Re: Using multi-row technique with COPY

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Simon Riggs <simon(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Using multi-row technique with COPY
Date: 2005-11-29 20:15:21
Message-ID: 200511292015.jATKFLe17985@candle.pha.pa.us
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Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > Tom Lane wrote:
> >> Something that would probably be reasonable, and require *no* weird new
> >> syntax, is to shortcut in a COPY into a table created in the current
> >> transaction. I believe we still keep a flag in the relcache indicating
> >> whether that's the case ...
>
> > So if the table is created in the current transaction, we don't log?
>
> Log, yes, unless it's a temp table. The point is we could avoid taking
> buffer content locks. Come to think of it, we could implement that
> trivially in the heapam.c routines; it would then apply to any table
> update whether generated by COPY or otherwise.

I am confused. This optimization prevents locking, but still requires
logging?

> > Yes, I guess, but do we want to propogate that into pg_dump output? I
> > would think not.
>
> Exactly my point; we don't have to change any syntax, so pg_dump
> doesn't care.

But can pg_dump take advantage of this optimization?

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