Re: Why does the number of rows are different in actual and estimated.

From: "Kevin Grittner" <kgrittn(at)mail(dot)com>
To: "AI Rumman" <rummandba(at)gmail(dot)com>, "Claudio Freire" <klaussfreire(at)gmail(dot)com>
Cc: "Evgeny Shishkin" <itparanoia(at)gmail(dot)com>,"Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>,"Andrew Dunstan" <andrew(at)dunslane(dot)net>,"postgres performance list" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Why does the number of rows are different in actual and estimated.
Date: 2012-12-14 19:14:27
Message-ID: 20121214191427.80090@gmx.com
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AI Rumman wrote:
> Claudio Freire <klaussfreire(at)gmail(dot)com>wrote:
>> I think it's more likely a missing FK constraint.

> 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.

-Kevin

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