{"id":3560,"date":"2021-01-18T18:41:54","date_gmt":"2021-01-18T10:41:54","guid":{"rendered":"https:\/\/www.gbase8.cn\/?p=3560"},"modified":"2024-01-22T09:08:58","modified_gmt":"2024-01-22T01:08:58","slug":"gbase-8a%e6%80%a7%e8%83%bd%e4%bc%98%e5%8c%96%e6%a1%88%e4%be%8b%ef%bc%8c%e5%a4%a7%e9%87%8f%e5%b0%8f%e8%a1%a8join%e6%97%b6%e6%8b%89%e4%ba%86%e5%a4%8d%e5%88%b6%e8%a1%a8%e5%af%bc%e8%87%b4%e5%8f%aa","status":"publish","type":"post","link":"https:\/\/www.gbase8.cn\/en\/3560","title":{"rendered":"\u5357\u5927\u901a\u7528GBase 8a\u6027\u80fd\u4f18\u5316\u6848\u4f8b\uff0c\u5927\u91cf\u5c0f\u8868join\u65f6\u62c9\u4e86\u590d\u5236\u8868\u5bfc\u81f4\u53ea\u67091\u4e2a\u8282\u70b9\u8fd0\u884c\uff0cgcluster_hash_redistribute_join_optimize \u53c2\u6570\u8c03\u6574"},"content":{"rendered":"<p>\u5728\u67d0\u4e2a\u9879\u76ee\u91cc\uff0c\u6709\u63a5\u8fd120\u4e2a\u8868\u53c2\u4e0eleft join,\u4f46\u6bcf\u4e2a\u8868\u547d\u4e2d\u7684\u6570\u636e\u91cf\u90fd\u5f88\u5c11\uff0c\u4e0d\u8d85\u8fc76\u4e07\u884c\u3002\u5728\u8fd0\u884c\u4e2d\uff0c\u53d1\u73b0\u6700\u8017\u65f6\u7684\u9636\u6bb5\u53ea\u67091\u4e2a\u8282\u70b9\u5728\u8fd0\u884c\uff0c\u4e14\u4ea7\u751f\u4e86\u5927\u91cf\u7684\u4e34\u65f6\u4e2d\u95f4\u6587\u4ef6\u3002\u67e5\u770b\u6267\u884c\u65e5\u5fd7\u786e\u8ba4\u6240\u6709\u6570\u636e\u8868\u90fd\u522b\u62c9\u6210\u4e86\u590d\u5236\u8868\uff0c\u6700\u540e\u57281\u4e2a\u8282\u70b9\u4e0a\u8fd0\u884c\u3002\u901a\u8fc7\u8c03\u6574gcluster_hash_redistribute_join_optimize\u53c2\u6570\uff0c\u5f3a\u884c\u5c06\u4e3b\u8868\uff0c\u867d\u7136\u6570\u636e\u91cf\u4e5f\u4e0d\u591a\uff0c\u62c9\u6210\u5206\u5e03\u8868\uff0c\u6027\u80fd\u67091\u500d\u4ee5\u4e0a\u7684\u63d0\u5347\u3002\u9884\u8ba1\u8282\u70b9\u8d8a\u591a\uff0c\u6027\u80fd\u63d0\u5347\u8d8a\u591a\u3002<\/p>\n\n\n\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_84 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Directory Navigation<\/p>\n<label for=\"ez-toc-cssicon-toggle-item-6a2aaa3c418c6\" 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 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href=\"https:\/\/www.gbase8.cn\/en\/3560\/#%E5%8F%82%E6%95%B03\" >\u53c2\u65703<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/www.gbase8.cn\/en\/3560\/#%E8%AF%B4%E6%98%8E3\" >\u8bf4\u660e3<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"https:\/\/www.gbase8.cn\/en\/3560\/#%E5%8F%82%E6%95%B0%E5%BD%B1%E5%93%8D%E6%89%A7%E8%A1%8C%E8%AE%A1%E5%88%92%E6%96%B9%E5%BC%8F\" >\u53c2\u6570\u5f71\u54cd\u6267\u884c\u8ba1\u5212\u65b9\u5f0f<\/a><\/li><\/ul><\/nav><\/div>\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%8F%82%E8%80%83\"><\/span>\u53c2\u8003<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<figure class=\"wp-block-embed is-type-wp-embed is-provider-\u8001\u7d2b\u7af9\u7684\u5bb6 wp-block-embed-\u8001\u7d2b\u7af9\u7684\u5bb6\"><div class=\"wp-block-embed__wrapper\">\n<blockquote class=\"wp-embedded-content\" data-secret=\"kFujQlIlGz\"><a href=\"https:\/\/www.gbase8.cn\/en\/3600\/\">GBase 8a \u6267\u884c\u8ba1\u5212Explain\u4ecb\u7ecd<\/a><\/blockquote><iframe loading=\"lazy\" class=\"wp-embedded-content\" sandbox=\"allow-scripts\" security=\"restricted\" style=\"position: absolute; clip: rect(1px, 1px, 1px, 1px);\" title=\"\u300aGBase 8a \u6267\u884c\u8ba1\u5212Explain\u4ecb\u7ecd\u300b\u2014\u8001\u7d2b\u7af9\u7684\u5bb6\" src=\"https:\/\/www.gbase8.cn\/3600\/embed#?secret=kFujQlIlGz\" data-secret=\"kFujQlIlGz\" width=\"600\" height=\"338\" frameborder=\"0\" marginwidth=\"0\" marginheight=\"0\" scrolling=\"no\"><\/iframe>\n<\/div><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%8F%82%E6%95%B0\"><\/span>\u53c2\u6570<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>gcluster_hash_redistribute_join_optimize<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%90%AB%E4%B9%89\"><\/span>\u542b\u4e49<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>\u662f\u5426\u542f\u7528Hash\u91cd\u5206\u5e03\u7684JOIN\u6a21\u5f0f\u3002\u9ed8\u8ba4\u503c\u662f2\u3002<br>\u53c2\u6570=0\u62c9\u590d\u5236\u8868<\/p>\n\n\n\n<p>\u53c2\u6570=1\u4e00\u76f4\u4f7f\u7528\u3002\u5728\u4e24\u4e2a\u5206\u5e03\u8868\u8fdb\u884c\u7b49\u503cJOIN\u8fd0\u7b97\u65f6\uff0c<br>\u5c06\u628a\u5176\u4e2d\u4e00\u4e2a\u8868\u7684\u6570\u636e\u6839\u636e\u8fde\u63a5\u6761\u4ef6\u5217\u7684\u503c\u8fdb\u884c\u54c8\u5e0c\u91cd\u5206\u5e03\u3002<br>\u7136\u540e\uff0c\u5229\u7528\u5404\u4e2a\u8fd0\u7b97\u8282\u70b9\u4e0a\u91cd\u5206\u5e03\u540e\u7684\u4e34\u65f6\u8868\u548c\u53e6\u4e00\u4e2a\u8fdb\u884cJOIN\u8fd0\u7b97\u3002<br>\u8fd9\u6837\uff0c\u5404\u8282\u70b9\u7684\u8fd0\u7b97\u7ed3\u679c\u76f4\u63a5\u6c47\u603b\u5373\u53ef\u5f97\u5230\u6700\u7ec8\u7ed3\u679c\u3002<br>\u8fd9\u79cd\u7b56\u7565\u53ef\u4ee5\u514d\u4e8e\u5c06\u5176\u4e2d\u4e00\u4e2a\u5206\u5e03\u8868\u5728\u6240\u6709\u8fd0\u7b97\u8282\u70b9\u4e0a\u62c9\u6210\u590d\u5236\u8868\uff0c\u800c\u662f\u6bcf\u4e2a\u8fd0\u7b97\u8282\u70b9\u53ea\u9700\u63a5\u6536\u8fd9\u4e2a\u8868\u7684\u4e00\u90e8\u5206\u6570\u636e\u3002<\/p>\n\n\n\n<p>\u53c2\u6570=2\u7531\u89c4\u5219\u51b3\u5b9a\uff1a\u4e24\u8868\u7684\u5c3a\u5bf8\u76f8\u5dee\u4e0d\u8d85\u8fc720%\u65f6\uff0c\u4f7f\u7528\u54c8\u5e0c\u91cd\u5206\u5e03JOIN\uff1b\u5426\u5219\u4e0d\u4f7f\u7528\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E8%AF%B4%E6%98%8E\"><\/span>\u8bf4\u660e<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>\u7531\u4e8e\u6570\u636e\u91cf\u5f88\u5c11\uff0c\u4e14\u5f88\u63a5\u8fd1\uff0c\u6700\u7ec8\u6267\u884c\u8ba1\u5212\u662f\u5c06\u8868\u90fd\u62c9\u6210\u4e86\u590d\u5236\u8868\uff0c\u5bfc\u81f4\u5728\u9010\u7ea7join\u540e\u5728\u5355\u4e2a\u8282\u70b9\u4ea7\u751f\u4e86\u5927\u91cf\u7684\u4e34\u65f6\u4e2d\u95f4\u6587\u4ef6\u3002<\/p>\n\n\n\n<p>\u901a\u8fc7\u8c03\u6574\u53c2\u6570\u4e3a1\uff0c\u5c06\u4e3b\u8868\u62c9\u6210\u4e86\u5206\u5e03\u8868\uff0c\u6700\u7ec8\u6240\u6709\u8ba1\u7b97\u8282\u70b9\u5168\u90e8\u80fd\u53c2\u4e0e\u8fd0\u7b97\uff0c\u63d0\u5347\u4e86\u6027\u80fd\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E8%BE%85%E5%8A%A9%E5%8F%82%E6%95%B0\"><\/span>\u8f85\u52a9\u53c2\u6570<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%8F%82%E6%95%B01\"><\/span>\u53c2\u65701<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>gcluster_hash_redist_threshold_row<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E8%AF%B4%E6%98%8E1\"><\/span>\u8bf4\u660e1<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>\u5f53\u8be5\u503c\u4e0d\u4e3a 0 \u65f6\uff0c\u82e5\u5c0f\u8868\u62c9\u8868\u7684\u6570\u636e\u884c\u6570\u5927\u4e8e\u8be5\u503c\uff0c\u8fdb\u884c HASH \u91cd\u5206\u5e03 JOIN\u3002<br>\u8be5\u53c2\u6570\u7684\u9ed8\u8ba4\u503c\u662f 0\u3002<\/p>\n\n\n\n<p>\u8be5\u53c2\u6570\u914d\u5408gcluster_hash_redistribute_join_optimize\u7684\u53c2\u6570\u503c2\u4f7f\u7528\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E6%A0%B7%E4%BE%8B\"><\/span>\u6837\u4f8b<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%B0%8F%E4%BA%8E%E5%8F%82%E6%95%B0%E8%B5%B0%E5%A4%8D%E5%88%B6%E8%A1%A8\"><\/span>\u5c0f\u4e8e\u53c2\u6570\u8d70\u590d\u5236\u8868<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1210\" height=\"499\" src=\"https:\/\/www.gbase8.cn\/wp-content\/uploads\/2021\/01\/image-15.png\" alt=\"\" class=\"wp-image-3597\"\/><\/figure>\n\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%A6%82%E6%9E%9C%E5%A4%A7%E4%BA%8E%E5%8F%82%E6%95%B0%E5%80%BC%EF%BC%8C%E5%88%99%E8%B5%B0%E9%87%8D%E5%88%86%E5%B8%83\"><\/span>\u5982\u679c\u5927\u4e8e\u53c2\u6570\u503c\uff0c\u5219\u8d70\u91cd\u5206\u5e03<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1212\" height=\"522\" src=\"https:\/\/www.gbase8.cn\/wp-content\/uploads\/2021\/01\/image-14.png\" alt=\"\" class=\"wp-image-3595\"\/><\/figure>\n\n\n\n<p><\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%8F%82%E6%95%B02\"><\/span>\u53c2\u65702<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>gcluster_hash_redistribute_join_optimize<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E8%AF%B4%E6%98%8E2\"><\/span>\u8bf4\u660e2<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>\u662f\u5426\u542f\u7528Hash\u91cd\u5206\u5e03\u7684JOIN\u6a21\u5f0f\u3002\u9ed8\u8ba4\u503c\u662f1\u3002<br>\u53c2\u6570=0\u7981\u7528\u3002<br>\u53c2\u6570=1\u4e00\u76f4\u4f7f\u7528\u3002\u5728\u4e24\u4e2a\u5206\u5e03\u8868\u8fdb\u884c\u7b49\u503cJOIN\u8fd0\u7b97\u65f6\uff0c\u5c06\u628a\u5176\u4e2d\u4e00\u4e2a\u8868\u7684\u6570\u636e\u6839\u636e\u8fde\u63a5\u6761\u4ef6\u5217\u7684\u503c\u8fdb\u884c\u54c8\u5e0c\u91cd\u5206\u5e03\u3002<br>\u7136\u540e\uff0c\u5229\u7528\u5404\u4e2a\u8fd0\u7b97\u8282\u70b9\u4e0a\u91cd\u5206\u5e03\u540e\u7684\u4e34\u65f6\u8868\u548c\u53e6\u4e00\u4e2a\u8fdb\u884cJOIN\u8fd0\u7b97\u3002\u8fd9\u6837\uff0c\u5404\u8282\u70b9\u7684\u8fd0\u7b97\u7ed3\u679c\u76f4\u63a5\u6c47\u603b\u5373\u53ef\u5f97\u5230\u6700\u7ec8\u7ed3\u679c\u3002<br>\u8fd9\u79cd\u7b56\u7565\u53ef\u4ee5\u514d\u4e8e\u5c06\u5176\u4e2d\u4e00\u4e2a\u5206\u5e03\u8868\u5728\u6240\u6709\u8fd0\u7b97\u8282\u70b9\u4e0a\u62c9\u6210\u590d\u5236\u8868\uff0c\u800c\u662f\u6bcf\u4e2a\u8fd0\u7b97\u8282\u70b9\u53ea\u9700\u63a5\u6536\u8fd9\u4e2a\u8868\u7684\u4e00\u90e8\u5206\u6570\u636e\u3002<br>\u53c2\u6570=2\u7531\u89c4\u5219\u51b3\u5b9a\uff1a\u4e24\u8868\u7684\u5c3a\u5bf8\u76f8\u5dee\u4e0d\u8d85\u8fc720%\u65f6\uff0c\u4f7f\u7528\u54c8\u5e0c\u91cd\u5206\u5e03JOIN\uff1b\u5426\u5219\u4e0d\u4f7f\u7528\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%8F%82%E6%95%B03\"><\/span>\u53c2\u65703<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>gcluster_hash_redistribute_groupby_optimize<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E8%AF%B4%E6%98%8E3\"><\/span>\u8bf4\u660e3<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p>\u8fd9\u4e2a\u53c2\u6570\u7528\u4e8e\u63a7\u5236\u662f\u5426\u542f\u7528Hash\u91cd\u5206\u5e03\u7684GROUP BY\u6a21\u5f0f\u3002<br>\u53c2\u6570=0\u7981\u7528\u3002<br>\u53c2\u6570=1\u542f\u7528\u3002\u8fdb\u884c\u5206\u7ec4\uff08groupby\uff09\u8fd0\u7b97\u4e4b\u524d\uff0c\u5c06\u4f1a\u628a\u4e34\u65f6\u7ed3\u679c\u5229\u7528\u54c8\u5e0c\u7b97\u6cd5\u91cd\u5206\u5e03\u5230\u5404\u4e2a\u8fd0\u7b97\u8282\u70b9\uff0c\u518d\u7531\u5404\u4e2a\u8282\u70b9\u8fdb\u884c\u5206\u7ec4\u8fd0\u7b97\u3002\u7531\u4e8e\u6570\u636e\u5728\u5206\u5230\u5404\u4e2a\u8282\u70b9\u4e4b\u524d\u5df2\u7ecf\u505a\u4e86\u54c8\u5e0c\uff0c\u56e0\u6b64\u4ea7\u751f\u7684\u7ed3\u679c\u76f4\u63a5\u6c47\u603b\u5373\u53ef\u5f97\u5230\u6700\u7ec8\u7ed3\u679c\uff0c\u4e0d\u518d\u9700\u8981\u7531\u6c47\u603b\u8282\u70b9\u518d\u505a\u4e00\u6b21\u5206\u7ec4\u3002<br>\u8be5\u53c2\u6570\u7684\u9ed8\u8ba4\u503c\u662f1\u3002<br>\u9700\u8981\u8bf4\u660e\u7684\u662f\uff1a\u5f53\u67e5\u8be2\u5305\u542bOLAP\u51fd\u6570\u3001ORDERBY\u3001LIMIT\u65f6\uff0c\u65e0\u6cd5\u4f7f\u7528\u672c\u53c2\u6570\u8fdb\u884c\u4f18\u5316\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%8F%82%E6%95%B0%E5%BD%B1%E5%93%8D%E6%89%A7%E8%A1%8C%E8%AE%A1%E5%88%92%E6%96%B9%E5%BC%8F\"><\/span><strong>\u53c2\u6570\u5f71\u54cd\u6267\u884c\u8ba1\u5212\u65b9\u5f0f<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<figure class=\"wp-block-table is-style-regular\"><table><tbody><tr><td><strong>join<\/strong><strong>\u573a\u666f<\/strong><strong><\/strong><\/td><td><strong>gcluster_hash_redistribute_join_optimize<\/strong><strong><\/strong> <strong>\u53c2\u6570<\/strong><strong>1<\/strong><strong><\/strong><\/td><td><strong>gcluster_hash_redist_threshold_row<\/strong><strong><\/strong> <strong>\u53c2\u6570<\/strong><strong>2<\/strong><strong><\/strong><\/td><td><strong>\u6267\u884c\u8ba1\u5212<\/strong><strong><\/strong><\/td><\/tr><tr><td><strong>\u4e24\u8868\u5747\u4e3a\u5206\u5e03\u8868\uff0c<\/strong><strong><\/strong> <strong>join<\/strong><strong>\u6761\u4ef6\u4e3a\u4e24\u8868<\/strong><strong>hash<\/strong><strong>\u5206\u5e03\u5217<\/strong><strong><\/strong><\/td><td> 2\u62161<\/td><td>\u65e0\u5f71\u54cd<\/td><td>\u76f4\u63a5\u672c\u5730\u8fdb\u884cjoin\u8fd0\u7b97 \u8d70\u9759\u6001hash join\u6267\u884c\u8ba1\u5212\uff0c<\/td><\/tr><tr><td><strong>\u4e00\u8868\u4e3a\u5206\u5e03\u8868\uff0c\u4e00\u8868\u4e3a\u590d\u5236\u8868<\/strong><strong><\/strong><\/td><td>\u65e0\u5f71\u54cd<\/td><td>\u65e0\u5f71\u54cd<\/td><td>\u76f4\u63a5\u672c\u5730\u8fdb\u884cjoin\u8fd0\u7b97 \u8d70\u5206\u5e03\u8868join\u590d\u5236\u8868\u6267\u884c\u8ba1\u5212<\/td><\/tr><tr><td><strong>\u4e24\u8868\u5747\u4e3a\u5206\u5e03\u8868<\/strong><strong><\/strong> <strong>join<\/strong><strong>\u6761\u4ef6\u4e3a\u5176\u4e2d\u4e00\u8868<\/strong><strong>hash<\/strong><strong>\u5206\u5e03\u5217<\/strong><strong><\/strong><\/td><td>=2 \u6839\u636e\u53c2\u65702\u5224\u65ad\u6267\u884c\u8ba1\u5212 <br>=1 \u8d70\u6267\u884c\u8ba1\u52121\uff09 <br>=0 \u8d70\u6267\u884c\u8ba1\u52122\uff09<\/td><td>\u53c2\u65701= 2\uff0c\u6839\u636e\u53c2\u65702\u7684\u6570\u503c\u8bc4\u4f30\uff0c\u5982\u4e0b\uff1a <br>IF \u5c0f\u8868\u6761\u6570 &lt; gcluster_hash_redist_threshold_row and \u5927\u8868\u548c\u5c0f\u8868\u7684\u6761\u6570\u5dee\u8ddd\u8d85\u8fc720% <br>Then \u8d70\u6267\u884c\u8ba1\u52122<br>Else \u8d70\u6267\u884c\u8ba1\u52121<br>END<\/td><td>1\uff09\u5c06\u975ejoin\u5217hash\u5206\u5e03\u8868\u6309\u7167join\u6761\u4ef6\u5217\u52a8\u6001\u91cd\u5206\u5e03\uff0c\u8d70\u52a8\u6001\u91cd\u5206\u5e03hash join\u6267\u884c\u8ba1\u52121<br>2\uff09\u5c06\u8f83\u5c0f\u7684\u8868\u62c9\u6210\u590d\u5236\u8868\uff0c\u8d70\u62c9\u590d\u5236\u8868\u6267\u884c\u8ba1\u5212<\/td><\/tr><tr><td><strong>\u4e24\u8868\u4e3a\u5206\u5e03\u8868\uff0c<\/strong><strong><\/strong> <strong>join<\/strong><strong>\u6761\u4ef6\u975e\u4e24\u8868\u4efb\u610f\u4e00\u8868<\/strong><strong>hash<\/strong><strong>\u5206\u5e03\u5217<\/strong><strong><\/strong><\/td><td>=2 \u6839\u636e\u53c2\u65702\u5224\u65ad\u6267\u884c\u8ba1\u5212 =1 \u8d70\u6267\u884c\u8ba1\u52121\uff09 =0 \u8d70\u6267\u884c\u8ba1\u52122\uff09<\/td><td>\u5982\u53c2\u65701 = 2\uff0c\u6839\u636e\u53c2\u65702\u7684\u6570\u503c\u8bc4\u4f30\uff0c\u5982\u4e0b\uff1a<br> IF \u5c0f\u8868\u6761\u6570 &lt; gcluster_hash_redist_threshold_row and \u5927\u8868\u548c\u5c0f\u8868\u7684\u6761\u6570\u5dee\u8ddd\u8d85\u8fc720% <br>Then \u8d70\u6267\u884c\u8ba1\u52122<br>Else \u8d70\u6267\u884c\u8ba1\u52121 <br>END <\/td><td>1\uff09\u5c06\u4e24\u4e2a\u975ejoin\u5217hash\u5206\u5e03\u8868\u6309\u7167join\u6761\u4ef6\u5217\u5206\u522b\u52a8\u6001\u91cd\u5206\u5e03\uff0c\u8d70\u52a8\u6001\u91cd\u5206\u5e03hash join<br>2\uff09\u5c06\u8f83\u5c0f\u7684\u8868\u62c9\u6210\u590d\u5236\u8868\uff0c\u8d70\u62c9\u5c0f\u8868\u62c9\u590d\u5236\u8868\u6267\u884c\u8ba1\u5212<\/td><\/tr><\/tbody><\/table><\/figure>","protected":false},"excerpt":{"rendered":"<p>\u5728\u67d0\u4e2a\u9879\u76ee\u91cc\uff0c\u6709\u63a5\u8fd120\u4e2a\u8868\u53c2\u4e0eleft join,\u4f46\u6bcf\u4e2a\u7684\u6570\u636e\u91cf\u90fd\u8d85\u8fc76\u4e07\u884c\u3002\u5728\u8fd0\u884c\u4e2d\uff0c\u53d1\u73b0\u6700\u8017\u65f6\u7684\u9636\u6bb5\u53ea\u67091\u4e2a\u8282\u70b9\u5728\u8fd0\u884c\uff0c\u4e14\u4ea7\u751f\u4e86\u5927\u91cf\u7684\u4e34\u65f6\u4e2d\u95f4\u6587\u4ef6\u3002\u67e5\u770b\u6267\u884c\u65e5\u5fd7\u786e\u8ba4\u6240\u6709\u6570\u636e\u8868\u90fd\u522b\u62c9\u6210\u4e86\u590d\u5236\u8868\uff0c\u6700\u540e\u57281\u4e2a\u8282\u70b9\u4e0a\u8fd0\u884c\u3002\u901a\u8fc7\u8c03\u6574gcluster_hash_redistribute_join_optimize\u53c2\u6570\uff0c\u5f3a\u884c\u5c06\u4e3b\u8868\uff0c\u867d\u7136\u6570\u636e\u91cf\u4e5f\u4e0d\u591a\uff0c\u62c9\u6210\u5206\u5e03\u8868\uff0c\u6027\u80fd\u67091\u500d\u4ee5\u4e0a\u7684\u63d0\u5347\u3002<\/p>","protected":false},"author":1,"featured_media":3597,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3,6],"tags":[48],"class_list":{"0":"post-3560","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","6":"hentry","7":"category-gbase8a","9":"tag-48"},"_links":{"self":[{"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/posts\/3560","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/comments?post=3560"}],"version-history":[{"count":16,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/posts\/3560\/revisions"}],"predecessor-version":[{"id":12504,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/posts\/3560\/revisions\/12504"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/media\/3597"}],"wp:attachment":[{"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/media?parent=3560"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/categories?post=3560"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/tags?post=3560"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}