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Message-ID: <43EC6531.60202@logix-tt.com>
Date: Fri, 10 Feb 2006 11:04:33 +0100
From: Markus Schaber <schabi@logix-tt.com>
Organization: Logical Tracking and Tracing International AG, Switzerland
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To: Greg Stark <gsstark@mit.edu>
Cc: Orion Henry <lab@orangekids.org>,
	pgsql-performance@postgresql.org
Subject: Re: Large Database Design Help
References: <43EB92DA.2080607@orangekids.org>
	<87ek2c71vl.fsf@stark.xeocode.com>
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Hi, Greg,

Greg Stark wrote:

>>    (Aside question: if I were to find a way to use COPY and I were loading
>>data on a single client_id, would dropping just the indexes for that client_id
>>accelerate the load?)
> Dropping indexes would accelerate the load but unless you're loading a large
> number of records relative the current size I'm not sure it would be a win
> since you would then have to rebuild the index for the entire segment.

And, additionally, rebuilding a partial index with "WHERE client_id=42"
needs a full table scan, which is very slow, so temporarily dropping the
indices will not be useful if you merge the tables.

Btw, I don't know whether PostgreSQL can make use of partial indices
when building other partial indices. If yes, you could temporarily drop
all but one of the partial indices for a specific client.


HTH,
Markus

-- 
Markus Schaber | Logical Tracking&Tracing International AG
Dipl. Inf.     | Software Development GIS

Fight against software patents in EU! www.ffii.org www.nosoftwarepatents.org