{"id":1276,"date":"2022-02-10T13:49:25","date_gmt":"2022-02-10T05:49:25","guid":{"rendered":"http:\/\/dba.qishuo.xin\/?p=1276"},"modified":"2022-02-11T08:23:13","modified_gmt":"2022-02-11T00:23:13","slug":"mariadb%e6%89%a7%e8%a1%8c%e8%ae%a1%e5%88%92%e5%88%86%e6%9e%90%ef%bc%881-join%e6%89%a7%e8%a1%8c%e8%bf%87%e7%a8%8b%e8%af%a6%e8%a7%a3%ef%bc%89","status":"publish","type":"post","link":"http:\/\/dba.qishuo.xin\/?p=1276","title":{"rendered":"MariaDB\u6267\u884c\u8ba1\u5212\u5206\u6790\uff081. Join\u6267\u884c\u8fc7\u7a0b\u8be6\u89e3\uff09"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_76 ez-toc-wrap-right counter-hierarchy ez-toc-counter ez-toc-light-blue ez-toc-container-direction\">\n<label for=\"ez-toc-cssicon-toggle-item-69e0de19e7050\" class=\"ez-toc-cssicon-toggle-label\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/label><input type=\"checkbox\"  id=\"ez-toc-cssicon-toggle-item-69e0de19e7050\" checked aria-label=\"Toggle\" \/><nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"http:\/\/dba.qishuo.xin\/?p=1276\/#1_Join%E8%BF%9E%E6%8E%A5%E6%A8%A1%E5%BC%8F%E4%B8%8E%E6%89%A7%E8%A1%8C%E9%A1%BA%E5%BA%8F\" >1. Join\u8fde\u63a5\u6a21\u5f0f\u4e0e\u6267\u884c\u987a\u5e8f<\/a><ul class='ez-toc-list-level-4' ><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"http:\/\/dba.qishuo.xin\/?p=1276\/#11_%E8%AF%AD%E6%B3%95\" >1.1. \u8bed\u6cd5<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"http:\/\/dba.qishuo.xin\/?p=1276\/#12_%E8%BF%9E%E6%8E%A5%E6%A8%A1%E5%BC%8F%E4%B8%8E%E7%BB%93%E6%9E%9C%E9%9B%86\" >1.2. \u8fde\u63a5\u6a21\u5f0f\u4e0e\u7ed3\u679c\u96c6<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"http:\/\/dba.qishuo.xin\/?p=1276\/#13_%E6%89%A7%E8%A1%8C%E9%A1%BA%E5%BA%8F\" >1.3. \u6267\u884c\u987a\u5e8f<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"http:\/\/dba.qishuo.xin\/?p=1276\/#2_%E8%81%94%E8%A1%A8%E7%AE%97%E6%B3%95\" >2. \u8054\u8868\u7b97\u6cd5<\/a><ul class='ez-toc-list-level-4' ><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"http:\/\/dba.qishuo.xin\/?p=1276\/#21_Simple_Nested-Loop%EF%BC%88SNLJ%EF%BC%8C%E6%99%AE%E9%80%9A%E5%B5%8C%E5%A5%97%E5%BE%AA%E7%8E%AF%E8%BF%9E%E6%8E%A5%EF%BC%89\" >2.1. Simple Nested-Loop\uff08SNLJ\uff0c\u666e\u901a\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\uff09<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"http:\/\/dba.qishuo.xin\/?p=1276\/#22_Block_Nested-Loop%EF%BC%88BNLJ%EF%BC%8C%E7%BC%93%E5%AD%98%E5%9D%97%E5%B5%8C%E5%A5%97%E5%BE%AA%E7%8E%AF%E8%BF%9E%E6%8E%A5%EF%BC%89\" >2.2. Block Nested-Loop\uff08BNLJ\uff0c\u7f13\u5b58\u5757\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\uff09<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"http:\/\/dba.qishuo.xin\/?p=1276\/#23_Index_Nested-Loop%EF%BC%88INLJ%EF%BC%8C%E7%B4%A2%E5%BC%95%E5%B5%8C%E5%A5%97%E5%BE%AA%E7%8E%AF%E8%BF%9E%E6%8E%A5%EF%BC%89\" >2.3. Index Nested-Loop\uff08INLJ\uff0c\u7d22\u5f15\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\uff09<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"http:\/\/dba.qishuo.xin\/?p=1276\/#24_Batched_Key_Access%EF%BC%88BKA%EF%BC%8C%E6%89%B9%E9%87%8F%E9%94%AE%E8%AE%BF%E9%97%AE%E8%81%94%E6%8E%A5%EF%BC%89\" >2.4. Batched Key Access\uff08BKA\uff0c\u6279\u91cf\u952e\u8bbf\u95ee\u8054\u63a5\uff09<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"http:\/\/dba.qishuo.xin\/?p=1276\/#3_%E6%80%BB%E7%BB%93\" >3. \u603b\u7ed3<\/a><\/li><\/ul><\/nav><\/div>\n<h3><span class=\"ez-toc-section\" id=\"1_Join%E8%BF%9E%E6%8E%A5%E6%A8%A1%E5%BC%8F%E4%B8%8E%E6%89%A7%E8%A1%8C%E9%A1%BA%E5%BA%8F\"><\/span>1. Join\u8fde\u63a5\u6a21\u5f0f\u4e0e\u6267\u884c\u987a\u5e8f<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<h4><span class=\"ez-toc-section\" id=\"11_%E8%AF%AD%E6%B3%95\"><\/span>1.1. \u8bed\u6cd5<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<pre><code class=\"language-sql line-numbers\">SELECT &lt;row_list&gt;\n FROM &lt;left_table&gt;\n   &lt;inner|left|right&gt; JOIN &lt;right_table&gt;\n     ON &lt;join condition&gt;\n       WHERE &lt;where_condition&gt;\n<\/code><\/pre>\n<h4><span class=\"ez-toc-section\" id=\"12_%E8%BF%9E%E6%8E%A5%E6%A8%A1%E5%BC%8F%E4%B8%8E%E7%BB%93%E6%9E%9C%E9%9B%86\"><\/span>1.2. \u8fde\u63a5\u6a21\u5f0f\u4e0e\u7ed3\u679c\u96c6<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p><strong>Join\u4e3b\u8981\u5206\u4e3a\u5916\u8fde\u63a5\u3001\u5185\u8fde\u63a5\u548c\u81ea\u7136\u8fde\u63a5<\/strong><\/p>\n<p><a href=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/02\/wp_editor_md_a0c5d5a5e18f0358a3e94c25c11a1ca1.jpg\" data-fancybox=\"images\" data-fancybox=\"images\"><img decoding=\"async\" src=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/02\/wp_editor_md_a0c5d5a5e18f0358a3e94c25c11a1ca1.jpg\" alt=\"\" \/><\/a><\/p>\n<ul>\n<li>left join :\u5de6\u8fde\u63a5\uff0c\u8fd4\u56de\u5de6\u8868\u4e2d\u6240\u6709\u7684\u8bb0\u5f55\u4ee5\u53ca\u53f3\u8868\u4e2d\u8fde\u63a5\u5b57\u6bb5\u76f8\u7b49\u7684\u8bb0\u5f55\u3002<\/li>\n<li>right join :\u53f3\u8fde\u63a5\uff0c\u8fd4\u56de\u53f3\u8868\u4e2d\u6240\u6709\u7684\u8bb0\u5f55\u4ee5\u53ca\u5de6\u8868\u4e2d\u8fde\u63a5\u5b57\u6bb5\u76f8\u7b49\u7684\u8bb0\u5f55\u3002<\/li>\n<li>inner join: \u5185\u8fde\u63a5\uff0c\u53c8\u53eb\u7b49\u503c\u8fde\u63a5\uff0c\u53ea\u8fd4\u56de\u4e24\u4e2a\u8868\u4e2d\u8fde\u63a5\u5b57\u6bb5\u76f8\u7b49\u7684\u884c\u3002<\/li>\n<li>full join:\u5916\u8fde\u63a5\uff0c\u8fd4\u56de\u4e24\u4e2a\u8868\u4e2d\u7684\u884c\uff1aleft join + right join\u3002<\/li>\n<li>cross join:\u7ed3\u679c\u662f\u7b1b\u5361\u5c14\u79ef\uff0c\u5c31\u662f\u7b2c\u4e00\u4e2a\u8868\u7684\u884c\u6570\u4e58\u4ee5\u7b2c\u4e8c\u4e2a\u8868\u7684\u884c\u6570\u3002<\/li>\n<\/ul>\n<p><a href=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/02\/wp_editor_md_6f3f77089e51a7846258c48cab4697b0.jpg\" data-fancybox=\"images\" data-fancybox=\"images\"><img decoding=\"async\" src=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/02\/wp_editor_md_6f3f77089e51a7846258c48cab4697b0.jpg\" alt=\"\" \/><\/a><\/p>\n<h4><span class=\"ez-toc-section\" id=\"13_%E6%89%A7%E8%A1%8C%E9%A1%BA%E5%BA%8F\"><\/span>1.3. \u6267\u884c\u987a\u5e8f<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p><strong>\u7b2c\u4e00\u6b65\uff1a\u6267\u884cFROM\u5b50\u53e5\u5bf9\u4e24\u5f20\u8868\u8fdb\u884c\u7b1b\u5361\u5c14\u79ef\u64cd\u4f5c<\/strong><br \/>\n<strong>\u7b2c\u4e8c\u6b65\uff1a\u6267\u884cON\u5b50\u53e5\u8fc7\u6ee4\u6389\u4e0d\u6ee1\u8db3\u6761\u4ef6\u7684\u884c<\/strong><br \/>\n<strong>\u7b2c\u4e09\u6b65\uff1aJOIN \u6dfb\u52a0\u5916\u90e8\u884c<\/strong><br \/>\n<strong>\u7b2c\u56db\u6b65\uff1aWHERE\u6761\u4ef6\u8fc7\u6ee4<\/strong><br \/>\n<strong>\u7b2c\u4e94\u6b65\uff1aSELECT<\/strong><\/p>\n<p><strong>SQL\u8bed\u53e5\u91cc\u7b2c\u4e00\u4e2a\u88ab\u6267\u884c\u7684\u603b\u662fFROM\u5b50\u53e5\uff1a<\/strong><br \/>\n- FROM:\u5bf9\u5de6\u53f3\u4e24\u5f20\u8868\u6267\u884c\u7b1b\u5361\u5c14\u79ef\uff0c\u4ea7\u751f\u7b2c\u4e00\u5f20\u8868vt1\u3002\u884c\u6570\u4e3a n * m\uff08n\u4e3a\u5de6\u8868\u7684\u884c\u6570\uff0cm\u4e3a\u53f3\u8868\u7684\u884c\u6570<br \/>\n<a href=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/02\/wp_editor_md_f569393e4993be4c4d9bc08f73f5b6a1.jpg\" data-fancybox=\"images\" data-fancybox=\"images\"><img decoding=\"async\" src=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/02\/wp_editor_md_f569393e4993be4c4d9bc08f73f5b6a1.jpg\" alt=\"\" \/><\/a><\/p>\n<ul>\n<li>ON:\u6839\u636eON\u7684\u6761\u4ef6\u9010\u884c\u7b5b\u9009vt1\uff0c\u5c06\u7ed3\u679c\u63d2\u5165vt2\u4e2d<\/p>\n<\/li>\n<li>\n<p>JOIN:\u6dfb\u52a0\u5916\u90e8\u884c\uff0c\u5982\u679c\u6307\u5b9a\u4e86LEFT JOIN(LEFT OUTER JOIN)\uff0c\u5219\u5148\u904d\u5386\u4e00\u904d\u5de6\u8868\u7684\u6bcf\u4e00\u884c\uff0c\u5176\u4e2d\u4e0d\u5728vt2\u7684\u884c\u4f1a\u88ab\u63d2\u5165\u5230vt2\uff0c\u8be5\u884c\u7684\u5269\u4f59\u5b57\u6bb5\u5c06\u88ab\u586b\u5145\u4e3aNULL\uff0c\u5f62\u6210vt3\uff1b\u5982\u679c\u6307\u5b9a\u4e86RIGHT JOIN\u4e5f\u662f\u540c\u7406\u3002\u4f46\u5982\u679c\u6307\u5b9a\u7684\u662fINNER JOIN\uff0c\u5219\u4e0d\u4f1a\u6dfb\u52a0\u5916\u90e8\u884c\uff0c\u4e0a\u8ff0\u63d2\u5165\u8fc7\u7a0b\u88ab\u5ffd\u7565\uff0cvt2=vt3\uff08\u6240\u4ee5INNER JOIN\u7684\u8fc7\u6ee4\u6761\u4ef6\u653e\u5728ON\u6216WHERE\u91cc \u6267\u884c\u7ed3\u679c\u662f\u6ca1\u6709\u533a\u522b\u7684\u3002\uff09<\/p>\n<\/li>\n<li>\n<p>WHERE:\u5bf9vt3\u8fdb\u884c\u6761\u4ef6\u8fc7\u6ee4\uff0c\u6ee1\u8db3\u6761\u4ef6\u7684\u884c\u88ab\u8f93\u51fa\u5230vt4<\/p>\n<\/li>\n<li>\n<p>SELECT:\u53d6\u51favt4\u7684\u6307\u5b9a\u5b57\u6bb5\u5230vt5<\/p>\n<\/li>\n<\/ul>\n<h3><span class=\"ez-toc-section\" id=\"2_%E8%81%94%E8%A1%A8%E7%AE%97%E6%B3%95\"><\/span>2. \u8054\u8868\u7b97\u6cd5<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>MySQL \u7684\u8054\u8868\u7b97\u6cd5\u662f\u57fa\u4e8e\u5d4c\u5957\u5faa\u73af\u7b97\u6cd5\uff08<strong>nested-loop algorithm<\/strong>\uff09\u800c\u884d\u751f\u51fa\u6765\u7684\u4e00\u7cfb\u5217\u7b97\u6cd5\uff0c\u6839\u636e\u4e0d\u540c\u6761\u4ef6\u800c\u9009\u7528\u4e0d\u540c\u7684\u7b97\u6cd5\uff0c\u5177\u4f53\u548cMySQL\u7d22\u5f15\u6709\u4e00\u5b9a\u5173\u7cfb\u3002<\/p>\n<p>\u5728\u4f7f\u7528\u7d22\u5f15\u5173\u8054\u7684\u60c5\u51b5\u4e0b\uff0c\u6709 Index Nested-Loop join \u548c Batched Key Access join \u4e24\u79cd\u7b97\u6cd5;\u5728\u672a\u4f7f\u7528\u7d22\u5f15\u5173\u8054\u7684\u60c5\u51b5\u4e0b\uff0c\u6709 Simple Nested-Loop join \u548c Block Nested-Loop join \u4e24\u79cd\u7b97\u6cd5\u3002<\/p>\n<h4><span class=\"ez-toc-section\" id=\"21_Simple_Nested-Loop%EF%BC%88SNLJ%EF%BC%8C%E6%99%AE%E9%80%9A%E5%B5%8C%E5%A5%97%E5%BE%AA%E7%8E%AF%E8%BF%9E%E6%8E%A5%EF%BC%89\"><\/span>2.1. Simple Nested-Loop\uff08SNLJ\uff0c\u666e\u901a\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\uff09<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p>\u7b80\u5355\u5d4c\u5957\u5faa\u73af\uff0c\u7b80\u79f0 SNL\uff1b\u9010\u6761\u9010\u6761\u5339\u914d\uff0c\u4f2a\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"line-numbers\">For each row r in R do                         -- \u626b\u63cfR\u8868(\u9a71\u52a8\u8868)\n    For each row s in S do                     -- \u626b\u63cfS\u8868(\u88ab\u9a71\u52a8\u8868)\n        If r and s satisfy the join condition  -- \u5982\u679cr\u548cs\u6ee1\u8db3join\u6761\u4ef6\n            Then output the tuple &lt;r, s&gt;       -- \u8fd4\u56de\u7ed3\u679c\u96c6\n<\/code><\/pre>\n<p><a href=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/02\/wp_editor_md_773fab98ec165a755048109f8aa02951.jpg\" data-fancybox=\"images\" data-fancybox=\"images\"><img decoding=\"async\" src=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/02\/wp_editor_md_773fab98ec165a755048109f8aa02951.jpg\" alt=\"\" \/><\/a><\/p>\n<p>R\u8868\u4e3a\u5916\u90e8\u8868\uff08\u9a71\u52a8\u8868\uff09\uff0cS\u8868\u4e3a\u5185\u90e8\u8868\uff08\u88ab\u9a71\u52a8\u8868\uff09\uff0c\u53ef\u4ee5\u770b\u5230\u4ece R \u4e2d\u5206\u522b\u53d6\u51fa\u6bcf\u4e00\u6761\u8bb0\u5f55\u53bb\u5339\u914d S \u8868\u7684\u5217\uff0c\u7136\u540e\u5408\u5e76\u6570\u636e\uff0c\u5bf9 S \u8868\u8fdb\u884c R \u8868\u7684\u884c\u6570\u6b21\u7684\u8bbf\u95ee\uff0c\u5bf9\u6570\u636e\u5e93\u5f00\u9500\u975e\u5e38\u5927\uff0c\u6027\u80fd\u6781\u5dee\u3002\uff08\u8fd9\u79cd\u7b97\u6cd5\u7b80\u5355\u7c97\u66b4\uff0c\u4f46\u6beb\u65e0\u6027\u80fd\u53ef\u8a00\uff0c\u65f6\u95f4\u6027\u80fd\u4e0a\u6765\u8bf4\u662f n\uff08R\u8868\u4e2d\u8bb0\u5f55\u6570\uff09 \u7684 m\uff08S\u8868\u7684\u6570\u91cf\uff09 \u6b21\u65b9\uff0c\u6240\u4ee5 MySQL \u505a\u4e86\u4f18\u5316\uff0c\u8054\u8868\u67e5\u8be2\u7684\u65f6\u5019\u4e0d\u4f1a\u51fa\u73b0\u8fd9\u79cd\u7b97\u6cd5\uff0c\u5373\u4f7f\u5728\u65e0 WHERE  \u6761\u4ef6\u4e14 ON \u7684\u8fde\u63a5\u952e\u4e0a\u65e0\u7d22\u5f15\u65f6\uff0c\u4e5f\u4e0d\u4f1a\u9009\u7528\u8fd9\u79cd\u7b97\u6cd5\u3002\uff09<\/p>\n<p>\u5047\u8bbe\u5728\u4e24\u5f20\u8868R\u548cS\u4e0a\u8fdb\u884c\u8054\u63a5\u7684\u5217\u90fd\u4e0d\u542b\u6709\u7d22\u5f15\uff0c\u5916\u8868\u7684\u8bb0\u5f55\u6570\u4e3aRN\uff0c\u5185\u8868\u7684\u8bb0\u5f55\u6570\u4f4dSN\u3002SNLJ\u7684\u5f00\u9500\u5982\u4e0b\u8868\u6240\u793a\uff1a<\/p>\n<table>\n<thead>\n<tr>\n<th align=\"left\">\u5f00\u9500\u7edf\u8ba1<\/th>\n<th align=\"left\">SNLJ<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td align=\"left\">\u5916\u8868\u626b\u63cf\u6b21\u6570\uff08O\uff09<\/td>\n<td align=\"left\">1<\/td>\n<\/tr>\n<tr>\n<td align=\"left\">\u5185\u8868\u626b\u63cf\u6b21\u6570\uff08I\uff09<\/td>\n<td align=\"left\">RN<\/td>\n<\/tr>\n<tr>\n<td align=\"left\">\u8bfb\u53d6\u8bb0\u5f55\u6570\uff08R\uff09<\/td>\n<td align=\"left\">RN + SN * RN<\/td>\n<\/tr>\n<tr>\n<td align=\"left\">Join\u6bd4\u8f83\u6b21\u6570\uff08M\uff09<\/td>\n<td align=\"left\">SN * RN<\/td>\n<\/tr>\n<tr>\n<td align=\"left\">\u56de\u8868\u8bfb\u53d6\u8bb0\u5f55\u6b21\u6570\uff08F\uff09<\/td>\n<td align=\"left\">0<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><strong>\u4e3e\u4e2a\u4f8b\u5b50\uff0c\u5f53 R \u6709 30 \u884c\u7b26\u5408\u6761\u4ef6\u7684\u6570\u636e\uff0c\u800c S \u6709 50 \u884c\u6570\u636e\uff0c\u5219\u9700\u8981\u5bf9 S \u6267\u884c\u5168\u8868\u626b\u63cf 30 \u6b21\uff0c\u603b\u5171\u9700\u8981\u8bfb\u53d6 S \u8868 50 * 30 = 1500 \u6570\u636e\u884c\u3002<\/strong><\/p>\n<h4><span class=\"ez-toc-section\" id=\"22_Block_Nested-Loop%EF%BC%88BNLJ%EF%BC%8C%E7%BC%93%E5%AD%98%E5%9D%97%E5%B5%8C%E5%A5%97%E5%BE%AA%E7%8E%AF%E8%BF%9E%E6%8E%A5%EF%BC%89\"><\/span>2.2. Block Nested-Loop\uff08BNLJ\uff0c\u7f13\u5b58\u5757\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\uff09<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p>\u7f13\u5b58\u5757\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\uff0c\u7b80\u79f0 BNL\uff0c\u662f\u5bf9 INL \u7684\u4e00\u79cd\u4f18\u5316\uff1b\u4e00\u6b21\u6027\u7f13\u5b58\u591a\u6761\u9a71\u52a8\u8868\u7684\u6570\u636e\uff0c\u7136\u540e\u62ff Join Buffer \u91cc\u7684\u6570\u636e\u6279\u91cf\u4e0e\u5185\u5c42\u5faa\u73af\u8bfb\u53d6\u7684\u6570\u636e\u8fdb\u884c\u5339\u914d\u3002<strong>\u6240\u4ee5\u7f13\u5b58\u5757\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\u7b97\u6cd5\u610f\u5728\u901a\u8fc7\u4e00\u6b21\u6027\u7f13\u5b58\u9a71\u52a8\u8868\u7684\u591a\u6761\u6570\u636e\uff0c\u4ee5\u6b64\u6765\u51cf\u5c11\u88ab\u9a71\u52a8\u8868\u7684\u626b\u8868\u6b21\u6570\uff0c\u4ece\u800c\u8fbe\u5230\u63d0\u5347\u6027\u80fd\u7684\u76ee\u7684\u3002<\/strong> <span style='color:red'>\u5f53\u88ab\u9a71\u52a8\u8868\u5728\u8fde\u63a5\u952e\u4e0a\u65e0\u7d22\u5f15\u4e14\u88ab\u9a71\u52a8\u8868\u5728 WHERE \u8fc7\u6ee4\u6761\u4ef6\u4e0a\u4e5f\u6ca1\u7d22\u5f15\u65f6\uff0c\u5e38\u5e38\u4f1a\u91c7\u7528\u6b64\u79cd\u7b97\u6cd5\u6765\u5b8c\u6210\u8054\u8868\u3002<\/span> \u4f2a\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"line-numbers\">For each tuple r in R do                             -- \u626b\u63cf\u5916\u8868R\n    store used columns as p from R in Join Buffer    -- \u5c06\u90e8\u5206\u6216\u8005\u5168\u90e8R\u7684\u8bb0\u5f55\u4fdd\u5b58\u5230Join Buffer\u4e2d\uff0c\u8bb0\u4e3ap\n    For each tuple s in S do                         -- \u626b\u63cf\u5185\u8868S\n        If p and s satisfy the join condition        -- p\u4e0es\u6ee1\u8db3join\u6761\u4ef6\n            Then output the tuple &lt;r, s&gt;             -- \u8fd4\u56de\u4e3a\u7ed3\u679c\u96c6\n<\/code><\/pre>\n<p><a href=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/02\/wp_editor_md_dd375b1ae9c02a10f9e1e739ed002e3e.jpg\" data-fancybox=\"images\" data-fancybox=\"images\"><img decoding=\"async\" src=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/02\/wp_editor_md_dd375b1ae9c02a10f9e1e739ed002e3e.jpg\" alt=\"\" \/><\/a><\/p>\n<p>Block Nested-Loop Join\u5bf9\u6bd4Simple Nested-Loop Join\u591a\u4e86\u4e00\u4e2a\u4e2d\u95f4\u5904\u7406\u7684\u8fc7\u7a0b\uff0c\u4e5f\u5c31\u662fjoin buffer\uff0c<span style='color:red'> \u4f7f\u7528join buffer \u5c06\u9a71\u52a8\u8868\u7684\u67e5\u8be2JOIN\u76f8\u5173\u5217\u90fd\u7ed9\u7f13\u51b2\u5230\u4e86JOIN BUFFER\u5f53\u4e2d\uff0c\u7136\u540e\u6279\u91cf\u4e0e\u88ab\u9a71\u52a8\u8868\u8fdb\u884c\u6bd4\u8f83\u3002\u8fd9\u4e00\u6765\u5b9e\u73b0\u7684\u8bdd\uff0c\u53ef\u4ee5\u5c06\u591a\u6b21\u6bd4\u8f83\u5408\u5e76\u5230\u4e00\u6b21\uff0c\u964d\u4f4e\u4e86\u975e\u9a71\u52a8\u8868\u7684\u8bbf\u95ee\u9891\u7387\uff08<strong>\u904d\u5386\u4e00\u6b21\u88ab\u9a71\u52a8\u8868\u5c31\u53ef\u4ee5\u6279\u91cf\u5339\u914d\u4e00\u6b21Join Buffer\u91cc\u9762\u7684\u9a71\u52a8\u8868\u6570\u636e<\/strong>\uff09\u3002<\/span><\/p>\n<p>\u5047\u8bbe\u5728\u4e24\u5f20\u8868R\u548cS\u4e0a\u8fdb\u884c\u8054\u63a5\u7684\u5217\u90fd\u4e0d\u542b\u6709\u7d22\u5f15\uff0c\u5916\u8868\u7684\u8bb0\u5f55\u6570\u4e3aRN\uff0c\u5185\u8868\u7684\u8bb0\u5f55\u6570\u4f4dSN\u3002BNLJ\u7684\u5f00\u9500\u5982\u4e0b\u8868\u6240\u793a\uff1a<\/p>\n<table>\n<thead>\n<tr>\n<th align=\"left\">\u5f00\u9500\u7edf\u8ba1<\/th>\n<th align=\"left\">SNLJ<\/th>\n<th align=\"left\">BNLJ<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td align=\"left\">\u5916\u8868\u626b\u63cf\u6b21\u6570\uff08O\uff09<\/td>\n<td align=\"left\">1<\/td>\n<td align=\"left\">1<\/td>\n<\/tr>\n<tr>\n<td align=\"left\">\u5185\u8868\u626b\u63cf\u6b21\u6570\uff08I\uff09<\/td>\n<td align=\"left\">RN<\/td>\n<td align=\"left\">RN * used_column_size \/ join_buffer_size + 1<\/td>\n<\/tr>\n<tr>\n<td align=\"left\">\u8bfb\u53d6\u8bb0\u5f55\u6570\uff08R\uff09<\/td>\n<td align=\"left\">RN + SN * RN<\/td>\n<td align=\"left\">RN + SN * I<\/td>\n<\/tr>\n<tr>\n<td align=\"left\">Join\u6bd4\u8f83\u6b21\u6570\uff08M\uff09<\/td>\n<td align=\"left\">SN * RN<\/td>\n<td align=\"left\">SN * RN<\/td>\n<\/tr>\n<tr>\n<td align=\"left\">\u56de\u8868\u8bfb\u53d6\u8bb0\u5f55\u6b21\u6570\uff08F\uff09<\/td>\n<td align=\"left\">0<\/td>\n<td align=\"left\">0<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>\u5907\u6ce8\uff1a\u5176\u4e2d used_column_size \u4e3a join \u5b57\u6bb5\u603b\u5927\u5c0f\uff0cjoin_buffer_size \u4e3a buffer \u7684\u5927\u5c0f\u3002<\/p>\n<p><strong>\u4e3e\u4e2a\u4f8b\u5b50\uff0c\u5f53 Table1 \u6709 30 \u884c\u7b26\u5408\u6761\u4ef6\u7684\u6570\u636e\uff0c\u800c Table2 \u6709 50 \u884c\u6570\u636e\uff0c\u6ca1\u6709 Join Buffer\u65f6\u5185\u5c42\u5faa\u73af\u7684\u8bfb\u8868\u6b21\u6570\u5e94\u8be5\u662f 30 \u6b21\uff0c\u5982\u679c Join Buffer \u53ef\u7528\u5e76\u53ef\u4ee5\u5b58 10 \u6761\u8bb0\u5f55\uff08Join Buffer \u5b58\u50a8\u7684\u662f\u9a71\u52a8\u8868\u4e2d\u53c2\u4e0e\u67e5\u8be2\u7684\u5217\uff0c\u5305\u62ec SELECT \u7684\u5217\u3001ON \u7684\u5217\u3001WHERE \u7684\u5217\uff0c\u800c\u4e0d\u662f\u9a71\u52a8\u8868\u4e2d\u6574\u884c\u6574\u884c\u7684\u5b8c\u6574\u8bb0\u5f55\uff1aOnly columns of interest to the join are stored in the join buffer, not whole rows.\uff09\uff0c\u90a3\u4e48\u9700\u8981\u5bf9 Table2 \u6267\u884c\u5168\u8868\u626b\u63cf 30 \/ 10 = 3 \u6b21\uff0c\u603b\u5171\u9700\u8981\u8bfb\u53d6 Table2 \u8868 50 * 3 = 150 \u6570\u636e\u884c\u3002<\/strong><\/p>\n<p><strong>Block Nested-Loop Join\u6781\u5927\u7684\u907f\u514d\u4e86\u88ab\u9a71\u52a8\u8868\u7684\u626b\u63cf\u6b21\u6570\uff0c\u5982\u679cJoin Buffer\u53ef\u4ee5\u7f13\u5b58\u9a71\u52a8\u8868\u7684\u6240\u6709\u6570\u636e\uff0c\u90a3\u4e48\u88ab\u9a71\u52a8\u8868\u7684\u626b\u63cf\u4ec5\u9700\u4e00\u6b21\uff0c\u8fd9\u548cHash Join\u975e\u5e38\u7c7b\u4f3c\u3002<span style='color:red'>\u4f46\u662fBlock Nested-Loop Join\u4f9d\u7136\u6ca1\u6709\u89e3\u51b3\u7684\u662fJoin\u6bd4\u8f83\u7684\u6b21\u6570\uff0c\u5176\u4ecd\u7136\u901a\u8fc7Join\u5224\u65ad\u5f0f\u8fdb\u884c\u6bd4\u8f83\u3002<\/span>\u53e6\u5916\uff0c\u5982\u679c\u8fd9\u4e2a\u88ab\u9a71\u52a8\u8868\u662f\u4e00\u4e2a\u5927\u7684\u51b7\u6570\u636e\u8868\uff0c\u9664\u4e86\u4f1a\u5bfc\u81f4 IO \u538b\u529b\u5927\u4ee5\u5916\uff0c\u8fd8\u4f1a\u5bf9 buffer pool\u4ea7\u751f\u4e25\u91cd\u7684\u5f71\u54cd\uff01<\/strong><\/p>\n<h4><span class=\"ez-toc-section\" id=\"23_Index_Nested-Loop%EF%BC%88INLJ%EF%BC%8C%E7%B4%A2%E5%BC%95%E5%B5%8C%E5%A5%97%E5%BE%AA%E7%8E%AF%E8%BF%9E%E6%8E%A5%EF%BC%89\"><\/span>2.3. Index Nested-Loop\uff08INLJ\uff0c\u7d22\u5f15\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\uff09<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p>\u7d22\u5f15\u5d4c\u5957\u5faa\u73af\uff0c\u7b80\u79f0 INL\uff0c\u662f\u57fa\u4e8e\u88ab\u9a71\u52a8\u8868\u7684\u7d22\u5f15\u8fdb\u884c\u8fde\u63a5\u7684\u7b97\u6cd5\uff1b\u9a71\u52a8\u8868\u7684\u8bb0\u5f55\u9010\u6761\u4e0e\u88ab\u9a71\u52a8\u8868\u7684\u7d22\u5f15\u8fdb\u884c\u5339\u914d\uff0c\u907f\u514d\u548c\u88ab\u9a71\u52a8\u8868\u7684\u6bcf\u6761\u8bb0\u5f55\u8fdb\u884c\u6bd4\u8f83\uff0c\u51cf\u5c11\u4e86\u5bf9\u88ab\u9a71\u52a8\u8868\u7684\u5339\u914d\u6b21\u6570\u3002\u4f2a\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n<pre><code class=\"line-numbers\">For each row r in R do                     -- \u626b\u63cfR\u8868\n    lookup s in S index                    -- \u67e5\u8be2S\u8868\u7684\u7d22\u5f15\uff08\u56fa\u5b9a3~4\u6b21IO\uff0cB+\u6811\u9ad8\u5ea6\uff09\n        If find s == r                     -- \u5982\u679cr\u5339\u914d\u4e86\u7d22\u5f15s\n            Then output the tuple &lt;r, s&gt;   -- \u8fd4\u56de\u7ed3\u679c\u96c6\n<\/code><\/pre>\n<p><a href=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/02\/wp_editor_md_5e615014ed6cd5070f49aadfd929f5ea.jpg\" data-fancybox=\"images\" data-fancybox=\"images\"><img decoding=\"async\" src=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/02\/wp_editor_md_5e615014ed6cd5070f49aadfd929f5ea.jpg\" alt=\"\" \/><\/a><\/p>\n<p>\u53ef\u4ee5\u770b\u5230\u5916\u8868\u4e2d\u7684\u6bcf\u6761\u8bb0\u5f55\u901a\u8fc7\u5185\u8868\u7684\u7d22\u5f15\u8fdb\u884c\u8bbf\u95ee\uff0c\u5c31\u662f\u8bfb\u53d6\u5916\u90e8\u8868\u4e00\u884c\u6570\u636e\uff0c\u7136\u540e\u53bb\u5185\u90e8\u8868\u7d22\u5f15\u8fdb\u884c\u4e8c\u5206\u67e5\u627e\u5339\u914d\uff1b\u800c\u4e00\u822cB+\u6811\u7684\u9ad8\u5ea6\u4e3a <code>3~4<\/code> \u5c42\uff0c\u4e5f\u5c31\u662f\u8bf4\u5339\u914d\u4e00\u6b21\u7684io\u6d88\u8017\u4e5f\u5c31 <code>3~4<\/code> \u6b21\uff0c\u56e0\u6b64\u7d22\u5f15\u67e5\u8be2\u7684\u6210\u672c\u662f\u6bd4\u8f83\u56fa\u5b9a\u7684\uff0c\u6545\u4f18\u5316\u5668\u90fd\u503e\u5411\u4e8e\u4f7f\u7528\u8bb0\u5f55\u6570\u5c11\u7684\u8868\u4f5c\u4e3a\u9a71\u52a8\u8868\u3002\u6545INLJ\u7684\u7b97\u6cd5\u6210\u672c\u5982\u4e0b\u8868\u6240\u793a\uff1a<\/p>\n<table>\n<thead>\n<tr>\n<th align=\"left\">\u5f00\u9500\u7edf\u8ba1<\/th>\n<th align=\"left\">SNLJ<\/th>\n<th align=\"left\">BNLJ<\/th>\n<th align=\"left\">INLJ<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td align=\"left\">\u5916\u8868\u626b\u63cf\u6b21\u6570\uff08O\uff09<\/td>\n<td align=\"left\">1<\/td>\n<td align=\"left\">1<\/td>\n<td align=\"left\">1<\/td>\n<\/tr>\n<tr>\n<td align=\"left\">\u5185\u8868\u626b\u63cf\u6b21\u6570\uff08I\uff09<\/td>\n<td align=\"left\">RN<\/td>\n<td align=\"left\">RN * used_column_size \/ join_buffer_size + 1<\/td>\n<td align=\"left\">0<\/td>\n<\/tr>\n<tr>\n<td align=\"left\">\u8bfb\u53d6\u8bb0\u5f55\u6570\uff08R\uff09<\/td>\n<td align=\"left\">RN + SN * RN<\/td>\n<td align=\"left\">RN + SN * I<\/td>\n<td align=\"left\">RN + Smatch<\/td>\n<\/tr>\n<tr>\n<td align=\"left\">Join\u6bd4\u8f83\u6b21\u6570\uff08M\uff09<\/td>\n<td align=\"left\">SN * RN<\/td>\n<td align=\"left\">SN * RN<\/td>\n<td align=\"left\">RN * IndexHeight<\/td>\n<\/tr>\n<tr>\n<td align=\"left\">\u56de\u8868\u8bfb\u53d6\u8bb0\u5f55\u6b21\u6570\uff08F\uff09<\/td>\n<td align=\"left\">0<\/td>\n<td align=\"left\">0<\/td>\n<td align=\"left\">Smatch (if possible)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>\u4e0a\u8868Smatch\u8868\u793a\u901a\u8fc7\u7d22\u5f15\u627e\u5230\u5339\u914d\u7684\u8bb0\u5f55\u6570\u91cf\u3002\u540c\u65f6\u53ef\u4ee5\u53d1\u73b0\uff0c\u901a\u8fc7\u7d22\u5f15\u53ef\u4ee5\u5927\u5e45\u964d\u4f4e\u5185\u8868\u7684Join\u7684\u6bd4\u8f83\u6b21\u6570\uff0c\u6bcf\u6b21\u6bd4\u8f831\u6761\u5916\u8868\u7684\u8bb0\u5f55\uff0c\u5176\u5b9e\u5c31\u662f\u4e00\u6b21indexlookup\uff08\u7d22\u5f15\u67e5\u627e\uff09\uff0c\u800c\u6bcf\u6b21index lookup\u7684\u6210\u672c\u5c31\u662f\u6811\u7684\u9ad8\u5ea6\uff0c\u5373IndexHeight\u3002<\/p>\n<h4><span class=\"ez-toc-section\" id=\"24_Batched_Key_Access%EF%BC%88BKA%EF%BC%8C%E6%89%B9%E9%87%8F%E9%94%AE%E8%AE%BF%E9%97%AE%E8%81%94%E6%8E%A5%EF%BC%89\"><\/span>2.4. Batched Key Access\uff08BKA\uff0c\u6279\u91cf\u952e\u8bbf\u95ee\u8054\u63a5\uff09<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p>Index Nested-Loop Join\u867d\u597d\uff0c\u4f46\u662f\u901a\u8fc7\u8f85\u52a9\u7d22\u5f15\u8fdb\u884c\u8054\u63a5\u540e\u9700\u8981\u56de\u8868\uff0c\u8fd9\u91cc\u9700\u8981\u5927\u91cf\u7684\u968f\u673aI\/O\u64cd\u4f5c\u3002\u82e5\u80fd\u4f18\u5316\u968f\u673aI\/O\uff0c\u90a3\u4e48\u5c31\u80fd\u6781\u5927\u7684\u63d0\u5347Join\u7684\u6027\u80fd\u3002\u4e3a\u6b64\uff0cMySQL 5.6\uff08MariaDB 5.3\uff09\u5f00\u59cb\u652f\u6301Batched Key Access Join\u7b97\u6cd5\uff08\u7b80\u79f0BKA\uff09\uff0c\u8be5\u7b97\u6cd5\u901a\u8fc7\u5e38\u89c1\u7684\u7a7a\u95f4\u6362\u65f6\u95f4\uff0c\u968f\u673aI\/O\u8f6c\u987a\u5e8fI\/O\uff0c\u4ee5\u6b64\u6765\u6781\u5927\u7684\u63d0\u5347Join\u7684\u6027\u80fd\u3002<\/p>\n<p><a href=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/02\/wp_editor_md_ab602007d97ad761a46feebc8288c0cc.jpg\" data-fancybox=\"images\" data-fancybox=\"images\"><img decoding=\"async\" src=\"http:\/\/dba.qishuo.xin\/wp-content\/uploads\/2022\/02\/wp_editor_md_ab602007d97ad761a46feebc8288c0cc.jpg\" alt=\"\" \/><\/a><\/p>\n<p>Batched Key Access Join\u7b97\u6cd5\u7684\u5de5\u4f5c\u6b65\u9aa4\u5982\u4e0b\uff1a<\/p>\n<ol>\n<li>\u5c06\u5916\u90e8\u8868\u4e2d\u76f8\u5173\u7684\u5217\u653e\u5165Join Buffer\u4e2d\u3002<\/li>\n<li>\u6279\u91cf\u7684\u5c06Key\uff08\u7d22\u5f15\u952e\u503c\uff09\u53d1\u9001\u5230Multi-Range Read\uff08MRR\uff09\u63a5\u53e3\u3002<\/li>\n<li>Multi-Range Read\uff08MRR\uff09\u901a\u8fc7\u6536\u5230\u7684Key\uff0c\u6839\u636e\u5176\u5bf9\u5e94\u7684ROWID\u8fdb\u884c\u6392\u5e8f\uff0c\u7136\u540e\u518d\u8fdb\u884c\u6570\u636e\u7684\u8bfb\u53d6\u64cd\u4f5c\u3002<\/li>\n<li>\u8fd4\u56de\u7ed3\u679c\u96c6\u7ed9\u5ba2\u6237\u7aef\u3002<\/li>\n<\/ol>\n<p>Batched Key Access Join\u7b97\u6cd5\u7684\u672c\u8d28\u4e0a\u6765\u8bf4\u8fd8\u662fSimple Nested-Loops Join\u7b97\u6cd5\uff0c\u5176\u53d1\u751f\u7684\u6761\u4ef6\u4e3a\u5185\u90e8\u8868\u4e0a\u6709\u7d22\u5f15\uff0c\u5e76\u4e14\u8be5\u7d22\u5f15\u4e3a\u975e\u4e3b\u952e\uff0c\u5e76\u4e14\u8054\u63a5\u9700\u8981\u8bbf\u95ee\u5185\u90e8\u8868\u4e3b\u952e\u4e0a\u7684\u7d22\u5f15\u3002\u8fd9\u65f6Batched Key Access Join\u7b97\u6cd5\u4f1a\u8c03\u7528Multi-Range Read\uff08MRR\uff09\u63a5\u53e3\uff0c\u6279\u91cf\u7684\u8fdb\u884c\u7d22\u5f15\u952e\u7684\u5339\u914d\u548c\u4e3b\u952e\u7d22\u5f15\u4e0a\u83b7\u53d6\u6570\u636e\u7684\u64cd\u4f5c\uff0c\u4ee5\u6b64\u6765\u63d0\u9ad8\u8054\u63a5\u7684\u6267\u884c\u6548\u7387\uff0c\u56e0\u4e3a\u8bfb\u53d6\u6570\u636e\u662f\u4ee5\u987a\u5e8f\u78c1\u76d8IO\u800c\u4e0d\u662f\u968f\u673a\u78c1\u76d8IO\u8fdb\u884c\u7684\u3002<\/p>\n<h3><span class=\"ez-toc-section\" id=\"3_%E6%80%BB%E7%BB%93\"><\/span>3. \u603b\u7ed3<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u603b\u7684\u6765\u8bf4\uff0c\u5e94\u7528 join \u9700\u8981\u6ce8\u610f\uff1a<\/p>\n<ol>\n<li>\u7528\u6765\u8fdb\u884c join \u7684\u5b57\u6bb5\u8981\u52a0\u7d22\u5f15\uff0c\u4f1a\u89e6\u53d1 INLJ \u7b97\u6cd5\uff0c\u5982\u679c\u662f\u4e3b\u952e\u7684\u805a\u7c07\u7d22\u5f15\uff0c\u6027\u80fd\u6700\u4f18\u3002<\/li>\n<li>\u5982\u679c\u65e0\u6cd5\u4f7f\u7528\u7d22\u5f15\uff0c\u90a3\u4e48\u6ce8\u610f\u8c03\u6574 join buffer \u5927\u5c0f\uff0c\u9002\u5f53\u8c03\u5927\u4e9b\u3002<\/li>\n<li>\u5c0f\u7ed3\u679c\u96c6\u9a71\u52a8\u5927\u7ed3\u679c\u96c6\u3002\u7528\u6570\u636e\u91cf\u5c0f\u7684\u8868\u53bb\u9a71\u52a8\u6570\u636e\u91cf\u5927\u7684\u8868\uff0c\u8fd9\u6837\u53ef\u4ee5\u51cf\u5c11\u5185\u5faa\u73af\u4e2a\u6570\uff0c\u4e5f\u5c31\u662f\u88ab\u9a71\u52a8\u8868\u7684\u626b\u63cf\u6b21\u6570\u3002<\/li>\n<li>\u8054\u8868\u987a\u5e8f\uff0c\u4e0d\u662f\u4e24\u4e24\u8054\u5408\u4e4b\u540e\uff0c\u518d\u53bb\u8054\u5408\u7b2c\u4e09\u5f20\u8868\uff0c\u800c\u662f\u9a71\u52a8\u8868\u7684\u4e00\u6761\u8bb0\u5f55\u7a7f\u5230\u5e95\uff0c\u5339\u914d\u5b8c\u6240\u6709\u5173\u8054\u8868\u4e4b\u540e\uff0c\u518d\u53d6\u9a71\u52a8\u8868\u7684\u4e0b\u4e00\u6761\u8bb0\u5f55\u91cd\u590d\u8054\u8868\u64cd\u4f5c\u3002<\/li>\n<\/ol>\n<p>\u53c2\u8003\uff1a<br \/>\n\u672c\u7ad9\u6848\u4f8b\uff1a<a target=\"_blank\" class=\"wp-editor-md-post-content-link\" href=\"http:\/\/dba.qishuo.xin\/?p=1231\" title=\"MariaDB\u6267\u884c\u8ba1\u5212\u6848\u4f8b\">MariaDB\u6267\u884c\u8ba1\u5212\u6848\u4f8b<\/a><br \/>\nMySQL\u8054\u63a5\u67e5\u8be2\u7b97\u6cd5\uff1ahttps:\/\/blog.csdn.net\/wakeupwakeup\/article\/details\/98757148<br \/>\nSQL \u4e4b \u8054\u8868\u7ec6\u8282: https:\/\/jhrs.com\/2019\/33621.html<br \/>\nMySQL JOIN \u7684\u6267\u884c\u8fc7\u7a0b: https:\/\/www.cnblogs.com\/youzhibing\/p\/12012952.html<\/p>\n","protected":false},"excerpt":{"rendered":"<p>1. Join\u8fde\u63a5\u6a21\u5f0f\u4e0e\u6267\u884c\u987a\u5e8f 1.1. \u8bed\u6cd5 &hellip;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[28,3],"tags":[12,62],"class_list":["post-1276","post","type-post","status-publish","format-standard","hentry","category-mariadb","category-mariadbmysql","tag-mariadb","tag-62"],"_links":{"self":[{"href":"http:\/\/dba.qishuo.xin\/index.php?rest_route=\/wp\/v2\/posts\/1276","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/dba.qishuo.xin\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/dba.qishuo.xin\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/dba.qishuo.xin\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/dba.qishuo.xin\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1276"}],"version-history":[{"count":23,"href":"http:\/\/dba.qishuo.xin\/index.php?rest_route=\/wp\/v2\/posts\/1276\/revisions"}],"predecessor-version":[{"id":1313,"href":"http:\/\/dba.qishuo.xin\/index.php?rest_route=\/wp\/v2\/posts\/1276\/revisions\/1313"}],"wp:attachment":[{"href":"http:\/\/dba.qishuo.xin\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1276"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/dba.qishuo.xin\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1276"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/dba.qishuo.xin\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1276"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}