| From: | Alan Li <ali(at)truviso(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Greg Smith <gsmith(at)gregsmith(dot)com>, Andrew Dunstan <andrew(at)dunslane(dot)net>, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: 8.4 open item: copy performance regression? |
| Date: | 2009-06-23 00:29:44 |
| Message-ID: | 782056770906221729o573f9511s184b966fc7118e2@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Mon, Jun 22, 2009 at 7:16 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Alan Li <ali(at)truviso(dot)com> writes:
> > How much concern is there for the contention for use cases where the WAL
> > can't be bypassed?
>
> If you mean "is something going to be done about it in 8.4", the
> answer is "no". This is a pre-existing issue that there is no simple
> fix for.
>
> regards, tom lane
>
>
> No no, I am certainly not implying anything for the 8.4 timeframe.
Moving forward, I imagine this being more of a problem for data warehouse
applications, where bulk inserts occur on existing fact tables. In this
case, the WAL cannot be bypassed (unless the bulk insert occurs on a newly
created partition). And since COPY is cpu-bound, it would perhaps be
advantageous to do parallel COPY's on the same table on multi-core systems,
which won't work with WAL bypassing either.
Thanks, Alan
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