{"id":1263,"date":"2010-01-17T18:14:46","date_gmt":"2010-01-17T10:14:46","guid":{"rendered":"http:\/\/www.orczhou.com\/?p=1263"},"modified":"2010-02-03T09:52:55","modified_gmt":"2010-02-03T01:52:55","slug":"myisam-key-buffer-2","status":"publish","type":"post","link":"https:\/\/www.orczhou.com\/index.php\/2010\/01\/myisam-key-buffer-2\/","title":{"rendered":"\u8be6\u89e3MyISAM Key Cache(\u4e2d\u7bc7)"},"content":{"rendered":"<p>\u5728<a href=\"http:\/\/www.orczhou.com\/index.php\/2010\/01\/myisam-key-buffer-1\/\">\u524d\u7bc7<\/a>\u4e2d\u4ecb\u7ecd\u4e86Key Cache\u7684\u57fa\u672c\u673a\u5236\uff0c\u5e76\u4e14\u4ecb\u7ecd\u4e86Key Cache\u7684LRU\u7b97\u6cd5\u3002\u4f5c\u4e3a\u5bf9LRU\u7b97\u6cd5\u7684\u6539\u8fdb\uff0cMyISAM\u8fd8\u63d0\u4f9b\u4e86\u53e6\u4e00\u4e2a\u7f13\u5b58\u7b97\u6cd5\uff1a\u201cMidpoint Insertion Strategy\u201d\u3002\u672c\u6587\u5c06\u91cd\u70b9\u4ecb\u7ecd\u8be5\u7b97\u6cd5\u7684\u539f\u7406\u548c\u914d\u7f6e\u3002<\/p>\n<p><font color=\"red\">1. \u76f8\u5173\u53c2\u6570<\/font> <\/p>\n<p>\u8be5\u7b56\u7565\u6d89\u53ca\u7684\u53c2\u6570\u6709\uff1a<a href=\"http:\/\/dev.mysql.com\/doc\/refman\/5.0\/en\/server-system-variables.html#sysvar_key_cache_division_limit\">key_cache_division_limit<\/a>\u3001<a href=\"http:\/\/dev.mysql.com\/doc\/refman\/5.0\/en\/server-system-variables.html#sysvar_key_cache_age_threshold\">key_cache_age_threshold<\/a><\/p>\n<p><font color=\"red\">2. \u539f\u7406\u4ecb\u7ecd<\/font> <\/p>\n<p>(1)\t\u8be5\u7b56\u7565\u5c06\u524d\u9762\u7684LRU\u961f\u5217\uff08LRU Chain\uff09\u5206\u6210\u4e24\u90e8\u5206\uff0chot sub-chain\u548cwarm sub-chain\u3002\u5e76\u6839\u636e\u53c2\u6570key_cache_division_limit\u5212\u5206\uff0c\u603b\u4fdd\u6301warm sub-chain\u5728\u8fd9\u4e2a\u767e\u5206\u6bd4\u4ee5\u4e0a\u3002\u9ed8\u8ba4\u60c5\u51b5key_cache_division_limit\u662f100\uff0c\u6240\u4ee5\u9ed8\u8ba4\u65f6\u5019\u53ea\u6709warm sub-chain,\u5373LRU Chain\u3002<br \/>\n(\u6ce8\uff1aMultiple Key cache\u60c5\u51b5\uff0c\u6bcf\u4e2akey cache\u90fd\u6709\u5bf9\u5e94\u7684key_cache_division_limit\u503c)<!--more--><\/p>\n<p>(2)\t\u5728warm sub-chain\u4e2d\u7684\u67d0\u4e2ablock\u5982\u679c\u88ab\u8bbf\u95ee\uff08Access\uff09\u6b21\u6570\u8d85\u8fc7\u67d0\u4e2a\u503c\u65f6\u5019\uff0c\u5c31\u5c06\u8be5block\u653e\u5230hot sub-chain\u7684\u5e95\u90e8\u3002<\/p>\n<p>(3)\t\u5728hot sub-chain\u4e2d\u7684block\u4f1a\u968f\u7740\u6bcf\u4e00\u6b21\u7684hit\u8c03\u6574\u4f4d\u7f6e\uff0chit\u8d8a\u591a\uff0c\u8d8a\u63a5\u8fd1\u5e95\u90e8\u3002\u5728\u9876\u90e8\u505c\u7559\u65f6\u95f4\u8fc7\u957f\u5c31\u4f1a\u88ab\u964d\u7ea7\u5230warm sub-chain\u4e2d\uff0c\u800c\u4e14\u662fwarm sub-chain\u7684\u9876\u90e8\uff08\u5f88\u53ef\u80fd\u5f88\u5feb\u5c31\u4f1a\u88ab\u79fb\u51fakey cache\uff09\u3002<\/p>\n<p>(4)\tHot sub-chain\u4e2d\u7684\u9876\u90e8\u7684block\u505c\u7559\u65f6\u95f4\u8d85\u8fc7\u4e00\u4e2a\u9608\u503c\u540e\u5c31\u4f1a\u88ab\u964d\u7ea7\u5230warm sub-chain\u3002\u8fd9\u4e2a\u9608\u503c\u7531\u53c2\u6570key_cache_age_threshold\u51b3\u5b9a\u3002\u5177\u4f53\u7684\u8ba1\u7b97\u65b9\u6cd5\u662f\uff1a\u8bbeN\u4e3akey cache\u4e2d\u7684block\u4e2a\u6570\uff0c\u5982\u679c\u5728\u6700\u8fd1\u7684\uff08N*key_cache_age_threshold\/100\uff09\u6b21\u8bbf\u95ee\u4e2d\uff0ckey cache\u9876\u90e8\u7684block\u4ecd\u7136\u6ca1\u6709\u88ab\u8bbf\u95ee\u5230\uff0c\u90a3\u4e48\u5c31\u4f1a\u88ab\u79fb\u5230warm sub-chain\u7684\u9876\u90e8\u3002<\/p>\n<p>(5)\t\u9ed8\u8ba4\u60c5\u51b5key_cache_division_limit = 100\uff0c\u8fd9\u65f6\u53ea\u6709\u53ea\u6709\u4e00\u4e2aChain\uff0c\u6240\u4ee5\u4e0d\u4f7f\u7528\u8be5\u7b56\u7565\u3002\u5373\u9000\u5316\u7684Midpoint Insertion Strategy\u662fLRU\u7b97\u6cd5\u3002<\/p>\n<p><font color=\"red\">3. \u5982\u4f55\u4f7f\u7528Midpoint Insertion Strategy<\/font><\/p>\n<p>\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7\u914d\u7f6e<a href=\"http:\/\/dev.mysql.com\/doc\/refman\/5.0\/en\/server-system-variables.html#sysvar_key_cache_division_limit\">key_cache_division_limit<\/a>\u3001<a href=\"http:\/\/dev.mysql.com\/doc\/refman\/5.0\/en\/server-system-variables.html#sysvar_key_cache_age_threshold\">key_cache_age_threshold<\/a>\u7684\u503c\u6765\u63a7\u5236\u3002\u53c2\u6570<a href=\"http:\/\/dev.mysql.com\/doc\/refman\/5.0\/en\/server-system-variables.html#sysvar_key_cache_division_limit\">key_cache_division_limit<\/a>\u63a7\u5236\u4e86Key Cache Chain\u4e2dwarm sub-chain\u7684\u767e\u5206\u6bd4\uff0c\u5982\u679c\u4f60\u7684Index Block\u4e2d\u660e\u663e\u670930%\u662f\u975e\u5e38Hot\uff08\u8f83\u4e4b\u5176\u4ed6\u7684Block\u66f4\u52a0\u88ab\u5e38\u5e38\u8bbf\u95ee\uff09\uff0c\u90a3\u4e48\u4f60\u53ef\u4ee5\u8bbe\u7f6e\u4f60\u7684warm sub-chain\u957f\u5ea6\u4e3a70%\uff0c\u5269\u4f5930%\u4f5c\u4e3ahot sub-chain\u3002\u53c2\u6570<a href=\"http:\/\/dev.mysql.com\/doc\/refman\/5.0\/en\/server-system-variables.html#sysvar_key_cache_age_threshold\">key_cache_age_threshold<\/a>\u5b9a\u4e49\u4e86warm sub-chain\u4e2d\u7684block\u88ab\u79fb\u9664\u7684\u673a\u5236\uff08\u53c2\u7167\u524d\u6587\u4ecb\u7ecd\uff09\u3002<\/p>\n<p>\uff08\u672a\u5b8c\u5f85\u7eed\uff09<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5728\u524d\u7bc7\u4e2d\u4ecb\u7ecd\u4e86Key Cache\u7684\u57fa\u672c\u673a\u5236\uff0c\u5e76\u4e14\u4ecb\u7ecd\u4e86Key Cache\u7684LRU\u7b97\u6cd5\u3002\u4f5c\u4e3a\u5bf9LRU\u7b97\u6cd5\u7684\u6539\u8fdb\uff0cMyISAM\u8fd8\u63d0\u4f9b\u4e86\u53e6\u4e00\u4e2a\u7f13\u5b58\u7b97\u6cd5\uff1a\u201cMidpoint Insertion Strategy\u201d\u3002\u672c\u6587\u5c06\u91cd\u70b9\u4ecb\u7ecd\u8be5\u7b97\u6cd5\u7684\u539f\u7406\u548c\u914d\u7f6e\u3002 1. \u76f8\u5173\u53c2\u6570 \u8be5\u7b56\u7565\u6d89\u53ca\u7684\u53c2\u6570\u6709\uff1akey_cache_division_limit\u3001key_cache_age_threshold 2. \u539f\u7406\u4ecb\u7ecd (1) \u8be5\u7b56\u7565\u5c06\u524d\u9762\u7684LRU\u961f\u5217\uff08LRU Chain\uff09\u5206\u6210\u4e24\u90e8\u5206\uff0chot sub-chain\u548cwarm sub-chain\u3002\u5e76\u6839\u636e\u53c2\u6570key_cache_division_limit\u5212\u5206\uff0c\u603b\u4fdd\u6301warm sub-chain\u5728\u8fd9\u4e2a\u767e\u5206\u6bd4\u4ee5\u4e0a\u3002\u9ed8\u8ba4\u60c5\u51b5key_cache_division_limit\u662f100\uff0c\u6240\u4ee5\u9ed8\u8ba4\u65f6\u5019\u53ea\u6709warm sub-chain,\u5373LRU Chain\u3002 (\u6ce8\uff1aMultiple Key cache\u60c5\u51b5\uff0c\u6bcf\u4e2akey cache\u90fd\u6709\u5bf9\u5e94\u7684key_cache_division_limit\u503c)<\/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],"tags":[44,43],"class_list":["post-1263","post","type-post","status-publish","format-standard","hentry","category-mysql","tag-myisam","tag-myisam-key-buffer"],"_links":{"self":[{"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/posts\/1263","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=1263"}],"version-history":[{"count":16,"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/posts\/1263\/revisions"}],"predecessor-version":[{"id":1375,"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/posts\/1263\/revisions\/1375"}],"wp:attachment":[{"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/media?parent=1263"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/categories?post=1263"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/tags?post=1263"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}