Re: lock contention on parallel COPY ?

From: Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Simon Riggs <simon(at)2ndQuadrant(dot)com>, Andrew Dunstan <andrew(at)dunslane(dot)net>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: lock contention on parallel COPY ?
Date: 2008-09-26 18:07:58
Message-ID: 48DD24FE.5050909@kaltenbrunner.cc
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Tom Lane wrote:
> Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
>> Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc> writes:
>>> samples % symbol name
>>> 55526 16.5614 LWLockAcquire
>>> 29721 8.8647 DoCopy
>>> 26581 7.9281 CopyReadLine
>>> 25105 7.4879 LWLockRelease
>>> 15743 4.6956 PinBuffer
>>> 14725 4.3919 heap_formtuple
>
>> Probably loading a table with a generated PK or loading data in
>> ascending sequence, so its contending heavily for the rightmost edge of
>> the index.
>
> No, given that DoCopy and CopyReadLine are right up there, I think we're
> still looking at the COPY phase, not index building.
>
> The profile will probably change completely once index building
> starts...

yeah this profile is only showing the COPY phase ...

Stefan

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