From: Tom Lane <tgl@sss.pgh.pa.us>
To: Rod Taylor <rbt@rbt.ca>
Cc: ow <oneway_111@yahoo.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: 7.4 - FK constraint performance
Date: Thu, 12 Feb 2004 23:25:36 -0500
Message-ID: <27443.1076646336@sss.pgh.pa.us> (raw)
In-Reply-To: <1076640825.10896.12.camel@jester>
References: <20040213010341.95282.qmail@web60801.mail.yahoo.com>
<25808.1076634636@sss.pgh.pa.us>
<1076640825.10896.12.camel@jester>
Rod Taylor <rbt@rbt.ca> writes:
> Statistics say there are 10 values. Statistics list the 10 most common
> values (all of them). Given this, would it not be reasonable to assume
> that 239 is a recent addition (if there at all) to the table and not
> very common?
We don't know that it's 239 when we make the plan. In order to know
that, we'd have to abandon caching of RI check query plans and re-plan
for each row. That strikes me as inevitably a losing proposition.
regards, tom lane
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To: pgsql-sql@postgresql.org
Cc: tgl@sss.pgh.pa.us, rbt@rbt.ca, oneway_111@yahoo.com
Subject: Re: 7.4 - FK constraint performance
In-Reply-To: <27443.1076646336@sss.pgh.pa.us>
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