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From: mao@postgres.Berkeley.EDU (Mike Olson)
Subject: Re: number of tuples processed
To: postgres@postgres.berkeley.edu
In-Reply-To: Your message of "Thu, 18 Jul 91 11:36:07 +0100."
             <9107181857.AA01414@postgres.Berkeley.EDU> 
Date: Thu, 18 Jul 91 14:45:54 PDT

> 1. Is (or will) there be a way to query the number of tuples that have
>    been replaced or added to a class after the execution of a 'replace'
>    or 'append' command ?

no, we don't have any easy way of doing this, though it probably wouldn't
be very hard to add.

> 2. What's about the column 'reltuples' in the system table 'pg_class'?
>    At the moment it does not seem to contain reasonable values. The value
>    is always 0! Is there another (efficient) possibility to query the number
>    of tuples in a class or will this column be used in version 3.0?

it gets set by the vacuum cleaner.  if it's always zero, then you're not
running the vacuum cleaner.  see the documentation for details.

as a special case, defining an index sets reltuples and relpages on the base
and index relations in order to get the planner to use them.  we don't keep
these values current all the time, since that would require an extra system
catalog update every time you added or deleted a tuple from your database.

					mike olson
					postgres research group
					uc berkeley
					mao@postgres.berkeley.edu