Re: lock contention on parallel COPY ?

From: Andrew Dunstan <andrew(at)dunslane(dot)net>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: lock contention on parallel COPY ?
Date: 2008-09-26 16:13:44
Message-ID: 48DD0A38.7000402@dunslane.net
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Tom Lane wrote:
> Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc> writes:
>
>> samples % symbol name
>> 1933314 21.8884 LWLockAcquire
>> 1677808 18.9957 XLogInsert
>> 848227 9.6034 LWLockRelease
>> 414179 4.6892 DoCopy
>> 332633 3.7660 CopyReadLine
>> 266580 3.0181 UnpinBuffer
>> 221693 2.5099 heap_formtuple
>>
>
> I suppose Andrew didn't yet put in the hack to avoid WAL logging
> during the COPY commands. The LWLockAcquires are presumably
> blocking on WALInsertLock, given that XLogInsert is also right
> up there ...
>
>
>

Yes I did. That's what the --truncate-before-load switch does (or should
do).

cheers

andrew

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