 | key2_part2 | key2_part3 | key3_part1 |\r\n+----+------------+------------+------------+------------+------------+------------+\r\n|  6 |          6 |          1 |          9 |          2 |          1 |          8 |\r\n|  8 |          9 |          9 |          1 |          6 |          6 |          6 |\r\n|  4 |          1 |          3 |          4 |          9 |          3 |          6 |\r\n| 10 |          9 |          7 |          5 |          7 |          1 |          2 |\r\n|  1 |          4 |          7 |          2 |          1 |          8 |          3 |\r\n|  6 |          6 |          3 |          9 |          3 |          9 |          7 |\r\n|  8 |         10 |          6 |          2 |          1 |          1 |          7 |\r\n|  0 |          9 |          4 |          4 |          8 |          7 |          6 |\r\n|  2 |          9 |          1 |          5 |          4 |          5 |          7 |\r\n|  2 |          7 |         10 |          6 |          1 |          8 |          6 |\r\n|  7 |         10 |          8 |          2 |          3 |          1 |          9 |\r\n|  7 |          3 |          3 |          7 |          7 |          2 |         10 |\r\n|  6 |          6 |          1 |          9 |          2 |          1 |          8 |\r\n|  8 |          9 |          9 |          1 |          6 |          6 |          6 |\r\n|  4 |          1 |          3 |          4 |          9 |          3 |          6 |\r\n| 10 |          9 |          7 |          5 |          7 |          1 |          2 |\r\n|  1 |          4 |          7 |          2 |          1 |          8 |          3 |\r\n|  6 |          6 |          3 |          9 |          3 |          9 |          7 |\r\n|  8 |         10 |          6 |          2 |          1 |          1 |          7 |\r\n|  0 |          9 |          4 |          4 |          8 |          7 |          6 |\r\n|  2 |          9 |          1 |          5 |          4 |          5 |          7 |\r\n|  2 |          7 |         10 |          6 |          1 |          8 |          6 |\r\n|  7 |         10 |          8 |          2 |          3 |          1 |          9 |\r\n|  7 |          3 |          3 |          7 |          7 |          2 |         10 |\r\n+----+------------+------------+------------+------------+------------+------------+<\/div><\/pre>\n","protected":false},"excerpt":{"rendered":"
\u5728MySQL\u5b98\u65b9\u624b\u518c\u4e0a\uff0c\u5173\u4e8eindex merge\u7684\u4ecb\u7ecd\u975e\u5e38\u975e\u5e38\u5c11\u3002\u751a\u81f3\u8fd8\u6709\u4e0d\u5c11\u8bef\u5bfc\u7684\u5730\u65b9\uff0c\u8fd9\u6b21\u628a5.1\u7248\u672c\u5173\u4e8e\u6b64\u7c7b\u4f18\u5316\u5904\u7406\u7684\u4ee3\u7801\u7ec6\u770b\u4e86\u4e00\u904d\uff0c\u4ee5\u6848\u4f8b\u7684\u65b9\u5f0f\u4ecb\u7ecd\u4e86\u5404\u79cd\u5b9e\u7528index merge\u8bbf\u95ee\u7c7b\u578b\u7684SQL\u3002\u540e\u7eed\u7684\u8fd8\u4f1a\u7ee7\u7eed\u4ecb\u7ecdindex merge\u5b9e\u73b0\u7684\u4e3b\u8981\u6570\u636e\u7ed3\u6784\uff0c\u4ee5\u53ca\u6210\u672c\u8bc4\u4f30\u3002 1. \u4ec0\u4e48\u662findex merge MySQL\u4f18\u5316\u5668\u5982\u679c\u53d1\u73b0\u53ef\u4ee5\u4f7f\u7528\u591a\u4e2a\u7d22\u5f15\u67e5\u627e\u540e\u7684\u4ea4\u96c6\/\u5e76\u96c6\u5b9a\u4f4d\u6570\u636e\uff0c\u90a3\u4e48MySQL\u4f18\u5316\u5668\u5c31\u4f1a\u5c1d\u8bd5index merge\u8fd9\u7c7b\u8bbf\u95ee\u65b9\u5f0f\u3002index merge\u4e3b\u8981\u5206\u4e3a\u4e24\u5927\u7c7b\uff0c\u591a\u4e2a\u7d22\u5f15\u4ea4\u96c6\u8bbf\u95ee(intersections)\uff0c\u591a\u4e2a\u7d22\u5f15\u5e76\u96c6\u8bbf\u95ee\uff0c\u5f53\u7136\u8fd9\u4e24\u7c7b\u8fd8\u53ef\u4ee5\u7ec4\u5408\u51fa\u66f4\u4e3a\u590d\u6742\u7684\u65b9\u5f0f\uff0c\u4f8b\u5982\u591a\u4e2a\u4ea4\u96c6\u540e\u505a\u5e76\u96c6\u3002 1.1 index merge\u7684\u9650\u5236\uff1arange\u4f18\u5148 MySQL\u57285.6.7\u4e4b\u524d\uff0c\u4f7f\u7528index merge\u6709\u4e00\u4e2a\u91cd\u8981\u7684\u524d\u63d0\u6761\u4ef6\uff1a\u6ca1\u6709range\u53ef\u4ee5\u4f7f\u7528\u3002\u8fd9\u4e2a\u9650\u5236\u964d\u4f4e\u4e86MySQL index merge\u53ef\u4ee5\u4f7f\u7528\u7684\u573a\u666f\u3002\u7406\u60f3\u72b6\u6001\u662f\u540c\u65f6\u8bc4\u4f30\u6210\u672c\u540e\u7136\u540e\u505a\u51fa\u9009\u62e9\u3002\u56e0\u4e3a\u8fd9\u4e2a\u9650\u5236\uff0c\u5c31\u6709\u4e86\u4e0b\u9762\u8fd9\u4e2a\u5df2\u77e5\u7684bad case(\u53c2\u8003)\uff1a SELECT * FROM t1 WHERE (goodkey1 < 10 OR goodkey2 < 20) AND badkey < 30; \u4f18\u5316\u5668\u53ef\u4ee5\u9009\u62e9\u4f7f\u7528goodkey1\u548cgoodkey2\u505aindex merge\uff0c\u4e5f\u53ef\u4ee5\u4f7f\u7528badkey\u505arange\u3002\u56e0\u4e3a\u4e0a\u9762\u7684\u539f\u5219\uff0c\u65e0\u8bbagoodkey1\u548cgoodkey2\u7684\u9009\u62e9\u5ea6\u5982\u4f55\uff0cMySQL\u90fd\u53ea\u4f1a\u8003\u8651range\uff0c\u800c\u4e0d\u4f1a\u4f7f\u7528index merge\u7684\u8bbf\u95ee\u65b9\u5f0f\u3002\u8fd9\u662f\u4e00\u4e2a\u60b2\u5267…\uff085.6.7\u7248\u672c\u9488\u5bf9\u6b64\u6709\u4fee\u590d)\n<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_eb_attr":"","inline_featured_image":false,"_tocer_settings":[],"footnotes":""},"categories":[6,5],"tags":[],"class_list":["post-4170","post","type-post","status-publish","format-standard","hentry","category-mysql","category-code-staff"],"_links":{"self":[{"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/posts\/4170","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/comments?post=4170"}],"version-history":[{"count":54,"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/posts\/4170\/revisions"}],"predecessor-version":[{"id":4261,"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/posts\/4170\/revisions\/4261"}],"wp:attachment":[{"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/media?parent=4170"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/categories?post=4170"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/tags?post=4170"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}