| From: | Bruce Momjian <bruce(at)momjian(dot)us> |
|---|---|
| To: | Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com> |
| Cc: | Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>, Robert Haas <robertmhaas(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Indirect indexes |
| Date: | 2016-10-19 16:40:43 |
| Message-ID: | 20161019164043.GN5087@momjian.us |
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| Lists: | pgsql-hackers |
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(at)momjian(dot)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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