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Rails 6 MySQLͷutf8mb4 ରԠͱ͸ԿͰ͋ͬͯԿͰ͸ ͳ͍ͷ͔ RejectKaigi 2019 @yahonda

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Rails, not Ruby?

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"Your proposal for RailsConf 2019 has not been accepted"

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Rails 6 RC1 is coming

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utf8mb4ͰͰ͖Δ͜ͱ

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Emoji

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[Railsdm 2018: Day3 ಛผߨԋ] Rails 6 ʹ޲͚ ͨ ActiveRecord ͷվળ

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yahonda “MySQLͷDEFAULT CHARACTER SETΛɺutf8mb4 ʹ͢Δͷ͸͍͍ΞΠσΟΞͩͱ ࢥΘΕ·͢Ͱ͠ΐ͏͔ɻ"

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kamipo “(σϑΥϧτΛutf8mb4ʹ͢Δͷ ͸)͜Ε͸ݫ͍͠" "key prefix lengthͷ໰୊ΛϢʔβʔʹԡ ͚͍͍ͭͯ͠ΜͩͬͨΒ(utf8mb4͕)σ ϑΥϧτʹͳΔ(Մೳੑ͕͋Δ)"

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"MySQL schema/ migration should default to CHARSET=utf8mb4” by DHH rails/rails#33596

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"Use utf8mb4 character set by default for MySQL database #33608” by yahonda rails/rails#33608

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Key prefix lengthͷ໰୊ͱ͸ • "ERROR 1071 (42000): Specified key was too long; max key length is 767 bytes" • Rails string type is mapped to MySQL varchar(255) • 255(characters) x 4(bytes) = 1020 > 767

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Key prefix length໰୊͸ Ͳ͏΍ͬͯղܾ͞Ε͔ͨ

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5.7 and 8.0 • innodb_default_row_format ͕༗ޮͳͷͰͦͷ··

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5.5 and 5.6 • Add ROW_FORMAT=DYNAMIC option if innodb_file_per_table = 1 AND innodb_file_format = 'Barracuda' • https://github.com/rails/rails/pull/34742

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Priority • ࠷༏ઌ • database.yml default value: encoding: utf8mb4 • σϑΥϧτͷdatabase.ymlΛฤूͨ͠৔߹ • options[:collation] • options[:charset] (options[:encoding] ͱಉ͡ҙຯ) • optionsͷࢦఆ͕ͳ͍ & MySQL 5.7.9Ҏ্ • utf8mb4 • optionsͷࢦఆ͕ͳ͍ & MySQL 5.6ҎԼ • "Configure a supported :charset and ensure innodb prefix is enabled to support indexes on varchar(255) string columns."

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What about collation?

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Rails 6 does not have any “default collation”

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https://github.com/ rails/rails/issues/ 33596

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Since proper collation is language dependent (that is the reason that Unicode provide multi level comparison), I personally would not like to provide any collation by default.

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I basically answer "Please consider using default collation (utf8mb4_general_ci in MySQL 5.7 case). If it has any issue for your use case (Sushi-Beer issue, etc), using utf8mb4_bin might avoid that issue.".

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Enjoy Rails 6!