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Subject: Re: VLDB Features
From: Hannu Krosing <hannu@skype.net>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Josh Berkus <josh@agliodbs.com>, Neil Conway <neilc@samurai.com>,
	pgsql-hackers@postgresql.org, Simon Riggs <simon@2ndquadrant.com>
In-Reply-To: <6430.1197699178@sss.pgh.pa.us>
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Date: Sat, 15 Dec 2007 13:10:30 +0200
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=C3=9Chel kenal p=C3=A4eval, L, 2007-12-15 kell 01:12, kirjutas Tom Lane:
> Josh Berkus <josh@agliodbs.com> writes:
> > There's no way we can do a transactionless load, then?  I'm thinking =
of the=20
> > load-into-new-partition which is a single pass/fail operation.  Would=
=20
> > ignoring individual row errors in for this case still cause these kin=
ds of=20
> > problems?
>=20
> Given that COPY fires triggers and runs CHECK constraints, there is no
> part of the system that cannot be exercised during COPY.  So I think
> supposing that we can just deal with some simplified subset of reality
> is mere folly.

But can't we _define_ such a subset, where we can do a transactionless
load ?

I don't think that most DW/VLDB schemas fire complex triggers or custom
data-modifying functions inside CHECK's.

Then we could just run the remaining simple CHECK constraints ourselves
and not abort on non-check, but just log the rows ?

The COPY ... WITH ERRORS TO ... would essentially become a big
conditional RULE through which the incoming data is processed.

------------------
Hannu