{"id":2671,"date":"2026-10-24T09:00:00","date_gmt":"2026-10-24T09:00:00","guid":{"rendered":"https:\/\/wayhope.kro.kr\/?p=2671"},"modified":"2026-10-24T09:21:27","modified_gmt":"2026-10-24T09:21:27","slug":"%ed%8a%b8%eb%9e%9c%ec%9e%ad%ec%85%98%ea%b3%bc-%eb%8f%99%ec%8b%9c%ec%84%b1-%ec%a0%9c%ec%96%b4-acid-%ea%b2%a9%eb%a6%ac-%ec%88%98%ec%a4%80-race-condition","status":"publish","type":"post","link":"https:\/\/wayhope.kro.kr\/?p=2671","title":{"rendered":"DB \ud2b8\ub79c\uc7ad\uc158\uacfc \ub3d9\uc2dc\uc131 \uc81c\uc5b4 #ACID, \uaca9\ub9ac \uc218\uc900, Race Condition"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">\ud2b8\ub79c\uc7ad\uc158(Transaction)\uc774\ub780?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\ud2b8\ub79c\uc7ad\uc158\uc740 \ub370\uc774\ud130\ubca0\uc774\uc2a4\uc5d0\uc11c \ud558\ub098\uc758 \ub17c\ub9ac\uc801\uc778 \uc791\uc5c5\uc744 \uc218\ud589\ud558\uae30 \uc704\ud55c SQL \uc5f0\uc0b0\uc758 \uc9d1\ud569\uc774\ub2e4. \uc5ec\ub7ec \uac1c\uc758 \uc791\uc5c5\uc744 \ud558\ub098\uc758 \ub2e8\uc704\ub85c \ubb36\uc5b4, \ubaa8\ub4e0 \uc791\uc5c5\uc774 \uc815\uc0c1\uc801\uc73c\ub85c \uc644\ub8cc\ub418\uac70\ub098 \uc804\uccb4 \uc791\uc5c5\uc774 \ucde8\uc18c\ub418\ub3c4\ub85d \ubcf4\uc7a5\ud55c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc608\ub97c \ub4e4\uc5b4 \uac8c\uc784 \uc11c\ubc84\uc5d0\uc11c \ud50c\ub808\uc774\uc5b4 A\uac00 \ud50c\ub808\uc774\uc5b4 B\uc5d0\uac8c 100\uace8\ub4dc\ub97c \uc804\uc1a1\ud55c\ub2e4\uace0 \uac00\uc815\ud558\uc790.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc774 \uc791\uc5c5\uc740 \ub2e4\uc74c\uacfc \uac19\uc740 \ub450 \uac00\uc9c0 \ubcc0\uacbd\uc73c\ub85c \uad6c\uc131\ub41c\ub2e4.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\ud50c\ub808\uc774\uc5b4 A\uc758 \uace8\ub4dc 100 \uac10\uc18c<\/li>\n\n\n\n<li>\ud50c\ub808\uc774\uc5b4 B\uc758 \uace8\ub4dc 100 \uc99d\uac00<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\ub9cc\uc57d A\uc758 \uace8\ub4dc\ub9cc \uac10\uc18c\ud55c \uc0c1\ud0dc\uc5d0\uc11c \uc11c\ubc84 \uc624\ub958\uac00 \ubc1c\uc0dd\ud55c\ub2e4\uba74 \uc5b4\ub5bb\uac8c \ub420\uae4c?<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A\uc758 \uace8\ub4dc\ub294 \uc0ac\ub77c\uc84c\uc9c0\ub9cc B\ub294 \uace8\ub4dc\ub97c \ubc1b\uc9c0 \ubabb\ud55c\ub2e4. \uc774\ub294 \ub370\uc774\ud130 \uc815\ud569\uc131\uc774 \uae68\uc9c4 \uc0c1\ud0dc\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ud2b8\ub79c\uc7ad\uc158\uc744 \uc0ac\uc6a9\ud558\uba74 \ub450 \uc791\uc5c5\uc744 \ud558\ub098\uc758 \ub2e8\uc704\ub85c \ucc98\ub9ac\ud560 \uc218 \uc788\ub2e4. \ubaa8\ub4e0 \uc791\uc5c5\uc774 \uc131\uacf5\ud558\uba74 <code>COMMIT<\/code>\uc73c\ub85c \ud655\uc815\ud558\uace0, \uc911\uac04\uc5d0 \uc624\ub958\uac00 \ubc1c\uc0dd\ud558\uba74 <code>ROLLBACK<\/code>\uc73c\ub85c \ubcc0\uacbd \uc0ac\ud56d\uc744 \ucde8\uc18c\ud55c\ub2e4.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>START TRANSACTION;\n\nUPDATE players\nSET gold = gold - 100\nWHERE player_id = 1;\n\nUPDATE players\nSET gold = gold + 100\nWHERE player_id = 2;\n\nCOMMIT;<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\uc2e4\uc81c \uc11c\ube44\uc2a4\uc5d0\uc11c\ub294 \uc1a1\uae08 \uae08\uc561\uc774 \uc591\uc218\uc778\uc9c0, A\uc5d0\uac8c \ucda9\ubd84\ud55c \uace8\ub4dc\uac00 \uc788\ub294\uc9c0, \ub450 \ud50c\ub808\uc774\uc5b4\uac00 \uc815\uc0c1\uc801\uc73c\ub85c \uc874\uc7ac\ud558\ub294\uc9c0 \ub4f1\uc758 \uac80\uc99d\ub3c4 \ud544\uc694\ud558\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc624\ub958 \ubc1c\uc0dd \uc2dc\uc5d0\ub294 \ub2e4\uc74c\uacfc \uac19\uc774 \ucc98\ub9ac\ud55c\ub2e4.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>START TRANSACTION;\n\nUPDATE players\nSET gold = gold - 100\nWHERE player_id = 1;\n\n-- \uc774\ud6c4 \uc791\uc5c5\uc5d0\uc11c \uc624\ub958\uac00 \ubc1c\uc0dd\ud588\ub2e4\uace0 \uac00\uc815\nROLLBACK;<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\ub2e8, \ud2b8\ub79c\uc7ad\uc158\uc744 \uc0ac\uc6a9\ud588\ub2e4\uace0 \ud574\uc11c \ubaa8\ub4e0 \ub3d9\uc2dc\uc131 \ubb38\uc81c\uac00 \uc790\ub3d9\uc73c\ub85c \ud574\uacb0\ub418\ub294 \uac83\uc740 \uc544\ub2c8\ub2e4. \uc5b4\ub5a4 \uaca9\ub9ac \uc218\uc900\uc744 \uc0ac\uc6a9\ud558\ub294\uc9c0, \ub370\uc774\ud130\ub97c \uc5b4\ub5bb\uac8c \uc77d\uace0 \uc218\uc815\ud558\ub294\uc9c0\uc5d0 \ub530\ub77c \ucd94\uac00\uc801\uc778 \ub3d9\uc2dc\uc131 \uc81c\uc5b4\uac00 \ud544\uc694\ud558\ub2e4.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">ACID\ub780?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">ACID\ub294 \ub370\uc774\ud130\ubca0\uc774\uc2a4 \ud2b8\ub79c\uc7ad\uc158\uc774 \uc2e0\ub8b0\uc131 \uc788\uac8c \ub3d9\uc791\ud558\uae30 \uc704\ud574 \uc694\uad6c\ub418\ub294 \ub124 \uac00\uc9c0 \uc18d\uc131\uc774\ub2e4.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Atomicity \u2014 \uc6d0\uc790\uc131<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\uc6d0\uc790\uc131\uc740 \ud2b8\ub79c\uc7ad\uc158\uc5d0 \ud3ec\ud568\ub41c \uc791\uc5c5\uc774 \uc804\ubd80 \uc131\uacf5\ud558\uac70\ub098 \uc804\ubd80 \ucde8\uc18c\ub418\uc5b4\uc57c \ud55c\ub2e4\ub294 \uc131\uc9c8\uc774\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uac8c\uc784 \uc7ac\ud654 \uac70\ub798\uc5d0\uc11c \uc1a1\uc2e0\uc790\uc758 \uc7ac\ud654 \ucc28\uac10\ub9cc \uc131\uacf5\ud558\uace0 \uc218\uc2e0\uc790\uc758 \uc7ac\ud654 \uc9c0\uae09\uc774 \uc2e4\ud328\ud55c\ub2e4\uba74 \uc548 \ub41c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ud2b8\ub79c\uc7ad\uc158\uc740 \uc774\ub7ec\ud55c \ubd80\ubd84\uc801\uc778 \ubcc0\uacbd\uc744 \ubc29\uc9c0\ud55c\ub2e4.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Consistency \u2014 \uc77c\uad00\uc131<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\uc77c\uad00\uc131\uc740 \ud2b8\ub79c\uc7ad\uc158\uc774 \uc644\ub8cc\ub41c \ud6c4\uc5d0\ub3c4 \ub370\uc774\ud130\ubca0\uc774\uc2a4\uac00 \uc815\uc758\ub41c \uc81c\uc57d \uc870\uac74\uacfc \ube44\uc988\ub2c8\uc2a4 \uaddc\uce59\uc744 \ub9cc\uc871\ud574\uc57c \ud55c\ub2e4\ub294 \uc131\uc9c8\uc774\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc608\ub97c \ub4e4\uc5b4 \ub2e4\uc74c\uacfc \uac19\uc740 \uaddc\uce59\uc774 \uc788\ub2e4\uace0 \uac00\uc815\ud558\uc790.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\uace8\ub4dc\ub294 0\ubcf4\ub2e4 \uc791\uc744 \uc218 \uc5c6\ub2e4.<\/li>\n\n\n\n<li>\uacc4\uc815 \uc774\uba54\uc77c\uc740 \uc911\ubcf5\ub420 \uc218 \uc5c6\ub2e4.<\/li>\n\n\n\n<li>\uc8fc\ubb38\uc5d0 \uc5f0\uacb0\ub41c \uc0ac\uc6a9\uc790\ub294 \uc2e4\uc81c\ub85c \uc874\uc7ac\ud574\uc57c \ud55c\ub2e4.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\uc774\ub7ec\ud55c \uaddc\uce59\uc740 \uc801\uc808\ud55c \ub370\uc774\ud130\ubca0\uc774\uc2a4 \uc81c\uc57d \uc870\uac74\uacfc \uc560\ud50c\ub9ac\ucf00\uc774\uc158 \uac80\uc99d\uc744 \ud1b5\ud574 \ubcf4\uc7a5\ud574\uc57c \ud55c\ub2e4.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>CREATE TABLE players (\n    player_id BIGINT PRIMARY KEY,\n    gold BIGINT NOT NULL CHECK (gold &gt;= 0)\n);<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\"><code>CHECK<\/code> \uc81c\uc57d \uc870\uac74\uc758 \uc2e4\uc81c \uc9c0\uc6d0 \ubc0f \ub3d9\uc791\uc740 DBMS\uc640 \ubc84\uc804\uc5d0 \ub530\ub77c \ud655\uc778\ud574\uc57c \ud55c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ud2b8\ub79c\uc7ad\uc158 \uc790\uccb4\uac00 \ubaa8\ub4e0 \ube44\uc988\ub2c8\uc2a4 \uaddc\uce59\uc744 \uc790\ub3d9\uc73c\ub85c \uac80\uc99d\ud558\ub294 \uac83\uc740 \uc544\ub2c8\ub2e4. \uc798\ubabb\ub41c \ub85c\uc9c1\uc73c\ub85c \uc2e4\ud589\ub41c \ud2b8\ub79c\uc7ad\uc158\ub3c4 \ub370\uc774\ud130\ubca0\uc774\uc2a4 \uc81c\uc57d \uc870\uac74\uc744 \uc704\ubc18\ud558\uc9c0 \uc54a\ub294\ub2e4\uba74 \ucee4\ubc0b\ub420 \uc218 \uc788\ub2e4.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Isolation \u2014 \uaca9\ub9ac\uc131<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\uaca9\ub9ac\uc131\uc740 \uc5ec\ub7ec \ud2b8\ub79c\uc7ad\uc158\uc774 \ub3d9\uc2dc\uc5d0 \uc2e4\ud589\ub420 \ub54c \uc11c\ub85c\uc758 \uc911\uac04 \uc791\uc5c5\uc5d0 \uc758\ud574 \uc798\ubabb\ub41c \uacb0\uacfc\uac00 \ubc1c\uc0dd\ud558\uc9c0 \uc54a\ub3c4\ub85d \uc2e4\ud589 \uac04\uc12d\uc744 \uc81c\uc5b4\ud558\ub294 \uc131\uc9c8\uc774\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc608\ub97c \ub4e4\uc5b4 \ub450 \uc694\uccad\uc774 \ub3d9\uc2dc\uc5d0 \ub3d9\uc77c\ud55c \uacc4\uc815\uc758 \uace8\ub4dc\ub97c \uc77d\uace0 \uc218\uc815\ud55c\ub2e4\uba74, \ud55c \uc694\uccad\uc758 \ubcc0\uacbd \uc0ac\ud56d\uc774 \ub2e4\ub978 \uc694\uccad\uc5d0 \uc758\ud574 \ub36e\uc5b4\uc368\uc9c8 \uc218 \uc788\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uaca9\ub9ac \uc218\uc900\uc740 \uc774\ub7ec\ud55c \ub3d9\uc2dc \uc2e4\ud589\uc758 \uac04\uc12d\uc744 \uc5b4\ub290 \uc815\ub3c4 \ud5c8\uc6a9\ud560 \uac83\uc778\uc9c0 \uacb0\uc815\ud55c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc644\uc804\ud55c \uc9c1\ub82c \uc2e4\ud589\uc5d0 \uac00\uae4c\uc6b8\uc218\ub85d \ub370\uc774\ud130 \uc815\ud569\uc131\uc744 \ud655\ubcf4\ud558\uae30 \uc27d\uc9c0\ub9cc, \uc7a0\uae08\uacfc \uc7ac\uc2dc\ub3c4\uc5d0 \ub530\ub978 \ube44\uc6a9\uc774 \uc99d\uac00\ud560 \uc218 \uc788\ub2e4.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Durability \u2014 \uc9c0\uc18d\uc131<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\uc9c0\uc18d\uc131\uc740 \ud2b8\ub79c\uc7ad\uc158\uc774 \uc131\uacf5\uc801\uc73c\ub85c \ucee4\ubc0b\ub41c \uc774\ud6c4 \uc7a5\uc560\uac00 \ubc1c\uc0dd\ud558\ub354\ub77c\ub3c4 \ud655\uc815\ub41c \ub370\uc774\ud130\uac00 \uc720\uc9c0\ub418\uc5b4\uc57c \ud55c\ub2e4\ub294 \uc131\uc9c8\uc774\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ub370\uc774\ud130\ubca0\uc774\uc2a4\ub294 \uc77c\ubc18\uc801\uc73c\ub85c \ud2b8\ub79c\uc7ad\uc158 \ub85c\uadf8\uc640 \ubcf5\uad6c \uba54\ucee4\ub2c8\uc998\uc744 \ud65c\uc6a9\ud574 \uc774\ub97c \ubcf4\uc7a5\ud55c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ub2e4\ub9cc \uc2e4\uc81c \uc7a5\uc560 \uc0c1\ud669\uc5d0\uc11c\uc758 \ubcf4\uc7a5 \ubc94\uc704\ub294 DBMS \uc124\uc815, \uc2a4\ud1a0\ub9ac\uc9c0, \ubcf5\uc81c \ubc29\uc2dd, \ub3d9\uae30\ud654 \uc815\ucc45\uc5d0 \ub530\ub77c \ub2ec\ub77c\uc9c8 \uc218 \uc788\ub2e4.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\ud2b8\ub79c\uc7ad\uc158\uc758 \uc8fc\uc694 \uba85\ub839\uc5b4<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\ud2b8\ub79c\uc7ad\uc158\uc744 \ub2e4\ub8f0 \ub54c \uc8fc\ub85c \uc0ac\uc6a9\ud558\ub294 \uba85\ub839\uc5b4\ub294 \ub2e4\uc74c\uacfc \uac19\ub2e4.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><th>\uba85\ub839\uc5b4<\/th><th>\uc124\uba85<\/th><\/tr><tr><td><code>START TRANSACTION<\/code><\/td><td>\ud2b8\ub79c\uc7ad\uc158 \uc2dc\uc791<\/td><\/tr><tr><td><code>COMMIT<\/code><\/td><td>\ubcc0\uacbd \uc0ac\ud56d \ud655\uc815<\/td><\/tr><tr><td><code>ROLLBACK<\/code><\/td><td>\ubcc0\uacbd \uc0ac\ud56d \ucde8\uc18c<\/td><\/tr><tr><td><code>SAVEPOINT<\/code><\/td><td>\ud2b8\ub79c\uc7ad\uc158 \ub0b4\ubd80\uc758 \ubcf5\uad6c \uc9c0\uc810 \uc124\uc815<\/td><\/tr><tr><td><code>ROLLBACK TO SAVEPOINT<\/code><\/td><td>\uc9c0\uc815\ud55c \ubcf5\uad6c \uc9c0\uc810\uae4c\uc9c0 \ub418\ub3cc\ub9ac\uae30<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">\uc608\ub97c \ub4e4\uc5b4 \uc5ec\ub7ec \uc791\uc5c5 \uc911 \uc77c\ubd80\ub9cc \ucde8\uc18c\ud574\uc57c \ud55c\ub2e4\uba74 <code>SAVEPOINT<\/code>\ub97c \uc0ac\uc6a9\ud560 \uc218 \uc788\ub2e4.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>START TRANSACTION;\n\nUPDATE players\nSET gold = gold - 100\nWHERE player_id = 1;\n\nSAVEPOINT after_deduction;\n\nUPDATE players\nSET gold = gold + 100\nWHERE player_id = 2;\n\n-- \ub450 \ubc88\uc9f8 \uc791\uc5c5\ub9cc \ucde8\uc18c\nROLLBACK TO SAVEPOINT after_deduction;\n\n-- \uccab \ubc88\uc9f8 \uc791\uc5c5\uae4c\uc9c0 \ud3ec\ud568\ud574 \uc804\uccb4 \ucde8\uc18c\nROLLBACK;<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\ud2b8\ub79c\uc7ad\uc158\uc740 \uac00\ub2a5\ud55c \ud55c \uc9e7\uac8c \uc720\uc9c0\ud558\ub294 \uac83\uc774 \uc88b\ub2e4. \ud2b8\ub79c\uc7ad\uc158\uc774 \uc624\ub798 \uc9c0\uc18d\ub418\uba74 \uc7a0\uae08 \uc720\uc9c0 \uc2dc\uac04\uc774 \uae38\uc5b4\uc9c0\uace0, \ub2e4\ub978 \uc694\uccad\uc758 \ub300\uae30 \uc2dc\uac04\uc774 \uc99d\uac00\ud558\uba70, \uad50\ucc29 \uc0c1\ud0dc\uac00 \ubc1c\uc0dd\ud560 \uac00\ub2a5\uc131\ub3c4 \ub192\uc544\uc9c4\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc678\ubd80 API \ud638\ucd9c\uc774\ub098 \uc0ac\uc6a9\uc790 \uc785\ub825 \ub300\uae30\ucc98\ub7fc \uc2dc\uac04\uc774 \uc624\ub798 \uac78\ub9ac\ub294 \uc791\uc5c5\uc744 \ub370\uc774\ud130\ubca0\uc774\uc2a4 \ud2b8\ub79c\uc7ad\uc158 \ub0b4\ubd80\uc5d0 \ub123\ub294 \uac83\ub3c4 \ud53c\ud574\uc57c \ud55c\ub2e4.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\uaca9\ub9ac \uc218\uc900(Isolation Level)<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\uaca9\ub9ac \uc218\uc900\uc740 \ub3d9\uc2dc\uc5d0 \uc2e4\ud589\ub418\ub294 \ud2b8\ub79c\uc7ad\uc158\uc774 \uc11c\ub85c\uc758 \ub370\uc774\ud130\ub97c \uc5bc\ub9c8\ub098 \ubcfc \uc218 \uc788\ub294\uc9c0 \uacb0\uc815\ud558\ub294 \uc124\uc815\uc774\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ub300\ud45c\uc801\uc778 \uaca9\ub9ac \uc218\uc900\uc740 \ub2e4\uc74c\uacfc \uac19\ub2e4.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Read Uncommitted<\/li>\n\n\n\n<li>Read Committed<\/li>\n\n\n\n<li>Repeatable Read<\/li>\n\n\n\n<li>Serializable<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\uaca9\ub9ac \uc218\uc900\uc744 \uc774\ud574\ud558\ub824\uba74 \uc138 \uac00\uc9c0 \ud604\uc0c1\uc744 \uba3c\uc800 \uc54c\uc544\uc57c \ud55c\ub2e4.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Dirty Read \u2014 \ub354\ud2f0 \ub9ac\ub4dc<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\ub2e4\ub978 \ud2b8\ub79c\uc7ad\uc158\uc774 \uc544\uc9c1 \ucee4\ubc0b\ud558\uc9c0 \uc54a\uc740 \ub370\uc774\ud130\ub97c \uc77d\ub294 \ud604\uc0c1\uc774\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ud2b8\ub79c\uc7ad\uc158 A\uac00 \uace8\ub4dc\ub97c 1,000\uc5d0\uc11c 500\uc73c\ub85c \ubcc0\uacbd\ud588\uc9c0\ub9cc \uc544\uc9c1 \ucee4\ubc0b\ud558\uc9c0 \uc54a\uc558\ub2e4\uace0 \uac00\uc815\ud558\uc790. \uc774\ub54c \ud2b8\ub79c\uc7ad\uc158 B\uac00 500\uc774\ub77c\ub294 \uac12\uc744 \uc77d\ub294\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc774\ud6c4 A\uac00 \ub864\ubc31\ud558\uba74 \uc2e4\uc81c \uace8\ub4dc\ub294 \ub2e4\uc2dc 1,000\uc774 \ub41c\ub2e4. B\ub294 \ucd5c\uc885\uc801\uc73c\ub85c \ud655\uc815\ub418\uc9c0 \uc54a\uc740 \ub370\uc774\ud130\ub97c \uc77d\uc740 \uc148\uc774\ub2e4.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Non-repeatable Read \u2014 \ubc18\ubcf5 \ubd88\uac00\ub2a5 \uc77d\uae30<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\ud558\ub098\uc758 \ud2b8\ub79c\uc7ad\uc158\uc5d0\uc11c \ub3d9\uc77c\ud55c \uc870\uac74\uc73c\ub85c \uac19\uc740 \ud589\uc744 \ub450 \ubc88 \uc77d\uc5c8\ub294\ub370 \uacb0\uacfc\uac00 \ub2ec\ub77c\uc9c0\ub294 \ud604\uc0c1\uc774\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ud2b8\ub79c\uc7ad\uc158 A\uac00 \ud50c\ub808\uc774\uc5b4\uc758 \uace8\ub4dc\ub97c \uc77d\uace0, \uadf8\uc0ac\uc774\uc5d0 \ud2b8\ub79c\uc7ad\uc158 B\uac00 \uace8\ub4dc\ub97c \ubcc0\uacbd\ud55c \ub4a4 \ucee4\ubc0b\ud55c\ub2e4. \uc774\ud6c4 A\uac00 \uac19\uc740 \ud589\uc744 \ub2e4\uc2dc \uc77d\uc73c\uba74 \ub2e4\ub978 \uac12\uc774 \ubc18\ud658\ub420 \uc218 \uc788\ub2e4.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Phantom Read \u2014 \ud32c\ud140 \ub9ac\ub4dc<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\ud558\ub098\uc758 \ud2b8\ub79c\uc7ad\uc158\uc5d0\uc11c \ub3d9\uc77c\ud55c \uc870\uac74\uc758 \uc870\ud68c\ub97c \ubc18\ubcf5\ud588\ub294\ub370, \ub2e4\ub978 \ud2b8\ub79c\uc7ad\uc158\uc758 \ubcc0\uacbd\uc73c\ub85c \uc870\ud68c \ub300\uc0c1 \ud589\uc758 \uc9d1\ud569\uc774 \ub2ec\ub77c\uc9c0\ub294 \ud604\uc0c1\uc774\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc608\ub97c \ub4e4\uc5b4 A\uac00 \uace8\ub4dc\uac00 1,000 \uc774\uc0c1\uc778 \ud50c\ub808\uc774\uc5b4\ub97c \uc870\ud68c\ud55c\ub2e4.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>SELECT *\nFROM players\nWHERE gold &gt;= 1000;<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\uc774\ud6c4 B\uac00 \uc870\uac74\uc5d0 \ud574\ub2f9\ud558\ub294 \ud50c\ub808\uc774\uc5b4\ub97c \ucd94\uac00\ud558\uac70\ub098 \uae30\uc874 \ud50c\ub808\uc774\uc5b4\uc758 \uace8\ub4dc\ub97c \ubcc0\uacbd\ud574 \ucee4\ubc0b\ud558\uba74, A\uac00 \uac19\uc740 \ucffc\ub9ac\ub97c \ub2e4\uc2dc \uc2e4\ud589\ud588\uc744 \ub54c \uc0c8\ub85c\uc6b4 \ud589\uc774 \ub098\ud0c0\ub0a0 \uc218 \uc788\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ud32c\ud140 \ub9ac\ub4dc\ub294 \ub2e8\uc21c\ud788 \uae30\uc874 \ud589\uc758 \uac12\uc774 \ubc14\ub00c\ub294 \ubb38\uc81c\uc640 \ub2ec\ub9ac, \uc870\uac74\uc5d0 \uc77c\uce58\ud558\ub294 \ud589\uc758 \uc9d1\ud569\uc774 \ub2ec\ub77c\uc9c0\ub294 \ubb38\uc81c\ub2e4.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Read Committed<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Read Committed\ub294 \ucee4\ubc0b\ub41c \ub370\uc774\ud130\ub9cc \uc77d\uc744 \uc218 \uc788\ub3c4\ub85d \ud558\ub294 \uaca9\ub9ac \uc218\uc900\uc774\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ub2e4\ub978 \ud2b8\ub79c\uc7ad\uc158\uc774 \ubcc0\uacbd\ud55c \ub370\uc774\ud130\uac00 \ucee4\ubc0b\ub418\uae30 \uc804\uc5d0\ub294 \uadf8 \ubcc0\uacbd \uc0ac\ud56d\uc744 \uc77d\uc744 \uc218 \uc5c6\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc77c\ubc18\uc801\uc73c\ub85c Dirty Read\ub97c \ubc29\uc9c0\ud558\uc9c0\ub9cc, \uac19\uc740 \ud2b8\ub79c\uc7ad\uc158 \uc548\uc5d0\uc11c\ub3c4 \ub3d9\uc77c\ud55c \ud589\uc744 \ub2e4\uc2dc \uc77d\uc5c8\uc744 \ub54c \uac12\uc774 \ub2ec\ub77c\uc9c8 \uc218 \uc788\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc608\ub97c \ub4e4\uc5b4 \ub2e4\uc74c\uacfc \uac19\uc740 \uc0c1\ud669\uc774\ub2e4.<\/p>\n\n\n\n<ol start=\"1\" class=\"wp-block-list\">\n<li>\ud2b8\ub79c\uc7ad\uc158 A\uac00 \ud50c\ub808\uc774\uc5b4\uc758 \uace8\ub4dc\ub97c \uc870\ud68c\ud55c\ub2e4. \uacb0\uacfc\ub294 1,000\uc774\ub2e4.<\/li>\n\n\n\n<li>\ud2b8\ub79c\uc7ad\uc158 B\uac00 \uace8\ub4dc\ub97c 500\uc73c\ub85c \ubcc0\uacbd\ud558\uace0 \ucee4\ubc0b\ud55c\ub2e4.<\/li>\n\n\n\n<li>\ud2b8\ub79c\uc7ad\uc158 A\uac00 \uac19\uc740 \uace8\ub4dc\ub97c \ub2e4\uc2dc \uc870\ud68c\ud55c\ub2e4. \uacb0\uacfc\ub294 500\uc774\ub2e4.<\/li>\n<\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">\ud2b8\ub79c\uc7ad\uc158 A\ub294 \ucee4\ubc0b\ub41c \ub370\uc774\ud130\ub9cc \uc77d\uc5c8\uc9c0\ub9cc, \uc870\ud68c \uc2dc\uc810\ub9c8\ub2e4 \uc11c\ub85c \ub2e4\ub978 \uac12\uc744 \uad00\ucc30\ud588\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\uc7a5\uc810<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\ucee4\ubc0b\ub418\uc9c0 \uc54a\uc740 \ub370\uc774\ud130\uc5d0 \ub300\ud55c \uc77d\uae30\ub97c \ubc29\uc9c0\ud55c\ub2e4.<\/li>\n\n\n\n<li>\ube44\uad50\uc801 \ub0ae\uc740 \uaca9\ub9ac \ube44\uc6a9\uc73c\ub85c \ub3d9\uc2dc\uc131\uc744 \ud655\ubcf4\ud560 \uc218 \uc788\ub2e4.<\/li>\n\n\n\n<li>\uc870\ud68c \uacb0\uacfc\uac00 \ub9e4\ubc88 \ub2ec\ub77c\uc9c8 \uc218 \uc788\ub2e4\ub294 \uc810\uc744 \uac10\uc548\ud558\uba74 \ub2e4\uc591\ud55c \uc77c\ubc18 \uc5c5\ubb34 \ucc98\ub9ac\uc5d0 \uc801\ud569\ud558\ub2e4.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\uc8fc\uc758\uc810<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Read Committed\ub9cc\uc73c\ub85c\ub294 \uc77d\uc740 \uac12\uc744 \uae30\uc900\uc73c\ub85c \uc218\ud589\ud558\ub294 \ud6c4\uc18d \uacc4\uc0b0\uc774 \uc548\uc804\ud558\ub2e4\uace0 \ubcf4\uc7a5\ud560 \uc218 \uc5c6\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc608\ub97c \ub4e4\uc5b4 \ud604\uc7ac \uace8\ub4dc\uac00 1,000\uc774\ub77c\ub294 \uc0ac\uc2e4\uc744 \uc77d\uc740 \ub4a4 900\uc744 \ucc28\uac10\ud558\ub294 \ub85c\uc9c1\uc774 \uc788\ub2e4\uace0 \uac00\uc815\ud558\uc790. \uc5ec\ub7ec \uc694\uccad\uc774 \ub3d9\uc2dc\uc5d0 \uc2e4\ud589\ub418\uba74 \uac01 \uc694\uccad\uc774 \ub3d9\uc77c\ud55c \ucd08\uae30\uac12\uc744 \uc77d\uc744 \uc218 \uc788\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ub530\ub77c\uc11c \uc7ac\ud654 \ucc28\uac10\ucc98\ub7fc \uc815\ud569\uc131\uc774 \uc911\uc694\ud55c \uc791\uc5c5\uc5d0\ub294 \uc870\uac74\ubd80 UPDATE, \ud589 \uc7a0\uae08 \ub610\ub294 \ubc84\uc804 \uae30\ubc18 \ub3d9\uc2dc\uc131 \uc81c\uc5b4\ub97c \ud568\uaed8 \uace0\ub824\ud574\uc57c \ud55c\ub2e4.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Repeatable Read<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Repeatable Read\ub294 \ud558\ub098\uc758 \ud2b8\ub79c\uc7ad\uc158\uc5d0\uc11c \ub3d9\uc77c\ud55c \ud589\uc744 \ubc18\ubcf5\ud574\uc11c \uc77d\uc744 \ub54c \uc77c\uad00\ub41c \uac12\uc744 \uad00\ucc30\ud558\ub3c4\ub85d \ud558\ub294 \uaca9\ub9ac \uc218\uc900\uc774\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc77c\ubc18\uc801\uc73c\ub85c Dirty Read\uc640 Non-repeatable Read\ub97c \ubc29\uc9c0\ud55c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc608\ub97c \ub4e4\uc5b4 \ub2e4\uc74c\uacfc \uac19\ub2e4.<\/p>\n\n\n\n<ol start=\"1\" class=\"wp-block-list\">\n<li>\ud2b8\ub79c\uc7ad\uc158 A\uac00 \uace8\ub4dc\ub97c \uc870\ud68c\ud55c\ub2e4. \uacb0\uacfc\ub294 1,000\uc774\ub2e4.<\/li>\n\n\n\n<li>\ud2b8\ub79c\uc7ad\uc158 B\uac00 \uace8\ub4dc\ub97c 500\uc73c\ub85c \ubcc0\uacbd\ud558\uace0 \ucee4\ubc0b\ud55c\ub2e4.<\/li>\n\n\n\n<li>\ud2b8\ub79c\uc7ad\uc158 A\uac00 \uac19\uc740 \ud589\uc744 \ub2e4\uc2dc \uc870\ud68c\ud55c\ub2e4. \uc5ec\uc804\ud788 1,000\uc744 \uad00\ucc30\ud560 \uc218 \uc788\ub2e4.<\/li>\n\n\n\n<li>\ud2b8\ub79c\uc7ad\uc158 A\uac00 \uc885\ub8cc\ub41c\ub2e4.<\/li>\n<\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">\uc774\ub7ec\ud55c \ub3d9\uc791\uc740 MVCC(Multi-Version Concurrency Control)\uc640 \uac19\uc740 \uba54\ucee4\ub2c8\uc998\uc744 \ud1b5\ud574 \uad6c\ud604\ub420 \uc218 \uc788\ub2e4. MVCC\ub294 \ub370\uc774\ud130\uc758 \uc5ec\ub7ec \ubc84\uc804\uc744 \ud65c\uc6a9\ud574 \uc77d\uae30 \uc791\uc5c5\uc774 \ud2b9\uc815 \uc2dc\uc810\uc758 \ub370\uc774\ud130\ub97c \uad00\ucc30\ud560 \uc218 \uc788\ub3c4\ub85d \ud55c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ub2e4\ub9cc Repeatable Read\uc758 \uc815\ud655\ud55c \ub3d9\uc791\uc740 DBMS\uc5d0 \ub530\ub77c \ub2e4\ub974\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc608\ub97c \ub4e4\uc5b4 MySQL InnoDB\ub294 \uc77c\ubc18\uc801\uc778 \uc77c\uad00 \uc77d\uae30\uc5d0\uc11c \ud2b8\ub79c\uc7ad\uc158 \uc2a4\ub0c5\uc0f7\uc744 \ud65c\uc6a9\ud55c\ub2e4. \ubc18\uba74 \uc7a0\uae08 \uc77d\uae30\uc778 <code>SELECT ... FOR UPDATE<\/code>\ub294 \uc77c\ubc18\uc801\uc778 \uc77c\uad00 \uc77d\uae30\uc640 \ub2e4\ub978 \ub3d9\uc791\uc744 \ubcf4\uc77c \uc218 \uc788\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ub610\ud55c Repeatable Read\uac00 \ubaa8\ub4e0 \ub3d9\uc2dc\uc131 \ubb38\uc81c\ub97c \ud574\uacb0\ud558\ub294 \uac83\uc740 \uc544\ub2c8\ub2e4. \ud2b9\ud788 \uc5ec\ub7ec \ud589\uc5d0 \uac78\uce5c \ube44\uc988\ub2c8\uc2a4 \uaddc\uce59\uc774\ub098 \uc870\uac74\uc744 \uac80\uc0ac\ud55c \ub4a4 \ub370\uc774\ud130\ub97c \ubcc0\uacbd\ud558\ub294 \uacbd\uc6b0\uc5d0\ub294 \ubcc4\ub3c4\uc758 \uc7a0\uae08 \ub610\ub294 \uc81c\uc57d \uc870\uac74\uc774 \ud544\uc694\ud560 \uc218 \uc788\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\uc7a5\uc810<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\ud2b8\ub79c\uc7ad\uc158 \ub0b4\ubd80\uc5d0\uc11c \ubc18\ubcf5 \uc870\ud68c\uc758 \uc77c\uad00\uc131\uc744 \ud655\ubcf4\ud558\uae30 \uc27d\ub2e4.<\/li>\n\n\n\n<li>\uc870\ud68c\uc640 \uacc4\uc0b0\uc774 \uc5ec\ub7ec \ub2e8\uacc4\ub85c \uc774\ub8e8\uc5b4\uc9c0\ub294 \uc791\uc5c5\uc5d0 \uc720\uc6a9\ud558\ub2e4.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\uc8fc\uc758\uc810<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\uc624\ub798 \uc9c0\uc18d\ub418\ub294 \ud2b8\ub79c\uc7ad\uc158\uc740 \uc624\ub798\ub41c \uc2a4\ub0c5\uc0f7\uc744 \uc720\uc9c0\ud560 \uc218 \uc788\ub2e4.<\/li>\n\n\n\n<li>DBMS\ubcc4\ub85c \ud32c\ud140 \ub9ac\ub4dc\uc640 \uc7a0\uae08 \ub3d9\uc791\uc774 \ub2e4\ub974\ub2e4.<\/li>\n\n\n\n<li>\ubc18\ubcf5 \uc870\ud68c\uc758 \uc77c\uad00\uc131\uc774 \ubcf4\uc7a5\ub41c\ub2e4\uace0 \ud574\uc11c \ubaa8\ub4e0 \uc4f0\uae30 \ucda9\ub3cc\uc774 \uc790\ub3d9\uc73c\ub85c \ud574\uacb0\ub418\ub294 \uac83\uc740 \uc544\ub2c8\ub2e4.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Serializable<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Serializable\uc740 \uc5ec\ub7ec \ud2b8\ub79c\uc7ad\uc158\uc758 \ub3d9\uc2dc \uc2e4\ud589 \uacb0\uacfc\uac00 \ud574\ub2f9 \ud2b8\ub79c\uc7ad\uc158\ub4e4\uc744 \uc5b4\ub5a4 \uc21c\uc11c\ub85c\ub4e0 \ud558\ub098\uc529 \uc2e4\ud589\ud55c \uacb0\uacfc\uc640 \ub3d9\ub4f1\ud558\ub3c4\ub85d \ubcf4\uc7a5\ud558\ub294 \uaca9\ub9ac \uc218\uc900\uc774\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc77c\ubc18\uc801\uc73c\ub85c \uac00\uc7a5 \uac15\ud55c \uaca9\ub9ac \uc218\uc900\uc73c\ub85c \ubd84\ub958\ub41c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc608\ub97c \ub4e4\uc5b4 \ud50c\ub808\uc774\uc5b4\uac00 \ud55c \ubc88\uc5d0 \ud558\ub098\uc758 \ud65c\uc131 \ud30c\ud2f0\uc5d0\ub9cc \uac00\uc785\ud560 \uc218 \uc788\ub2e4\uace0 \uac00\uc815\ud558\uc790.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ud2b8\ub79c\uc7ad\uc158 A\uc640 B\uac00 \ub3d9\uc2dc\uc5d0 \ud65c\uc131 \ud30c\ud2f0 \uac00\uc785 \uc5ec\ubd80\ub97c \uc870\ud68c\ud55c \ub4a4 \uac01\uac01 \ub2e4\ub978 \ud30c\ud2f0\uc5d0 \uac00\uc785\ud558\ub824\uace0 \ud558\uba74, \ub2e8\uc21c\ud55c \uc870\ud68c \ud6c4 \uc0bd\uc785 \ub85c\uc9c1\ub9cc\uc73c\ub85c\ub294 \uaddc\uce59\uc774 \uae68\uc9c8 \uc218 \uc788\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Serializable\uc740 \uc774\ub7ec\ud55c \ud2b8\ub79c\uc7ad\uc158 \uac04 \uc758\uc874\uc131\uc744 \uc81c\uc5b4\ud574 \uc9c1\ub82c \uc2e4\ud589\uacfc \ub3d9\ub4f1\ud55c \uacb0\uacfc\ub97c \ubcf4\uc7a5\ud558\ub3c4\ub85d \ud55c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uad6c\ud604 \ubc29\uc2dd\uc740 DBMS\ub9c8\ub2e4 \ub2e4\ub974\ub2e4. \uc7a0\uae08\uc744 \ud65c\uc6a9\ud560 \uc218\ub3c4 \uc788\uace0, \ucda9\ub3cc\uc744 \uac10\uc9c0\ud574 \ud2b8\ub79c\uc7ad\uc158\uc744 \uc911\ub2e8\uc2dc\ud0a4\uace0 \uc7ac\uc2dc\ub3c4\ub97c \uc694\uad6c\ud560 \uc218\ub3c4 \uc788\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\uc7a5\uc810<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\ubcf5\uc7a1\ud55c \ub3d9\uc2dc\uc131 \uc0c1\ud669\uc5d0\uc11c \ub370\uc774\ud130 \uc815\ud569\uc131\uc744 \uac15\ud558\uac8c \ubcf4\uc7a5\ud55c\ub2e4.<\/li>\n\n\n\n<li>\uc5ec\ub7ec \ud589\uc744 \ud3ec\ud568\ud558\ub294 \uc870\uac74\uacfc \ube44\uc988\ub2c8\uc2a4 \uaddc\uce59\uc744 \ucc98\ub9ac\ud560 \ub54c \uc720\uc6a9\ud558\ub2e4.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\ub2e8\uc810<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\uc7a0\uae08 \ub300\uae30, \ucda9\ub3cc \uac10\uc9c0, \ud2b8\ub79c\uc7ad\uc158 \uc7ac\uc2dc\ub3c4\ub85c \uc778\ud574 \ucc98\ub9ac\ub7c9\uc774 \ub0ae\uc544\uc9c8 \uc218 \uc788\ub2e4.<\/li>\n\n\n\n<li>\ud2b8\ub79c\uc7ad\uc158\uc774 \uc2e4\ud328\ud560 \uc218 \uc788\uc73c\ubbc0\ub85c \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc5d0\uc11c \uc7ac\uc2dc\ub3c4 \uc815\ucc45\uc744 \uc124\uacc4\ud574\uc57c \ud55c\ub2e4.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Serializable\uc744 \uc0ac\uc6a9\ud55c\ub2e4\uace0 \ud574\uc11c \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc758 \uc7ac\uc2dc\ub3c4 \ub85c\uc9c1\uc774\ub098 \ube44\uc988\ub2c8\uc2a4 \uaddc\uce59 \uac80\uc99d\uc774 \ubd88\ud544\uc694\ud574\uc9c0\ub294 \uac83\uc740 \uc544\ub2c8\ub2e4.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\uaca9\ub9ac \uc218\uc900 \ube44\uad50<\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><th>\uaca9\ub9ac \uc218\uc900<\/th><th>Dirty Read<\/th><th>Non-repeatable Read<\/th><th>\ud32c\ud140 \ub9ac\ub4dc<\/th><\/tr><tr><td>Read Uncommitted<\/td><td>\ud5c8\uc6a9 \uac00\ub2a5<\/td><td>\ud5c8\uc6a9 \uac00\ub2a5<\/td><td>\ud5c8\uc6a9 \uac00\ub2a5<\/td><\/tr><tr><td>Read Committed<\/td><td>\ubc29\uc9c0<\/td><td>\ubc1c\uc0dd \uac00\ub2a5<\/td><td>\ubc1c\uc0dd \uac00\ub2a5<\/td><\/tr><tr><td>Repeatable Read<\/td><td>\ubc29\uc9c0<\/td><td>\ubc29\uc9c0<\/td><td>DBMS\ubcc4 \ucc28\uc774<\/td><\/tr><tr><td>Serializable<\/td><td>\ubc29\uc9c0<\/td><td>\ubc29\uc9c0<\/td><td>\ubc29\uc9c0<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">\uc774 \ud45c\ub294 SQL \ud45c\uc900\uc758 \uc77c\ubc18\uc801\uc778 \uaca9\ub9ac \uc218\uc900 \ud2b9\uc131\uc744 \uae30\uc900\uc73c\ub85c \ud55c \uac83\uc774\ub2e4. \uc2e4\uc81c DBMS\uc758 \uad6c\ud604\uacfc \uc7a0\uae08 \uc77d\uae30 \ubc29\uc2dd\uc5d0 \ub530\ub77c \uad6c\uccb4\uc801\uc778 \ub3d9\uc791\uc740 \ub2ec\ub77c\uc9c8 \uc218 \uc788\ub2e4.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\ub099\uad00\uc801 \ub3d9\uc2dc\uc131 \uc81c\uc5b4(Optimistic Concurrency Control)<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\ub099\uad00\uc801 \ub3d9\uc2dc\uc131 \uc81c\uc5b4\ub294 \ub300\ubd80\ubd84\uc758 \uc791\uc5c5\uc774 \ucda9\ub3cc\ud558\uc9c0 \uc54a\ub294\ub2e4\uace0 \uac00\uc815\ud558\uace0, \ub370\uc774\ud130\ub97c \ubcc0\uacbd\ud558\ub294 \uc2dc\uc810\uc5d0 \ucda9\ub3cc \uc5ec\ubd80\ub97c \uac80\uc0ac\ud558\ub294 \ubc29\uc2dd\uc774\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc77c\ubc18\uc801\uc73c\ub85c \ub370\uc774\ud130\ub97c \uc77d\uc744 \ub54c \ubc84\uc804 \ubc88\ud638\ub97c \ud568\uaed8 \uc870\ud68c\ud558\uace0, \uc218\uc815\ud560 \ub54c \uae30\uc874 \ubc84\uc804\uc774 \uadf8\ub300\ub85c\uc778\uc9c0 \ud655\uc778\ud55c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc608\ub97c \ub4e4\uc5b4 \ud50c\ub808\uc774\uc5b4 \ub370\uc774\ud130\uc5d0 <code>version<\/code> \uceec\ub7fc\uc744 \ucd94\uac00\ud55c\ub2e4.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>CREATE TABLE players (\n    player_id BIGINT PRIMARY KEY,\n    gold BIGINT NOT NULL,\n    version BIGINT NOT NULL DEFAULT 0\n);<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\ub370\uc774\ud130\ub97c \uc870\ud68c\ud55c\ub2e4.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>SELECT player_id, gold, version\nFROM players\nWHERE player_id = 1;<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\uc870\ud68c \uacb0\uacfc\uac00 \ub2e4\uc74c\uacfc \uac19\ub2e4\uace0 \uac00\uc815\ud558\uc790.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>player_id: 1\ngold: 1000\nversion: 3<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\uc774\uc81c \uace8\ub4dc\ub97c 100 \uac10\uc18c\uc2dc\ud0a4\uba74\uc11c \ubc84\uc804\ub3c4 \uc99d\uac00\uc2dc\ud0a8\ub2e4.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>UPDATE players\nSET\n    gold = gold - 100,\n    version = version + 1\nWHERE player_id = 1\n  AND version = 3\n  AND gold &gt;= 100;<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\uc5c5\ub370\uc774\ud2b8 \uacb0\uacfc\uac00 \ud55c \ud589\uc774\uba74 \ud574\ub2f9 \ubc84\uc804\uc744 \uae30\uc900\uc73c\ub85c \ubcc0\uacbd\uc5d0 \uc131\uacf5\ud55c \uac83\uc774\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ubc18\ub300\ub85c \ub2e4\ub978 \uc694\uccad\uc774 \uba3c\uc800 \ub370\uc774\ud130\ub97c \uc218\uc815\ud574 \ubc84\uc804\uc774 4\uac00 \ub418\uc5c8\ub2e4\uba74, <code>version = 3<\/code> \uc870\uac74\uc774 \uc77c\uce58\ud558\uc9c0 \uc54a\uc544 \uc5c5\ub370\uc774\ud2b8 \uacb0\uacfc\ub294 0\ud589\uc774 \ub41c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc774 \uacbd\uc6b0 \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc740 \ucd5c\uc2e0 \ub370\uc774\ud130\ub97c \ub2e4\uc2dc \uc870\ud68c\ud558\uace0 \uc791\uc5c5\uc744 \uc7ac\uc2dc\ub3c4\ud558\uac70\ub098, \ucda9\ub3cc\uc744 \uc0ac\uc6a9\uc790\uc5d0\uac8c \ubc18\ud658\ud574\uc57c \ud55c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\uc7a5\uc810<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\uc7a0\uae08\uc744 \uc7a5\uc2dc\uac04 \uc720\uc9c0\ud558\uc9c0 \uc54a\uace0\ub3c4 \ucda9\ub3cc\uc744 \uac10\uc9c0\ud560 \uc218 \uc788\ub2e4.<\/li>\n\n\n\n<li>\ucda9\ub3cc\uc774 \ub4dc\ubb38 \ud658\uacbd\uc5d0\uc11c \ud6a8\uc728\uc801\uc774\ub2e4.<\/li>\n\n\n\n<li>\uc6f9 API\uc758 \ud504\ub85c\ud544 \uc218\uc815, \uc124\uc815 \ubcc0\uacbd, \uc7ac\uace0 \uc218\uc815 \ub4f1\uc5d0 \uc801\uc6a9\ud560 \uc218 \uc788\ub2e4.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\ub2e8\uc810<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\ucda9\ub3cc\uc774 \ube48\ubc88\ud558\uba74 \uc7ac\uc2dc\ub3c4 \ube44\uc6a9\uc774 \uc99d\uac00\ud55c\ub2e4.<\/li>\n\n\n\n<li>\ucda9\ub3cc\uc774 \ubc1c\uc0dd\ud588\uc744 \ub54c \ub370\uc774\ud130\ub97c \ub2e4\uc2dc \uc870\ud68c\ud558\uace0 \ube44\uc988\ub2c8\uc2a4 \ub85c\uc9c1\uc744 \uc7ac\uc2e4\ud589\ud574\uc57c \ud560 \uc218 \uc788\ub2e4.<\/li>\n\n\n\n<li>\ubaa8\ub4e0 \ubcc0\uacbd \uacbd\ub85c\uac00 \ubc84\uc804 \uc870\uac74\uc744 \uc9c0\ucf1c\uc57c \ud55c\ub2e4.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\ub099\uad00\uc801 \ub3d9\uc2dc\uc131 \uc81c\uc5b4\ub294 \ucda9\ub3cc\uc744 \ubb34\uc870\uac74 \ubc29\uc9c0\ud558\ub294 \ubc29\uc2dd\uc774 \uc544\ub2c8\ub77c, \ucda9\ub3cc\uc744 \uac10\uc9c0\ud574 \uc798\ubabb\ub41c \ub36e\uc5b4\uc4f0\uae30\ub97c \ubc29\uc9c0\ud558\ub294 \ubc29\uc2dd\uc774\ub2e4.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\ube44\uad00\uc801 \ub3d9\uc2dc\uc131 \uc81c\uc5b4(Pessimistic Concurrency Control)<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\ube44\uad00\uc801 \ub3d9\uc2dc\uc131 \uc81c\uc5b4\ub294 \ub3d9\uc2dc\uc5d0 \uc2e4\ud589\ub418\ub294 \uc791\uc5c5\uc774 \ucda9\ub3cc\ud560 \uac00\ub2a5\uc131\uc774 \uc788\ub2e4\uace0 \ubcf4\uace0, \ub370\uc774\ud130\ub97c \ubcc0\uacbd\ud558\uae30 \uc804\uc5d0 \uc7a0\uae08\uc744 \ud68d\ub4dd\ud558\ub294 \ubc29\uc2dd\uc774\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ub300\ud45c\uc801\uc778 \ubc29\ubc95\uc740 <code>SELECT ... FOR UPDATE<\/code>\ub97c \uc0ac\uc6a9\ud558\ub294 \uac83\uc774\ub2e4.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>START TRANSACTION;\n\nSELECT gold\nFROM players\nWHERE player_id = 1\nFOR UPDATE;\n\n-- \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc5d0\uc11c \uc794\uc561 \ud655\uc778\n\nUPDATE players\nSET gold = gold - 100\nWHERE player_id = 1\n  AND gold &gt;= 100;\n\nCOMMIT;<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\uc9c0\uc6d0\ub418\ub294 \ud2b8\ub79c\uc7ad\uc158 \ubc0f \ud14c\uc774\ube14 \uc5d4\uc9c4\uc5d0\uc11c <code>FOR UPDATE<\/code>\ub294 \ud574\ub2f9 \ud589\uc5d0 \ub300\ud55c \uc7a0\uae08\uc744 \ud68d\ub4dd\ud574 \ub2e4\ub978 \ud2b8\ub79c\uc7ad\uc158\uc758 \ucda9\ub3cc\ud558\ub294 \ubcc0\uacbd \uc791\uc5c5\uc744 \uc81c\uc5b4\ud55c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc77c\ubc18\uc801\uc73c\ub85c \uc7a0\uae08\uc740 \ud2b8\ub79c\uc7ad\uc158\uc774 \ucee4\ubc0b\ub418\uac70\ub098 \ub864\ubc31\ub420 \ub54c \ud574\uc81c\ub41c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\uc7a5\uc810<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\ub3d9\uc2dc\uc5d0 \uac19\uc740 \ub370\uc774\ud130\ub97c \ubcc0\uacbd\ud558\ub294 \uc694\uccad\uc744 \uc9c1\uc811 \uc81c\uc5b4\ud560 \uc218 \uc788\ub2e4.<\/li>\n\n\n\n<li>\ucda9\ub3cc\uc774 \uc7a6\uc740 \ub370\uc774\ud130\uc5d0 \uc801\ud569\ud558\ub2e4.<\/li>\n\n\n\n<li>\uc77d\uae30\uc640 \uc218\uc815 \uc0ac\uc774\uc5d0 \ubc1c\uc0dd\ud558\ub294 \uacbd\uc7c1 \uc0c1\ud669\uc744 \uc904\uc77c \uc218 \uc788\ub2e4.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\ub2e8\uc810<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\uc7a0\uae08 \ub300\uae30\uac00 \ubc1c\uc0dd\ud560 \uc218 \uc788\ub2e4.<\/li>\n\n\n\n<li>\uc7a0\uae08\uc744 \uc624\ub798 \uc720\uc9c0\ud558\uba74 \ucc98\ub9ac\ub7c9\uc774 \uac10\uc18c\ud55c\ub2e4.<\/li>\n\n\n\n<li>\uc7a0\uae08 \ud68d\ub4dd \uc21c\uc11c\uac00 \uaf2c\uc774\uba74 \uad50\ucc29 \uc0c1\ud0dc\uac00 \ubc1c\uc0dd\ud560 \uc218 \uc788\ub2e4.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">\ub099\uad00\uc801 \ubc29\uc2dd\uacfc \ube44\uad00\uc801 \ubc29\uc2dd\uc758 \ube44\uad50<\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><th>\ud56d\ubaa9<\/th><th>\ub099\uad00\uc801 \uc81c\uc5b4<\/th><th>\ube44\uad00\uc801 \uc81c\uc5b4<\/th><\/tr><tr><td>\uae30\ubcf8 \uac00\uc815<\/td><td>\ucda9\ub3cc\uc774 \ub4dc\ubb3c\ub2e4<\/td><td>\ucda9\ub3cc \uac00\ub2a5\uc131\uc774 \ub192\ub2e4<\/td><\/tr><tr><td>\uc81c\uc5b4 \uc2dc\uc810<\/td><td>\uc218\uc815 \uc2dc \ucda9\ub3cc \uac80\uc0ac<\/td><td>\uc218\uc815 \uc804 \uc7a0\uae08 \ud68d\ub4dd<\/td><\/tr><tr><td>\uc8fc\uc694 \uae30\ubc95<\/td><td>\ubc84\uc804 \uceec\ub7fc, \uc870\uac74\ubd80 UPDATE<\/td><td>\ud589 \uc7a0\uae08, <code>FOR UPDATE<\/code><\/td><\/tr><tr><td>\ucda9\ub3cc \ucc98\ub9ac<\/td><td>\uc2e4\ud328 \uac10\uc9c0 \ud6c4 \uc7ac\uc2dc\ub3c4<\/td><td>\uc7a0\uae08 \ub300\uae30 \ub610\ub294 \uc2e4\ud328<\/td><\/tr><tr><td>\uc801\ud569\ud55c \uc0c1\ud669<\/td><td>\ucda9\ub3cc\uc774 \uc801\uc740 \uc77c\ubc18 \uc218\uc815<\/td><td>\uacbd\ud569\uc774 \uc7a6\uc740 \ud575\uc2ec \ub370\uc774\ud130<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">\ub458 \uc911 \ud558\ub098\uac00 \ud56d\uc0c1 \uc6b0\uc6d4\ud55c \uac83\uc740 \uc544\ub2c8\ub2e4. \ub370\uc774\ud130\uc758 \ucda9\ub3cc \ube48\ub3c4, \ud2b8\ub79c\uc7ad\uc158 \uae38\uc774, \uc7ac\uc2dc\ub3c4 \ube44\uc6a9, \ud5c8\uc6a9 \uac00\ub2a5\ud55c \uc9c0\uc5f0 \uc2dc\uac04\uc744 \uae30\uc900\uc73c\ub85c \uc120\ud0dd\ud574\uc57c \ud55c\ub2e4.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\ud589 \uc7a0\uae08(Row Lock)\uacfc \uad50\ucc29 \uc0c1\ud0dc(Deadlock)<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">\ud589 \uc7a0\uae08\uc774\ub780?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\ud589 \uc7a0\uae08\uc740 \ub370\uc774\ud130\ubca0\uc774\uc2a4\uc5d0\uc11c \ud2b9\uc815 \ud589\uc5d0 \ub300\ud55c \ub3d9\uc2dc \uc811\uadfc\uc744 \uc81c\uc5b4\ud558\ub294 \uc7a0\uae08\uc774\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc608\ub97c \ub4e4\uc5b4 \ud55c \ud50c\ub808\uc774\uc5b4\uc758 \uace8\ub4dc\ub97c \ucc28\uac10\ud558\ub294 \ub3d9\uc548 \ub2e4\ub978 \ud2b8\ub79c\uc7ad\uc158\uc774 \uac19\uc740 \ud589\uc744 \uc218\uc815\ud558\ub824\uace0 \ud558\uba74, \uc7a0\uae08 \ucda9\ub3cc\ub85c \uc778\ud574 \ud6c4\uc18d \uc791\uc5c5\uc774 \ub300\uae30\ud560 \uc218 \uc788\ub2e4.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>START TRANSACTION;\n\nSELECT gold\nFROM players\nWHERE player_id = 1\nFOR UPDATE;\n\nUPDATE players\nSET gold = gold - 100\nWHERE player_id = 1;\n\nCOMMIT;<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\ud589 \uc7a0\uae08\uc740 \uc5ec\ub7ec \uc694\uccad\uc774 \ub3d9\uc77c\ud55c \ub370\uc774\ud130\ub97c \ub3d9\uc2dc\uc5d0 \ubcc0\uacbd\ud560 \ub54c \uc815\ud569\uc131\uc744 \ud655\ubcf4\ud558\ub294 \ub370 \uc720\uc6a9\ud558\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ub2e4\ub9cc \uc7a0\uae08 \ubc94\uc704\uc640 \uc2e4\uc81c \uc7a0\uae08 \ubc29\uc2dd\uc740 DBMS, \uc778\ub371\uc2a4, \uaca9\ub9ac \uc218\uc900, \uc2e4\ud589 \uacc4\ud68d \ub4f1\uc5d0 \ub530\ub77c \ub2ec\ub77c\uc9c4\ub2e4. \ud2b9\ud788 \uc778\ub371\uc2a4\ub97c \uc801\uc808\ud558\uac8c \uc0ac\uc6a9\ud558\uc9c0 \uc54a\uc73c\uba74 \uc608\uc0c1\ubcf4\ub2e4 \ub113\uc740 \ubc94\uc704\uc758 \uc7a0\uae08\uc774\ub098 \ub354 \ub9ce\uc740 \ub300\uae30\uac00 \ubc1c\uc0dd\ud560 \uc218 \uc788\ub2e4.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\uad50\ucc29 \uc0c1\ud0dc\ub780?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\uad50\ucc29 \uc0c1\ud0dc\ub294 \ub450 \uac1c \uc774\uc0c1\uc758 \ud2b8\ub79c\uc7ad\uc158\uc774 \uc11c\ub85c \uc0c1\ub300\ubc29\uc774 \ubcf4\uc720\ud55c \uc7a0\uae08\uc774 \ud574\uc81c\ub418\uae30\ub97c \uae30\ub2e4\ub9ac\uba74\uc11c \uc9c4\ud589\ud560 \uc218 \uc5c6\ub294 \uc0c1\ud0dc\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc608\ub97c \ub4e4\uc5b4 \ub2e4\uc74c\uacfc \uac19\uc740 \uc0c1\ud669\uc744 \uc0dd\uac01\ud560 \uc218 \uc788\ub2e4.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\ud2b8\ub79c\uc7ad\uc158 A\uac00 \ud50c\ub808\uc774\uc5b4 1\uc758 \ud589\uc744 \uc7a0\uadfc\ub2e4.<\/li>\n\n\n\n<li>\ud2b8\ub79c\uc7ad\uc158 B\uac00 \ud50c\ub808\uc774\uc5b4 2\uc758 \ud589\uc744 \uc7a0\uadfc\ub2e4.<\/li>\n\n\n\n<li>\ud2b8\ub79c\uc7ad\uc158 A\uac00 \ud50c\ub808\uc774\uc5b4 2\uc758 \uc7a0\uae08\uc744 \uc694\uccad\ud558\uace0 \ub300\uae30\ud55c\ub2e4.<\/li>\n\n\n\n<li>\ud2b8\ub79c\uc7ad\uc158 B\uac00 \ud50c\ub808\uc774\uc5b4 1\uc758 \uc7a0\uae08\uc744 \uc694\uccad\ud558\uace0 \ub300\uae30\ud55c\ub2e4.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\uc774\uc81c A\ub294 B\ub97c \uae30\ub2e4\ub9ac\uace0, B\ub294 A\ub97c \uae30\ub2e4\ub9b0\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">&lt;box border radius=&#8221;lg&#8221; padding={3} gap={2}&gt;<br>&lt;title size=&#8221;md&#8221;&gt;\uad50\ucc29 \uc0c1\ud0dc\uc758 \ub300\uae30 \uad00\uacc4&lt;\/title&gt;<br>&lt;box align=&#8221;center&#8221; gap={1}&gt;<br>&lt;box background=&#8221;surface-secondary&#8221; radius=&#8221;md&#8221; padding={3} width=&#8221;70%&#8221; align=&#8221;center&#8221;&gt;<br>**\ud2b8\ub79c\uc7ad\uc158 A**<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\"> <code> &lt;text size=\"sm\"&gt;\ud50c\ub808\uc774\uc5b4 1 \uc7a0\uae08 \ubcf4\uc720&lt;\/text&gt;\n&lt;\/box&gt;\n&lt;icon name=\"arrow-down\" size=\"lg\"\/&gt;\n&lt;text color=\"danger\" weight=\"medium\"&gt;\ud50c\ub808\uc774\uc5b4 2 \uc7a0\uae08 \ub300\uae30&lt;\/text&gt;\n&lt;divider\/&gt;\n&lt;box background=\"surface-secondary\" radius=\"md\" padding={3} width=\"70%\" align=\"center\"&gt;\n  **\ud2b8\ub79c\uc7ad\uc158 B**\n\n  &lt;text size=\"sm\"&gt;\ud50c\ub808\uc774\uc5b4 2 \uc7a0\uae08 \ubcf4\uc720&lt;\/text&gt;\n&lt;\/box&gt;\n&lt;icon name=\"arrow-up\" size=\"lg\"\/&gt;\n&lt;text color=\"danger\" weight=\"medium\"&gt;\ud50c\ub808\uc774\uc5b4 1 \uc7a0\uae08 \ub300\uae30&lt;\/text&gt;<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">&lt;\/box&gt;<br>&lt;text color=&#8221;secondary&#8221; size=&#8221;sm&#8221;&gt;\uc11c\ub85c\uac00 \ubcf4\uc720\ud55c \uc7a0\uae08\uc744 \uae30\ub2e4\ub9ac\ubbc0\ub85c \uc5b4\ub290 \ud2b8\ub79c\uc7ad\uc158\ub3c4 \uc2a4\uc2a4\ub85c \uc9c4\ud589\ud560 \uc218 \uc5c6\ub2e4.&lt;\/text&gt;<br>&lt;\/box&gt;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ub370\uc774\ud130\ubca0\uc774\uc2a4\ub294 \uc77c\ubc18\uc801\uc73c\ub85c \uad50\ucc29 \uc0c1\ud0dc\ub97c \uac10\uc9c0\ud558\uba74 \ud2b8\ub79c\uc7ad\uc158 \uc911 \ud558\ub098\ub97c \uc911\ub2e8\uc2dc\ucf1c \uc21c\ud658 \ub300\uae30\ub97c \ud574\uc18c\ud55c\ub2e4. \ub530\ub77c\uc11c \uad50\ucc29 \uc0c1\ud0dc\uac00 \ubc1c\uc0dd\ud588\ub2e4\uace0 \ud574\uc11c \ubc18\ub4dc\uc2dc \ub370\uc774\ud130\ubca0\uc774\uc2a4 \uc804\uccb4\uac00 \uba48\ucd94\ub294 \uac83\uc740 \uc544\ub2c8\ub2e4.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\uad50\ucc29 \uc0c1\ud0dc \uc608\ubc29 \ubc29\ubc95<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\uc77c\uad00\ub41c \uc7a0\uae08 \uc21c\uc11c \uc720\uc9c0<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ubaa8\ub4e0 \ud2b8\ub79c\uc7ad\uc158\uc774 \ud50c\ub808\uc774\uc5b4 ID \uc624\ub984\ucc28\uc21c\ucc98\ub7fc \ub3d9\uc77c\ud55c \uc21c\uc11c\ub85c \ud589\uc744 \uc7a0\uadf8\ub3c4\ub85d \uc124\uacc4\ud55c\ub2e4.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>START TRANSACTION;\n\nSELECT player_id, gold\nFROM players\nWHERE player_id IN (1, 2)\nORDER BY player_id\nFOR UPDATE;\n\n-- \uac80\uc99d \ud6c4 \ub450 \ud50c\ub808\uc774\uc5b4\uc758 \ub370\uc774\ud130 \ubcc0\uacbd\n\nCOMMIT;<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\uc2e4\uc81c \uc7a0\uae08 \ud68d\ub4dd \uc21c\uc11c\ub294 \uc2e4\ud589 \uacc4\ud68d\uacfc DBMS \uad6c\ud604\uc758 \uc601\ud5a5\uc744 \ubc1b\uc744 \uc218 \uc788\uc73c\ubbc0\ub85c, <code>ORDER BY<\/code>\ub9cc\uc73c\ub85c \ubaa8\ub4e0 \uad50\ucc29 \uc0c1\ud0dc\uac00 \uc81c\uac70\ub41c\ub2e4\uace0 \uac00\uc815\ud574\uc11c\ub294 \uc548 \ub41c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\ud2b8\ub79c\uc7ad\uc158\uc744 \uc9e7\uac8c \uc720\uc9c0<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc7a0\uae08\uc744 \ud68d\ub4dd\ud55c \uc0c1\ud0dc\uc5d0\uc11c \uc678\ubd80 API\ub97c \ud638\ucd9c\ud558\uac70\ub098 \ubd88\ud544\uc694\ud55c \uc5f0\uc0b0\uc744 \uc218\ud589\ud558\uc9c0 \uc54a\ub294\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\uc778\ub371\uc2a4 \ud65c\uc6a9<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc870\uac74\uc5d0 \ub9de\ub294 \ud589\uc744 \ud6a8\uc728\uc801\uc73c\ub85c \ucc3e\uc73c\uba74 \ubd88\ud544\uc694\ud55c \ub370\uc774\ud130 \uc811\uadfc\uacfc \uc7a0\uae08 \ubc94\uc704\ub97c \uc904\uc774\ub294 \ub370 \ub3c4\uc6c0\uc774 \ub41c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>\uc7ac\uc2dc\ub3c4 \uc815\ucc45 \uad6c\ud604<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uad50\ucc29 \uc0c1\ud0dc\ub85c \ud2b8\ub79c\uc7ad\uc158\uc774 \uc911\ub2e8\ub418\uba74 \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc5d0\uc11c \uc804\uccb4 \ud2b8\ub79c\uc7ad\uc158\uc744 \ub2e4\uc2dc \uc2e4\ud589\ud560 \uc218 \uc788\ub3c4\ub85d \uc124\uacc4\ud55c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc7ac\uc2dc\ub3c4\uc5d0\ub294 \ud69f\uc218 \uc81c\ud55c\uacfc \uc9c0\uc218\ud615 \ubc31\uc624\ud504(Exponential Backoff)\ub97c \uc801\uc6a9\ud558\ub294 \uac83\uc774 \uc88b\ub2e4. \ub2e8, \ubb34\uc870\uac74 \ubc18\ubcf5\ud574\uc11c \uc7ac\uc2dc\ub3c4\ud558\uba74 \uc11c\ubc84 \ubd80\ud558\uac00 \ub354 \ucee4\uc9c8 \uc218 \uc788\ub2e4.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Race Condition(\uacbd\uc7c1 \uc0c1\ud0dc)<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Race Condition\uc740 \uc5ec\ub7ec \uc791\uc5c5\uc774 \ub3d9\uc2dc\uc5d0 \uc2e4\ud589\ub420 \ub54c \uc2e4\ud589 \uc21c\uc11c\ub098 \ud0c0\uc774\ubc0d\uc5d0 \ub530\ub77c \uacb0\uacfc\uac00 \ub2ec\ub77c\uc9c0\ub294 \ubb38\uc81c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ub370\uc774\ud130\ubca0\uc774\uc2a4\ubfd0 \uc544\ub2c8\ub77c \uba40\ud2f0\uc2a4\ub808\ub4dc \ud504\ub85c\uadf8\ub7a8, \ubd84\uc0b0 \uc2dc\uc2a4\ud15c, \uc2e4\uc2dc\uac04 \uac8c\uc784 \uc11c\ubc84\uc5d0\uc11c\ub3c4 \ubc1c\uc0dd\ud55c\ub2e4.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\uc7ac\ud654 \ucc28\uac10\uc5d0\uc11c \ubc1c\uc0dd\ud558\ub294 Race Condition<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\ud50c\ub808\uc774\uc5b4\uc758 \uace8\ub4dc\uac00 1,000\uc774\ub77c\uace0 \uac00\uc815\ud558\uc790.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ub450 \uac1c\uc758 \uc694\uccad\uc774 \ub3d9\uc2dc\uc5d0 \uac01\uac01 800\uace8\ub4dc\uc9dc\ub9ac \uc544\uc774\ud15c\uc744 \uad6c\ub9e4\ud558\ub824\uace0 \ud55c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc798\ubabb\ub41c \uad6c\ud604\uc740 \ub2e4\uc74c\uacfc \uac19\ub2e4.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>const player = await repository.findById(playerId);\n\nif (player.gold &gt;= 800) {\n  await repository.updateGold(\n    playerId,\n    player.gold - 800\n  );\n\n  await purchaseItem(playerId, itemId);\n}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\ub450 \uc694\uccad\uc758 \uc2e4\ud589 \uc21c\uc11c\uac00 \ub2e4\uc74c\uacfc \uac19\ub2e4\uba74 \ubb38\uc81c\uac00 \ubc1c\uc0dd\ud55c\ub2e4.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><th>\uc21c\uc11c<\/th><th>\uc694\uccad A<\/th><th>\uc694\uccad B<\/th><\/tr><tr><td>1<\/td><td>\uace8\ub4dc 1,000 \uc870\ud68c<\/td><td><\/td><\/tr><tr><td>2<\/td><td><\/td><td>\uace8\ub4dc 1,000 \uc870\ud68c<\/td><\/tr><tr><td>3<\/td><td>\uad6c\ub9e4 \uac00\ub2a5 \ud310\uc815<\/td><td><\/td><\/tr><tr><td>4<\/td><td><\/td><td>\uad6c\ub9e4 \uac00\ub2a5 \ud310\uc815<\/td><\/tr><tr><td>5<\/td><td>\uace8\ub4dc\ub97c 200\uc73c\ub85c \ubcc0\uacbd<\/td><td><\/td><\/tr><tr><td>6<\/td><td><\/td><td>\uace8\ub4dc\ub97c 200\uc73c\ub85c \ubcc0\uacbd<\/td><\/tr><tr><td>7<\/td><td>\uc544\uc774\ud15c \uad6c\ub9e4 \uc644\ub8cc<\/td><td><\/td><\/tr><tr><td>8<\/td><td><\/td><td>\uc544\uc774\ud15c \uad6c\ub9e4 \uc644\ub8cc<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">\ucd5c\uc885 \uace8\ub4dc\ub294 200\uc778\ub370 \uc544\uc774\ud15c\uc740 \ub450 \uac1c \uc9c0\uae09\ub420 \uc218 \uc788\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\uc774\ub294 \ub450 \uc694\uccad\uc774 \ub3d9\uc77c\ud55c \ucd08\uae30\uac12\uc744 \uc77d\uace0 \uac01\uac01 \uad6c\ub9e4\uac00 \uac00\ub2a5\ud558\ub2e4\uace0 \ud310\ub2e8\ud588\uae30 \ub54c\ubb38\uc774\ub2e4. \uc774\uc640 \uac19\uc740 \ubb38\uc81c\ub97c Lost Update \ub610\ub294 \uccb4\ud06c \ud6c4 \uc0ac\uc6a9(TOCTOU) \ubb38\uc81c\uc640 \uc5f0\uad00 \uc9c0\uc5b4 \uc124\uba85\ud560 \uc218 \uc788\ub2e4.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\ud574\uacb0 \ubc29\ubc95: \uc870\uac74\ubd80 UPDATE<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\uc870\uac74 \uac80\uc0ac\uc640 \ub370\uc774\ud130 \ubcc0\uacbd\uc744 \ud558\ub098\uc758 SQL \ubb38\uc7a5\uc73c\ub85c \uacb0\ud569\ud560 \uc218 \uc788\ub2e4.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>UPDATE players\nSET gold = gold - 800\nWHERE player_id = 1\n  AND gold &gt;= 800;<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\uc5c5\ub370\uc774\ud2b8 \uacb0\uacfc\uac00 \ud55c \ud589\uc774\uba74 \ucc28\uac10\uc5d0 \uc131\uacf5\ud55c \uac83\uc774\uace0, 0\ud589\uc774\uba74 \ud50c\ub808\uc774\uc5b4\uac00 \uc5c6\uac70\ub098 \uace8\ub4dc\uac00 \ubd80\uc871\ud55c \uac83\uc774\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ub450 \uc694\uccad\uc774 \ub3d9\uc2dc\uc5d0 \uc2e4\ud589\ub418\ub354\ub77c\ub3c4 \ub3d9\uc77c\ud55c \ud589\uc5d0 \ub300\ud55c \ubcc0\uacbd\uc740 \ub370\uc774\ud130\ubca0\uc774\uc2a4\uc758 \ub3d9\uc2dc\uc131 \uc81c\uc5b4\ub97c \uac70\uce5c\ub2e4. \uba3c\uc800 \ucc98\ub9ac\ub41c \uc694\uccad\uc774 \uace8\ub4dc\ub97c 200\uc73c\ub85c \uc904\uc600\ub2e4\uba74, \ub098\uc911 \uc694\uccad\uc740 \ucd5c\uc2e0 \uac12\uc5d0 \ub300\ud574 \uc870\uac74\uc744 \ud655\uc778\ud558\uace0 \uc2e4\ud328\ud558\uac8c \ub41c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ub2e4\ub9cc \uc2e4\uc81c \uc544\uc774\ud15c \uad6c\ub9e4\ub294 \uace8\ub4dc \ucc28\uac10\ub9cc\uc73c\ub85c \ub05d\ub098\uc9c0 \uc54a\ub294\ub2e4. \ucc28\uac10\uacfc \uc544\uc774\ud15c \uc9c0\uae09\uc744 \ud558\ub098\uc758 \ud2b8\ub79c\uc7ad\uc158\uc73c\ub85c \ubb36\uc5b4\uc57c \ud55c\ub2e4.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>START TRANSACTION;\n\nUPDATE players\nSET gold = gold - 800\nWHERE player_id = 1\n  AND gold &gt;= 800;\n\n-- \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc5d0\uc11c UPDATE \uc601\ud5a5 \ud589 \uc218 \ud655\uc778\n-- 0\ud589\uc774\uba74 ROLLBACK\n-- 1\ud589\uc774\uba74 \uc778\ubca4\ud1a0\ub9ac\uc5d0 \uc544\uc774\ud15c \uc9c0\uae09\n\nINSERT INTO inventory (player_id, item_id, quantity)\nVALUES (1, 101, 1);\n\nCOMMIT;<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\uc774 \uc608\uc81c\uc5d0\uc11c \uc560\ud50c\ub9ac\ucf00\uc774\uc158\uc740 \ubc18\ub4dc\uc2dc UPDATE \uc601\ud5a5 \ud589 \uc218\ub97c \ud655\uc778\ud574\uc57c \ud55c\ub2e4. \ucc28\uac10\uc5d0 \uc2e4\ud328\ud588\ub2e4\uba74 \uc544\uc774\ud15c\uc744 \uc9c0\uae09\ud558\uc9c0 \uc54a\uace0 \ud2b8\ub79c\uc7ad\uc158\uc744 \ub864\ubc31\ud574\uc57c \ud55c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ub610\ud55c \ub3d9\uc77c\ud55c \uad6c\ub9e4 \uc694\uccad\uc774 \ub124\ud2b8\uc6cc\ud06c \uc7ac\uc2dc\ub3c4\ub85c \uc911\ubcf5 \ucc98\ub9ac\ub418\ub294 \ubb38\uc81c\uae4c\uc9c0 \ubc29\uc9c0\ud558\ub824\uba74 \ubcc4\ub3c4\uc758 \uc8fc\ubb38 ID \ub610\ub294 \uba71\ub4f1\uc131 \ud0a4\ub97c \uc0ac\uc6a9\ud574\uc57c \ud55c\ub2e4.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\ud574\uacb0 \ubc29\ubc95: \ud589 \uc7a0\uae08<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\uc870\uac74\ubd80 UPDATE \ub300\uc2e0 \ud589 \uc7a0\uae08\uc73c\ub85c \ub370\uc774\ud130\ub97c \ubcf4\ud638\ud560 \uc218\ub3c4 \uc788\ub2e4.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>START TRANSACTION;\n\nSELECT gold\nFROM players\nWHERE player_id = 1\nFOR UPDATE;\n\n-- \uc870\ud68c\ub41c \uace8\ub4dc\uac00 800 \uc774\uc0c1\uc778\uc9c0 \ud655\uc778\n\nUPDATE players\nSET gold = gold - 800\nWHERE player_id = 1;\n\n-- \uc544\uc774\ud15c \uc9c0\uae09\n\nCOMMIT;<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\uc774 \ubc29\uc2dd\uc5d0\uc11c\ub294 \uc7a0\uae08\uc744 \ud68d\ub4dd\ud55c \ud2b8\ub79c\uc7ad\uc158\uc774 \uac80\uc99d\uacfc \ubcc0\uacbd\uc744 \uc218\ud589\ud558\ub294 \ub3d9\uc548 \ucda9\ub3cc\ud558\ub294 \ubcc0\uacbd \uc791\uc5c5\uc774 \ub300\uae30\ud55c\ub2e4.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\ub2e4\ub9cc \uc608\uc81c\ub294 \ud575\uc2ec \ub3d9\uc791\uc744 \ubcf4\uc5ec \uc8fc\uae30 \uc704\ud55c \uac83\uc774\ub2e4. \uc2e4\uc81c \uad6c\ud604\uc5d0\uc11c\ub294 \uace8\ub4dc\uac00 \ubd80\uc871\ud55c \uacbd\uc6b0 \ub864\ubc31\ud558\uace0, \ud50c\ub808\uc774\uc5b4\uac00 \uc874\uc7ac\ud558\ub294\uc9c0 \ud655\uc778\ud558\uba70, \uc544\uc774\ud15c \uc9c0\uae09 \uc2e4\ud328 \uc2dc \ucc28\uac10\ub3c4 \ucde8\uc18c\ud574\uc57c \ud55c\ub2e4.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Race Condition\uc744 \ubc29\uc9c0\ud558\ub294 \ud575\uc2ec \uc6d0\uce59<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\uac80\uc99d\uacfc \ubcc0\uacbd\uc744 \uac00\ub2a5\ud55c \ud55c \ud558\ub098\uc758 \uc6d0\uc790\uc801 \uc791\uc5c5\uc73c\ub85c \uacb0\ud569\ud55c\ub2e4.<\/li>\n\n\n\n<li>\uc5ec\ub7ec \ub370\uc774\ud130 \ubcc0\uacbd\uc774 \ud568\uaed8 \uc131\uacf5\ud574\uc57c \ud55c\ub2e4\uba74 \ud2b8\ub79c\uc7ad\uc158\uc73c\ub85c \ubb36\ub294\ub2e4.<\/li>\n\n\n\n<li>\ucda9\ub3cc\uc774 \ubc1c\uc0dd\ud560 \uc218 \uc788\ub294 \ud589\uc740 \uc870\uac74\ubd80 UPDATE, \ub099\uad00\uc801 \uc7a0\uae08 \ub610\ub294 \ube44\uad00\uc801 \uc7a0\uae08\uc73c\ub85c \ubcf4\ud638\ud55c\ub2e4.<\/li>\n\n\n\n<li>\ub3d9\uc77c\ud55c \uc694\uccad\uc774 \ubc18\ubcf5 \uc2e4\ud589\ub420 \uc218 \uc788\ub2e4\uba74 \uba71\ub4f1\uc131\uc744 \ud655\ubcf4\ud55c\ub2e4.<\/li>\n\n\n\n<li>\uc11c\ubc84 \uba54\ubaa8\ub9ac\uc758 \uac12\ub9cc \uc2e0\ub8b0\ud558\uc9c0 \ub9d0\uace0, \uc911\uc694\ud55c \uc0c1\ud0dc\ub294 \ub370\uc774\ud130\ubca0\uc774\uc2a4\uc5d0\uc11c \uc6d0\uc790\uc801\uc73c\ub85c \uac80\uc99d\ud558\uace0 \ubcc0\uacbd\ud55c\ub2e4.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\uc2e4\ubb34\uc5d0\uc11c \uc5b4\ub5a4 \ubc29\ubc95\uc744 \uc120\ud0dd\ud574\uc57c \ud560\uae4c?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\ubaa8\ub4e0 \uc0c1\ud669\uc5d0 \uac00\uc7a5 \uac15\ud55c \uaca9\ub9ac \uc218\uc900\uc774\ub098 \uac00\uc7a5 \ub9ce\uc740 \uc7a0\uae08\uc744 \uc801\uc6a9\ud558\ub294 \uac83\uc774 \uc815\ub2f5\uc740 \uc544\ub2c8\ub2e4. \uc911\uc694\ud55c \uac83\uc740 \ub370\uc774\ud130\uc758 \uc815\ud569\uc131 \uc694\uad6c \uc0ac\ud56d\uacfc \ub3d9\uc2dc\uc131 \ud2b9\uc131\uc744 \ubd84\uc11d\ud574 \uc801\uc808\ud55c \uc81c\uc5b4 \ubc29\ubc95\uc744 \uc120\ud0dd\ud558\ub294 \uac83\uc774\ub2e4.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><th>\uc0c1\ud669<\/th><th>\uad8c\uc7a5 \uc811\uadfc<\/th><\/tr><tr><td>\uc77c\ubc18\uc801\uc778 \ubaa9\ub85d \uc870\ud68c<\/td><td>Read Committed \ub4f1 \uc11c\ube44\uc2a4\uc5d0 \uc801\ud569\ud55c \uaca9\ub9ac \uc218\uc900<\/td><\/tr><tr><td>\uc5ec\ub7ec \ubc88\uc758 \uc870\ud68c\uc5d0\uc11c \ub3d9\uc77c\ud55c \uc2a4\ub0c5\uc0f7 \ud544\uc694<\/td><td>Repeatable Read \ub610\ub294 DBMS\uc758 \uc2a4\ub0c5\uc0f7 \uae30\ub2a5<\/td><\/tr><tr><td>\uace8\ub4dc\u00b7\ud3ec\uc778\ud2b8 \ucc28\uac10<\/td><td>\uc870\uac74\ubd80 UPDATE\uc640 \ud2b8\ub79c\uc7ad\uc158<\/td><\/tr><tr><td>\ub3d9\uc2dc\uc5d0 \uc218\uc815\ub420 \uac00\ub2a5\uc131\uc774 \ub0ae\uc740 \ud504\ub85c\ud544<\/td><td>\ubc84\uc804 \uae30\ubc18 \ub099\uad00\uc801 \ub3d9\uc2dc\uc131 \uc81c\uc5b4<\/td><\/tr><tr><td>\uacbd\ud569\uc774 \uc7a6\uc740 \ud575\uc2ec \uc7ac\ud654<\/td><td>\uc870\uac74\ubd80 UPDATE \ub610\ub294 \uc9e7\uc740 \ud589 \uc7a0\uae08 \ud2b8\ub79c\uc7ad\uc158<\/td><\/tr><tr><td>\uc5ec\ub7ec \ud589\uc5d0 \uac78\uce5c \ubcf5\uc7a1\ud55c \uc815\ud569\uc131 \uaddc\uce59<\/td><td>\uc81c\uc57d \uc870\uac74, \uc7a0\uae08, \ud544\uc694\uc5d0 \ub530\ub77c Serializable<\/td><\/tr><tr><td>\uc911\ubcf5 \uad6c\ub9e4 \uc694\uccad \ubc29\uc9c0<\/td><td>\uba71\ub4f1\uc131 \ud0a4\uc640 \uace0\uc720 \uc81c\uc57d \uc870\uac74<\/td><\/tr><tr><td>\uc5ec\ub7ec \ud2b8\ub79c\uc7ad\uc158\uc758 \uc7a0\uae08 \ucda9\ub3cc<\/td><td>\uc77c\uad00\ub41c \uc7a0\uae08 \uc21c\uc11c\uc640 \uc81c\ud55c\ub41c \uc7ac\uc2dc\ub3c4<\/td><\/tr><\/tbody><\/table><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>\ud2b8\ub79c\uc7ad\uc158(Transaction)\uc774\ub780? \ud2b8\ub79c\uc7ad\uc158\uc740 \ub370\uc774\ud130\ubca0\uc774\uc2a4\uc5d0\uc11c \ud558\ub098\uc758 \ub17c\ub9ac\uc801\uc778 \uc791\uc5c5\uc744 \uc218\ud589\ud558\uae30 \uc704\ud55c SQL \uc5f0\uc0b0\uc758 \uc9d1\ud569\uc774\ub2e4. \uc5ec\ub7ec \uac1c\uc758 \uc791\uc5c5\uc744 \ud558\ub098\uc758 \ub2e8\uc704\ub85c \ubb36\uc5b4, \ubaa8\ub4e0 \uc791\uc5c5\uc774 \uc815\uc0c1\uc801\uc73c\ub85c \uc644\ub8cc\ub418\uac70\ub098 \uc804\uccb4 \uc791\uc5c5\uc774 \ucde8\uc18c\ub418\ub3c4\ub85d \ubcf4\uc7a5\ud55c\ub2e4. \uc608\ub97c \ub4e4\uc5b4 \uac8c\uc784 \uc11c\ubc84\uc5d0\uc11c \ud50c\ub808\uc774\uc5b4 A\uac00 \ud50c\ub808\uc774\uc5b4 B\uc5d0\uac8c 100\uace8\ub4dc\ub97c \uc804\uc1a1\ud55c\ub2e4\uace0 \uac00\uc815\ud558\uc790. \uc774 \uc791\uc5c5\uc740 \ub2e4\uc74c\uacfc \uac19\uc740 \ub450 \uac00\uc9c0 \ubcc0\uacbd\uc73c\ub85c \uad6c\uc131\ub41c\ub2e4. \ub9cc\uc57d A\uc758 \uace8\ub4dc\ub9cc \uac10\uc18c\ud55c \uc0c1\ud0dc\uc5d0\uc11c \uc11c\ubc84 \uc624\ub958\uac00 \ubc1c\uc0dd\ud55c\ub2e4\uba74 \uc5b4\ub5bb\uac8c \ub420\uae4c? A\uc758 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-2671","post","type-post","status-publish","format-standard","hentry","category-dev-logs"],"_links":{"self":[{"href":"https:\/\/wayhope.kro.kr\/index.php?rest_route=\/wp\/v2\/posts\/2671","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wayhope.kro.kr\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wayhope.kro.kr\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wayhope.kro.kr\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/wayhope.kro.kr\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2671"}],"version-history":[{"count":2,"href":"https:\/\/wayhope.kro.kr\/index.php?rest_route=\/wp\/v2\/posts\/2671\/revisions"}],"predecessor-version":[{"id":2692,"href":"https:\/\/wayhope.kro.kr\/index.php?rest_route=\/wp\/v2\/posts\/2671\/revisions\/2692"}],"wp:attachment":[{"href":"https:\/\/wayhope.kro.kr\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2671"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wayhope.kro.kr\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2671"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wayhope.kro.kr\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2671"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}