{"id":553,"date":"2022-06-26T11:18:50","date_gmt":"2022-06-26T03:18:50","guid":{"rendered":"https:\/\/www.ccagml.com\/?p=553"},"modified":"2023-02-07T11:24:17","modified_gmt":"2023-02-07T03:24:17","slug":"%e6%b8%b8%e6%88%8f%e7%b3%bb%e7%bb%9fmysql%e6%89%a7%e8%a1%8c%e8%b6%85%e6%97%b6%e9%97%ae%e9%a2%98%e6%8e%92%e6%9f%a5","status":"publish","type":"post","link":"https:\/\/www.ccagml.com\/?p=553","title":{"rendered":"\u6e38\u620f\u7cfb\u7edfMySQl\u6267\u884c\u8d85\u65f6\u95ee\u9898\u6392\u67e5"},"content":{"rendered":"<h1>\u80cc\u666f<\/h1>\n<p>\u6211\u4eec\u6e38\u620f\u6709\u4e00\u4e2a\u8001\u6392\u884c\u699c,\u4e00\u76f4\u7206\u51fa\u6570\u636e\u5e93\u8bed\u53e5\u6267\u884c\u8d85\u65f6,\u7531\u4e8e\u662f\u6df1\u591c\u5904\u7406\u6570\u636e,\u5e76\u6ca1\u6709\u5f71\u54cd,\u6240\u4ee5\u4e00\u76f4\u6ca1\u5904\u7406,\u6700\u8fd1\u8fd8\u662f\u51b3\u5b9a\u6539\u4e00\u6539<\/p>\n<h1>\u529f\u80fd\u80cc\u666f<\/h1>\n<p>\u8fd9\u4e2a\u6e38\u620f\u6709\u4e00\u4e2a\u529f\u80fd\u662f\u6bcf\u5929\u751f\u6210\u6700\u8fd1\u4e00\u6bb5\u65f6\u95f4\u6d3b\u8dc3\u7684\u73a9\u5bb6\u88ab\u70b9\u8d5e\u6570\u7684\u6392\u884c\u699c<\/p>\n<h1>1.\u7ebf\u4e0a\u7684\u5927\u91cf\u7684\u8bed\u53e5\u6267\u884c\u592a\u4e45\u65e5\u5fd7<\/h1>\n<pre><code class=\"line-numbers\">    [ERROR]cost too much time(22709).(select rid,name,be_concerned from user_L where  be_concerned &gt;= 1 and exp &gt;= 1 and last_login_time &gt; '20220523230203' order by be_concerned desc limit 500,200)\n    [ERROR]cost too much time(25810).(select rid,name,be_concerned from user_1 where  be_concerned &gt;= 1 and exp &gt;= 1 and last_login_time &gt; '20220523230203' order by be_concerned desc limit 500,200)\n<\/code><\/pre>\n<h1>2.user\u8868\u7ed3\u6784<\/h1>\n<pre><code class=\"line-numbers\">    mysql&gt; desc user_1;\n    +----------------------+-------------+------+-----+---------+-------+\n    | Field                | Type        | Null | Key | Default | Extra |\n    +----------------------+-------------+------+-----+---------+-------+\n    | rid                  | varchar(12) | NO   | PRI | NULL    |       |\n    | name                 | varchar(30) | YES  |     | NULL    |       |\n    | last_login_time      | varchar(14) | YES  | MUL | NULL    |       |\n    | exp                  | int(10)     | YES  | MUL | NULL    |       |\n    | be_concerned         | int(12)     | YES  | MUL | NULL    |       |\n    '''\n    '''\n<\/code><\/pre>\n<h1>3.Mysql explain \u6267\u884c\u8ba1\u5212\u5206\u6790 \u4ee5user_1\u4e3a\u4f8b\u5b50<\/h1>\n<pre><code class=\"line-numbers\">    mysql&gt; explain select rid,name,be_concerned from user_1 where  be_concerned &gt;= 1 and exp &gt;= 1 and last_login_time &gt; '20220523230203' order by be_concerned desc limit 500,200;\n    +----+-------------+--------+-------+-------------------------------------------------------------------------+---------------------------+---------+------+-------+-------------+\n    | id | select_type | table  | type  | possible_keys                                                           | key                       | key_len | ref  | rows  | Extra       |\n    +----+-------------+--------+-------+-------------------------------------------------------------------------+---------------------------+---------+------+-------+-------------+\n    |  1 | SIMPLE      | user_1 | range | user_1_exp_index,user_1_be_concerned_index,user_1_last_login_time_index | user_1_be_concerned_index | 5       | NULL | 12688 | Using where |\n    +----+-------------+--------+-------+-------------------------------------------------------------------------+---------------------------+---------+------+-------+-------------+\n    1 row in set (0.00 sec)\n    - \n<\/code><\/pre>\n<h1>4.Explain \u6267\u884c\u8ba1\u5212\u5b57\u6bb5\u7b80\u5355\u8bf4\u660e<\/h1>\n<ul>\n<li>select_type:\u8868\u793a\u67e5\u8be2\u662f\u7b80\u5355\u7684\u8fd8\u662f\u590d\u6742\u7684\n<ul>\n<li>SIMPLE\uff1a\u8868\u793a\u6700\u7b80\u5355\u7684 select \u67e5\u8be2\u8bed\u53e5<\/li>\n<li>PRIMARY\uff1a\u5f53\u67e5\u8be2\u8bed\u53e5\u4e2d\u5305\u542b\u4efb\u4f55\u590d\u6742\u7684\u5b50\u90e8\u5206\uff0c\u6700\u5916\u5c42\u67e5\u8be2\u5219\u88ab\u6807\u8bb0\u4e3a PRIMARY\u3002<\/li>\n<li>SUBQUERY\uff1a\u5f53 select \u6216 where \u5217\u8868\u4e2d\u5305\u542b\u4e86\u5b50\u67e5\u8be2\uff0c\u8be5\u5b50\u67e5\u8be2\u88ab\u6807\u8bb0\u4e3a SUBQUERY\u3002<\/li>\n<li>DERIVED\uff1a\u8868\u793a\u5305\u542b\u5728 from \u5b50\u53e5\u4e2d\u7684\u5b50\u67e5\u8be2\u7684 select\uff0c\u5728\u6211\u4eec\u7684 from \u5217\u8868\u4e2d\u5305\u542b\u7684\u5b50\u67e5\u8be2\u4f1a\u88ab\u6807\u8bb0\u4e3a derived\u3002<\/li>\n<li>UNION\uff1a\u5982\u679c union \u540e\u8fb9\u53c8\u51fa\u73b0\u7684 select \u8bed\u53e5\uff0c\u5219\u4f1a\u88ab\u6807\u8bb0\u4e3a union\uff1b\u82e5 union \u5305\u542b\u5728 from \u5b50\u53e5\u7684\u5b50\u67e5\u8be2\u4e2d\uff0c\u5916\u5c42 select \u5c06\u88ab\u6807\u8bb0\u4e3a derived\u3002<\/li>\n<li>UNION RESULT\uff1a\u4ee3\u8868\u4ece union \u7684\u4e34\u65f6\u8868\u4e2d\u8bfb\u53d6\u6570\u636e<\/li>\n<\/ul>\n<\/li>\n<li>type:\u7c7b\u578b,\u662f\u4e2a\u9700\u8981\u6ce8\u610f\u7684\u6307\u6807,\u4ece\u4e0a\u5230\u4e0b,\u8d8a\u6765\u8d8a\u5dee\n<ul>\n<li>system \u5f53\u8868\u4ec5\u6709\u4e00\u884c\u8bb0\u5f55\u65f6\uff08\u7cfb\u7edf\u8868\uff09\uff0c\u6570\u636e\u91cf\u5f88\u5c11\uff0c\u5f80\u5f80\u4e0d\u9700\u8981\u8fdb\u884c\u78c1\u76d8 IO\uff0c\u901f\u5ea6\u975e\u5e38\u5feb\u3002<\/li>\n<li>const  \u8868\u793a\u67e5\u8be2\u65f6\u547d\u4e2d primary key \u4e3b\u952e\u6216\u8005 unique \u552f\u4e00\u7d22\u5f15\uff0c\u6216\u8005\u88ab\u8fde\u63a5\u7684\u90e8\u5206\u662f\u4e00\u4e2a\u5e38\u91cf\u503c\u3002\u8fd9\u7c7b\u626b\u63cf\u6548\u7387\u6781\u9ad8\uff0c\u8fd4\u56de\u6570\u636e\u91cf\u5c11\uff0c\u901f\u5ea6\u975e\u5e38\u5feb\u3002<\/li>\n<li>eq_ref \u67e5\u8be2\u65f6\u547d\u4e2d\u4e3b\u952e primary key \u6216\u8005 unique key \u7d22\u5f15\uff0c type \u5c31\u662f eq_ref\u3002<\/li>\n<li>ref \u533a\u522b\u4e8e eq_ref\uff0cref \u8868\u793a\u4f7f\u7528\u975e\u552f\u4e00\u6027\u7d22\u5f15\uff0c\u4f1a\u627e\u5230\u5f88\u591a\u4e2a\u7b26\u5408\u6761\u4ef6\u7684\u884c\u3002<\/li>\n<li>ref_or_null \u8fd9\u79cd\u8fde\u63a5\u7c7b\u578b\u7c7b\u4f3c\u4e8e ref\uff0c\u533a\u522b\u5728\u4e8e MySQL \u4f1a\u989d\u5916\u641c\u7d22\u5305\u542b NULL \u503c\u7684\u884c\u3002<\/li>\n<li>index_merge \u4f7f\u7528\u4e86\u7d22\u5f15\u5408\u5e76\u4f18\u5316\u65b9\u6cd5\uff0c\u67e5\u8be2\u4f7f\u7528\u4e86\u4e24\u4e2a\u4ee5\u4e0a\u7684\u7d22\u5f15\u3002<\/li>\n<li>unique_subquery \u66ff\u6362\u4e0b\u9762\u7684 IN \u5b50\u67e5\u8be2\uff0c\u5b50\u67e5\u8be2\u8fd4\u56de\u4e0d\u91cd\u590d\u7684\u96c6\u5408\u3002<\/li>\n<li>index_subquery  \u533a\u522b\u4e8e unique_subquery\uff0c\u7528\u4e8e\u975e\u552f\u4e00\u7d22\u5f15\uff0c\u53ef\u4ee5\u8fd4\u56de\u91cd\u590d\u503c\u3002<\/li>\n<li>range \u4f7f\u7528\u7d22\u5f15\u9009\u62e9\u884c\uff0c\u4ec5\u68c0\u7d22\u7ed9\u5b9a\u8303\u56f4\u5185\u7684\u884c\u3002\u7b80\u5355\u70b9\u8bf4\u5c31\u662f\u9488\u5bf9\u4e00\u4e2a\u6709\u7d22\u5f15\u7684\u5b57\u6bb5\uff0c\u7ed9\u5b9a\u8303\u56f4\u68c0\u7d22\u6570\u636e\u3002\u5728 where \u8bed\u53e5\u4e2d\u4f7f\u7528 bettween&#8230;and\u3001&lt;\u3001>\u3001&lt;=\u3001in \u7b49\u6761\u4ef6\u67e5\u8be2 type \u90fd\u662f range\u3002<\/li>\n<li>index Index \u4e0e ALL \u5176\u5b9e\u90fd\u662f\u8bfb\u5168\u8868\uff0c\u533a\u522b\u5728\u4e8e index \u662f\u904d\u5386\u7d22\u5f15\u6811\u8bfb\u53d6\uff0c\u800c ALL \u662f\u4ece\u786c\u76d8\u4e2d\u8bfb\u53d6\u3002<\/li>\n<li>ALL \u5c06\u904d\u5386\u5168\u8868\u4ee5\u627e\u5230\u5339\u914d\u7684\u884c\uff0c\u6027\u80fd\u6700\u5dee\u3002<\/li>\n<\/ul>\n<\/li>\n<li>possible_keys:\u53ef\u80fd\u4f1a\u7528\u5230\u7684\u7d22\u5f15<\/li>\n<li>key \u5b9e\u9645\u7528\u5230\u7684\u7d22\u5f15<\/li>\n<li>rows \u4f30\u8ba1\u7684\u6570\u636e\u91cf<\/li>\n<li>Extra \u4e00\u4e9b\u989d\u5916\u7684\u8bf4\u660e\n<ul>\n<li>Using index \u4f7f\u7528\u4e86\u7d22\u5f15<\/li>\n<li>Using where \u6ca1\u6709\u627e\u5230\u53ef\u7528\u7684\u7d22\u5f15<\/li>\n<li>Using temporary \u4e34\u65f6\u8868\u5b58\u50a8\u7ed3\u679c<\/li>\n<li>Using filesort \u9700\u8981\u6587\u4ef6\u6392\u5e8f<\/li>\n<li>Using join buffer \u8054\u8868\u67e5\u8be2\u9700\u8981\u7f13\u51b2\u533a<\/li>\n<li>Impossible where where\u8bed\u53e5\u4e0d\u592a\u5bf9<\/li>\n<li>No tables used \u6ca1\u6709from\u8bed\u53e5<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h1>5. \u5206\u6790\u6211\u4eec\u7684\u6267\u884c\u8ba1\u5212<\/h1>\n<ul>\n<li>select_type = SIMPLE<\/li>\n<li>type = range<\/li>\n<li>possible_keys = user_1_exp_index,user_1_be_concerned_index,user_1_last_login_time_index<\/li>\n<li>key = user_1_be_concerned_index<\/li>\n<li>rows = 12688<\/li>\n<li>\u53ef\u4ee5\u770b\u51fa\u7b26\u5408\u67e5\u8be2\u6761\u4ef6\u7684\u9884\u4f30\u8ba1\u884c\u6570\u670912688,\u800c\u5b9e\u9645\u4e0a\u5927\u90e8\u5206\u6570\u636e\u90fd\u6ca1\u6709\u7528<\/li>\n<\/ul>\n<h1>6. \u540e\u7eed\u5904\u7406<\/h1>\n<ul>\n<li>\u56e0\u4e3a\u67e5\u8be2\u8bed\u53e5\u7684\u6761\u4ef6\u592a\u8fc7\u5bbd\u6cdb,\u5bfc\u81f4\u67e5\u8be2\u5230\u8bb8\u591a\u65e0\u7528\u6570\u636e,\u901a\u8fc7\u7f29\u5c0f\u67e5\u8be2\u8bed\u53e5\u7684\u8303\u56f4,\u89e3\u51b3\u95ee\u9898<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>\u80cc\u666f \u6211\u4eec\u6e38\u620f\u6709\u4e00\u4e2a\u8001\u6392\u884c\u699c,\u4e00\u76f4\u7206\u51fa\u6570\u636e\u5e93\u8bed\u53e5\u6267\u884c\u8d85\u65f6,\u7531\u4e8e\u662f\u6df1\u591c\u5904\u7406\u6570\u636e,\u5e76\u6ca1\u6709\u5f71\u54cd,\u6240\u4ee5\u4e00\u76f4\u6ca1\u5904\u7406,\u6700\u8fd1<a href=\"https:\/\/www.ccagml.com\/?p=553\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">\u6e38\u620f\u7cfb\u7edfMySQl\u6267\u884c\u8d85\u65f6\u95ee\u9898\u6392\u67e5<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[22,30],"tags":[],"_links":{"self":[{"href":"https:\/\/www.ccagml.com\/index.php?rest_route=\/wp\/v2\/posts\/553"}],"collection":[{"href":"https:\/\/www.ccagml.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ccagml.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ccagml.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ccagml.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=553"}],"version-history":[{"count":1,"href":"https:\/\/www.ccagml.com\/index.php?rest_route=\/wp\/v2\/posts\/553\/revisions"}],"predecessor-version":[{"id":554,"href":"https:\/\/www.ccagml.com\/index.php?rest_route=\/wp\/v2\/posts\/553\/revisions\/554"}],"wp:attachment":[{"href":"https:\/\/www.ccagml.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=553"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ccagml.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=553"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ccagml.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=553"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}