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| author | Ryuta Kamizono <kamipo@gmail.com> | 2015-12-23 22:38:41 +0900 |
|---|---|---|
| committer | Ryuta Kamizono <kamipo@gmail.com> | 2015-12-23 22:47:44 +0900 |
| commit | 9c5732d23447a2880dafc7f80254b1c9e42863f8 (patch) | |
| tree | af10e717cc2feb94c56fc0eb54fbb9cabd52bf45 /activerecord/lib/active_record/connection_adapters | |
| parent | a093afd8ce6d15ea38972141f6000fe3798b6667 (diff) | |
| download | rails-9c5732d23447a2880dafc7f80254b1c9e42863f8.tar.gz rails-9c5732d23447a2880dafc7f80254b1c9e42863f8.tar.bz2 rails-9c5732d23447a2880dafc7f80254b1c9e42863f8.zip | |
Avoid `distinct` if a subquery has already materialized
Follow up to #19359 and avoid #22241.
Diffstat (limited to 'activerecord/lib/active_record/connection_adapters')
| -rw-r--r-- | activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb index f8c9e13392..b9a9c22198 100644 --- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb +++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb @@ -965,11 +965,13 @@ module ActiveRecord subsubselect = select.clone subsubselect.projections = [key] + # Materialize subquery by adding distinct + # to work with MySQL 5.7.6 which sets optimizer_switch='derived_merge=on' + subsubselect.distinct unless select.limit || select.offset || select.orders.any? + subselect = Arel::SelectManager.new(select.engine) subselect.project Arel.sql(key.name) - # Materialized subquery by adding distinct - # to work with MySQL 5.7.6 which sets optimizer_switch='derived_merge=on' - subselect.from subsubselect.distinct.as('__active_record_temp') + subselect.from subsubselect.as('__active_record_temp') end def mariadb? |