{"id":1182,"date":"2016-01-03T10:11:02","date_gmt":"2016-01-03T10:11:02","guid":{"rendered":"http:\/\/haisins.epac.to\/wordpress\/?p=1182"},"modified":"2016-01-03T10:11:02","modified_gmt":"2016-01-03T10:11:02","slug":"redo-log%ec%9d%98-%ec%83%9d%ec%84%b1%ec%9b%90%eb%a6%ac","status":"publish","type":"post","link":"http:\/\/haisins.synology.me\/wordpress\/?p=1182","title":{"rendered":"Redo Log\uc758 \uc0dd\uc131\uc6d0\ub9ac"},"content":{"rendered":"

 # Redo Log\uc758 \uc0dd\uc131\uc6d0\ub9ac<\/SPAN>
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*Write Log Ahead<\/SPAN><\/DIV>
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\uc2e4\uc81c \ub370\uc774\ud130\ub97c \ubcc0\uacbd\ud558\uae30 \uc804\uc5d0 Redo Log\uc5d0 \uba3c\uc800 \uae30\ub85d\uc744 \ud55c \ud6c4 \ub370\uc774\ud130\ub97c \ubcc0\uacbd\ud569\ub2c8\ub2e4.<\/SPAN><\/DIV>
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*Log force at Commit<\/SPAN><\/DIV>
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Commit \uc694\uccad\uc774 \ub4e4\uc5b4\uc624\uba74 Redo Log File\uc5d0 \uc800\uc7a5\ud55c \ud6c4 Commit\uc744 \uc644\ub8cc\ud569\ub2c8\ub2e4<\/SPAN><\/DIV>
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<\/P>
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 <\/P><\/SPAN><\/DIV>
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Redo Log\uac00 \uc0dd\uc131\ub418\uace0 \uae30\ub85d\ub418\ub294 \uc6d0\ub9ac\ub97c \uc0b4\ud3b4\ubcf4\uaca0\uc2b5\ub2c8\ub2e4<\/SPAN><\/DIV>
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Step 1. \uc0ac\uc6a9\uc790\uac00 \ud2b9\uc815 \ub370\uc774\ud130\uc758 \ubcc0\uacbd\uc744 \uc694\uccad\ud558\ub294 \ucffc\ub9ac\ub97c \uc218\ud589\ud558\uba74 \ud574\ub2f9 SQL\uc744 \ubc1b\uc740
\uc11c\ubc84 \ud504\ub85c\uc138\uc2a4\ub294 \uc6d0\ud558\ub294 Block\uc774 Database Buffer Cache\uc5d0 \uc788\ub294\uc9c0 \ud655\uc778\ud55c \ud6c4 \uc5c6\uc744 \uacbd\uc6b0 \ub370\uc774\ud130 \ud30c\uc77c\uc5d0\uc11c
\ucc3e\uc544 \ubcf5\uc0ac\ud55c \ud6c4 \uba54\ubaa8\ub9ac\ub85c \uac00\uc838\uc628\ub2e4. \uadf8 \ud6c4 \ud574\ub2f9 \ube14\ub85d\uc5d0 Lock\uc744 \uc124\uc815(page fix \ub77c\uace0 \ud568)\ud55c \ud6c4 PGA\uc5d0\uc11c redo change vector\ub97c \uc0dd\uc131\ud55c\ub2e4.
#Change Vector : \ubcc0\uacbd\ub41c \ub370\uc774\ud130\ub97c \ub098\uc911\uc5d0 \ubcf5\uad6c\ub97c \ud560 \ubaa9\uc801\uc73c\ub85c Redo Log\uc5d0 \uae30\ub85d\ud560 \ubcc0\uacbd\ub41c \ub370\uc774\ud130\uc5d0 \ub300\ud55c \ubaa8\ub4e0 \uc815\ubcf4\uc758 \uc138\ud2b8.(\ub0b4\uc6a9 : Undo\uad00\ub828 2\uac00\uc9c0 + Redo\uad00\ub828 2\uac00\uc9c0) <\/DIV>
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Step 2. \uc11c\ubc84 \ud504\ub85c\uc138\uc2a4\ub294 PGA\uc5d0\uc11c Change Vector\ub97c \uc0dd\uc131\ud55c \ud6c4 Redo Log Buffer \uc5d0\uc11c \ud544\uc694\ud55c \uc6a9\ub7c9\uc744 \uacc4\uc0b0. PGA\uc5d0\uc11c \uc0dd\uc131\ub41c Change Vector\ub97c Redo Log Buffer\uc5d0 \ubcf5\uc0ac\ud558\uae30 \uc704\ud574 Redo Copy Latch\ub97c \ud68d\ub4dd\ud574\uc57c \ud55c\ub2e4.
<\/DIV>
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Step 3. Redo Copy Latch\ub97c \ud655\ubcf4\ud55c \uc11c\ubc84 \ud504\ub85c\uc138\uc2a4\ub294 Redo Log Buffer\uc5d0 \ub0b4\uc6a9\uc744 \uae30\ub85d\ud558\uae30 \uc704\ud574 \ub2e4\uc74c \ub2e8\uacc4\uc778 Redo Allocation Latch\ub97c \ud655\ubcf4\ud574\uc57c \ud569\ub2c8\ub2e4.
8i \uc774\uc804\uc5d0\ub294 Redo Alloction Latch\uac00 \ud55c\uac1c \ubfd0\uc774\uc5b4\uc11c \uacbd\ud569\uc774 \ub9ce\uc774 \ubc1c\uc0dd\ud558\uc600\ub2e4. \uadf8\ub798\uc11c 9i \ub4e4\uc5b4\uc11c Shared Redo strand \uae30\ub2a5\uc774 \ub3c4\uc785\ub418\uace0 10g\uc774\ud6c4 \ubd80\ud130\ub294 Private Redo strand\uac00 \ub3c4\uc785\ub418\uc5c8\ub2e4.     
#Shared Redo Strand : \ud558\ub098\uc758 Redo Log Buffer\ub97c \ub9c8\uce58 \ub514\uc2a4\ud06c\uc758 \ud30c\ud2f0\uc158\uacfc \uac19\uc774 \uc5ec\ub7ec \uac1c\ub85c \ub098\ub214\uc73c\ub85c\uc368 \uc5ec\ub7ec \uc11c\ubc84 \ud504\ub85c\uc138\uc2a4\uac00 \ub3d9\uc2dc\uc5d0 \uc791\uc5c5\ud558\uac8c \ud558\uc5ec \uc131\ub2a5\uc744 \ub192\uc774\ub294 \uae30\ub2a5.
#Private Redo Strand : Change Vector\ub97c \uc0dd\uc131\ud55c \ud6c4 \ud544\uc694\ud55c \uacbd\uc6b0 LGWR\uc774 Redo Log File\uc5d0 \ubc14\ub85c \uae30\ub85d.(zero copy redo \ub77c\uace0\ub3c4 \ud568), shared pool\uc5d0 private stands \uc601\uc5ed\uc744 \ub46c \uadf8 \uacf3\uc5d0 \uccb4\uc778\uc9c0\ubca1\ud130\ub97c \uc0dd\uc131\ud6c4
\ud544\uc694\ud558\uba74 \ubc14\ub85c redo log buffer\uc5d0 \uae30\ub85d\ud55c\ub2e4(latch\ub97c \uc5bb\uae30\uc704\ud574 \uacbd\ud569\uc774 \ud544\uc694\uc5c6\uace0, pga\uc5d0\uc11c \ub9ac\ub450\ubc84\ud37c\ub85c \ubcf5\uc0ac\uac00 \ubd88\ud544\uc694\ud558\ub2e4)<\/DIV>
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Step 4. Redo Log Buffer\uc5d0 \uae30\ub85d\ub41c \ub0b4\uc6a9\ub4e4\uc740 \ud2b9\uc815\uc0c1\ud669\uc774 \ub418\uba74 LGWR\uac00 \uc77c\ubd80\ub97c Redo Log file\uc5d0 \uae30\ub85d\ud558\uace0 Redo Entry(Redo Buffer\uc5d0 \uae30\ub85d\ub41c Chagne Vector)\ub97c Redo Log Buffer\uc5d0\uc11c \uc0ad\uc81c(Flush)\ud569\ub2c8\ub2e4.
\uc774\ub54c\uc5d0 Redo Writing Latch\ub97c \ud655\ubcf4\ud55c \ud6c4\uc5d0 \uae30\ub85d\uc744 \ud558\ub77c\uace0 \uc694\uccad\ud569\ub2c8\ub2e4.
\ud2b9\uc815\uc0c1\ud669
1) 3\ucd08\ub9c8\ub2e4
2) Redo Log Buffer\uc758 \uc804\uccb4 \ud06c\uae30\uc758 1\/3\uc774 \ucc3c\uac70\ub098 1M\uac00 \ub118\uc744 \uacbd\uc6b0
3) \uc0ac\uc6a9\uc790\uac00 commit or rollback\uc744 \uc218\ud589\ud560 \ub54c
4) DBWR \uc774 LGWR\uc5d0\uac8c \uc4f0\uae30\ub97c \uc694\uccad\ud560 \ub54c<\/SPAN><\/DIV>
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<\/DIV><\/SPAN>
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 <\/P>
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 <\/P><\/p>\n","protected":false},"excerpt":{"rendered":"

 # Redo Log\uc758 \uc0dd\uc131\uc6d0\ub9ac *Write Log Ahead \uc2e4\uc81c \ub370\uc774\ud130\ub97c \ubcc0\uacbd\ud558\uae30 \uc804\uc5d0 Redo Log\uc5d0 \uba3c\uc800 \uae30\ub85d\uc744 \ud55c \ud6c4 \ub370\uc774\ud130\ub97c \ubcc0\uacbd\ud569\ub2c8\ub2e4. *Log force at Commit Commit \uc694\uccad\uc774 \ub4e4\uc5b4\uc624\uba74 Redo Log File\uc5d0 \uc800\uc7a5\ud55c \ud6c4 Commit\uc744 \uc644\ub8cc\ud569\ub2c8\ub2e4   Redo Log\uac00 \uc0dd\uc131\ub418\uace0 \uae30\ub85d\ub418\ub294 \uc6d0\ub9ac\ub97c \uc0b4\ud3b4\ubcf4\uaca0\uc2b5\ub2c8\ub2e4 Step 1. \uc0ac\uc6a9\uc790\uac00 \ud2b9\uc815 \ub370\uc774\ud130\uc758 \ubcc0\uacbd\uc744 \uc694\uccad\ud558\ub294 \ucffc\ub9ac\ub97c \uc218\ud589\ud558\uba74 \ud574\ub2f9 SQL\uc744 \ubc1b\uc740\uc11c\ubc84 \ud504\ub85c\uc138\uc2a4\ub294 \uc6d0\ud558\ub294 Block\uc774 […]<\/p>\n","protected":false},"author":1,"featured_media":1183,"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":"https:\/\/i0.wp.com\/haisins.synology.me\/wordpress\/wp-content\/uploads\/1\/cfile28.uf.211EB0455688F2B80228BB.png?fit=736%2C528","amp_enabled":true,"_links":{"self":[{"href":"http:\/\/haisins.synology.me\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/1182"}],"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=1182"}],"version-history":[{"count":0,"href":"http:\/\/haisins.synology.me\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/1182\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/haisins.synology.me\/wordpress\/index.php?rest_route=\/wp\/v2\/media\/1183"}],"wp:attachment":[{"href":"http:\/\/haisins.synology.me\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1182"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/haisins.synology.me\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1182"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/haisins.synology.me\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1182"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}