Re: [SQL] bad select performance fixed by forbidding hash joins - Mailing list pgsql-sql

From Tom Lane
Subject Re: [SQL] bad select performance fixed by forbidding hash joins
Date
Msg-id 16442.940512643@sss.pgh.pa.us
Whole thread Raw
In response to Re: [SQL] bad select performance fixed by forbidding hash joins  (Nik Putnam <nputnam@spinon.berkeley.edu>)
List pgsql-sql
Nik Putnam <nputnam@spinon.berkeley.edu> writes:
> I tried this out to see if it would speed up *my* query too.
> The query went much faster, but gave different results!
> [nputnam@spinon ~]$ setenv PGOPTIONS "-fh"
> [nputnam@spinon ~]$ psql -e expression < query.sql
> gives 15 rows of output in 1s.
> [nputnam@spinon ~]$ unsetenv PGOPTIONS
> [nputnam@spinon ~]$ psql -e expression < query.sql
> gives 289 rows of output in 51s
> The slow one is giving the right answer.
> Why might they be different?

That would be a bug, without question.  Can you provide a repeatable
test case?
        regards, tom lane


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