Have you run into this trouble with grouping in oracle, especially after transferring your database into different system running obviously a different version of oracle ? Be cool.
Oracle introduced a hash-based GROUP BY in 10.2. Previously, a GROUP BY operation involved sorting the data on the relevent columns, then accumulating aggregate results.
What does it means ?
before 10.2 : select name , id from table group by id, name => will work
after 10.2 : select name , id from table group by id, name => will not work
but select name , id from table group by id, name order by id, name => will work
To disable the hash-based group by using the following command under a user with sysdba' privilege:
> alter system set "_gby_hash_aggregation_enabled" = FALSE scope=BOTH;
> commit;
Oracle introduced a hash-based GROUP BY in 10.2. Previously, a GROUP BY operation involved sorting the data on the relevent columns, then accumulating aggregate results.
What does it means ?
before 10.2 : select name , id from table group by id, name => will work
after 10.2 : select name , id from table group by id, name => will not work
but select name , id from table group by id, name order by id, name => will work
To disable the hash-based group by using the following command under a user with sysdba' privilege:
> alter system set "_gby_hash_aggregation_enabled" = FALSE scope=BOTH;
> commit;
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