Re: Slow planning, fast execution for particular 3-table query

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От Justin Pryzby
Тема Re: Slow planning, fast execution for particular 3-table query
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Msg-id 20191107001838.GG4999@telsasoft.com
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Ответ на Re: Slow planning, fast execution for particular 3-table query  (David Rowley <david.rowley@2ndquadrant.com>)
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On Thu, Nov 07, 2019 at 01:15:30PM +1300, David Rowley wrote:
> On Thu, 7 Nov 2019 at 11:59, Justin Pryzby <pryzby@telsasoft.com> wrote:
> >
> > On Mon, Nov 04, 2019 at 03:04:45AM +0000, David Wheeler wrote:
> > > Postgres version 9.5.19
> > > Each of the tables has between 3-4 indexes, and all the indexes include tid as first parameter.
> 
> > But note that index definition will be prohibited since:
> >
> > https://www.postgresql.org/docs/9.6/release-9-6.html
> > |Disallow creation of indexes on system columns, except for OID columns (David Rowley)
> > |Such indexes were never considered supported, and would very possibly misbehave since the system might change the
system-columnfields of a tuple without updating indexes. However, previously there were no error checks to prevent them
frombeing created.
 
> 
> David will have meant the user column named "tid" rather than the
> system column named "ctid".

Ah.  And David must have meant David W :)

Justin 



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