| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Amit Khandekar <amitdkhan(dot)pg(at)gmail(dot)com>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: why not parallel seq scan for slow functions |
| Date: | 2017-11-06 03:37:56 |
| Message-ID: | 14748.1509939476@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> This looks like it's on the right track to me. I hope Tom will look
> into it, but if he doesn't I may try to get it committed myself.
I do plan to take a look at it during this CF.
> + /* Set or update cheapest_total_path and related fields */
> + set_cheapest(current_rel);
> I wonder if it's really OK to call set_cheapest() a second time for
> the same relation...
It's safe enough, we do it in some places already when converting
a relation to dummy. But having to do that in a normal code path
suggests that something's not right about the design ...
regards, tom lane
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