{"id":1913,"date":"2019-08-12T08:00:28","date_gmt":"2019-08-12T00:00:28","guid":{"rendered":"https:\/\/coderbee.net\/?p=1913"},"modified":"2019-08-11T19:04:13","modified_gmt":"2019-08-11T11:04:13","slug":"mysql-innodb-mrr-%e4%bc%98%e5%8c%96","status":"publish","type":"post","link":"https:\/\/coderbee.net\/index.php\/db\/20190812\/1913","title":{"rendered":"MySQL InnoDB MRR \u4f18\u5316"},"content":{"rendered":"<p>MRR \u662f Multi-Range Read \u7684\u7b80\u5199\uff0c\u76ee\u7684\u662f\u51cf\u5c11\u78c1\u76d8\u968f\u673a\u8bbf\u95ee\uff0c\u5c06\u968f\u673a\u8bbf\u95ee\u8f6c\u5316\u4e3a\u8f83\u4e3a\u987a\u5e8f\u7684\u8bbf\u95ee\u3002\u9002\u7528\u4e8e range\/ref\/eq_ref \u7c7b\u578b\u7684\u67e5\u8be2\u3002<\/p>\n<p>\u5b9e\u73b0\u539f\u7406\uff1a<\/p>\n<ol>\n<li>\u5728\u4e8c\u7ea7\u7d22\u5f15\u67e5\u627e\u540e\uff0c\u6839\u636e\u5f97\u5230\u7684\u4e3b\u952e\u5230\u805a\u7c07\u7d22\u5f15\u627e\u51fa\u9700\u8981\u7684\u6570\u636e\u3002<\/li>\n<li>\u4e8c\u7ea7\u7d22\u5f15\u67e5\u627e\u5f97\u5230\u7684\u4e3b\u952e\u7684\u987a\u5e8f\u662f\u4e0d\u786e\u5b9a\u7684\uff0c\u56e0\u4e3a\u4e8c\u7ea7\u7d22\u5f15\u7684\u987a\u5e8f\u4e0e\u805a\u7c07\u7d22\u5f15\u7684\u987a\u5e8f\u4e0d\u4e00\u5b9a\u4e00\u81f4\uff1b<\/li>\n<li>\u5982\u679c\u6ca1\u6709 MRR\uff0c\u90a3\u4e48\u5728\u805a\u7c07\u7d22\u5f15\u67e5\u627e\u65f6\u5c31\u53ef\u80fd\u51fa\u73b0\u4e71\u5e8f\u8bfb\u53d6\u6570\u636e\u9875\uff0c\u8fd9\u5bf9\u4e8e\u673a\u68b0\u786c\u76d8\u662f\u53ca\u5176\u4e0d\u53cb\u597d\u7684\u3002<\/li>\n<li>\n<p>MRR \u7684\u4f18\u5316\u65b9\u5f0f\uff1a<\/p>\n<blockquote>\n<ul>\n<li>\u5c06\u67e5\u627e\u5230\u7684\u4e8c\u7ea7\u7d22\u5f15\u952e\u503c\u653e\u5728\u4e00\u4e2a\u7f13\u5b58\u4e2d\uff1b<\/li>\n<li>\u5c06\u7f13\u5b58\u4e2d\u7684\u952e\u503c\u6309\u7167 \u4e3b\u952e \u8fdb\u884c\u6392\u5e8f\uff1b<\/li>\n<li>\u6839\u636e\u6392\u5e8f\u540e\u7684\u4e3b\u952e\u53bb\u805a\u7c07\u7d22\u5f15\u8bbf\u95ee\u5b9e\u9645\u7684\u6570\u636e\u6587\u4ef6\u3002<\/li>\n<\/ul>\n<\/blockquote>\n<\/li>\n<li>\n<p>\u5f53\u4f18\u5316\u5668\u4f7f\u7528\u4e86 MRR \u65f6\uff0c\u6267\u884c\u8ba1\u5212\u7684 Extra \u5217\u4f1a\u51fa\u73b0 &#8220;Using MRR&#8221; \u3002<\/p>\n<\/li>\n<li>\u5982\u679c\u67e5\u8be2\u4f7f\u7528\u7684\u4e8c\u7ea7\u7d22\u5f15\u7684\u987a\u5e8f\u672c\u8eab\u4e0e\u7ed3\u679c\u96c6\u7684\u987a\u5e8f\u4e00\u81f4\uff0c\u90a3\u4e48\u4f7f\u7528 MRR \u540e\u9700\u8981\u5bf9\u5f97\u5230\u7684\u7ed3\u679c\u96c6\u8fdb\u884c\u6392\u5e8f\u3002<\/li>\n<\/ol>\n<p><!--more--><\/p>\n<p>\u4f7f\u7528 MRR \u8fd8\u53ef\u4ee5\u51cf\u5c11\u7f13\u51b2\u6c60\u4e2d\u9875\u88ab\u66ff\u6362\u7684\u6b21\u6570\uff0c\u6279\u91cf\u5904\u7406\u5bf9\u952e\u503c\u7684\u67e5\u8be2\u64cd\u4f5c\u3002<\/p>\n<p>\u53ef\u4ee5\u4f7f\u7528\u547d\u4ee4 <code>select @@optimizer_switch;<\/code> \u67e5\u770b\u662f\u5426\u5f00\u542f\u4e86 MRR\uff1a<\/p>\n<pre><code>index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=on,index_condition_pushdown=on,mrr=off,mrr_cost_based=on,block_nested_loop=on,batched_key_access=off,materialization=on,semijoin=on,loosescan=on,firstmatch=on,duplicateweedout=on,subquery_materialization_cost_based=on,use_index_extensions=on,condition_fanout_filter=on,derived_merge=on,use_invisible_indexes=off,skip_scan=on\n<\/code><\/pre>\n<p><code>mrr_cost_based=on<\/code> \u8868\u793a\u662f\u5426\u901a\u8fc7 cost based \u7684\u65b9\u5f0f\u6765\u9009\u62e9\u4f7f\u7528 MRR \u3002<\/p>\n<p>\u7528 <code>set @@optimizer_switch='mrr=on\/off';<\/code> \u547d\u4ee4\u5f00\u542f\u6216\u5173\u95ed MRR \u3002<\/p>\n<p><code>select @@read_rnd_buffer_size ;<\/code> \u53c2\u6570\u7528\u6765\u63a7\u5236\u952e\u503c\u7684\u7f13\u51b2\u533a\u5927\u5c0f\uff0c\u9ed8\u8ba4 256K\uff0c\u5f53\u5927\u4e8e\u8be5\u53c2\u6570\u503c\u65f6\uff0c\u6267\u884c\u5668\u6839\u636e\u4e3b\u952e\u5bf9\u5df2\u7f13\u5b58\u7684\u6570\u636e\u8fdb\u884c\u6392\u5e8f\uff0c\u7136\u540e\u518d\u901a\u8fc7\u4e3b\u952e\u53d6\u5f97\u884c\u6570\u636e\u3002<\/p>\n<hr \/>\n<p>\u6b22\u8fce\u5173\u6ce8\u6211\u7684\u5fae\u4fe1\u516c\u4f17\u53f7: <strong>coderbee\u7b14\u8bb0<\/strong>\uff0c\u53ef\u4ee5\u66f4\u53ca\u65f6\u56de\u590d\u4f60\u7684\u8ba8\u8bba\u3002<br \/>\n<img loading=\"lazy\" decoding=\"async\" width=\"258\" height=\"258\" src=\"https:\/\/coderbee.net\/wp-content\/uploads\/2019\/01\/coderbee-note.jpg\" class=\"alignnone size-full wp-image-1707\" \/><\/p>\n","protected":false},"excerpt":{"rendered":"<p>MRR \u662f Multi-Range Read \u7684\u7b80\u5199\uff0c\u76ee\u7684\u662f\u51cf\u5c11\u78c1\u76d8\u968f\u673a\u8bbf\u95ee\uff0c\u5c06 &hellip; <a href=\"https:\/\/coderbee.net\/index.php\/db\/20190812\/1913\">\u7ee7\u7eed\u9605\u8bfb <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[319,149],"_links":{"self":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/1913"}],"collection":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/comments?post=1913"}],"version-history":[{"count":2,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/1913\/revisions"}],"predecessor-version":[{"id":1915,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/1913\/revisions\/1915"}],"wp:attachment":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/media?parent=1913"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/categories?post=1913"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/tags?post=1913"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}