| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> |
| Cc: | Kim Rose Carlsen <krc(at)hiper(dot)dk>, "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [GENERAL] Remove useless joins (VARCHAR vs TEXT) |
| Date: | 2017-09-17 19:30:49 |
| Message-ID: | 3592.1505676649@sss.pgh.pa.us |
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| Lists: | pgsql-general pgsql-hackers |
David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> writes:
> On 17 September 2017 at 08:07, Kim Rose Carlsen <krc(at)hiper(dot)dk> wrote:
>> It seems there are some difference in VARCHAR vs TEXT when postgres tries to
>> decide if a LEFT JOIN is useful or not.
> Yeah, it looks like the code to check for distinctness in the subquery
> fails to consider that the join condition may contain RelabelTypes
> instead of plain Vars.
>
> The attached fixes.
Looks like a good fix to me (except for the copied-and-pasted,
not-quite-on-point comment ;-)). Pushed.
regards, tom lane
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