Re: Surjective functional indexes

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Konstantin Knizhnik <k(dot)knizhnik(at)postgrespro(dot)ru>
Cc: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Surjective functional indexes
Date: 2017-05-25 16:37:40
Message-ID: 15995.1495730260@sss.pgh.pa.us
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Konstantin Knizhnik <k(dot)knizhnik(at)postgrespro(dot)ru> writes:
> My proposal is to check value of function for functional indexes instead
> of just comparing set of effected attributes.
> Obviously, for some complex functions it may have negative effect on
> update speed.
> This is why I have added "surjective" option to index.

This seems overcomplicated. We would have to compute the function
value at some point anyway. Can't we refactor to do that earlier?

regards, tom lane

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