| From: | Qingqing Zhou <zhouqq(dot)postgres(at)gmail(dot)com> |
|---|---|
| To: | Kouhei Kaigai <kaigai(at)ak(dot)jp(dot)nec(dot)com> |
| Cc: | Greg Stark <stark(at)mit(dot)edu>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Our trial to TPC-DS but optimizer made unreasonable plan |
| Date: | 2015-08-19 17:32:25 |
| Message-ID: | CAJjS0u2k2tNcJJwXfMGnT_+jfZK3EYdTgWOuAadNPbEgt_xT=A@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Aug 18, 2015 at 5:59 PM, Kouhei Kaigai <kaigai(at)ak(dot)jp(dot)nec(dot)com> wrote:
> BTW, did you register the patch on the upcoming commit-fest?
>
Not yet, it is in WIP status.
> I think it may be a helpful feature, if we can add alternative
> subquery-path towards cte-scan on set_cte_pathlist() and choose
> them according to the cost estimation.
>
Are you suggesting that we keep both subquery-path (whenever possible)
and cte-path so that optimizer can choose among them?
I could imagine that if we could support "materialize cte once and use
multiple times" execution, then we shall be able to benefit from
keeping cte-path. But seems we still don't support this execution
mode.
Regards,
Qingqing
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