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MySQL ã¨å¯¿å¸ãƒ“ールå•é¡Œ - ã‹ã¿ã½ã‚ーる
MySQL 㨠Unicode Collation Algorithm (UCA) - ã‹ã¿ã½ã‚ーる ã«é–¢é€£ã™ã‚‹ãƒˆãƒ”ックã§ã€ MySQL ã«ã¯å¯¿å¸ãƒ“ールå•é¡Œã¨ã„ã†ã®ãŒã‚る。 寿å¸ãƒ“ールå•é¡Œã©ã£ã‹ã§è©³ã—ããŠè©±ã‚’èžãã¹ãã よãªã。。。— RKajiyama (@RKajiyama) March 18, 2015 ã“ã‚Œã¯ã©ã†ã„ã†å•é¡Œã‹ã¨ã„ã†ã¨ã€ MySQL ã® Unicode ã§ã¯ binary collation ã«ã—ã¦ã‚³ãƒ¼ãƒ‰ãƒã‚¤ãƒ³ãƒˆã§æ¯”較ã—ãªã„ã¨ðŸ£ã¨ðŸºã«é™ã‚‰ãšçµµæ–‡å—ãŒåŒå€¤åˆ¤å®šã•ã‚Œã‚‹ã¨ã„ã†å•é¡Œã§ã™ã€‚ ã‚れ？ MySQL ã® utf8mb4 charset ã£ã¦ã€4ãƒã‚¤ãƒˆæ–‡å—åŒå£«ã‚’比較ã™ã‚‹ã¨åŒã˜æ–‡å—扱ã„ã•ã‚Œã‚‹ï¼Ÿ SELECT 'ðŸ£'='ðŸº' → 1 MySQLçš„ã«ã¯å¯¿å¸ã¨ãƒ“ールã¯åŒã˜æ‰±ã„。— ã¨ã¿ãŸã¾ã•ã²ã‚ (@tmtms) December 22, 2014 MySQL㧠select
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Using filesort
去年ソートã«é–¢ã™ã‚‹è¨˜äº‹ã‚’書ã„ãŸãŒã€ä»Šæ—¥ã¯ãã®ç¶šãã§ã‚る。 MySQLã§EXPLAIN SELECT...を実行ã™ã‚‹ã¨Extraフィールドã§ã‚ˆã見ã‹ã‘る「Using filesortã€ã¨ã„ã†æ–‡å—列。Filesortã£ã¦ä¸€ä½“ãªã‚“ã ã‚ã†ï¼Ÿã¨æ€ã£ãŸã“ã¨ã¯ãªã„ã ã‚ã†ã‹ã€‚å˜åˆ€ç›´å…¥ã«è¨€ã£ã¦Filesortã®æ£ä½“ã¯ã‚¯ã‚¤ãƒƒã‚¯ã‚½ãƒ¼ãƒˆã§ã‚る。 クエリã«ORDER BYãŒå«ã¾ã‚Œã‚‹å ´åˆã€MySQLã¯ã‚る程度ã®å¤§ãã•ã¾ã§ã¯å…¨ã¦ãƒ¡ãƒ¢ãƒªå†…ã§ã‚¯ã‚¤ãƒƒã‚¯ã‚½ãƒ¼ãƒˆã‚’処ç†ã™ã‚‹ã€‚ã‚る程度ã®å¤§ãã•ã¨ã¯sort_buffer_sizeã§ã‚ã‚Šã€ã“ã‚Œã¯ã‚»ãƒƒã‚·ãƒ§ãƒ³ã”ã¨ã«å¤‰æ›´å¯èƒ½ã§ã‚る。ソートã«å¿…è¦ãªãƒ¡ãƒ¢ãƒªãŒsort_buffer_sizeより大ãããªã‚‹ã¨ã€ãƒ†ãƒ³ãƒãƒ©ãƒªãƒ•ã‚¡ã‚¤ãƒ«ï¼ˆãƒ†ãƒ³ãƒãƒ©ãƒªãƒ†ãƒ¼ãƒ–ルã§ã¯ãªã„）ãŒä½œæˆã•ã‚Œã€ãƒ¡ãƒ¢ãƒªã¨ãƒ•ã‚¡ã‚¤ãƒ«ã‚’併用ã—ã¦ã‚¯ã‚¤ãƒƒã‚¯ã‚½ãƒ¼ãƒˆãŒå®Ÿè¡Œã•ã‚Œã‚‹ã€‚ Filesortã¯å…¨ã¦ã®ã‚½ãƒ¼ãƒˆå‡¦ç†ã«ãŠã„ã¦å®Ÿè¡Œã•ã‚Œã‚‹ã‚ã‘ã§ã¯ãªã„。å‰å›žã®è¨˜äº‹
グループ内ã®ä¸Šä½ N 件を抽出ã™ã‚‹ SQL ãŒã†ã¾ã書ã‘ãªã„ - ngyukiã®æ—¥è¨˜
ã“ã®è¨˜äº‹ã«ã¯ç¶šããŒã‚ã‚Šã¾ã™ グループ内ã®ä¸Šä½ N 件を抽出ã™ã‚‹ SQL ã¯ã‚¹ãƒˆã‚¢ãƒ‰ã§ã„ã„ã‚“ã˜ã‚ƒãªã„？ - ngã®æ—¥è¨˜ MySQL ã§ç°¡å˜ã«å‡ºæ¥ãã†ã§å‡ºæ¥ãªã„ SQL ã«ã€Œã‚°ãƒ«ãƒ¼ãƒ—内ã®ä¸Šä½ N 件を抽出ã™ã‚‹ SQLã€ãŒã‚ã‚Šã¾ã™ã€‚å¹´ã« 1 回ãらã„ã“ã®å•é¡Œã«ã¤ã„ã¦è€ƒãˆã€æ¯Žå›žåŒã˜çµè«–ã«ãªã‚Šã€Œã‚れー去年もåŒã˜ã“ã¨è€ƒãˆãŸæ°—ãŒã™ã‚‹ãªãƒ¼ã€ã¨ãªã£ã¦ã„ã‚‹ã®ã§ã€æ¥å¹´ã‚‚åŒã˜ã“ã¨ã‚’考ãˆã‚‹ã§ã‚ã‚ã†è‡ªåˆ†ã«å‘ã‘ã¦ãƒ¡ãƒ¢ã‚’残ã—ã¦ãŠãã¾ã™ã€‚ ãªãŠã€ã“ã®å†…容㯠MySQL 5.5.19 ã§è©¦ã—ã¦ã„ã¾ã™*1。 (2012/07/26 追記：テストデータを増やã—ãŸã€users ã® name ãŒæŠ½å‡ºã•ã‚Œã¦ã„ãªã„ã®ã‚’ä¿®æ£) テストデータ drop table if exists groups; drop table if exists users; create table groups ( gid int not null prim
rails + MySQL on OSX: Library not loaded: libmysqlclient.18.dylib
I'm just starting out with Ruby (and rails). I did the setup according to http://ruby.railstutorial.org/ruby-on-rails-tutorial-book#sec:ruby gems, using rvm. I have everything working well with sqlite. Now I'd like to try converting things over to MySQL, since that's what I do most of my development with. In my Gemfile I've replaced sqlite with mysql2: group :development, :test do # gem 'sqlite3',
MySQL Bug #79977 "utf8mb4_unicode_520_ci don't make sense for Japanese FTS" ã§è¨€ã„ãŸã„ã“ã¨
MySQL Bug #79977 "utf8mb4_unicode_520_ci don't make sense for Japanese FTS" ã§è¨€ã„ãŸã„ã“㨠英語ã§æ›¸ã„ã¦ãŸã‚‰è‡ªåˆ†ã§ã‚‚よãã‚ã‹ã‚‰ãªããªã£ã¦ããŸã®ã§ã€‚ MySQL Bugs: #79977: utf8mb4_unicode_520_ci don't make sense for Japanese FTS * 本質的ã«ã¯Â MySQL Bugs: #76553: Sushi-Beer issue of MySQL with utf8mb4 ã®é–¢é€£ã€‚ * Unicode実装ãŒä¸å®Œå…¨ã ã‹ã‚‰èµ·ã“ã£ã¦ã„ã‚‹å•é¡Œã€‚ * 丸ã‚å•é¡Œ * motherã‚’æ„味ã™ã‚‹æ›¸ãæ–¹ã«ã€ã¯ã¯ï¼ˆã²ã‚‰ãŒãªï¼‰ã¨ãƒãƒï¼ˆã‚«ã‚¿ã‚«ãƒŠï¼‰ã¨ï¾Šï¾Šï¼ˆåŠè§’カタカナ）ãŒã‚ã£ã¦ã€ * ã“れらã¯ï¼ˆæ–‡å—ã®å½¢ã¯é•ã†ã‘ã©ï¼‰åŒã˜éŸ³ã§åŒã˜æ„味ã ã‹ã‚‰ã€å¤§æ¦‚ã®å ´åˆåŒã˜æ–‡å—ã¨ã—ã¦æ‰±ã£ã¦ãれるã¨å¬‰ã—ã„。
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MySQL5.5ã‹ã‚‰5.6ã«ã—ãŸã‚‰ICP(Index Condition Pushdown)ã§å›°ã£ãŸ - Qiita
ã¯ã˜ã‚ã« ã¤ã„ã«AdventCalenderã‚‚ï¼’æ—¥ã§ã™ã。 MySQL Casual Advent Calendar24日目ã®æ‹…当ã®@gotyooooã§ã™ã€‚ 昨日ã¯@kuwa_twã•ã‚“ã®ã‚·ã‚§ãƒ«ã‚¹ã‚¯ãƒªãƒ—トã ã‘ã§MySQLã‹ã‚‰MongoDBã¸ã®ç§»è¡Œã—ã¡ã‚ƒã†ã§ã—ãŸã€‚ Mongoã®ãƒ¡ãƒ¢ãƒªé£Ÿã„ã¾ãã‚Šãªä»•æ§˜ãŒæ°—ã«ãªã£ã¦ã¾ã™ãƒ»ãƒ»ãƒ»ã€‚RDBã•ã„ã“ーｗ MySQL界隈ã§ã¯ã‚„ã£ã±ã‚ŠMariaDBã¯RHEL7ã¨ã‹ã§æ¨™æº–ã«ãªã£ãŸã‚Šã¨ã€ç†±ã„ã§ã™ã‚ˆã。é©å½“ãªã‚‚ã®ã§ã¾ãšã¯è©¦ã—ã¦ã¿ãŸã„ã§ã™ã€‚Galera clusterã£ã¦ãã†ã„ã°ã©ã†ãªã£ãŸã‚“ã ã‚・・・。 本日ã®å†…容 標題ã®é€šã‚Šã§ã™ã€‚今更ãªãŒã‚‰5.5ã‹ã‚‰5.6ã«ç§»è¡Œã—ãŸãƒ‡ãƒ¼ã‚¿ãƒ™ãƒ¼ã‚¹ã§ICPã«ã‚ˆã‚Šå•é¡ŒãŒèµ·ã“ã£ã¦ã—ã¾ã„ã¾ã—ãŸã€‚ãã®ã“ã¨ã‚’書ã“ã†ã¨æ€ã„ã¾ã™ã€‚ ICP(Index Condition Pushdown)ã¨ã¯ï¼Ÿ 5.6ã®æ–°æ©Ÿèƒ½ デフォルトON ç°¡å˜ã«æ©Ÿèƒ½èª¬æ˜Ž マルãƒã‚«
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MySQL 今更ãªãŒã‚‰online-schema-changeã«ã¤ã„㦠| Ore no homepage
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MySQL :: MySQL 8.4 Reference Manual :: B.3.2.8 Packet Too Large
A communication packet is a single SQL statement sent to the MySQL server, a single row that is sent to the client, or a binary log event sent from a replication source server to a replica. The largest possible packet that can be transmitted to or from a MySQL 8.4 server or client is 1GB. When a MySQL client or the mysqld server receives a packet bigger than max_allowed_packet bytes, it issues an
MySQL :: MySQL 8.4 Reference Manual :: 15.2.17 UPDATE Statement
SAVEPOINT, ROLLBACK TO SAVEPOINT, and RELEASE SAVEPOINT Statements
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MySQL5.0/5.1ã§ã‚¹ãƒãƒ¼ã‚¯ã‚¨ãƒªãƒã‚°ã‚’記録 - よんã¡ã‚…Blog
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stop using numbers as IDs. just use UUIDs. seriously — Postgres: The Bits You Haven’t Found by pvh UUID ã®é•ã„ v1 Generate a UUID from a host ID, sequence number, and the current time. v3 Generate a UUID from the MD5 hash of a namespace UUID and a name. v4 Generate a random UUID v5 Generate a UUID from the SHA-1 hash of a namespace UUID and a name. ã“ã®å†…ã€ID ã¨ã—ã¦åˆ©ç”¨ã§ãã‚‹ã®ã¯ v1 㨠v4 ã®2ã¤ã€‚v1 ã¯æœ€å¾Œ 48 ビットãŒãƒãƒ¼ãƒ‰å›ºæœ‰ã®ãƒŽãƒ¼
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MERGE,UPSERTã¨è¨€ã‚れるã€UPDATEæ–‡ã¨INSERT文をæ¡ä»¶ã«ã‚ˆã£ã¦è‡ªå‹•çš„ã«åˆ‡ã‚Šæ›¿ãˆã‚‹ã“ã¨ãŒã§ãã‚‹SQLæ–‡ã¯ã€MySQLã§ã¯2種類用æ„ã•ã‚Œã¦ã„ã¾ã™ã€‚ REPLACEã€INSERT ON DUPLICATE KEY UPDATEã§ã™ã€‚ ãã‚Œãžã‚Œã®é•ã„㯠REPLACE INSERTæ–‡ã¨åŒã˜æ§‹æ–‡ã§INSERTã®éƒ¨åˆ†ã‚’REPLACEã«ç½®ãæ›ãˆãŸã‚‚㮠動作ã¨ã—ã¦ã¯é€šå¸¸ã®INSERTã¨åŒã˜ã§DUPLICATE KEYãŒç™ºç”Ÿã—ãŸå ´åˆã«è©²å½“ã®ãƒ¬ã‚³ãƒ¼ãƒ‰ã‚’削除ã—ã¦INSERT INSERT ON DUPLICATE KEY UPDATE INSERTæ–‡ã®ã‚ªãƒ—ションã¨ã—ã¦è¨˜è¿° 動作ã¨ã—ã¦ã¯é€šå¸¸ã®INSERTã¨åŒã˜ã§DUPLICATE KEYãŒç™ºç”Ÿã—ãŸå ´åˆã«ã‚ªãƒ—ションã§æŒ‡å®šã—ãŸUPDATE文を実行 REPLACEæ–‡ã¯æ†¶ãˆã‚„ã™ã„ã“ã¨ã‚‚ã‚ã£ã¦ã€çŸ¥ã£ã¦ã„る人も多ã„ã‹ã¨æ€ã„ã¾ã™ãŒã€ã‚¢ãƒ—リケーションã§å®Ÿéš›ã«ä½¿
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