From: Tom Lane <tgl@sss.pgh.pa.us>
To: Kevin Grittner <kgrittn@mail.com>
Cc: AI Rumman <rummandba@gmail.com>
Cc: Claudio Freire <klaussfreire@gmail.com>
Cc: Evgeny Shishkin <itparanoia@gmail.com>
Cc: Andrew Dunstan <andrew@dunslane.net>
Cc: postgres performance list <pgsql-performance@postgresql.org>
Subject: Re: Why does the number of rows are different in actual and estimated.
Date: Fri, 14 Dec 2012 14:22:05 -0500
Message-ID: <4673.1355512925@sss.pgh.pa.us> (raw)
In-Reply-To: <20121214191427.80090@gmx.com>
References: <20121214191427.80090@gmx.com>
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"Kevin Grittner" <kgrittn@mail.com> writes:
> AI Rumman wrote:
>> Does FK Constraint help to improve performance? Or it is only
>> for maintaining data integrity?
> I'm not aware of any situation where adding a foreign key
> constraint would improve performance.
There's been talk of teaching the planner to use the existence of FK
constraints to improve plans, but I don't believe any such thing is
in the code today.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, kgrittn@mail.com, rummandba@gmail.com, klaussfreire@gmail.com, itparanoia@gmail.com, andrew@dunslane.net
Subject: Re: Why does the number of rows are different in actual and estimated.
In-Reply-To: <4673.1355512925@sss.pgh.pa.us>
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