{"id":41627,"date":"2023-11-25T20:28:59","date_gmt":"2023-03-09T03:45:28","guid":{"rendered":"https:\/\/www.silicloud.com\/zh\/blog\/postgresql-%e6%8e%92%e5%ba%8f%e7%b4%a2%e5%bc%95\/"},"modified":"2024-05-04T10:46:36","modified_gmt":"2024-05-04T02:46:36","slug":"postgresql-%e6%8e%92%e5%ba%8f%e7%b4%a2%e5%bc%95","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/zh\/blog\/postgresql-%e6%8e%92%e5%ba%8f%e7%b4%a2%e5%bc%95\/","title":{"rendered":"PostgreSQL \u6392\u5e8f\u7d22\u5f15"},"content":{"rendered":"<h1>PostgreSQL \u6392\u5e8f\u7d22\u5f15<\/h1>\n<ul class=\"post-ul\">\u6700\u65b0\u9806(desc)\u3067\u30bd\u30fc\u30c8\u3059\u308b\u30af\u30a8\u30ea\u306e\u5834\u5408\u3001\u5fdc\u7b54\u6642\u9593\u9ad8\u901f\u5316\u306e\u52b9\u679c\u304c\u671f\u5f85\u3067\u304d\u308b<\/ul>\n<h2>\u8981\u6c42<\/h2>\n<p>psql (9.3.2)\u53ef\u4ee5\u8fdb\u884c\u7b80\u8981\u53d9\u8ff0\u3002<\/p>\n<h2>\u521b\u5efa\u7d22\u5f15<\/h2>\n<pre class=\"post-pre\"><code>CREATE INDEX idx_hoge_code_desc ON hoge(code DESC);\r\n<\/code><\/pre>\n<ul class=\"post-ul\">\n<li style=\"list-style-type: none;\">\n<ul class=\"post-ul\">hoge \u306b\u5bfe\u3057\u3066\u3001\u30c6\u30fc\u30d6\u30eb\u30ed\u30c3\u30af \u304c\u767a\u751f\u3059\u308b\u306e\u3067\u3001\u30b5\u30fc\u30d3\u30b9\u505c\u6b62\u4e2d\u7b49\u306b\u5b9f\u884c\u3059\u308b\u306e\u304c\u30d9\u30bf\u30fc<\/ul>\n<\/li>\n<\/ul>\n<p>\u30ec\u30b3\u30fc\u30c9\u306e\u591a\u3044\u30c6\u30fc\u30d6\u30eb \u306e\u5834\u5408\u3001\u5b9f\u884c\u6642\u9593\u304c\u9577\u6642\u9593\u304b\u304b\u308b\u53ef\u80fd\u6027\u304c\u3042\u308b\u306e\u3067\u3001\u4e8b\u524d\u306b\u540c\u3058\u30c7\u30fc\u30bf\u306eDB\u3092\u540c\u7b49\u30b9\u30da\u30c3\u30af\u306e\u5225\u30b5\u30fc\u30d0\u7b49\u306b\u6e96\u5099\u3057\u3066\u3001\u6642\u9593\u3092\u4e88\u6e2c\u3057\u3066\u304a\u304f\u3002\u30ad\u30e3\u30c3\u30b7\u30e5\u306f\u6050\u3089\u304f\u5b9f\u884c\u6642\u9593\u306b\u306f\u5f71\u97ff\u3057\u306a\u3055\u305d\u3046\u3002<br \/>\n\u9014\u4e2d\u3067\u6b62\u3081\u305f\u3044\u5834\u5408\u306f Ctrl + c \u3067\u30ad\u30e3\u30f3\u30bb\u30eb\u53ef\u80fd\u3001\u6050\u3089\u304f\u554f\u984c\u306a\u3044<\/p>\n<h2>\u5982\u679c\u9700\u8981\u521b\u5efa\u6216\u5220\u9664\u7d22\u5f15<\/h2>\n<pre class=\"post-pre\"><code>DROP index idx_hoge_code_desc;\r\n<\/code><\/pre>\n<h2>\u786e\u8ba4 (qu\u00e8<\/h2>\n<pre class=\"post-pre\"><code># \\d hoge\r\n                                        Table \"public.hoge\"\r\n     Column     |            Type             |                        Modifiers\r\n----------------+-----------------------------+---------------------------------------------------------\r\n code           | integer                     | not null default nextval('hoge_code_seq'::regclass)\r\n \u2026\r\nIndexes:\r\n    \"idx_hoge_code_desc\" btree (code DESC)\r\n<\/code><\/pre>\n<pre class=\"post-pre\"><code># \\d idx_hoge_code_desc\r\nIndex \"public.idx_hoge_code_desc\"\r\n     Column     |  Type   |   Definition\r\n----------------+---------+----------------\r\n code           | integer | code\r\n \u2026\r\nbtree, for table \"public.hoge\"\r\n<\/code><\/pre>\n<p>DESC \u306e\u60c5\u5831\u304c\u8868\u793a\u3055\u308c\u306a\u3044\u2026 \u78ba\u8a8d\u3059\u308b\u65b9\u6cd5\u77e5\u3063\u3066\u308b\u65b9\u3044\u3089\u3063\u3057\u3083\u3063\u305f\u3089\u6559\u3048\u3066\u304f\u3060\u3055\u3044<\/p>\n<h2>\u7d22\u5f15\u524d\u540e\u7684\u7edf\u8ba1\u6570\u636e\u5bf9\u6bd4\u3002<\/h2>\n<ul class=\"post-ul\">\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u4f5c\u6210 \u524d<\/ul>\n<pre class=\"post-pre\"><code># explain analyze select * from hoge where order by code desc limit 50;\r\n                                                                           QUERY PLAN\r\n----------------------------------------------------------------------------------------------------------------------------------------------------------------\r\n Limit  (cost=0.44..2146.45 rows=50 width=44) (actual time=6797.790..6822.734 rows=50 loops=1)\r\n   -&gt;  Index Scan Backward using hoge_pkey on hoge  (cost=0.44..1418472.53 rows=33049 width=44) (actual time=6797.787..6822.728 rows=50 loops=1)\r\n   \u2026\r\n Total runtime: 6822.785 ms\r\n<\/code><\/pre>\n<ul class=\"post-ul\">\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u4f5c\u6210 \u5f8c<\/ul>\n<pre class=\"post-pre\"><code># explain analyze select * from hoge where order by code desc limit 50;\r\n                                                                           QUERY PLAN\r\n----------------------------------------------------------------------------------------------------------------------------------------------------------------\r\n Limit  (cost=0.56..44.30 rows=50 width=44) (actual time=0.089..0.221 rows=50 loops=1)\r\n   -&gt;  Index Scan using idx_hoge_code_desc on hoge  (cost=0.56..28818.94 rows=32950 width=44) (actual time=0.086..0.206 rows=50 loops=1)\r\n Total runtime: 0.279 ms\r\n<\/code><\/pre>\n<p>\u65e9\u4e0a\u597d<\/p>\n","protected":false},"excerpt":{"rendered":"<p>PostgreSQL \u6392\u5e8f\u7d22\u5f15 \u6700\u65b0\u9806(desc)\u3067\u30bd\u30fc\u30c8\u3059\u308b\u30af\u30a8\u30ea\u306e\u5834\u5408\u3001\u5fdc\u7b54\u6642\u9593\u9ad8\u901f\u5316\u306e\u52b9\u679c\u304c\u671f\u5f85\u3067\u304d\u308b  [&hellip;]<\/p>\n","protected":false},"author":10,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-41627","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v21.5 (Yoast SEO v21.5) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>PostgreSQL \u6392\u5e8f\u7d22\u5f15 - Blog - Silicon Cloud<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, 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