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Re: Query running slower than same on Oracle

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Sailer, Denis (YBUSA-CDR)" <Denis(dot)Sailer(at)Yellowbook(dot)com>
Cc: "'pgsql-performance(at)postgresql(dot)org'" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Query running slower than same on Oracle
Date: 2003-06-25 21:50:45
Message-ID: 18325.1056577845@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
"Sailer, Denis (YBUSA-CDR)" <Denis(dot)Sailer(at)Yellowbook(dot)com> writes:
> We are evaluating PostgreSQL for a typical data warehouse application.  I
> have 3 tables below that are part of a Star schema design.  The query listed
> below runs in 16 seconds on Oracle 9.2 and 3+ minutes on PostgreSQL 7.3.3
> Here are the details.

The majority of the runtime seems to be going into the sort step.  There
is not much to be done about this in 7.3, but 7.4 should use a hashed
aggregation approach for this query, which'd eliminate the sort step and
hopefully reduce the time a great deal.  Since you're only doing
evaluation at this point, it might be worth your while to try out CVS
tip ...

			regards, tom lane

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Subject: Re: Query running slower than same on Oracle
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Subject: Query running slower than same on Oracle

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