{"id":9734,"date":"2022-06-21T10:51:44","date_gmt":"2022-06-21T02:51:44","guid":{"rendered":"https:\/\/www.gbase8.cn\/?p=9734"},"modified":"2022-06-21T10:51:45","modified_gmt":"2022-06-21T02:51:45","slug":"gbase-8a%e9%92%88%e5%af%b9group%e5%88%97%e5%94%af%e4%b8%80%e5%80%bc%e5%a4%9a%e7%9a%84%e5%bb%b6%e8%bf%9f%e8%81%9a%e5%90%88%e4%bc%98%e5%8c%96%e5%8f%82%e6%95%b0","status":"publish","type":"post","link":"https:\/\/www.gbase8.cn\/en\/9734","title":{"rendered":"\u5357\u5927\u901a\u7528GBase 8a\u9488\u5bf9group\u5217\u552f\u4e00\u503c\u591a\u7684\u5ef6\u8fdf\u805a\u5408\u4f18\u5316\u53c2\u6570"},"content":{"rendered":"<p>GBase 8a\u5728\u505a\u975eHash\u5217\u7684group\u65f6\uff0c\u9ed8\u8ba4\u7b56\u7565\u662f\u5c06\u5404\u4e2a\u8282\u70b9\u7684\u6570\u636e\u5148\u5728\u672c\u5730group\u540e\uff0c\u518d\u5c06\u7ed3\u679c\u53d1\u5230\u4e34\u65f6\u8868\u505a\u4e8c\u6b21\u805a\u5408\u3002\u6b64\u65b9\u6848\u5728\u805a\u5408\u5217\u552f\u4e00\u503c\u5c11\uff0c\u805a\u5408\u7ed3\u679c\u884c\u6570\u76f8\u6bd4\u539f\u59cb\u6570\u636e\u884c\u6570\u6709\u660e\u663e\u964d\u4f4e\u65f6\u662f\u975e\u5e38\u9002\u5408\u7684\uff0c\u4f46\u5982\u679c\u805a\u5408\u7ed3\u679c\u6ca1\u6709\u964d\u4f4e\uff0c\u6bd4\u59821000\u4e07\u884c\u805a\u5408\u540e999\u4e07\u884c\uff0c\u6c47\u603b\u5230\u4e34\u65f6\u8868\u540e\u4e8c\u6b21\u805a\u5408\uff0c\u7ed3\u679c\u8fd8\u662f\u5728999\u4e07\u884c\uff0c\u5219\u7b2c\u4e00\u6b21\u7684\u672c\u5730\u805a\u5408\u5c31\u51fa\u73b0\u4e86\u8d44\u6e90\u6d6a\u8d39\u3002GBase 8a\u63d0\u4f9b\u4e86\u4e00\u4e2a\u53ef\u9009\u53c2\u6570\uff0c\u901a\u8fc7\u5ef6\u8fdf\u805a\u5408\u6765\u63d0\u5347\u6027\u80fd\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-6a2abfe8a4fdb\" 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-6a2abfe8a4fdb\"  aria-label=\"Toggle\" \/><nav><ul class='ez-toc-list ez-toc-list-level-1' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.gbase8.cn\/en\/9734\/#%E5%8F%82%E6%95%B0\" >\u53c2\u6570<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.gbase8.cn\/en\/9734\/#%E8%AF%B4%E6%98%8E\" >\u8bf4\u660e<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.gbase8.cn\/en\/9734\/#%E6%89%A7%E8%A1%8C%E8%AE%A1%E5%88%92\" >\u6267\u884c\u8ba1\u5212<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.gbase8.cn\/en\/9734\/#%E6%80%BB%E7%BB%93\" >Summary<\/a><\/li><\/ul><\/nav><\/div>\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<pre class=\"wp-block-code\"><code>gcluster_delayed_group_by_optimize<\/code><\/pre>\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>\u662f\u5426\u9488\u5bf9group\u5f00\u542f\u5ef6\u8fdf\u805a\u5408\uff0c\u9ed8\u8ba4\u503c0\uff0c \u4e0d\u5f00\u542f\u3002 \u8bbe\u7f6e\u4e3a1\u5f00\u59cb<\/p>\n\n\n\n<p>\u5ef6\u8fdf\u805a\u5408\uff0c\u5c31\u662f\u4e0d\u5728\u672c\u5730\u505agroup\u540e\u518d\u53d1\u9001\u6570\u636e\uff0c\u800c\u662f\u76f4\u63a5\u53d1\u9001\u6570\u636e\u5230\u4e34\u65f6\u8868\uff0c\u5728\u4e34\u65f6\u8868\u505a\u6700\u540e\u7684\u805a\u5408\u3002<\/p>\n\n\n\n<p>\u8be5\u53c2\u6570\u5bf9group\u5217\u4e0d\u5305\u542bhash\u5206\u5e03\u5217\u65f6\u624d\u6709\u6548\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E6%89%A7%E8%A1%8C%E8%AE%A1%E5%88%92\"><\/span>\u6267\u884c\u8ba1\u5212<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>\u5982\u4e0b\u662f\u968f\u673a\u5206\u5e03\u8868\u7684\u666e\u901a\u6267\u884c\u8ba1\u5212\u3002<\/p>\n\n\n\n<p>\u53ef\u4ee5\u770b\u523000\u6b65\u9aa4\u65f6\uff0c\u5148\u505a\u4e86\u672c\u5730group,\u7136\u540e\u5c06\u7ed3\u679c\u6839\u636eid\u5217\u505a\u4e86\u5206\u53d1\uff0c01\u6b65\u9aa4\u5bf9\u4e34\u65f6\u8868\u505a\u4e86\u6700\u7ec8\u7684group\u805a\u5408\u5e76\u8fd4\u56de\u3002<\/p>\n\n\n\n<p>\u6574\u4f53\u770b\uff0cgroup\u4e862\u6b21\uff0c\u4e00\u6b21\u672c\u5730\uff0c\u4e00\u6b21\u4e34\u65f6\u8868\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code has-small-font-size\"><code>gbase> show create table tt;\r\n+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+\r\n| Table | Create Table                                                                                                                                                                                                      |\r\n+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+\r\n| tt    | CREATE TABLE \"tt\" (\r\n  \"id\" int(11) DEFAULT NULL,\r\n  \"id3\" int(11) DEFAULT NULL,\r\n  \"id2\" int(11) DEFAULT NULL,\r\n  \"name\" varchar(100) DEFAULT NULL\r\n) ENGINE=EXPRESS DEFAULT CHARSET=utf8 TABLESPACE='sys_tablespace' |\r\n+-------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+\r\n1 row in set (Elapsed: 00:00:00.00)\r\n\r\ngbase> explain select id,count(*) from tt group by id;\r\n+----+--------------+-----------+---------+-------------+\r\n| ID | MOTION       | OPERATION | TABLE   | CONDITION   |\r\n+----+--------------+-----------+---------+-------------+\r\n| 01 | &#91;RESULT]     |  Step     | &lt;00>    |             |\r\n|    |              |  <span class=\"has-inline-color has-luminous-vivid-orange-color\">GROUP    |         | GROUP BY id<\/span> |\r\n| 00 | &#91;REDIST(id)] |  Table    | tt&#91;DIS] |             |\r\n|    |              | <span class=\"has-inline-color has-luminous-vivid-orange-color\"><strong> <\/strong>GROUP    |         | GROUP BY id<\/span> |\r\n+----+--------------+-----------+---------+-------------+\r\n4 rows in set (Elapsed: 00:00:00.01)\r\n<\/code><\/pre>\n\n\n\n<p>\u5f00\u542f\u5ef6\u8fdfgroup\u7684\u6267\u884c\u8ba1\u5212\u3002<\/p>\n\n\n\n<p>00\u6b65\u9aa4\uff0c\u5c06\u672c\u5730\u6570\u636e\u76f4\u63a5\u6839\u636eid\u5217\u505a\u4e86\u91cd\u5206\u5e03\u5230\u4e34\u65f6\u8868\uff0c01\u6b65\u9aa4\u5b8c\u6210\u8ba1\u7b97\u5e76\u8fd4\u56de\u7ed3\u679c\u3002\u3001<\/p>\n\n\n\n<p>\u6574\u4f53\u53ea\u505a\u4e861\u6b21group\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code has-small-font-size\"><code>gbase> set gcluster_delayed_group_by_optimize=1;\r\nQuery OK, 0 rows affected (Elapsed: 00:00:00.01)\r\n\r\ngbase> explain select id,count(*) from tt group by id;\r\n+----+--------------+-----------+---------+-------------+\r\n| ID | MOTION       | OPERATION | TABLE   | CONDITION   |\r\n+----+--------------+-----------+---------+-------------+\r\n| 01 | &#91;RESULT]     |  Step     | &lt;00>    |             |\r\n|    |              |  GROUP    |         | GROUP BY id |\r\n| 00 | &#91;REDIST(id)] |  Table    | tt&#91;DIS] |             |\r\n+----+--------------+-----------+---------+-------------+\r\n3 rows in set (Elapsed: 00:00:00.00)\r\n<\/code><\/pre>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E6%80%BB%E7%BB%93\"><\/span>Summary<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>\u9488\u5bf9group\u540e\u6570\u636e\u884c\u6570\u6bd4\u4f8b\uff0c\u5982\u679c\u5f88\u9ad8\uff0c\u53ef\u4ee5\u6253\u5f00\u8fd9\u4e2a\u53c2\u6570\u6d4b\u8bd5\u6548\u679c\u3002\u652f\u6301session\u8bbe\u7f6e\uff0c\u4ee5\u53cahint\u65b9\u5f0f\u3002<\/p>\n\n\n\n<p>\u53c2\u8003 <a href=\"https:\/\/www.gbase8.cn\/en\/8995\/#SESSION%E5%8F%82%E6%95%B0hint\">https:\/\/www.gbase8.cn\/8995#SESSION%E5%8F%82%E6%95%B0hint<\/a><\/p>\n\n\n\n<p>\u5177\u4f53\u6027\u80fd\u63d0\u5347\uff0c\u8981\u4ee5\u989d\u59161\u6b21\u7684group\u6027\u80fd\u6d88\u8017\uff0c\u5bf9\u6bd4\u5206\u53d1\u66f4\u591a\u6570\u636e\u7684\u6d88\u8017\uff0c\u4ee5\u5b9e\u9645\u5bf9\u6bd4\u4e3a\u51c6\u3002<\/p>","protected":false},"excerpt":{"rendered":"<p>\u5357\u5927\u901a\u7528GBase 8a\u5728\u505a\u975eHash\u5217\u7684group\u65f6\uff0c\u9ed8\u8ba4\u7b56\u7565\u662f\u5c06\u5404\u4e2a\u8282\u70b9\u7684\u6570\u636e\u5148\u5728\u672c\u5730group\u540e\uff0c\u518d\u5c06\u7ed3\u679c\u53d1\u5230\u4e34\u65f6\u8868\u505a\u4e8c\u6b21\u805a\u5408\u3002\u6b64\u65b9\u6848\u5728\u805a\u5408\u5217\u552f\u4e00\u503c\u5c11\uff0c\u805a\u5408\u7ed3\u679c\u884c\u6570\u76f8\u6bd4\u539f\u59cb\u6570\u636e\u884c\u6570\u6709\u660e\u663e\u964d\u4f4e\u65f6\u662f\u975e\u5e38\u9002\u5408\u7684\uff0c\u4f46\u5982\u679c\u805a\u5408\u7ed3\u679c\u6ca1\u6709\u964d\u4f4e\uff0c\u6bd4\u59821000\u4e07\u884c\u805a\u5408\u540e999\u4e07\u884c\uff0c\u6c47\u603b\u5230\u4e34\u65f6\u8868\u540e\u4e8c\u6b21\u805a\u5408\uff0c\u7ed3\u679c\u8fd8\u662f\u5728999\u4e07\u884c\uff0c\u5219\u7b2c\u4e00\u6b21\u7684\u672c\u5730\u805a\u5408\u5c31\u51fa\u73b0\u4e86\u8d44\u6e90\u6d6a\u8d39\u3002GBase 8a\u63d0\u4f9b\u4e86\u4e00\u4e2a\u53ef\u9009\u53c2\u6570\uff0c\u901a\u8fc7\u5ef6\u8fdf\u805a\u5408\u6765\u63d0\u5347\u6027\u80fd\u3002<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[],"class_list":["post-9734","post","type-post","status-publish","format-standard","hentry","category-gbase8a"],"_links":{"self":[{"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/posts\/9734","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=9734"}],"version-history":[{"count":8,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/posts\/9734\/revisions"}],"predecessor-version":[{"id":9742,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/posts\/9734\/revisions\/9742"}],"wp:attachment":[{"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/media?parent=9734"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/categories?post=9734"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.gbase8.cn\/en\/wp-json\/wp\/v2\/tags?post=9734"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}