Postgres Pro
Downloads
Home   >   mailing lists

Re: [HACKERS] Surjective functional indexes - Mailing list pgsql-hackers

From Christoph Berg
Subject Re: [HACKERS] Surjective functional indexes
Date
Msg-id 20170913075144.auntuti3usqp2jl5@msg.df7cb.de
Whole thread Raw
In response to Re: [HACKERS] Surjective functional indexes  (Konstantin Knizhnik <k.knizhnik@postgrespro.ru>)
Responses Re: [HACKERS] Surjective functional indexes  (Konstantin Knizhnik <k.knizhnik@postgrespro.ru>)
List pgsql-hackers
Tree view 
Re: Konstantin Knizhnik 2017-09-01 <f530ede0-1bf6-879c-c362-34325514f692@postgrespro.ru>
> +       Functional index is based on on projection function: function which extract subset of its argument.
> +       In mathematic such functions are called non-injective. For injective function if any attribute used in the
indexed
> +       expression is changed, then value of index expression is also changed.

This is Just Wrong. I still think what you are doing here doesn't have
anything to do with the function being injective or not.

Christoph


-- 
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers

pgsql-hackers by date:

Previous
From: Alexey Chernyshov
Date:
Subject: Re: [HACKERS] [PATCH] Pageinspect - add functions on GIN and GiSTindexes from gevel
Next
From: Ashutosh Sharma
Date:
Subject: Re: [HACKERS] [PATCH] Pageinspect - add functions on GIN and GiSTindexes from gevel