{"id":1163,"date":"2016-01-03T10:02:18","date_gmt":"2016-01-03T10:02:18","guid":{"rendered":"http:\/\/haisins.epac.to\/wordpress\/?p=1163"},"modified":"2016-01-03T10:02:18","modified_gmt":"2016-01-03T10:02:18","slug":"select-%eb%ac%b8%ec%9e%a5%ec%9d%98-%ec%8b%a4%ed%96%89-%ec%9b%90%eb%a6%ac","status":"publish","type":"post","link":"http:\/\/haisins.synology.me\/wordpress\/?p=1163","title":{"rendered":"Select \ubb38\uc7a5\uc758 \uc2e4\ud589 \uc6d0\ub9ac"},"content":{"rendered":"<p><P> <SPAN><\/P><br \/>\n<DIV style=\"FONT-SIZE: 19px\"><SPAN><B># Select \ubb38\uc7a5\uc758 \uc2e4\ud589 \uc6d0\ub9ac&nbsp;<\/B><\/SPAN><\/DIV><br \/>\n<DIV><SPAN><br \/><\/SPAN><\/DIV><br \/>\n<DIV><SPAN><B>Parse(\uad6c\ubb38\ubd84\uc11d) &#8211;&gt; Bind(\uce58\ud658) &#8211;&gt; Excute(\uc2e4\ud589) &#8211;&gt; Fetch(\uc778\ucd9c)<\/B><\/SPAN><\/DIV><br \/>\n<DIV><SPAN><br \/><\/SPAN><\/DIV><br \/>\n<DIV style=\"FONT-SIZE: 16px\"><SPAN><B>(1) Parse (\uad6c\ubb38 \ubd84\uc11d \ub2e8\uacc4)<\/B><\/SPAN><\/DIV><br \/>\n<DIV><SPAN>&nbsp;\ubb38\ubc95\uac80\uc0ac : select, from, where \ub4f1\uc758 Keyword\ub97c \uac80\uc0ac\ud569\ub2c8\ub2e4&nbsp;<\/SPAN><\/DIV><br \/>\n<DIV><SPAN>&nbsp;\uc758\ubbf8\uac80\uc0ac : \uc704 \ubb38\ubc95\ub4e4\uc744 \uc81c\uc678\ud55c \uce7c\ub7fc\uba85, \ud14c\uc774\ube14\uba85 \ub4f1\uc758 \uc0ac\uc6a9\uc790\uc758 \ucffc\ub9ac\ub0b4\uc6a9\uc5d0 \ub530\ub77c \ub2ec\ub77c\uc9c0\ub294 \uac12\ub4e4\uc744 \uac80\uc0ac\ud569\ub2c8\ub2e4(ex:\uba85\uc2dc\ud55c \uce7c\ub7fc\uc774\ub098 \ud14c\uc774\ube14\uc774 \uc788\ub294\uc9c0 \uac80\uc0ac)<\/SPAN><\/DIV><br \/>\n<DIV><SPAN>&nbsp;\uad8c\ud55c\uac80\uc0ac : \uc704 2\uac00\uc9c0 \uacfc\uc815\uc744 \uac70\uce5c \ud6c4 \ud574\ub2f9 \ucffc\ub9ac\ub97c \uc9c4\ud589\ud560 \uc218 \uc788\ub294 \uad8c\ud55c\uc774 \uc788\ub294\uc9c0 \uac80\uc0ac\ud569\ub2c8\ub2e4<\/SPAN><\/DIV><br \/>\n<DIV><SPAN>&nbsp;\uc2e4\ud589\uacc4\ud68d : \uc774\ud6c4 \uc2e4\ud589\uacc4\ud68d\uc774 Shared Pool-Library Cache\uc5d0 \uc788\ub294\uc9c0 \uac80\uc0ac\ud569\ub2c8\ub2e4. \uc788\ub2e4\uba74 Soft Parse\uc774\uace0, \uc5c6\ub2e4\uba74 \uc2e4\ud589\uacc4\ud68d\uc744 \uc0dd\uc131\ud574\uc57c \ub418\uae30 \ub54c\ubb38\uc5d0 Hard Parse\ub97c \ud558\uac8c \ub429\ub2c8\ub2e4.(\uc2e4\ud589\uacc4\ud68d\uc740 \uc635\ud2f0\ub9c8\uc774\uc800\uac00 \ud568)<\/SPAN><\/DIV><br \/>\n<DIV><SPAN>&nbsp;Soft Parse\uc778\uc9c0 \uac80\uc0ac\ud560\ub54c \uc4f0\uc774\ub294 \uac83\uc774 Hash\ud568\uc218\uc778\ub370, SQL\ubb38\uc7a5 \ub4f1\uc744 ASCII\uac12\uc73c\ub85c \ubcc0\uacbd\ud6c4 Hash \ud568\uc218\ub97c \ud1b5\ud574 hash\uac12\uc73c\ub85c \ubcc0\uacbd\ud574\uc11c Library Cache\uc5d0 \uc788\ub294 hash\uac12\ub4e4\uacfc \ube44\uad50\ud558\uac8c \ub429\ub2c8\ub2e4.<\/SPAN><\/DIV><br \/>\n<DIV><SPAN>&nbsp;\uac12\ub4e4\uc774 \uc2e4\uc81c\ub85c \ub4e4\uc5b4\uac00 \uc788\ub294 \uacf5\uac04\uc744 \ucee4\uc11c\ub77c\uace0 \ubd80\ub985\ub2c8\ub2e4. \ud604\uc7ac Library Cache\uc548\uc5d0 \uc788\ub294 \ucee4\uc11c\ub294 \uacf5\uc720\ucee4\uc11c\ub97c \uc758\ubbf8\ud569\ub2c8\ub2e4<\/SPAN><\/DIV><br \/>\n<DIV><SPAN>&nbsp;Hash List : LRU \ub9ac\uc2a4\ud2b8\ucc98\ub7fc Hash\ub3c4 \uad00\ub9ac\ud560 \uc218 \uc788\ub294 \ub9ac\uc2a4\ud2b8\uac00 \ud544\uc694\ud569\ub2c8\ub2e4. \uc5ec\uae30\uc5d0\uc11c\ub3c4 \uc0ac\uc6a9\uc790\ub4e4\uc758 \uc0ac\uc6a9 \uc6b0\uc120\uad8c\uc744 \ubd80\uc5ec\ud558\uae30 \uc704\ud574 Latch\ub97c \uc0ac\uc6a9\ud569\ub2c8\ub2e4<\/SPAN><\/DIV><br \/>\n<DIV><SPAN><br \/><\/SPAN><\/DIV><br \/>\n<DIV><SPAN><U>**Soft parse\uac00 \uc131\ub2a5\uc774 \uc88b\ub2e4\uace0 \ud558\uc9c0\ub9cc \ub9cc\uc57d 10\uba85\uc758 \uc0ac\uc6a9\uc790\uac01 \ucc3e\ub294 \ubaa8\ub4e0 \ub370\uc774\ud130\uac00 Library Cache\uc5d0 \uc788\ub2e4 &nbsp;\ud558\ub354\ub77c\ub3c4 \uc9c0\uae08\uacfc \uac19\uc774 Latch\uac00 1\uac1c \ubc16\uc5d0 \uc5c6\uc5b4\uc11c \ub3d9\uc2dc\uc5d0 \uc791\uc5c5 \ud560 \uc218 \uc788\ub294 \uc0ac\uc6a9\uc790\uac00 1\uba85 \ubc16\uc5d0 \uc5c6\ub2e4\uba74 \uc18d\ub3c4\uac00 \ub290\ub824\uc9c0\uac8c<\/U><\/SPAN><\/DIV><br \/>\n<DIV><SPAN><U>&nbsp;\ub429\ub2c8\ub2e4. \uc989 Soft Parse\ub77c\uace0 \ubb34\uc870\uac74 \ube60\ub974\ub2e4\ub294 \uc0dd\uac01\uc740 \uc544\ub2d0 \uc218 \uc788\ub2e4\ub294 \uac83\uc785\ub2c8\ub2e4.<\/U><\/SPAN><\/DIV><br \/>\n<DIV><SPAN><br \/><\/SPAN><\/DIV><br \/>\n<DIV><SPAN>-\uc635\ud2f0\ub9c8\uc774\uc800\ub294 RBO(Rule Based Optimizer) CBO(Cost Base Optimizer)\ub85c \ub098\ub269\ub2c8\ub2e4. \ucc28\uc774\ub294 \uc2e4\ud589\uacc4\ud68d\uc744 \uc138\uc6b0\ub294 \ubc29\uc2dd\uc758 \ucc28\uc774\uc785\ub2c8\ub2e4<\/SPAN><\/DIV><br \/>\n<DIV><SPAN><\/SPAN>&nbsp;<\/DIV><br \/>\n<DIV><SPAN><br \/><\/SPAN><\/DIV><br \/>\n<DIV style=\"FONT-SIZE: 16px\"><SPAN><B>(2)Bind(\uce58\ud658)<\/B><\/SPAN><\/DIV><br \/>\n<DIV><SPAN>-1\ubc88\ub9cc \ud30c\uc2f1\ud574\uc11c \uc2e4\ud589\uacc4\ud68d\uc744 1\uac1c\ub9cc \uc0dd\uc131 \ud55c \ud6c4 \ud559\ubc88\uacfc \uc774\ub984\ub9cc \ubc14\uafb8\uc5b4\uc11c 1000\ubc88 \uc2e4\ud589\ud558\ub294 \uac83\uc774 \ud6e8?\uc530 \ub354 \ubd80\ub2f4\ub3c4 \uc801\uace0 \ucffc\ub9ac \uc218\ud589\uc18d\ub3c4\ub3c4 \ube60\ub97c \uac83\uc785\ub2c8\ub2e4.<\/SPAN><\/DIV><br \/>\n<DIV><SPAN>&#8211; Parsing \uc791\uc5c5 (\uad6c\ubb38\ubd84\uc11d) \uc774 \ub05d\ub098\uba74 Bind \ub2e8\uacc4\ub85c \ub118\uc5b4\uac00\ub294\ub370 \uc774 \ub2e8\uacc4\ub97c \uc608\ub97c \ub4e4\uc5b4\ubcf4\uba74,<\/SPAN><\/DIV><br \/>\n<DIV><SPAN>&#8211; emp \ud14c\uc774\ube14\uc5d0\uc11c \uc0ac\uc6d0 \ubc88\ud638\ub97c \uc785\ub825\ubc1b\uc544 100 \uba85\uc758 \uc0ac\uc6d0 \uc815\ubcf4\ub97c \ucd9c\ub825 \ud55c\ub2e4\uace0 \ud558\uba74, \uc0ac\uc6d0\ubc88\ud638 \uac12\ub9cc \ub2e4\ub974\uace0 SQL \ubb38\uc7a5\uc740 \ub3d9\uc77c\ud560 \uac83\uc774\ub2e4. \uc774\ub7f4 \uacbd\uc6b0, 100 \uac1c\uc758 SQL \uc744 Parsing \ud574\uc11c 100 \uac1c\uc758 \uc2e4\ud589 \uacc4\ud68d\uc744 \ub9cc\ub4dc\ub294 \uac83 \ubcf4\ub2e4 &nbsp; &nbsp; &nbsp; 1\ubc88\ub9cc parsing \ud574\uc11c 1 \uac1c\uc758 \uc2e4\ud589 \uacc4\ud68d\uc744 \ub9cc\ub4e4\uc5b4\uc11c \uc0ac\uc6d0\ubc88\ud638\ub9cc \ubc14\uafd4\uc11c 100\ubc88 \uc2e4\ud589\ud558\ub294 \uac83\uc774 \uc218\ud589 \uc18d\ub3c4\uac00 \ud6e8\uc52c \ube60\ub974\ub2e4.<\/SPAN><\/DIV><br \/>\n<DIV><SPAN>&#8211; \uc774\ub7f0 \uc791\uc5c5\uc744 Bind \ub77c \ud558\uba70, \uc5ec\uae30\uc11c \uc0ac\uc6a9\ub418\uc5b4\uc9c0\ub294 \uc0ac\uc6d0\ubc88\ud638\ub97c Bind \ubcc0\uc218\ub77c\uace0 \ud55c\ub2e4.<\/SPAN><\/DIV><br \/>\n<DIV style=\"FONT-SIZE: 16px\"><SPAN><B><br \/><\/B><\/SPAN><\/DIV><br \/>\n<DIV style=\"FONT-SIZE: 16px\"><SPAN><B>(3)Excute(\uc2e4\ud589)<\/B><\/SPAN><\/DIV><br \/>\n<DIV><SPAN>-\ud558\ub4dc \ub514\uc2a4\ud06c\uc758 \ub370\uc774\ud130 \ud30c\uc77c\uc5d0\uc11c \ub370\uc774\ud130\uac00 \ub4e4\uc5b4\uc788\ub294 \ube14\ub85d\uc744 \ucc3e\uc544 \uba54\ubaa8\ub9ac(Database Buffer Cache)\ub85c \ubcf5\uc0ac\ud574 \uc624\ub294 \uacfc\uc815<\/SPAN><\/DIV><br \/>\n<DIV><SPAN>-DB Cache\uc5d0 \ud574\ub2f9 \ube14\ub85d\uc774 \uc5c6\uc744 \uacbd\uc6b0\uc5d0\ub294 \uc11c\ubc84\ud504\ub85c\uc138\uc2a4\uac00 \ucc3e\ub294 \ube14\ub85d\uc758 \uc8fc\uc18c\ub97c hash\ud568\uc218\uc5d0 \ub123\uc5b4&nbsp;<\/SPAN><\/DIV><br \/>\n<DIV><SPAN>hash value\ub97c \ub9cc\ub4e0 \ub2e4\uc74c \uc774\ub984 DB cache hash list\ub97c \ube44\uad50\ud574\uc11c \ub3d9\uc77c\ud55c value\uac00 \uc788\ub294\uc9c0 \uac80\uc0ac\ub97c \ud569\ub2c8\ub2e4. \uc788\ub2e4\uba74 \ub2e4\uc74c \ub2e8\uacc4\uc778 fetch\ub85c \uc9c4\ud589\ud558\uace0 \uc5c6\ub2e4\uba74 \uc11c\ubc84\ud504\ub85c\uc138\uc2a4\uac00 \ud558\ub4dc \ub514\uc2a4\ud06c\ub85c \uac00\uc11c \ud574\ub2f9 \ube14\ub85d\uc744 \ucc3e\uc544 DB Cache\ub85c \ubcf5\uc0ac\ud574 \uc624\uac8c \ub429\ub2c8\ub2e4.<\/SPAN><\/DIV><br \/>\n<DIV><SPAN><br \/><\/SPAN><\/DIV><br \/>\n<DIV style=\"FONT-SIZE: 15px\"><SPAN><U>*Block \ub2e8\uc704\uc758 I\/O<\/U><\/SPAN><\/DIV><br \/>\n<DIV><SPAN>-Block : \ub370\uc774\ud130 \ud30c\uc77c\uc774 \uba54\ubaa8\ub9ac\uc640 \ud558\ub4dc\ub514\uc2a4\ud06c\ub97c \uc624\uace0 \uac08 \ub54c \uc774\ub3d9\ud558\ub294 \ub2e8\uc704.<\/SPAN><\/DIV><br \/>\n<DIV><SPAN>&nbsp;DB_BLOCK_SIZE \ud30c\ub77c\ubbf8\ud130\uc758 \ud06c\uae30\ub85c \uacb0\uc815\ub418\uba70, DB\uac00 \uc0dd\uc131\ub420 \ub54c \uc801\uc6a9\ub418\uc5b4 \uadf8 \uc774\ud6c4\uc5d0\ub294 DB\ub97c \uc0c8\ub85c \uc0dd\uc131\ud558\uc9c0 \uc54a\ub294\ud55c \ubcc0\uacbd\ud560 \uc218 \uc5c6\uc2b5\ub2c8\ub2e4<\/SPAN><\/DIV><br \/>\n<DIV><SPAN>&nbsp;9i : 4k<\/SPAN><\/DIV><br \/>\n<DIV><SPAN>&nbsp;10g : 8k<\/SPAN><\/DIV><br \/>\n<DIV><SPAN>&nbsp;\uc0ac\uc774\uc988\uac00 \ud06c\uba74 I\/O\ub97c \uc904\uc77c \uc218 \uc788\ub294 \ubc18\uba74 \uacf5\uac04 \ub0ad\ube44\uac00 \ub9ce\uc774 \uc0dd\uae38 \uc218\uac00 \uc788\uace0 DB Buffer Cache\uc5d0\uc11c Wait\uac00 \ub9ce\uc774 \uc0dd\uaca8 \uc131\ub2a5\uc774 \uc800\ud558\ub420 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/SPAN><\/DIV><br \/>\n<DIV><SPAN><br \/><\/SPAN><\/DIV><br \/>\n<DIV style=\"FONT-SIZE: 16px\"><SPAN><B>(4)Fetch(\uc778\ucd9c)<\/B><\/SPAN><\/DIV><br \/>\n<DIV><SPAN>-\ubcf5\uc0ac\ud55c \ube14\ub85d\uc5d0\uc11c \ud544\uc694\ud55c \ub0b4\uc6a9 \ucd94\ucd9c<\/SPAN><\/DIV><\/SPAN><\/p>\n","protected":false},"excerpt":{"rendered":"<p># Select \ubb38\uc7a5\uc758 \uc2e4\ud589 \uc6d0\ub9ac&nbsp; Parse(\uad6c\ubb38\ubd84\uc11d) &#8211;&gt; Bind(\uce58\ud658) &#8211;&gt; Excute(\uc2e4\ud589) &#8211;&gt; Fetch(\uc778\ucd9c) (1) Parse (\uad6c\ubb38 \ubd84\uc11d \ub2e8\uacc4) &nbsp;\ubb38\ubc95\uac80\uc0ac : select, from, where \ub4f1\uc758 Keyword\ub97c \uac80\uc0ac\ud569\ub2c8\ub2e4&nbsp; &nbsp;\uc758\ubbf8\uac80\uc0ac : \uc704 \ubb38\ubc95\ub4e4\uc744 \uc81c\uc678\ud55c \uce7c\ub7fc\uba85, \ud14c\uc774\ube14\uba85 \ub4f1\uc758 \uc0ac\uc6a9\uc790\uc758 \ucffc\ub9ac\ub0b4\uc6a9\uc5d0 \ub530\ub77c \ub2ec\ub77c\uc9c0\ub294 \uac12\ub4e4\uc744 \uac80\uc0ac\ud569\ub2c8\ub2e4(ex:\uba85\uc2dc\ud55c \uce7c\ub7fc\uc774\ub098 \ud14c\uc774\ube14\uc774 \uc788\ub294\uc9c0 \uac80\uc0ac) &nbsp;\uad8c\ud55c\uac80\uc0ac : \uc704 2\uac00\uc9c0 \uacfc\uc815\uc744 \uac70\uce5c \ud6c4 \ud574\ub2f9 \ucffc\ub9ac\ub97c \uc9c4\ud589\ud560 \uc218 \uc788\ub294 [&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":[],"jetpack_featured_media_url":"","amp_enabled":true,"_links":{"self":[{"href":"http:\/\/haisins.synology.me\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/1163"}],"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=1163"}],"version-history":[{"count":0,"href":"http:\/\/haisins.synology.me\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/1163\/revisions"}],"wp:attachment":[{"href":"http:\/\/haisins.synology.me\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1163"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/haisins.synology.me\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1163"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/haisins.synology.me\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1163"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}