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Support default expression and expression indexes for MySQL#34307
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MySQL 8.0.13 and higher supports functional key parts that indexexpression values rather than column or column prefix values.https://dev.mysql.com/doc/refman/8.0/en/create-index.html
MySQL 8.0.13 and higher supports default value to be a function orexpression.https://dev.mysql.com/doc/refman/8.0/en/create-table.html
1ac65ef toa2ad8f4Compare| lengths=options.delete(:lengths) | ||
| columns=index[-2].map{ |name| | ||
| [name.to_sym,expressions[name] || +quote_column_name(name)] |
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Why would we want to dupquote_column_name(name) here?
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This is because the quoted columns would be mutated byadd_index_length andadd_index_sort_order:
rails/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
Lines 109 to 112 ina3dcba4
| defadd_index_length(quoted_columns, **options) | |
| lengths=options_for_index_columns(options[:length]) | |
| quoted_columns.eachdo |name,column| | |
| column <<"(#{lengths[name]})"iflengths[name].present? |
rails/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
Lines 1195 to 1198 ina3dcba4
| defadd_index_sort_order(quoted_columns, **options) | |
| orders=options_for_index_columns(options[:order]) | |
| quoted_columns.eachdo |name,column| | |
| column <<"#{orders[name].upcase}"iforders[name].present? |
chrismaximinOct 26, 2018 • edited
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Ah I see, I thoughtquote_column_name would return something that was already duped somehow... because it is the case of
rails/activerecord/lib/active_record/connection_adapters/abstract/quoting.rb
Lines 67 to 69 in6149080
| defquote_column_name(column_name) | |
| column_name.to_s | |
| end |
... but I didn't realise the method may always return the same object like ...
| defquote_column_name(name) | |
| @quoted_column_names[name] ||="`#{super.gsub('`','``')}`" | |
| end |
... got it :)
I'm just realising that there's no way (AFAIK) to know whether a method returns an object that is referenced elsewhere or not, which is kind of sad, because we may be duplicating strings for no reason (if a method returns a new object or an existing object), maybe we should do something about that one day.
chrismaximinOct 26, 2018 • edited
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Nevermind, I misread this whole thing 👍
Support default expression and expression indexes for MySQLrails/rails#34307
MySQL 8.0.13 is released a few days ago.
https://mysqlserverteam.com/the-mysql-8-0-13-maintenance-release-is-generally-available/
Now we can supports default expression and expression indexes for mysql2 adapter.