| From: | Peter Geoghegan <pg(at)heroku(dot)com> |
|---|---|
| To: | Rushabh Lathia <rushabh(dot)lathia(at)gmail(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Gather Merge |
| Date: | 2017-01-17 20:31:42 |
| Message-ID: | CAM3SWZQ4hUYU7fE56RR4ScXbiC1S-qTatNEp0i0qaymK9Od_GQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Jan 17, 2017 at 4:26 AM, Rushabh Lathia
<rushabh(dot)lathia(at)gmail(dot)com> wrote:
> Another observation is, HashAggregate (case 1) is performs better compare to
> GroupAggregate (case 2), but still it doesn't justify the cost difference of
> those two.
It may not be the only issue, or even the main issue, but I'm fairly
suspicious of the fact that cost_sort() doesn't distinguish between
the comparison cost of text and int4, for example.
--
Peter Geoghegan
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