From: Jignesh K. Shah <J.K.Shah@Sun.COM>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Gregory Stark <stark@enterprisedb.com>
Cc: pgsql-performance@postgresql.org
Cc: pgsql-hackers@postgresql.org
Subject: Re: [HACKERS] 8.3beta1 testing on Solaris
Date: Fri, 26 Oct 2007 09:25:02 -0400
Message-ID: <4721EAAE.3020801@sun.com> (raw)
In-Reply-To: <29721.1193359867@sss.pgh.pa.us>
References: <4720FB72.8060800@sun.com>
<26010.1193345641@sss.pgh.pa.us>
<871wbi95nb.fsf@oxford.xeocode.com>
<29721.1193359867@sss.pgh.pa.us>
The problem I saw was first highlighted by EAStress runs with PostgreSQL
on Solaris with 120-150 users. I just replicated that via my smaller
internal benchmark that we use here to recreate that problem.
EAStress should be just fine to highlight it.. Just put pg_clog on
O_DIRECT or something so that all IOs go to disk making it easier to
observe.
In the meanwhile I will try to get more information.
Regards,
Jignesh
Tom Lane wrote:
> Gregory Stark <stark@enterprisedb.com> writes:
>
>> Didn't we already go through this? He and Simon were pushing to bump up
>> NUM_CLOG_BUFFERS and you were arguing that the test wasn't representative and
>> some other clog.c would have to be reengineered to scale well to larger
>> values.
>>
>
> AFAIR we never did get any clear explanation of what the test case is.
> I guess it must be write-mostly, else lazy XID assignment would have
> helped this by reducing the rate of XID consumption.
>
> It's still true that I'm leery of a large increase in the number of
> buffers without reengineering slru.c. That code was written on the
> assumption that there were few enough buffers that a linear search
> would be fine. I'd hold still for 16, or maybe even 32, but I dunno
> how much impact that will have for such a test case.
>
> regards, tom lane
>
> ---------------------------(end of broadcast)---------------------------
> TIP 9: In versions below 8.0, the planner will ignore your desire to
> choose an index scan if your joining column's datatypes do not
> match
>
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To: pgsql-performance@postgresql.org
Cc: J.K.Shah@Sun.COM, tgl@sss.pgh.pa.us, stark@enterprisedb.com, pgsql-hackers@postgresql.org
Subject: Re: [HACKERS] 8.3beta1 testing on Solaris
In-Reply-To: <4721EAAE.3020801@sun.com>
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