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| author | Rafael França <rafaelmfranca@gmail.com> | 2016-11-05 20:05:47 -0400 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2016-11-05 20:05:47 -0400 |
| commit | 2b2c096125edc3becc970bea331d8f26cd6a3ed5 (patch) | |
| tree | 6d7e4da07b6583d2851a94977dd64353d36ef393 | |
| parent | 81e16dad6c151611d0c1e5fd7927378d58e6344a (diff) | |
| parent | 62bb8b9dfdf4101b4cefedb36a97531e750d623c (diff) | |
| download | rails-2b2c096125edc3becc970bea331d8f26cd6a3ed5.tar.gz rails-2b2c096125edc3becc970bea331d8f26cd6a3ed5.tar.bz2 rails-2b2c096125edc3becc970bea331d8f26cd6a3ed5.zip | |
Merge pull request #26972 from kamipo/avoid_unscope_order_when_limit_value_present
Avoid `unscope(:order)` when `limit_value` is presented for `count`
| -rw-r--r-- | activerecord/CHANGELOG.md | 13 | ||||
| -rw-r--r-- | activerecord/lib/active_record/relation/calculations.rb | 12 |
2 files changed, 17 insertions, 8 deletions
diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md index 400f4942c4..d2adc530a4 100644 --- a/activerecord/CHANGELOG.md +++ b/activerecord/CHANGELOG.md @@ -1,5 +1,14 @@ -* Fix an Active Record DateTime field NoMethodError caused by incomplete - datetime. [Bug #24195](https://github.com/rails/rails/issues/24195) +* Avoid `unscope(:order)` when `limit_value` is presented for `count`. + + If `limit_value` is presented, records fetching order is very important + for performance. Should not unscope the order in the case. + + *Ryuta Kamizono* + +* Fix an Active Record DateTime field NoMethodError caused by incomplete + datetime. + + Fixes #24195. *Sen Zhang* diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb index e4676f79a5..827688a663 100644 --- a/activerecord/lib/active_record/relation/calculations.rb +++ b/activerecord/lib/active_record/relation/calculations.rb @@ -223,17 +223,17 @@ module ActiveRecord end def execute_simple_calculation(operation, column_name, distinct) #:nodoc: - # PostgreSQL doesn't like ORDER BY when there are no GROUP BY - relation = unscope(:order) - column_alias = column_name - if operation == "count" && (relation.limit_value || relation.offset_value) + if operation == "count" && (limit_value || offset_value) # Shortcut when limit is zero. - return 0 if relation.limit_value == 0 + return 0 if limit_value == 0 - query_builder = build_count_subquery(relation, column_name, distinct) + query_builder = build_count_subquery(spawn, column_name, distinct) else + # PostgreSQL doesn't like ORDER BY when there are no GROUP BY + relation = unscope(:order) + column = aggregate_column(column_name) select_value = operation_over_aggregate_column(column, operation, distinct) |