From: David Aldridge <>
Date: Wed, 23 Apr 2008 13:37:39 -0700 (PDT)
Message-ID: <>

There have also been a few genuine bugs as well -- I'm using it in and haven't seen any issues though.

Searching the metalink bug database for _gby_hash_aggregation_enabled=false generally shows them.

  • Original Message ---- From: "Elliott, Patrick" <> To: "Elliott, Patrick" <>; "" <>; "" <> Sent: Wednesday, April 23, 2008 3:20:58 PM Subject: RE: HASH GROUP BY

Now I understand what you mean by buggy. It no longer sorts the rows. If you have code that relies on a group by being in sorted order, then the code will no longer work. If you have had to disable this in the past to get correct results, then you will need to continue disabling it indefinitely. The only way to fix it and reenable the hashing group by is to change the code.  

select column_a, column_b, count(column_c) from table_abc
group by column_a, column_b
order by column_a, column_b  

You need to add the order by above to your code where you just had the "group by" alone before.  


From: [] On Behalf Of Elliott, Patrick Sent: Wednesday, April 23, 2008 1:44 PM
To:; Subject: RE: HASH GROUP BY

This is enabled by default in version and up. Are you explicitly disabling it in your environment?  


From: [] On Behalf Of Rob Dempsey Sent: Wednesday, April 23, 2008 12:08 PM To:


Our current Oracle version ->  

Does anyone know what version this feature has been fixed in. I would like to enable the feature, but it seems to have been very buggy (especially with wrong results)  

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Received on Wed Apr 23 2008 - 15:37:39 CDT

Original text of this message