Re: question about seq scan and index scan - Mailing list pgsql-general

From Stephan Szabo
Subject Re: question about seq scan and index scan
Date
Msg-id 20021025111313.W38137-100000@megazone23.bigpanda.com
Whole thread Raw
In response to Re: question about seq scan and index scan  (Hervé Piedvache <herve@elma.fr>)
Responses Re: question about seq scan and index scan  (Hervé Piedvache <herve@elma.fr>)
List pgsql-general
On Fri, 25 Oct 2002, [iso-8859-15] Herv� Piedvache wrote:


> Thanks for you help ... to "explain" us why Postgresql do not use all the
> time the index scan for this kind of request for 3 tables with the same
> primary key id.

Depending on the number of rows returned, index scan may not be faster
than a sequential scan.  As you up the constant, the estimated number of
rows drops which make the index scan a better and better plan.  Are
the estimated number of rows for the scan of a (4379, 3987, and 29)
realistic for mynumber>(23000, 23500, 24000)


pgsql-general by date:

Previous
From: "Paul Ottar Tornes"
Date:
Subject: [General] Warning: Unable to connect to PostgreSQL server: unknown host name:
Next
From: Robert Treat
Date:
Subject: Re: [General] Warning: Unable to connect to PostgreSQL