Re: COPY with no WAL, in certain circumstances

FYI, I am going need to add documentation in the COPY manual page or no
one will know about this performance enhancement.

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Simon Riggs wrote:
> http://archives.postgresql.org/pgsql-hackers/2006-10/msg01172.php
>
> As discussed on -hackers, its possible to avoid writing any WAL at all
> for COPY in these circumstances:
>
> BEGIN;
> CREATE TABLE foo..
> COPY foo...
> COMMIT;
>
> BEGIN;
> TRUNCATE foo..
> COPY foo...
> COMMIT;
>
> The enclosed patch implements this, as discussed. There is no user
> interface to enable/disable, just as with CTAS and CREATE INDEX; no
> docs, just code comments.
>
> This plays nicely with the --single-transaction option in psql to allow
> fast restores/upgrades.
>
> YMMV but disk bound COPY will benefit greatly from this patch, some
> tests showing 100% gain. COPY is still *very* CPU intensive, so some
> tests have shown negligible benefit, fyi, but that isn't the typical
> case.
>
> Applies cleanly to CVS HEAD, passes make check.
>
> --
> Simon Riggs
> EnterpriseDB http://www.enterprisedb.com
>

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