Date: Wed, 19 Oct 2016 12:40:43 -0400
From: Bruce Momjian <bruce@momjian.us>
To: Pavan Deolasee <pavan.deolasee@gmail.com>
Cc: Alexander Korotkov <a.korotkov@postgrespro.ru>,
	Robert Haas <robertmhaas@gmail.com>,
	Alvaro Herrera <alvherre@2ndquadrant.com>,
	Pg Hackers <pgsql-hackers@postgresql.org>
Subject: Re: Indirect indexes
Message-ID: <20161019164043.GN5087@momjian.us>
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On Wed, Oct 19, 2016 at 07:23:28PM +0530, Pavan Deolasee wrote:
>     AFAICS, even without considering VACUUM, indirect indexes would be always
>     used with recheck.
>     As long as they don't contain visibility information.  When indirect
>     indexed column was updated, indirect index would refer same PK with
>     different index keys.
>     There is no direct link between indirect index tuple and heap tuple, only
>     logical link using PK.  Thus, you would anyway have to recheck.
> 
> 
> 
> I agree. Also, I think the recheck mechanism will have to be something like
> what I wrote for WARM i.e. only checking for index quals won't be enough and we
> would actually need to verify that the heap tuple satisfies the key in the
> indirect index. 

I personally would like to see how far we get with WARM before adding
this feature that requires a DBA to evaluate and enable it.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
+                      Ancient Roman grave inscription +


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