{"id":1872,"date":"2010-09-18T01:41:59","date_gmt":"2010-09-18T01:41:59","guid":{"rendered":"http:\/\/www.icocean.com\/blog\/?p=1872"},"modified":"1970-01-01T07:00:00","modified_gmt":"1970-01-01T07:00:00","slug":"mysql%E8%B0%83%E4%BC%98%E4%B8%AD%E4%B8%A4%E4%B8%AA%E9%87%8D%E8%A6%81%E5%8F%82%E6%95%B0table-cache%E5%92%8Ckey-buffer-size","status":"publish","type":"post","link":"https:\/\/www.icocean.com\/blog\/?p=1872","title":{"rendered":"Mysql\u8c03\u4f18\u4e2d\u4e24\u4e2a\u91cd\u8981\u53c2\u6570table_cache\u548ckey_buffer_size"},"content":{"rendered":"

table_cache\u6307\u793a\u8868\u9ad8\u901f\u7f13\u5b58\u7684\u5927\u5c0f\u3002\u5f53Mysql\u8bbf\u95ee\u4e00\u4e2a\u8868\u65f6\uff0c\u5982\u679c\u5728Mysql\u8868\u7f13\u51b2\u533a\u4e2d\u8fd8\u6709\u7a7a\u95f4\uff0c\u90a3\u4e48\u8fd9\u4e2a\u8868\u5c31\u88ab\u6253\u5f00\u5e76\u653e\u5165\u8868\u7f13\u51b2\u533a\uff0c\u8fd9\u6837\u505a\u7684\u597d\u5904\u662f\u53ef\u4ee5\u66f4\u5feb\u901f\u5730\u8bbf\u95ee\u8868\u4e2d\u7684\u5185\u5bb9\u3002\u4e00\u822c\u6765\u8bf4\uff0c\u53ef\u4ee5\u901a\u8fc7\u67e5\u770b\u6570\u636e\u5e93\u8fd0\u884c\u5cf0\u503c\u65f6\u95f4\u7684\u72b6\u6001\u503cOpen_tables\u548cOpened_tables\uff0c\u7528\u4ee5\u5224\u65ad\u662f\u5426\u9700\u8981\u589e\u52a0table_cache\u7684\u503c\uff0c\u5373\u5982\u679copen_tables\u63a5\u8fd1table_cache\u7684\u65f6\u5019\uff0c\u5e76\u4e14Opened_tables\u8fd9\u4e2a\u503c\u5728\u9010\u6b65\u589e\u52a0\uff0c\u90a3\u5c31\u8981\u8003\u8651\u589e\u52a0\u8fd9\u4e2a\u503c\u7684\u5927\u5c0f\u4e86\u3002<\/p>\n

  \u5728mysql\u9ed8\u8ba4\u5b89\u88c5\u60c5\u51b5\u4e0b\uff0ctable_cache\u7684\u503c\u57282G\u5185\u5b58\u4ee5\u4e0b\u7684\u673a\u5668\u4e2d\u7684\u503c\u9ed8\u8ba4\u65f6256\u5230512\uff0c\u5982\u679c\u673a\u5668\u67094G\u5185\u5b58,\u5219\u9ed8\u8ba4\u8fd9\u4e2a\u503c\u662f 2048\uff0c\u4f46\u8fd9\u975e\u610f\u5473\u7740\u673a\u5668\u5185\u5b58\u8d8a\u5927\uff0c\u8fd9\u4e2a\u503c\u5e94\u8be5\u8d8a\u5927\uff0c\u56e0\u4e3atable_cache\u52a0\u5927\u540e\uff0c\u4f7f\u5f97mysql\u5bf9SQL\u54cd\u5e94\u7684\u901f\u5ea6\u66f4\u5feb\u4e86\uff0c\u4e0d\u53ef\u907f\u514d\u7684\u4f1a\u4ea7\u751f\u66f4\u591a\u7684\u6b7b\u9501\uff08dead lock\uff09\uff0c\u8fd9\u6837\u53cd\u800c\u4f7f\u5f97\u6570\u636e\u5e93\u6574\u4e2a\u4e00\u5957\u64cd\u4f5c\u6162\u4e86\u4e0b\u6765\uff0c\u4e25\u91cd\u5f71\u54cd\u6027\u80fd\u3002\u6240\u4ee5\u5e73\u65f6\u7ef4\u62a4\u4e2d\u8fd8\u662f\u8981\u6839\u636e\u5e93\u7684\u5b9e\u9645\u60c5\u51b5\u53bb\u4f5c\u51fa\u5224\u65ad\uff0c\u627e\u5230\u6700\u9002\u5408\u4f60\u7ef4\u62a4\u7684\u5e93\u7684 table_cache\u503c\uff0c\u6709\u4eba\u8bf4\uff1a\u201c\u6027\u80fd\u4f18\u5316\u662f\u4e00\u95e8\u827a\u672f\u201d\uff0c\u8fd9\u8bdd\u4e00\u70b9\u6ca1\u9519\u3002\u5927\u51e1\u827a\u672f\u54c1\uff0c\u5927\u90fd\u662f\u7ecf\u8fc7\u5343\u9524\u767e\u70bc\uff0c\u7cbe\u96d5\u7ec6\u7422\u800c\u6210\u3002<\/p>\n

   \u8fd9\u91cc\u8fd8\u8981\u8bf4\u660e\u4e00\u4e2a\u95ee\u9898\uff0c\u5c31\u662ftable_cache\u52a0\u5927\u540e\u78b0\u5230\u6587\u4ef6\u63cf\u8ff0\u7b26\u4e0d\u591f\u7528\u7684\u95ee\u9898\uff0c\u5728mysql\u7684\u914d\u7f6e\u6587\u4ef6\u4e2d\u6709\u8fd9\u4e48\u4e00\u6bb5\u63d0\u793a<\/p>\n

\u5f15\u7528
\u201cThe number of open tables for all threads. Increasing this value increases the number of file descriptors that mysqld requires.
Therefore you have to make sure to set the amount of open files allowed to at least 4096 in the variable “open-files-limit” in\u201d section [mysqld_safe]\u201d<\/p>\n

\u8bf4\u7684\u5c31\u662f\u8981\u6ce8\u610f\u8fd9\u4e2a\u95ee\u9898\uff0c\u4e00\u60f3\u5230\u8fd9\u91cc\uff0c\u90e8\u5206\u5144\u5f1f\u53ef\u80fd\u4f1a\u7528ulimit -n \u4f5c\u51fa\u8c03\u6574\uff0c\u4f46\u662f\u8fd9\u4e2a\u8c03\u6574\u5b9e\u9645\u662f\u4e0d\u5bf9\u7684\uff0c\u6362\u4e2a\u7ec8\u7aef\u540e\uff0c\u8fd9\u4e2a\u503c\u53c8\u4f1a\u56de\u5230\u539f\u59cb\u503c\uff0c\u6240\u4ee5\u6700\u597d\u7528sysctl\u6216\u8005\u4fee\u6539\/etc\/sysctl.conf\u6587\u4ef6\uff0c\u540c\u65f6\u8fd8\u8981\u5728\u914d\u7f6e\u6587\u4ef6\u4e2d\u628aopen_files_limit\u8fd9\u4e2a\u53c2\u6570\u589e\u5927\uff0c\u5bf9\u4e8e4G\u5185\u5b58\u670d\u52a1\u5668\uff0c\u76f8\u4fe1\u73b0\u5728\u8d2d\u4e70\u7684\u670d\u52a1\u5668\u90fd\u5dee\u4e0d\u591a\u75284G\u7684\u4e86\uff0c\u90a3\u8fd9\u4e2a open_files_limit\u81f3\u5c11\u8981\u589e\u5927\u52304096\uff0c\u5982\u679c\u6ca1\u6709\u4ec0\u4e48\u7279\u6b8a\u60c5\u51b5\uff0c\u8bbe\u7f6e\u62108192\u5c31\u53ef\u4ee5\u4e86\u3002<\/p>\n

   \u4e0b\u9762\u8bf4\u8bf4key_buffer_size\u8fd9\u4e2a\u53c2\u6570\uff0ckey_buffer_sizeO\u8868\u793a\u7d22\u5f15\u7f13\u51b2\u533a\u7684\u5927\u5c0f\uff0c\u4e25\u683c\u8bf4\u662f\u5b83\u51b3\u5b9a\u4e86\u6570\u636e\u5e93\u7d22\u5f15\u5904\u7406\u7684\u901f\u5ea6\uff0c\u5c24\u5176\u662f\u7d22\u5f15\u8bfb\u7684\u901f\u5ea6\u3002\u6839\u636e\u7f51\u7edc\u4e00\u4e9b\u9ad8\u624b\u5199\u7684\u6587\u7ae0\u8868\u793a\u53ef\u4ee5\u68c0\u67e5\u72b6\u6001\u503cKey_read_requests\u548cKey_reads\uff0c\u5373\u53ef\u77e5\u9053 key_buffer_size\u8bbe\u7f6e\u662f\u5426\u5408\u7406\u3002\u6bd4\u4f8bkey_reads \/ key_read_requests\u5e94\u8be5\u5c3d\u53ef\u80fd\u7684\u4f4e\uff0c\u81f3\u5c11\u662f1:100\uff0c1:1000\u66f4\u597d\uff0c\u867d\u7136\u6211\u8fd8\u6ca1\u6709\u627e\u5230\u7406\u8bba\u7684\u4f9d\u636e\uff0c\u4f46\u662f\uff0c\u6211\u5728\u81ea\u5df1\u7ef4\u62a4\u7684\u51e0\u53f0\u5b9e\u9645\u8fd0\u884c\u826f\u597d\u7684\u5e93\u505a\u8fc7\u7684\u6d4b\u8bd5\u540e\u8868\u660e\uff0c\u8fd9\u4e2a\u6bd4\u503c\u63a5\u8fd11\uff1a20000\uff0c\u8fd9\u4ece\u7ed3\u679c\u8bc1\u660e\u4e86\u4ed6\u4eec\u8bf4\u8fd9\u8bdd\u7684\u6b63\u786e\u6027\uff0c\u6211\u4eec\u4e0d\u59a8\u7528\u4e4b\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"

table_cache\u6307\u793a\u8868\u9ad8\u901f\u7f13\u5b58\u7684\u5927\u5c0f\u3002\u5f53Mysql\u8bbf\u95ee\u4e00\u4e2a\u8868\u65f6\uff0c\u5982\u679c\u5728Mysql\u8868\u7f13\u51b2\u533a\u4e2d\u8fd8\u6709\u7a7a\u95f4\uff0c\u90a3\u4e48 […]<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[24],"tags":[366,392,1881],"class_list":["post-1872","post","type-post","status-publish","format-standard","hentry","category-lamp","tag-mysql","tag-392","tag-1881","category-24-id","post-seq-1","post-parity-odd","meta-position-corners","fix"],"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/www.icocean.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/1872","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.icocean.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.icocean.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.icocean.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.icocean.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1872"}],"version-history":[{"count":0,"href":"https:\/\/www.icocean.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/1872\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.icocean.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1872"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.icocean.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1872"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.icocean.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1872"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}