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Data Bases > Pgsql Performance > Re: Group by mo...
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Re: Group by more efficient than distinct?

by mlists@[EMAIL PROTECTED] (Thomas Pundt) Apr 18, 2008 at 09:25 AM

On Freitag, 18. April 2008, Francisco Reyes wrote:
| I am trying to get a distinct set of rows from 2 tables.
| After looking at someone else's query I noticed they were doing a group
by
| to obtain the unique list.
|
| After comparing on multiple machines with several tables, it seems using
| group by to obtain a distinct list is substantially faster than using
| select distinct.
|
| Is there any dissadvantage of using "group by" to obtain a unique list?

Searching the archives suggests that the code related to "group by" is
much
newer than the one related to "distinct" and thus might benefit from more
optimization paths.

Ciao,
Thomas

-- 
Thomas Pundt <thomas.pundt@[EMAIL PROTECTED]
> ---- http://rp-online.de/
----

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 14 Posts in Topic:
Group by more efficient than distinct?
lists@[EMAIL PROTECTED]   2008-04-17 23:46:08 
Re: Group by more efficient than distinct?
mlists@[EMAIL PROTECTED]   2008-04-18 09:25:04 
Re: Group by more efficient than distinct?
stark@[EMAIL PROTECTED]   2008-04-18 10:36:02 
Re: Group by more efficient than distinct?
lists@[EMAIL PROTECTED]   2008-04-18 12:35:04 
Re: Group by more efficient than distinct?
lists@[EMAIL PROTECTED]   2008-04-20 11:15:36 
Re: Group by more efficient than distinct?
lists@[EMAIL PROTECTED]   2008-04-22 01:34:40 
Re: Group by more efficient than distinct?
mark@[EMAIL PROTECTED] (  2008-04-21 19:50:22 
Re: Group by more efficient than distinct?
mark@[EMAIL PROTECTED] (  2008-04-21 21:39:15 
Re: Group by more efficient than distinct?
lists@[EMAIL PROTECTED]   2008-04-20 11:12:10 
Re: Group by more efficient than distinct?
llonergan@[EMAIL PROTECTE  2008-04-20 22:35:58 
Re: Group by more efficient than distinct?
matthew@[EMAIL PROTECTED]  2008-04-22 11:34:23 
Re: Group by more efficient than distinct?
mark@[EMAIL PROTECTED] (  2008-04-22 08:01:20 
Re: Group by more efficient than distinct?
matthew@[EMAIL PROTECTED]  2008-04-22 13:22:20 
Re: Group by more efficient than distinct?
mark@[EMAIL PROTECTED] (  2008-04-22 09:04:30 

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tan12V112 Mon Dec 1 8:19:18 CST 2008.