{"id":2649,"date":"2013-05-30T12:01:49","date_gmt":"2013-05-30T03:01:49","guid":{"rendered":"http:\/\/www.techscore.com\/blog\/?p=2649"},"modified":"2018-11-14T16:33:55","modified_gmt":"2018-11-14T07:33:55","slug":"postgresql-index-only-scan-%e5%a5%ae%e9%97%98%e8%a8%98-%e3%81%9d%e3%81%ae2","status":"publish","type":"post","link":"https:\/\/www.techscore.com\/blog\/2013\/05\/30\/postgresql-index-only-scan-%e5%a5%ae%e9%97%98%e8%a8%98-%e3%81%9d%e3%81%ae2\/","title":{"rendered":"PostgreSQL Index Only Scan \u596e\u95d8\u8a18 \u305d\u306e2"},"content":{"rendered":"<p>\u3069\u3046\u3082\u3002\u6751\u4e0a\u3067\u3059\u3002<\/p>\n<p>\u524d\u56de\u306b\u5f15\u304d\u7d9a\u304dPostgreSQL\u3067\u3059\u3002<\/p>\n<p>\u4eca\u306f\u3053\u3093\u306a\u611f\u3058\u3067\u3059\u3002<\/p>\n<p>\u8ffd\u8a18\u578b\u30a2\u30fc\u30ad\u30c6\u30af\u30c1\u30e3<br \/>\n\u30d0\u30ad\u30e5\u30fc\u30e0\u3000\u3000\u3000\u3000\u3000\u2190 \u524d\u56de\u3053\u3053\u307e\u3067<br \/>\nVisibility Map\u3000\u3000\u2190 \u4eca\u56de\u3053\u3053<br \/>\n\u30d7\u30e9\u30f3\u6f14\u7b97\u5b50<br \/>\nIndex Only Scan<\/p>\n<p>\u3068\u3046\u3053\u3068\u3067\u4eca\u65e5\u306fVisibility Map\u3067\u3059\u3002<\/p>\n<h2>\u30d0\u30ad\u30e5\u30fc\u30e0\u3063\u3066\u9045\u304f\u306a\u3044\u306e\uff1f<\/h2>\n<p>\u30d0\u30ad\u30e5\u30fc\u30e0\u306e\u51e6\u7406\u3063\u3066\u30c6\u30fc\u30d6\u30eb\u3092\u53c2\u7167\u3057\u3066\u3001\u4e0d\u8981\u9818\u57df\u3092\u63a2\u3057\u3066\u3001\u7a7a\u304d\u9818\u57df\u306b\u3057\u307e\u3059\u3002<br \/>\n\u3064\u307e\u308a\u5bfe\u8c61\u30c6\u30fc\u30d6\u30eb\u5168\u4f53\u3092\u30b9\u30ad\u30e3\u30f3\u3059\u308b\u306e\u3067\u3001\u9045\u304f\u306a\u308b\u3088\u3046\u306a\u30a4\u30e1\u30fc\u30b8\u3067\u3059\u3002<\/p>\n<p><a href=\"https:\/\/www.techscore.com\/blog\/wp\/wp-content\/uploads\/2013\/05\/postgresql-techscore-blog2-1.png\" rel=\"facebox\" rel=\"attachment wp-att-2653\"><img loading=\"lazy\" class=\"alignnone size-medium wp-image-2653\" alt=\"postgresql-techscore-blog2-1\" src=\"https:\/\/www.techscore.com\/blog\/wp\/wp-content\/uploads\/2013\/05\/postgresql-techscore-blog2-1-300x153.png\" width=\"300\" height=\"153\" srcset=\"https:\/\/www.techscore.com\/blog\/wp\/wp-content\/uploads\/2013\/05\/postgresql-techscore-blog2-1-300x153.png 300w, https:\/\/www.techscore.com\/blog\/wp\/wp-content\/uploads\/2013\/05\/postgresql-techscore-blog2-1.png 494w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><\/p>\n<p>\u3067\u3082\u3001PostgreSQL8.4\u304b\u3089\u305d\u306e\u8fba\u304c\u6539\u5584\u3055\u308c\u3066\u3044\u307e\u3059\u3002<br \/>\n\u305d\u306e\u6a5f\u80fd\u304cVisibility Map\u3067\u3059\u3002<\/p>\n<h2>Visibility Map<\/h2>\n<p>Visibility Map(VM:\u53ef\u8996\u6027\u30de\u30c3\u30d7)\u306f\u30d0\u30fc\u30b8\u30e7\u30f38.4\u304b\u3089\u8ffd\u52a0\u3055\u308c\u305f\u3082\u306e\u3067\u3059\u3002<\/p>\n<p>\u30fbVisibility Map\u3068\u306f\u3002\u3002\u3002<br \/>\n<strong>\u3059\u3079\u3066\u306e\u30c8\u30e9\u30f3\u30b6\u30af\u30b7\u30e7\u30f3\u304b\u3089\u53ef\u8996\u304b\u3069\u3046\u304b\u30921\u30da\u30fc\u30b81\u30d3\u30c3\u30c8\u3067\u6301\u3064<\/strong><\/p>\n<p>\u30fbVisibility Map\u306f\u5b9f\u614b\u306f\u4f55\u304b\uff1f<br \/>\n<strong>\u300c\u30d5\u30a1\u30a4\u30eb\u30ce\u30fc\u30c9_vm\u300d\u3068\u3044\u3046\u30d5\u30a1\u30a4\u30eb\u540d\u3067\u4fdd\u5b58\u3055\u308c\u3066\u3044\u308b<\/strong><\/p>\n<p>\u30fb\u30d3\u30c3\u30c8\u306e\u610f\u5473\u306f<br \/>\n<strong>\u30d3\u30c3\u30c8\u304c\u7acb\u3063\u3066\u3044\u308b\u30fb\u30fb\u30fb\u30da\u30fc\u30b8\u5185\u306e\u884c\u304c\u3059\u3079\u3066\u306e\u30c8\u30e9\u30f3\u30b6\u30af\u30b7\u30e7\u30f3\u3067\u53ef\u8996\u306e\u72b6\u614b<\/strong><br \/>\n<strong>\u30d3\u30c3\u30c8\u304c\u305f\u3063\u3066\u3044\u306a\u3044\u30fb\u30fb\u30fb\u3042\u308b\u30c8\u30e9\u30f3\u30b6\u30af\u30b7\u30e7\u30f3\u3067\u53ef\u8996\u3067\u306a\u3044\u53ef\u80fd\u6027\u304c\u3042\u308b<\/strong><\/p>\n<p>\u30fb\u30d0\u30ad\u30e5\u30fc\u30e0<br \/>\n<strong>\u30d0\u30ad\u30e5\u30fc\u30e0\u6642\u306fVisibility Map\u3092\u53c2\u7167\u3057\u3066\u52b9\u7387\u3088\u304f\u30d0\u30ad\u30e5\u30fc\u30e0<\/strong><\/p>\n<p>\u7b87\u6761\u66f8\u304d\u306b\u3057\u3066\u3082\u308f\u304b\u3089\u306a\u3044\u3068\u601d\u3046\u306e\u3067\u3001\u56f3\u306b\u3057\u3066\u307f\u308b\u3068<\/p>\n<p><a href=\"https:\/\/www.techscore.com\/blog\/wp\/wp-content\/uploads\/2013\/05\/postgresql-techscore-blog2-2.png\" rel=\"facebox\" rel=\"attachment wp-att-2656\"><img loading=\"lazy\" class=\"alignnone size-medium wp-image-2656\" alt=\"postgresql-techscore-blog2-2\" src=\"https:\/\/www.techscore.com\/blog\/wp\/wp-content\/uploads\/2013\/05\/postgresql-techscore-blog2-2.png\" width=\"300\" height=\"246\" \/><\/a><\/p>\n<p>\u3053\u3093\u306a\u611f\u3058\u3067\u3059\u3002<\/p>\n<p>\u7c21\u5358\u306b\u8a00\u3046\u3068\u4e0d\u8981\u9818\u57df(\u30ac\u30d9\u30fc\u30b8)\u3092Visibility Map\u306b\u3088\u3063\u3066\u7ba1\u7406\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u3063\u305f\u306e\u3067\u3001Visibility Map\u3092\u53c2\u7167\u3057\u3066\u3001\u4e0d\u8981\u9818\u57df\u306e\u56de\u53ce\u3092\u52b9\u7387\u826f\u304f\u3059\u308b\u3068\u3044\u3046\u3053\u3068\u3067\u3059\u3002<\/p>\n<h2>Free Scan Map<\/h2>\n<p>Visibility Map\u306e\u30d5\u30a1\u30a4\u30eb(\u30d5\u30a1\u30a4\u30eb\u30ce\u30fc\u30c9_vm)\u3092\u5b9f\u969b\u306b\u898b\u305f\u65b9\u306f\u300c\u30d5\u30a1\u30a4\u30eb\u30ce\u30fc\u30c9_fsm\u300d\u3068\u3044\u3046\u30d5\u30a1\u30a4\u30eb\u3082\u898b\u305f\u3093\u3067\u306f\u306a\u3044\u3067\u3057\u3087\u3046\u304b\uff1f<\/p>\n<p><strong>\u3053\u3044\u3064\u306a\u3093\u3084\u306d\u3093\uff1f<\/strong><\/p>\n<p>\u3063\u3066\u601d\u3046\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u304c\u3001\u3053\u308c\u306f\u300cFree Scan Map\u300d\u3068\u3044\u3046\u3082\u306e\u3067\u3059\u3002<br \/>\n\u3053\u308c\u306f\u7a7a\u304d\u9818\u57df\u304c\u3069\u3053\u306b\u3042\u308b\u304b\u3092\u7ba1\u7406\u3057\u3066\u3044\u308b\u6a5f\u69cb\u3067\u3059\u3002<\/p>\n<p>\u30d0\u30ad\u30e5\u30fc\u30e0\u306b\u3088\u3063\u3066\u7a7a\u304d\u9818\u57df\u306f\u3001\u6b21\u306e\u66f4\u65b0(Insert\u3084Update)\u3067\u518d\u5229\u7528\u3055\u308c\u3001\u7a7a\u304d\u9818\u57df\u306b\u30c7\u30fc\u30bf\u304c\u633f\u5165\u3055\u308c\u307e\u3059\u3002<br \/>\n\u3053\u306e\u6642\u306b\u7a7a\u304d\u9818\u57df\u304c\u3069\u3053\u306b\u3042\u308b\u304b\u308f\u304b\u3089\u306a\u3051\u308c\u3070\u3001\u307e\u305f\u30c6\u30fc\u30d6\u30eb\u3092\u30b9\u30ad\u30e3\u30f3\u3057\u3066\u3001\u7a7a\u304d\u9818\u57df\u3092\u898b\u3064\u3051\u3066\u30c7\u30fc\u30bf\u3092\u633f\u5165\u3059\u308b\u3053\u3068\u306b\u306a\u308a\u307e\u3059\u3002<br \/>\n\u3053\u308c\u3092\u52b9\u7387\u5316\u3059\u308b\u305f\u3081\u306b\u3001\u7a7a\u304d\u9818\u57df\u3092\u7ba1\u7406\u3059\u308bFree Scan Map\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<p>Visibility Map\u306f\u4e0d\u8981\u9818\u57df\u3092\u7ba1\u7406\u3059\u308b\u3082\u306e\u3067\u3001Free Scan Map\u306f\u7a7a\u304d\u9818\u57df\u3092\u7ba1\u7406\u3059\u308b\u3082\u306e\u3067\u3059\u3002<\/p>\n<h2>\u307e\u3068\u3081<\/h2>\n<p>\u3068\u3044\u3046\u3053\u3068\u3067\u4eca\u56de\u306fVisibility Map\u3067\u3057\u305f\u3002<br \/>\nVisibility Map\u306f\u30d0\u30ad\u30e5\u30fc\u30e0\u6642\u306b\u4f7f\u7528\u3055\u308c\u3066\u3044\u308b\u6a5f\u69cb\u3067\u3059\u304c\u3001Index Only Scan\u6642\u306b\u3082\u4f7f\u7528\u3055\u308c\u3066\u3044\u307e\u3059\u3002<br \/>\n\u8a73\u3057\u304f\u306fIndex Only Scan\u306e\u6642\u306b\u8aac\u660e\u3057\u307e\u3059\u3002<\/p>\n<p>\u8ffd\u8a18\u578b\u30a2\u30fc\u30ad\u30c6\u30af\u30c1\u30e3<br \/>\n\u30d0\u30ad\u30e5\u30fc\u30e0<br \/>\nVisibility Map\u3000\u3000\u3000 \u2190 \u30a4\u30de\u30b3\u30b3<br \/>\n\u30d7\u30e9\u30f3\u6f14\u7b97\u5b50<br \/>\nIndex Only Scan<\/p>\n<p>\u3068\u3044\u3046\u3053\u3068\u3067\u3001\u6b21\u56de\u306f\u30d7\u30e9\u30f3\u6f14\u7b97\u5b50\u306b\u3064\u3044\u3066\u3067\u3059\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u3069\u3046\u3082\u3002\u6751\u4e0a\u3067\u3059\u3002<\/p>\n<p>\u524d\u56de\u306b\u5f15\u304d\u7d9a\u304dPostgreSQL\u3067\u3059\u3002<\/p>\n<p>\u4eca\u306f\u3053\u3093\u306a\u611f\u3058\u3067\u3059\u3002<br \/><a href=\"https:\/\/www.techscore.com\/blog\/2013\/05\/30\/postgresql-index-only-scan-%e5%a5%ae%e9%97%98%e8%a8%98-%e3%81%9d%e3%81%ae2\/\">\u7d9a\u304d\u3092\u8aad\u3080...<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[97],"tags":[206],"_links":{"self":[{"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/posts\/2649"}],"collection":[{"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/comments?post=2649"}],"version-history":[{"count":1,"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/posts\/2649\/revisions"}],"predecessor-version":[{"id":17931,"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/posts\/2649\/revisions\/17931"}],"wp:attachment":[{"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/media?parent=2649"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/categories?post=2649"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/tags?post=2649"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}