| From: | Etsuro Fujita <fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp> |
|---|---|
| To: | Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: postgres_fdw: oddity in costing aggregate pushdown paths |
| Date: | 2018-11-30 09:51:29 |
| Message-ID: | 5C010821.7050102@lab.ntt.co.jp |
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| Lists: | pgsql-hackers |
(2018/11/28 13:38), Etsuro Fujita wrote:
> BTW another thing I noticed is this comment on costing aggregate
> pushdown paths using local statistics in estimate_path_cost_size:
>
> * Also, core does not care about costing HAVING expressions and
> * adding that to the costs. So similarly, here too we are not
> * considering remote and local conditions for costing.
>
> I think this was true when aggregate pushdown went in, but isn't anymore
> because of commit 7b6c07547190f056b0464098bb5a2247129d7aa2. So we
> should update estimate_path_cost_size so that it accounts for the
> selectivity and cost of the HAVING expressions as well?
There seems to be no objections, I updated the patch as such. Attached
is an updated version of the patch.
Best regards,
Etsuro Fujita
| Attachment | Content-Type | Size |
|---|---|---|
| postgres-fdw-aggregate-pushdown-costsize-2.patch | text/x-patch | 4.4 KB |
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