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default_scope behavior causes the generated SQL to be invalid for PostgreSQL

#5836

When I have something like

class Model < ActiveRecord::Base
  default_scope order(:ordering_column)
end

and I call

@counts = Model.group(:grouping_column).count

in the controller(or elsewhere), ActiveRecord still appends ORDER BY 'ordering_column' to the generated SQL. This causes no problems in SQLite (probably ignored) but raises an Invalid SQL error with PostgreSQL, saying that the ordering column isn't in the query.

Either the PostgreSQL adapter or Arel should probably discard the unnecessary ORDER_BY statement for this to behave nicely.

Reported by Mert Torun · October 18th, 2010 @ 03:34 PM

Activity

Andrew White
- Importance changed from to Low
Is there any situation where an ORDER BY statement is useful in a COUNT query - I can't think of one. Perhaps AR::Relation should drop the order clause on all count queries?

As a workaround you can use except to remove the order clause:
```
@counts = Model.except(:order).group(:grouping_column).count
```
October 18th, 2010 @ 04:10 PM
Santiago Pastorino
- State changed from new to open
This issue has been automatically marked as stale because it has not been commented on for at least three months.

The resources of the Rails core team are limited, and so we are asking for your help. If you can still reproduce this error on the 3-0-stable branch or on master, please reply with all of the information you have about it and add "[state:open]" to your comment. This will reopen the ticket for review. Likewise, if you feel that this is a very important feature for Rails to include, please reply with your explanation so we can consider it.

Thank you for all your contributions, and we hope you will understand this step to focus our efforts where they are most helpful.

February 2nd, 2011 @ 04:29 PM
Santiago Pastorino
- State changed from open to stale
February 2nd, 2011 @ 04:29 PM
bingbing
gucci watches

March 26th, 2011 @ 01:25 AM