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Re: Using multi-row technique with COPY

From: Harald Fuchs <hf0923x(at)protecting(dot)net>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Using multi-row technique with COPY
Date: 2005-11-29 12:35:09
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers
In article <20051129004435(dot)GR78939(at)pervasive(dot)com>,
"Jim C. Nasby" <jnasby(at)pervasive(dot)com> writes:

> On Sun, Nov 27, 2005 at 07:44:55PM +0000, Simon Riggs wrote:
>> not have any unique indexes or row triggers. It should be possible to
>> take advantage of this automatically when those requirements are met,
>> without any new options. Just as it was with Seq Scans, this is worth
>> about 10% reduction in CPU for a COPY FROM.
> <snip> 
>> FSM access would need to change slightly to allow for whole-block-only
>> requests to be made for heaps, without damaging the average row length
>> calculation. It might be simpler to ignore FSM entirely?

> Does that mean that this fast copy would end up not re-using space on
> pages that have space available? ISTM that's something users would want
> to be able to over-ride. In fact, it seems like it shouldn't be a
> default behavior...

Why not?  If you later do INSERT/UPDATE/DELETE, space will get reused
anyway, and if you don't (i.e. one-time bulk load on a constant
table), you should afterwards do a VACUUM FULL ANALYZE anyway.

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