From: | Maxim Boguk <maxim(dot)boguk(at)gmail(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | pgsql-bugs(at)postgresql(dot)org |
Subject: | Re: BUG #6662: Database do not push condition to subquery, test case for bug 6658 |
Date: | 2012-05-23 01:53:37 |
Message-ID: | CAK-MWwQr6ZQca02Jf86c5qsw2ipaY9N_11DnSzo2u6CLCo0dXA@mail.gmail.com |
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Lists: | pgsql-bugs |
Hi,
Thank you very much for answer.
Explicit casting resolved an issue.
Just single question:
if anytextcat() and textanycat() are marked volatile,
why the database allows create index on supposedly to be volatile
expression:
create index test_val_special on test((val || ''));
?
P
On Wed, May 23, 2012 at 11:46 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> maxim(dot)boguk(at)gmail(dot)com writes:
> > I managed create simple self-contained test case for 6658.
>
> This works fine in HEAD. The reason it doesn't work fine in 9.1 (or
> 9.0) is that in those branches, anytextcat() and textanycat() are marked
> volatile, for reasons that were good at the time but were superseded by
> later policy changes. So you have a subselect containing a volatile
> output expression, which prevents flattening of the subselect, so the
> restriction clause doesn't get pushed down to where it could be used
> with the index. For some history see
>
> http://git.postgresql.org/gitweb/?p=postgresql.git&a=commitdiff&h=c82d931dd180965a9a0c06acc764404f91de8170
>
> http://git.postgresql.org/gitweb/?p=postgresql.git&a=commitdiff&h=aab353a60b95aadc00f81da0c6d99bde696c4b75
>
> http://git.postgresql.org/gitweb/?p=postgresql.git&a=commitdiff&h=3db6524fe63f0598dcb2b307bb422bc126f2b15d
>
> If this is a big problem for you, you could safely adjust the
> provolatile marking of those functions by hand in 9.1. It might be
> better just to include an explicit cast to text, though, instead of
> relying on the assumption that the system will let you concat an integer
> directly to a text string.
>
> regards, tom lane
>
--
Maxim Boguk
Senior Postgresql DBA.
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