{"id":1252,"date":"2010-01-14T10:12:40","date_gmt":"2010-01-14T02:12:40","guid":{"rendered":"http:\/\/www.orczhou.com\/?p=1252"},"modified":"2010-02-28T18:53:58","modified_gmt":"2010-02-28T10:53:58","slug":"myisam-key-buffer-1","status":"publish","type":"post","link":"https:\/\/www.orczhou.com\/index.php\/2010\/01\/myisam-key-buffer-1\/","title":{"rendered":"\u8be6\u89e3MyISAM Key Cache(\u524d\u7bc7)"},"content":{"rendered":"<p>\u672c\u6587\u5c06\u5206\u4e3a\u524d\u3001\u4e2d\u3001\u540e\u4e09\u7bc7\uff0c\u5206\u522b\u4ecb\u7ecdMyISAM Key Cache\u7684\u4e00\u822c\u673a\u5236\u3001Mid-point strategy\u3001\u72b6\u6001\u3001\u53c2\u6570\u548c\u547d\u4ee4\u3002<\/p>\n<p>\u201cCache\u4e3a\u738b\u201d\uff0c<a href=\"http:\/\/www.orczhou.com\/index.php\/2009\/08\/query-cache-1\/\">\u65e0\u6240\u4e0d\u5728<\/a>\u3002\u4e3a\u4e86\u6700\u5c0f\u5316\u78c1\u76d8I\/O\uff0cMyISAM\u5c06\u6700\u9891\u7e41\u8bbf\u95ee\u7684\u7d22\u5f15\u5757\uff08\u201cindex block\u201d\uff09\u90fd\u653e\u5728\u5185\u5b58\u4e2d\uff0c\u8fd9\u6837\u7684\u5185\u5b58\u7f13\u51b2\u533a\u6211\u4eec\u79f0\u4e4b\u4e3aKey Cache\uff0c\u5b83\u7684\u5927\u5c0f\u53ef\u4ee5\u901a\u8fc7\u53c2\u6570key_buffer_size\u6765\u63a7\u5236\u3002\u5728MyISAM\u7684\u7d22\u5f15\u6587\u4ef6\u4e2d\uff08MYI\uff09\uff0c\u8fde\u7eed\u7684\u5355\u5143\uff08contiguous unit\uff09\u7ec4\u6210\u4e00\u4e2aBlock\uff0cIndex block\u7684\u5927\u5c0f\u7b49\u4e8e\u8be5BTree\u7d22\u5f15\u8282\u70b9\u7684\u5927\u5c0f\u3002Key Cache\u5c31\u662f\u4ee5Block\u4e3a\u5355\u4f4d\u7684\u3002<!--more--><\/p>\n<p><font color=\"red\">1. MyISAM\u5982\u4f55\u4f7f\u7528Key Cache<\/font><\/p>\n<p>\u5f53MySQL\u8bf7\u6c42(\u8bfb\u6216\u5199)MyISAM\u7d22\u5f15\u6587\u4ef6\u4e2d\u67d0\u4e2aIndex Block\u65f6\uff0c\u9996\u5148\u4f1a\u770bKey Cache\u961f\u5217\u4e2d\u662f\u5426\u5df2\u7ecf\u7f13\u5b58\u4e86\u5bf9\u5e94block\u3002\u5982\u679c\u6709\uff0c\u5c31\u76f4\u63a5\u5728Key Cache\u961f\u5217\u4e2d\u8fdb\u884c\u8bfb\u5199\u4e86\uff0c\u4e0d\u518d\u9700\u8981\u8bf7\u6c42\u78c1\u76d8\u3002\u5982\u679c\u662f\u5199\u8bf7\u6c42\uff0c\u90a3\u4e48Key Cache\u4e2d\u7684\u5bf9\u5e94Block\u5c31\u4f1a\u88ab\u6807\u8bb0\u4e3aDirty\uff08\u548c\u78c1\u76d8\u4e0d\u4e00\u81f4\uff09\u3002\u5728MyISAM\u5728Key Cache\u6210\u529f\u8bf7\u6c42\uff08\u8bfb\u5199\uff09\u67d0\u4e2aBlock\u540e\uff0c\u4f1a\u5c06\u8be5Block\u653e\u5230Key Cache\u961f\u5217\u7684\u5934\u90e8\u3002<\/p>\n<p>\u5982\u679cKey Cache\u4e2d\u6ca1\u6709\u5f85\u8bf7\u6c42\uff08\u8bfb\u6216\u5199\uff09\u7684Block\uff0cMyISAM\u4f1a\u5411\u78c1\u76d8\u8bf7\u6c42\u5bf9\u5e94\u7684Block\uff0c\u5e76\u5c06\u5176\u653e\u5230Key Cache\u7684\u961f\u5217\u5934\u90e8\u3002\u961f\u5217\u5982\u679c\u6ee1\u4e86\uff0c\u4f1a\u5c06\u961f\u5217\u5c3e\u90e8\u7684Block\u5220\u9664\uff0c\u8be5Block\u5982\u679c\u662fDirty\u7684\uff0c\u4f1a\u5c06\u5176Flush\u5230\u78c1\u76d8\u4e0a\u3002\u6211\u4eec\u770b\u5230MyISAM\u7ef4\u62a4\u4e86\u4e00\u4e2aLRU\uff08Least Recently Used\uff09\u7684Key Cache\u961f\u5217\u3002\u961f\u5217\u4e2d\u7684Dirty Block\u4f1a\u5728Block\u88ab\u8e22\u51fa\u961f\u5217\u65f6Flush\u5230\u78c1\u76d8\u4e0a\u3002<\/p>\n<p><font color=\"red\">2. \u56fe\u89e3<\/font><\/p>\n<p>\u4e0b\u56fe\u5c55\u793a\u4e86\u8bbf\u95eeIndex Block\u7684\u8fc7\u7a0b\uff1a\uff08\u9ed1\u8272\u90e8\u5206\u4e3a\u78c1\u76d8\u4e2d\u7684Index\u6587\u4ef6\uff09<\/p>\n<p><a href=\"http:\/\/www.flickr.com\/photos\/26825745@N06\/4268165359\/\" title=\"Key_Cache by orczhou, on Flickr\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/farm3.static.flickr.com\/2776\/4268165359_9f4e322c1f_o.png\" width=\"550\" height=\"598\" alt=\"Key_Cache\" \/><\/a><\/p>\n<p><font color=\"red\">3. \u5e76\u53d1\u8bbf\u95ee<\/font><\/p>\n<p>Key Cache\u4e2d\u7684index Block\u662f\u53ef\u4ee5\u88ab\u5e76\u53d1\u8bbf\u95ee\u7684\uff08Shared access \uff09\uff0c\u4e0b\u9762\u662f\u4e00\u4e9b\u89c4\u5219\uff1a<\/p>\n<ol>\n<li>\u591a\u4e2a\u6ca1\u6709\u66f4\u65b0\u64cd\u4f5c\u7684session\u53ef\u4ee5\u5e76\u53d1\u540c\u4e00\u4e2ablock buffer<\/li>\n<li>\u591a\u4e2asession\u540c\u65f6\u8bbf\u95ee\u67d0\u4e00\u4e2ablock buffer\uff0c\u5982\u679c\u67d0\u4e2asession\u662fupdate\u64cd\u4f5c\uff0c\u5219\u4f18\u5148\u8bbf\u95ee<\/li>\n<li>\u591a\u4e2asession\u5982\u679c\u90fd\u9700\u8981\u8fdb\u884cblock replacement\uff0c\u662f\u53ef\u4ee5\u5e76\u53d1\u64cd\u4f5c\u3002\uff08\u4eceindex file\u4e2d\u8bfb\u53d6block\u66f4\u65b0\u5230key cache\uff0c\u4f46\u662fkey cache\u5df2\u6ee1\uff0c\u9700\u8981\u5220\u9664\u4e00\u4e9bblock buffer\u7684\u64cd\u4f5c\u53eb\u505ablock replacement\uff09<\/li>\n<\/ol>\n<p>&nbsp;<\/p>\n<p><font color=\"red\">4. \u8865\u5145\u8bf4\u660e<\/font><\/p>\n<p>Key cache\u4e2d\u7684Block\u5927\u5c0f\u53ef\u80fd\u548c\u7d22\u5f15\u6587\u4ef6\u4e2d\u7684Index Block\u5927\u5c0f\u4e0d\u540c\uff0c\u53ef\u80fd\u662f\u5927\u4e8e\u3001\u5c0f\u4e8e\u3001\u7b49\u4e8e\u4e2d\u7684\u4efb\u4f55\u4e00\u79cd\uff0c\u4f46\u662f\u4e00\u822c\u90fd\u662f\u6210\u500d\u6570\u5173\u7cfb\u7684\u3002Key Cache\u7684block\u5927\u5c0f\u7531\u53c2\u6570<a href=\"http:\/\/dev.mysql.com\/doc\/refman\/5.0\/en\/server-system-variables.html#sysvar_key_cache_block_size\">Key_cache_block_size<\/a>\u63a7\u5236\u3002<\/p>\n<p>\uff08\u672a\u5b8c\u5f85\u7eed\uff09<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u672c\u6587\u5c06\u5206\u4e3a\u524d\u3001\u4e2d\u3001\u540e\u4e09\u7bc7\uff0c\u5206\u522b\u4ecb\u7ecdMyISAM Key Cache\u7684\u4e00\u822c\u673a\u5236\u3001Mid-point strategy\u3001\u72b6\u6001\u3001\u53c2\u6570\u548c\u547d\u4ee4\u3002 \u201cCache\u4e3a\u738b\u201d\uff0c\u65e0\u6240\u4e0d\u5728\u3002\u4e3a\u4e86\u6700\u5c0f\u5316\u78c1\u76d8I\/O\uff0cMyISAM\u5c06\u6700\u9891\u7e41\u8bbf\u95ee\u7684\u7d22\u5f15\u5757\uff08\u201cindex block\u201d\uff09\u90fd\u653e\u5728\u5185\u5b58\u4e2d\uff0c\u8fd9\u6837\u7684\u5185\u5b58\u7f13\u51b2\u533a\u6211\u4eec\u79f0\u4e4b\u4e3aKey Cache\uff0c\u5b83\u7684\u5927\u5c0f\u53ef\u4ee5\u901a\u8fc7\u53c2\u6570key_buffer_size\u6765\u63a7\u5236\u3002\u5728MyISAM\u7684\u7d22\u5f15\u6587\u4ef6\u4e2d\uff08MYI\uff09\uff0c\u8fde\u7eed\u7684\u5355\u5143\uff08contiguous unit\uff09\u7ec4\u6210\u4e00\u4e2aBlock\uff0cIndex block\u7684\u5927\u5c0f\u7b49\u4e8e\u8be5BTree\u7d22\u5f15\u8282\u70b9\u7684\u5927\u5c0f\u3002Key Cache\u5c31\u662f\u4ee5Block\u4e3a\u5355\u4f4d\u7684\u3002<\/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":[44,43,45],"class_list":["post-1252","post","type-post","status-publish","format-standard","hentry","category-mysql","tag-myisam","tag-myisam-key-buffer","tag-45"],"_links":{"self":[{"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/posts\/1252","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=1252"}],"version-history":[{"count":20,"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/posts\/1252\/revisions"}],"predecessor-version":[{"id":1497,"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/posts\/1252\/revisions\/1497"}],"wp:attachment":[{"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/media?parent=1252"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/categories?post=1252"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.orczhou.com\/index.php\/wp-json\/wp\/v2\/tags?post=1252"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}