Re: postgres 8.4, COPY, and high concurrency - Mailing list pgsql-performance

From Jeff Janes
Subject Re: postgres 8.4, COPY, and high concurrency
Date
Msg-id CAMkU=1wu72umecMkhwvA9ERbK5diFZ8ex5RbOatDWccF9Fp8iA@mail.gmail.com
Whole thread Raw
In response to Re: postgres 8.4, COPY, and high concurrency  (Jon Nelson <jnelson+pgsql@jamponi.net>)
Responses Re: postgres 8.4, COPY, and high concurrency
List pgsql-performance
On Wed, Nov 14, 2012 at 6:41 AM, Jon Nelson <jnelson+pgsql@jamponi.net> wrote:
>
> UPDATE: I have been able to replicate the issue. The parent table (the
> one referenced in the LIKE portion of the CREATE TABLE statement) had
> three indices.
>
> Now that I've been able to replicate the issue, are there tests that I
> can perform that would be useful to people?
> I will also try to build a stand-alone test.

While the WAL is suppressed for the table inserts, it is not
suppressed for the index inserts, and the index WAL traffic is enough
to lead to contention.

I don't know why that is the case, it seems like the same method that
allows us to bypass WAL for the table would work for the indices as
well.  Maybe it is just that no one bothered to implement it.  After
all, building the index after the copy will be even more efficient
than building it before but by-passing WAL.

But it does seem like the docs could at least be clarified here.

Cheers,

Jeff


pgsql-performance by date:

Previous
From: Tom Lane
Date:
Subject: Re: SOLVED - RE: Poor performance using CTE
Next
From: Jon Nelson
Date:
Subject: Re: postgres 8.4, COPY, and high concurrency