| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com> |
| Cc: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Hubert Lubaczewski <depesz(at)depesz(dot)com>, pgsql-hackers mailing list <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: explain analyze output with parallel workers - question about meaning of information for explain.depesz.com |
| Date: | 2017-12-05 18:48:50 |
| Message-ID: | CA+TgmoYCqMtjD_421od1CwTBcN=QoDg=V1nPtNVPLcED1XHq+w@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Dec 5, 2017 at 2:49 AM, Thomas Munro
<thomas(dot)munro(at)enterprisedb(dot)com> wrote:
> As for how to aggregate the information, isn't it reasonable to show
> data from the last loop on the basis that it's representative?
> Summing wouldn't make too much sense, because you didn't use that much
> memory all at once.
Sorts can be rescanned even without parallel query, so I guess we
should try to make the parallel case kinda like the non-parallel case.
If I'm not wrong, that will just use the stats from the most recent
execution (i.e. the last loop) -- see show_sort_info() in explain.c.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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