Re: COPY with no WAL, in certain circumstances

From: "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)postgresql(dot)org, Robert Treat <xzilla(at)users(dot)sourceforge(dot)net>, pgsql-patches(at)postgresql(dot)org, Simon Riggs <simon(at)2ndquadrant(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>
Subject: Re: COPY with no WAL, in certain circumstances
Date: 2007-01-07 02:37:47
Message-ID: 1168137467.869.13.camel@localhost.localdomain
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> > Is there some technical reason that the INSERT statements need to use WAL in
> > these scenarios?
>
> First, there's enough other overhead to an INSERT that you'd not save
> much percentagewise. Second, not using WAL doesn't come for free: the
> cost is having to fsync the whole table afterwards. So it really only
> makes sense for commands that one can expect are writing pretty much
> all of the table. I could easily see it being a net loss for individual
> INSERTs.

What about multi value inserts? Just curious.

Joshua D. Drake

>
> regards, tom lane
>
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