{"id":209770,"date":"2022-08-18T15:50:16","date_gmt":"2022-08-18T07:50:16","guid":{"rendered":"https:\/\/www.keaglegz.com\/209770.html"},"modified":"2022-08-18T15:50:16","modified_gmt":"2022-08-18T07:50:16","slug":"%e5%88%a4%e6%96%ad%e7%b4%a2%e5%bc%95%e5%88%9b%e5%bb%ba%e6%98%af%e5%90%a6%e5%90%88%e7%90%86-2","status":"publish","type":"post","link":"https:\/\/www.dongwubaike.cn\/fanhao\/209770.html","title":{"rendered":"\u5224\u65ad\u7d22\u5f15\u521b\u5efa\u662f\u5426\u5408\u7406"},"content":{"rendered":"\n<p>  \t<span>\u2460\u4ece\u5927\u91cf\u7684\u6570\u636e\u4e2d\u83b7\u53d6\u5c0f\u90e8\u5206\u6570\u636e\uff0c\u8fd9\u6837\u7684\u7d22\u5f15\u624d\u662f\u5408\u7406<\/span><\/p>\n<p>  \t<span>a=i_s.statistic.cardinality<\/span><\/p>\n<p>  \t<span>select table_name,CARDINALITY from statistics where table_schema=&#039;dbt3&#039; and table_name=&#039;orders&#039; and index_name=&#039;i_o_orderDATE&#039;;<\/span><\/p>\n<p>  \t<span>b=i_s.tables.tables_rows<\/span><\/p>\n<p>  \t<span>select table_name,table_rows from tables where table_schema=&#039;dbt3&#039; and table_name=&#039;orders&#039;;<\/span><\/p>\n<p>  \t<span>a\/b &lt; 10%,\u5219\u7d22\u5f15\u521b\u5efa\u4e0d\u5408\u7406<\/span><\/p>\n<p>  \t<span>\u2461\u7d22\u5f15\u521b\u5efa\u7684\u5efa\u8bae<\/span><\/p>\n<p>  \t<span>\u3002\u54ea\u4e9b\u5b57\u6bb5\u4e0d\u5efa\u8bae\u521b\u5efa\u7d22\u5f15<\/span><\/p>\n<p>  \t<span>\u5b57\u6bb5\u7684\u91cd\u590d\u503c\u6bd4\u8f83\u591a<\/span><\/p>\n<p>  \t<span>\u5b57\u6bb5\u7ecf\u5e38\u66f4\u65b0<\/span><\/p>\n<p>  \t<span>\u4e0d\u7ecf\u5e38\u67e5\u8be2\u7684\u5b57\u6bb5<\/span><\/p>\n<p>  \t<span>\u3002\u54ea\u4e9b\u5b57\u6bb5\u5efa\u8bae\u521b\u5efa\u7d22\u5f15<\/span><\/p>\n<p>  \t<span>where\u5b50\u53e5<\/span><\/p>\n<p>  \t<span>order by \u5b50\u53e5<\/span><\/p>\n<p>  \t<span>group by \u5b50\u53e5<\/span><\/p>\n<p>  \t<span>\u805a\u5408\u51fd\u6570<\/span><\/p>\n<p>  \t<span>\u4f5c\u4e3a\u5173\u8054\u6761\u4ef6<\/span><\/p>\n<p>  \t<span>\u7ecf\u5e38\u67e5\u8be2\u7684\u5b57\u6bb5<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u2460\u4ece\u5927\u91cf\u7684\u6570\u636e\u4e2d\u83b7\u53d6\u5c0f\u90e8\u5206\u6570\u636e\uff0c\u8fd9\u6837\u7684\u7d22\u5f15\u624d\u662f\u5408\u7406   \ta=i_s.statistic.cardinality<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[],"tags":[],"class_list":["post-209770","post","type-post","status-publish","format-standard","hentry"],"_links":{"self":[{"href":"https:\/\/www.dongwubaike.cn\/fanhao\/wp-json\/wp\/v2\/posts\/209770","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.dongwubaike.cn\/fanhao\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.dongwubaike.cn\/fanhao\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.dongwubaike.cn\/fanhao\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.dongwubaike.cn\/fanhao\/wp-json\/wp\/v2\/comments?post=209770"}],"version-history":[{"count":0,"href":"https:\/\/www.dongwubaike.cn\/fanhao\/wp-json\/wp\/v2\/posts\/209770\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.dongwubaike.cn\/fanhao\/wp-json\/wp\/v2\/media?parent=209770"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.dongwubaike.cn\/fanhao\/wp-json\/wp\/v2\/categories?post=209770"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.dongwubaike.cn\/fanhao\/wp-json\/wp\/v2\/tags?post=209770"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}