From: | Bruno Wolff III <bruno(at)wolff(dot)to> |
---|---|
To: | Adam Sherman <adam(at)tritus(dot)ca> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: Performance Problem |
Date: | 2003-05-12 15:42:43 |
Message-ID: | 20030512154243.GA5758@wolff.to |
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Thread: | |
Lists: | pgsql-general |
On Mon, May 12, 2003 at 09:57:12 -0400,
Adam Sherman <adam(at)tritus(dot)ca> wrote:
>
> BEGIN
> while(list)
> lookup for existing entry (SELECT)
> if not, INSERT
> if yes, UPDATE
> log a message
> COMMIT
>
> With approx. 30K items the process takes way too long. On the order of 10+
> minutes.
>
> I notice that the process seems to slow down as it completes more and more
> items. ie, the first 10K takes just a few moments while the last 10K takes
> most of the time. Note that I'm running test where the only existing
> entries will have been inserted in the same transaction.
>
> I need to know if the bottleneck is PG or higher up so I can go hunting
> there.
Are there deferred constraints? They are still order n squared. Some
fixes went in to 7.3 but the last order n squared issue wasn't fixed
until 7.4. There was some discussion of back porting the fix to 7.3.3
(which might be available in about a month) but I am not sure whether
or that is going to happen.
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