From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
---|---|
To: | Mark Dilger <hornschnorter(at)gmail(dot)com> |
Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Request more documentation for incompatibility of parallelism and plpgsql exec_run_select |
Date: | 2017-07-03 15:10:39 |
Message-ID: | CA+TgmoYEeC2_p1HXj1-Xii7oXyjFdL5S0HOm4VbMqvZyxOBRWA@mail.gmail.com |
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Lists: | pgsql-hackers |
On Fri, Jun 30, 2017 at 9:32 AM, Mark Dilger <hornschnorter(at)gmail(dot)com> wrote:
>> On Jun 29, 2017, at 8:55 PM, Mark Dilger <hornschnorter(at)gmail(dot)com> wrote:
>> Changing myfunc to create a temporary table, to execute the sql to populate
>> that temporary table, and to then loop through the temporary table's rows
>> fixes the problem. For the real-world example where I hit this, that single
>> change decreases the runtime from 13.5 seconds to 2.5 seconds.
>
> Actually, this is wrong. On further review, by the time I had changed the
> function definition, the data in the test server I was querying had likely changed
> enough for the performance to change. That duped me into thinking I had
> found a work-around. I can no longer reproduce any performance improvement
> in this manner.
Also note that temporary tables are yet another thing that doesn't
work with parallel query yet.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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