{"id":1123,"date":"2016-01-02T16:21:56","date_gmt":"2016-01-02T16:21:56","guid":{"rendered":"http:\/\/haisins.epac.to\/wordpress\/?p=1123"},"modified":"2016-01-02T16:21:56","modified_gmt":"2016-01-02T16:21:56","slug":"%eb%b9%84%ec%9a%a9%ea%b8%b0%eb%b0%98-%ec%a7%88%ec%9d%98-%ec%b5%9c%ec%a0%81%ed%99%94cost-based-query-optimization","status":"publish","type":"post","link":"http:\/\/haisins.synology.me\/wordpress\/?p=1123","title":{"rendered":"\ube44\uc6a9\uae30\ubc18 \uc9c8\uc758 \ucd5c\uc801\ud654(Cost-based Query Optimization)"},"content":{"rendered":"<p style=\"margin-left: 23pt\"><span style=\"color:black\">\uc9c8\uc758 \ucd5c\uc801\ud654\ub294 \uad00\uacc4\ud615 \ub370\uc774\ud130\ubca0\uc774\uc2a4\uc758 \uc131\ub2a5, \ud2b9\ud788\ub098 \ubcf5\uc7a1\ud55c SQL \ubb38\uc7a5\uc758 \uc218\ud589\uc5d0 \uc788\uc5b4\uc11c \uc544\uc8fc \uc911\uc694\ud55c \uc694\uc18c\uc774\uba70, \uc624\ub77c\ud074 \ub370\uc774\ud130\ubca0\uc774\uc2a4\ub294 \ube44\uc6a9\uae30\ubc18 \ucd5c\uc801\ud654 \uae30\ubc95\uc744 \uc0ac\uc6a9\ud569\ub2c8\ub2e4. \ube44\uc6a9\uae30\ubc18 \ucd5c\uc801\ud654 \uae30\ubc95\uc5d0\uc11c\ub294 \uc8fc\uc5b4\uc9c4 \uc9c8\uc758\uc5d0 \ub300\ud574 \ub2e4\uc591\ud55c \uc2e4\ud589 \uacc4\ud68d(execution plan)\uc774 \ub9cc\ub4e4\uc5b4\uc9c0\uace0, \uc774 \uac01\uac01\uc758 \uacc4\ud68d\uc5d0 \ub300\ud574 \ube44\uc6a9\uc774 \ucd94\uc815\ub429\ub2c8\ub2e4. \uc774 \uacb0\uacfc\ub97c \ubc14\ud0d5\uc73c\ub85c \uc9c8\uc758 \ucd5c\uc801\ud654\ub294 \ucd94\uc815\ub41c \ube44\uc6a9\uc774 \ucd5c\uc18c\uc778 \uac83\uc744 \ucd5c\uc0c1\uc758 \uacc4\ud68d\uc73c\ub85c \uc120\ud0dd\ud558\uac8c \ub429\ub2c8\ub2e4.<br \/>\n<\/span><\/p>\n<p style=\"margin-left: 23pt\"><span style=\"color:black\">\uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc774 \ub9e4\uc6b0 \ubcf5\uc7a1\ud55c SQL \ucf54\ub4dc\ub97c \uc0dd\uc131\ud560 \uc9c0\ub3c4 \ubaa8\ub974\uae30 \ub54c\ubb38\uc5d0, \uc9c8\uc758 \uc635\ud2f0\ub9c8\uc774\uc800\ub294 \uc88b\uc740 \uc131\ub2a5\uc744 \ubcf4\uc7a5\ud558\uae30 \uc704\ud574 \ud604\uba85\ud558\uace0 \uacac\uace0\ud574\uc57c\ub9cc \ud569\ub2c8\ub2e4. \uc624\ub77c\ud074 \ub370\uc774\ud130\ubca0\uc774\uc2a4\uc758 \ube44\uc6a9\uae30\ubc18 \uc635\ud2f0\ub9c8\uc774\uc800\ub294 \ube44\uc6a9 \ubaa8\ub378\uc758 \uc815\ud655\uc131\uacfc \uc644\ubcbd\uc131, \uadf8\ub9ac\uace0 \ud2b9\uc815 \uc9c8\uc758\uc758 \ub300\uc0c1\uc774 \ub418\ub294 \ub370\uc774\ud130\ub97c \uc561\uc138\uc2a4\ud558\uae30 \uc704\ud55c \uac00\uc7a5 \ud6a8\uc728\uc801\uc778 \ubc29\ubc95\uc744 \uacb0\uc815\ud558\ub294\ub370 \uc0ac\uc6a9\ub418\ub294 \uae30\uc220\uacfc \ubc29\ubc95\uc5d0 \uc758\ud574 \ud6cc\ub96d\ud55c \uc2e4\ud589 \uacc4\ud68d\uc744 \ub9cc\ub4e4\uc5b4\ub0c5\ub2c8\ub2e4.<br \/>\n<\/span><\/p>\n<p style=\"margin-left: 23pt\">&nbsp;<br \/>\n&nbsp;<\/p>\n<ul>\n<li>\n<div><span style=\"color:black\"><span style=\"font-size:13pt\"><strong>SQL \ubcc0\ud658(transformation)<\/strong><\/span><br \/>\n\t\t\t\t<\/span><\/div>\n<p style=\"margin-left: 54pt\"><span style=\"color:black\">Scan, join, aggregation \ub4f1\uc744 \uc704\ud574 \uc561\uc138\uc2a4\ud574\uc57c \ud560 \ub370\uc774\ud130\uc758 \uc591\uc744 \uc904\uc784\uc73c\ub85c\uc368 \uc9c8\uc758 \uc131\ub2a5\uc744 \ud5a5\uc0c1\uc2dc\ud0a4\uae30 \uc704\ud574, view merging, predicate pushing \ub4f1\uacfc \uac19\uc740 \uae30\ubc95\uc73c\ub85c \uc8fc\uc5b4\uc9c4 SQL \ubb38\uc7a5\uc744 \uc2a4\uc2a4\ub85c \ubcc0\ud658\uc2dc\ucf1c\uc11c, \uacb0\uacfc\ub294 \uac19\uc9c0\ub9cc, \ud6a8\uc728\uc801\uc73c\ub85c \ucc98\ub9ac\ub420 \uc218 \uc788\ub3c4\ub85d \ud558\ub294 \uae30\ub2a5\uc785\ub2c8\ub2e4. \ub610\ud55c \uc624\ub77c\ud074 \ub370\uc774\ud130\ubca0\uc774\uc2a4\ub294 \uc635\ud2f0\ub9c8\uc774\uc800\uc758 \ucd94\uc815\ub41c \ube44\uc6a9\uc744 \uadfc\uac70\ub85c, materialized view rewrite, star transformation \ub4f1\uacfc \uac19\uc740 \uae30\ubc95\uc744 \uc774\uc6a9\ud574 \ube44\uc6a9\uae30\ubc18 \uc9c8\uc758 \ubcc0\ud658\uc744 \uc801\uc6a9\ud560 \uc218\ub3c4 \uc788\uc2b5\ub2c8\ub2e4.<span style=\"font-family:\uad74\ub9bc; font-size:12pt\"><br \/>\n\t\t\t\t\t<\/span><\/span><\/p>\n<\/li>\n<li>\n<div><span style=\"color:black\"><span style=\"font-size:13pt\"><strong>Cost estimate<\/strong><\/span><br \/>\n\t\t\t\t<\/span><\/div>\n<p style=\"margin-left: 54pt\"><span style=\"color:black\">\uc2e4\ud589 \uacc4\ud68d\uc758 \ube44\uc6a9\uc744 \ucd5c\ub300\ud55c \uc815\ud655\ud788 \ucd94\uc815\ud558\uae30 \uc704\ud574\uc11c \uc624\ub77c\ud074 \ub370\uc774\ud130\ubca0\uc774\uc2a4\ub294 \uc624\ube0c\uc81d\ud2b8 \ub808\ubca8 \ud1b5\uacc4\uc815\ubcf4\uc640 \uc2dc\uc2a4\ud15c \ud1b5\uacc4\uc815\ubcf4 \ub4f1\uc744 \ud65c\uc6a9\ud55c \ube44\uc6a9 \ubaa8\ub378\uc744 \uc0ac\uc6a9\ud569\ub2c8\ub2e4. \uc624\ub77c\ud074 \ub370\uc774\ud130\ubca0\uc774\uc2a4\uc758 \uae30\ubcf8 \ube44\uc6a9 \ubaa8\ub378\uc740 &#8220;CPU+IO&#8221;\ub85c, \uc9c8\uc758\ub97c \uc218\ud589\ud558\ub294 \ub3d9\uc548 \ubc1c\uc0dd\ud560 IO \uc624\ud37c\ub808\uc774\uc158\uc758 \uc608\uc0c1 \uc218\uc640 \uc720\ud615\ubfd0 \uc544\ub2c8\ub77c \ub370\uc774\ud130\ubca0\uc774\uc2a4\uc758 CPU \uc0ac\uc774\ud074 \uc218\ub3c4 \uace0\ub824\ud558\uac8c \ub429\ub2c8\ub2e4.<span style=\"font-family:\uad74\ub9bc; font-size:12pt\"><br \/>\n\t\t\t\t\t<\/span><\/span><\/p>\n<p style=\"margin-left: 54pt\"><span style=\"color:black\">\ud1b5\uacc4\uc815\ubcf4\uc640 \uc131\ub2a5 \uc815\ubcf4\ub97c \ubaa8\uc73c\ub294 \uc791\uc5c5\uc740 \ud6a8\uc728\uc801\uc774\uace0 \uc790\ub3d9\ud654\ub420 \ud544\uc694\uac00 \uc788\uc2b5\ub2c8\ub2e4. \uc624\ub77c\ud074 \ub370\uc774\ud130\ubca0\uc774\uc2a4\uc5d0\uc11c\ub294 \ud1b5\uacc4\uc815\ubcf4\uac00 \uc5c6\uac70\ub098 \uc624\ub798\ub41c \uc624\ube0c\uc81d\ud2b8\ub4e4\uc744 \uc790\ub3d9\uc73c\ub85c \ubd84\uc11d\ud558\uace0, \ub370\uc774\ud130\ub97c \uc790\ub3d9\uc73c\ub85c \uc0d8\ud50c\ub9c1\ud574\uc11c \ud1b5\uacc4\uc815\ubcf4\ub97c \ucd94\ucd9c\ud560 \uc218 \uc788\ub294 \uae30\ub2a5\uc774 \uc81c\uacf5\ub418\uba70, \uacb0\uacfc\uc801\uc73c\ub85c SQL \uc218\ud589\uc758 \uc131\ub2a5\uc744 \ud5a5\uc0c1\uc2dc\ud0ac \uc218 \uc788\uc2b5\ub2c8\ub2e4.<br \/>\n<\/span><\/p>\n<p style=\"margin-left: 54pt\"><span style=\"color:black\">\uc624\ub77c\ud074 \ub370\uc774\ud130\ubca0\uc774\uc2a4\ub294 \ub450\uac00\uc9c0 \uc635\ud2f0\ub9c8\uc774\uc800 \ubaa8\ub4dc\ub97c \uc81c\uacf5\ud558\ub294\ub370, \uccab\ubc88\uc9f8\ub294 \uc9c8\uc758 \uacb0\uacfc\uc758 \ucd5c\ucd08 n row\ub97c \ubf51\uc544\ub0b4\ub294 \uc2dc\uac04\uc744 \ucd5c\uc18c\ud654\ud558\uae30 \uc704\ud55c \ubaa8\ub4dc\uc774\uace0, \ub450\ubc88\uc9f8\ub294 \ubaa8\ub4e0 row\ub97c \ubf51\uc544\ub0b4\ub294 \uc2dc\uac04\uc744 \ucd5c\uc18c\ud654\ud558\uae30 \uc704\ud55c \ubaa8\ub4dc\uc785\ub2c8\ub2e4.<br \/>\n<\/span><\/p>\n<p style=\"margin-left: 54pt\">&nbsp;<br \/>\n&nbsp;<\/p>\n<\/li>\n<li>\n<div><span style=\"color:black\"><span style=\"font-size:13pt\"><strong>\ud5a5\uc0c1\ub41c \uc635\ud2f0\ub9c8\uc774\uc800 \ud1b5\uacc4\uc815\ubcf4 \uad00\ub9ac<\/strong><\/span><br \/>\n\t\t\t\t<\/span><\/div>\n<p style=\"margin-left: 54pt\"><span style=\"color:black\">\ud1b5\uacc4\uc815\ubcf4\ub97c \uc218\uc9d1\ud558\ub294 \uac83\uc774 \uc790\ub3d9\ud654\ub418\uc5b4 \uc788\uc9c0\ub9cc, \ub54c\ub85c\ub294 \uba74\ubc00\ud788 \uac80\ud1a0\ud560 \ud544\uc694\uac00 \uc788\uc2b5\ub2c8\ub2e4. \uc6d0\ud558\ub294 \ub300\ub85c \uc2e4\ud589 \uacc4\ud68d\uc774 \ub9cc\ub4e4\uc5b4\uc9c0\ub294 \uc9c0 \uac80\uc99d\ud55c \ud6c4 \uadf8 \uacb0\uacfc\ub97c \ubcf4\uace0 \ud310\ub2e8\ud558\ub294 \uac83\uc774 \uc88b\uc744 \uc218\ub3c4 \uc788\uc2b5\ub2c8\ub2e4. Oracle Database 11g\uc5d0\uc11c\ub294 \uc774\ub807\uac8c \ud1b5\uacc4\uc815\ubcf4\ub97c \uc218\uc9d1\ud558\ub294 \ub2e8\uacc4\uc640 \ubc30\ud3ec\ud558\ub294 \ub2e8\uacc4\ub97c \uad6c\ubd84\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4. \uac80\uc99d \uacfc\uc815\uc744 \ud1b5\ud574 \ubcf4\ub2e4 \uc548\uc815\uc801\uc778 \uc6b4\uc601\uc744 \ubcf4\uc7a5\ud560 \uc218 \uc788\ub294 \ubc29\ubc95\uc774 \uc81c\uacf5\ub418\ub294 \uac83\uc785\ub2c8\ub2e4.<span style=\"font-family:\uad74\ub9bc; font-size:12pt\"><br \/>\n\t\t\t\t\t<\/span><\/span><\/p>\n<\/li>\n<li>\n<div><span style=\"color:black\"><span style=\"font-size:13pt\"><strong>\uc9c0\ub2a5\ud654\ub41c \ucee4\uc11c \uacf5\uc720(cursor sharing)<\/strong><\/span><br \/>\n\t\t\t\t<\/span><\/div>\n<p style=\"margin-left: 54pt\"><span style=\"color:black\">\ubc14\uc778\ub4dc \ubcc0\uc218\ub97c \uc0ac\uc6a9\ud558\ub294 \uacbd\uc6b0 \ucc98\uc74c\uc5d0 \uc2e4\uc81c \uc5b4\ub5a4 \uac12\uc774 \ub4e4\uc5b4\uc624\ub290\ub0d0\uc5d0 \ub530\ub77c \uc2e4\ud589 \uacc4\ud68d\uc740 \uc815\ud574\uc9d1\ub2c8\ub2e4. \ud574\ub2f9 SQL\uc774 age out\ub418\uc9c0 \uc54a\ub294 \ud55c \uc774 \uc2e4\ud589 \uacc4\ud68d\uc740 \uacc4\uc18d \uc0ac\uc6a9\ub429\ub2c8\ub2e4. \ud558\uc9c0\ub9cc \ud574\ub2f9 \uac12\uc774 \ud3b8\uc911\ub41c \uacbd\uc6b0 \uc815\ud574\uc9c4 \uc2e4\ud589 \uacc4\ud68d\uc744 \uacc4\uc18d \uc0ac\uc6a9\ud558\ub294 \uac83\uc740 \ubd88\ud569\ub9ac\ud569\ub2c8\ub2e4. Oracle Database 11g\uc5d0\uc11c\ub294 \uc774\uc640 \uac19\uc774 \uc2e4\uc81c \ubc14\uc778\ub4dc \uac12\uc5d0 \ub530\ub77c \ub2e4\ub974\uac8c \uc2e4\ud589 \uacc4\ud68d\uc744 \ub9cc\ub4e4\uc5b4 \uc0ac\uc6a9\ud558\ub294 \uac83\uc774 \uc88b\uc740\uc9c0 \ud310\ub2e8\ud560 \uc218 \ub2a5\ub825\uc774 \ucd94\uac00\ub418\uc5c8\uc2b5\ub2c8\ub2e4. \ub530\ub77c\uc11c \ub2a5\ub3d9\uc801\uc73c\ub85c \uc131\ub2a5 \ud5a5\uc0c1\uc744 \uc5bb\uc744 \uc218 \uc788\uac8c \ub429\ub2c8\ub2e4.<span style=\"font-family:\uad74\ub9bc; font-size:12pt\"><br \/>\n\t\t\t\t\t<\/span><\/span><\/p>\n<p><span style=\"color:black\">&nbsp;<br \/>\n<\/span>&nbsp;<\/p>\n<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>\uc9c8\uc758 \ucd5c\uc801\ud654\ub294 \uad00\uacc4\ud615 \ub370\uc774\ud130\ubca0\uc774\uc2a4\uc758 \uc131\ub2a5, \ud2b9\ud788\ub098 \ubcf5\uc7a1\ud55c SQL \ubb38\uc7a5\uc758 \uc218\ud589\uc5d0 \uc788\uc5b4\uc11c \uc544\uc8fc \uc911\uc694\ud55c \uc694\uc18c\uc774\uba70, \uc624\ub77c\ud074 \ub370\uc774\ud130\ubca0\uc774\uc2a4\ub294 \ube44\uc6a9\uae30\ubc18 \ucd5c\uc801\ud654 \uae30\ubc95\uc744 \uc0ac\uc6a9\ud569\ub2c8\ub2e4. \ube44\uc6a9\uae30\ubc18 \ucd5c\uc801\ud654 \uae30\ubc95\uc5d0\uc11c\ub294 \uc8fc\uc5b4\uc9c4 \uc9c8\uc758\uc5d0 \ub300\ud574 \ub2e4\uc591\ud55c \uc2e4\ud589 \uacc4\ud68d(execution plan)\uc774 \ub9cc\ub4e4\uc5b4\uc9c0\uace0, \uc774 \uac01\uac01\uc758 \uacc4\ud68d\uc5d0 \ub300\ud574 \ube44\uc6a9\uc774 \ucd94\uc815\ub429\ub2c8\ub2e4. \uc774 \uacb0\uacfc\ub97c \ubc14\ud0d5\uc73c\ub85c \uc9c8\uc758 \ucd5c\uc801\ud654\ub294 \ucd94\uc815\ub41c \ube44\uc6a9\uc774 \ucd5c\uc18c\uc778 \uac83\uc744 \ucd5c\uc0c1\uc758 \uacc4\ud68d\uc73c\ub85c \uc120\ud0dd\ud558\uac8c \ub429\ub2c8\ub2e4. \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc774 \ub9e4\uc6b0 \ubcf5\uc7a1\ud55c SQL \ucf54\ub4dc\ub97c [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_bbp_topic_count":0,"_bbp_reply_count":0,"_bbp_total_topic_count":0,"_bbp_total_reply_count":0,"_bbp_voice_count":0,"_bbp_anonymous_reply_count":0,"_bbp_topic_count_hidden":0,"_bbp_reply_count_hidden":0,"_bbp_forum_subforum_count":0,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"spay_email":""},"categories":[9],"tags":[633,634,635,636,162],"jetpack_featured_media_url":"","amp_enabled":true,"_links":{"self":[{"href":"http:\/\/haisins.synology.me\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/1123"}],"collection":[{"href":"http:\/\/haisins.synology.me\/wordpress\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/haisins.synology.me\/wordpress\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/haisins.synology.me\/wordpress\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/haisins.synology.me\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1123"}],"version-history":[{"count":0,"href":"http:\/\/haisins.synology.me\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/1123\/revisions"}],"wp:attachment":[{"href":"http:\/\/haisins.synology.me\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1123"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/haisins.synology.me\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1123"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/haisins.synology.me\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1123"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}