Re: PATCH: postpone building buckets to the end of Hash (in HashJoin) - Mailing list pgsql-hackers

From Robert Haas
Subject Re: PATCH: postpone building buckets to the end of Hash (in HashJoin)
Date
Msg-id CA+TgmobuD-tVMabWucfPDJmAwNjKxy5nMTLoJP3tRgMpKtQXgg@mail.gmail.com
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In response to Re: PATCH: postpone building buckets to the end of Hash (in HashJoin)  (Tomas Vondra <tomas.vondra@2ndquadrant.com>)
List pgsql-hackers
On Tue, Jan 19, 2016 at 4:49 PM, Tomas Vondra
<tomas.vondra@2ndquadrant.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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