Re: 64-bit CommandIds

From: Hans-Juergen Schoenig <hs(at)cybertec(dot)at>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, Zoltan Boszormenyi <zb(at)cybertec(dot)at>, pgsql-patches <pgsql-patches(at)postgresql(dot)org>
Subject: Re: 64-bit CommandIds
Date: 2008-04-25 18:03:25
Message-ID: 48121CED.3090707@cybertec.at
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Tom Lane wrote:
> Hans-Juergen Schoenig <hs(at)cybertec(dot)at> writes:
>
>> Alvaro Herrera wrote:
>>
>>> Question for Hans-Juergen and Zoltan: have you tested 8.3 and do you
>>> still see the need for this?
>>>
>
>
>> i have seen this problem two or three times within the past 2-3 years or
>> so. so, it can basically happen in the field for some special purpose
>> applications but i don't see this as an every day problem. it would be
>> nice to have it in.
>>
>
> So these experiences were pre-8.3, right?
>
> The reason that I'm harping on that is that plpgsql does a
> CommandCounterIncrement for each expression it evaluates, whether
> or not there's any visible database access. As of 8.3 that won't
> cause consumption of CIDs, but before it did. I suspect that in a
> lot of real-world scenarios, CID consumption from triggers will be
> down by an order of magnitude.
>
> regards, tom lane
>

we found those problems when we dealt with stored procedures basically
(during huge analysis and data modification transactions - rollup and
materialize stuff, basically). i would think as well that it should have
improved a lot.

i have not tested with 8.3, however.
on 8.2 it took something like 18 hours to reach that threshold - just to
give you an impression.

many thanks,

hans

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