| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> |
| Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: PATCH: postpone building buckets to the end of Hash (in HashJoin) |
| Date: | 2016-01-19 23:29:24 |
| Message-ID: | CA+TgmobuD-tVMabWucfPDJmAwNjKxy5nMTLoJP3tRgMpKtQXgg@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Jan 19, 2016 at 4:49 PM, Tomas Vondra
<tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:
> I can totally see why this would slow-down the BuildBuckets function, but I
> don't quite see why it should make the other code significantly slower. Yet
> BuildBuckets takes just ~25ms while the total duration increases by ~200ms
> (for the 1x10 dataset).
>
> I do understand calling BuildBuckets may affect the code executed after that
> as it keeps other data in the cache, but i would not expect ~175ms.
I don't know. There could be some other explanation, but I don't have
a guess as to what it is.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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