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Re: lock contention on parallel COPY ?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Simon Riggs <simon(at)2ndQuadrant(dot)com>
Cc: Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc>, 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 18:00:02
Message-ID: 23005.1222452002@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
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...

			regards, tom lane

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