Re: [HACKERS] sort on huge table - Mailing list pgsql-hackers

From Tom Lane
Subject Re: [HACKERS] sort on huge table
Date
Msg-id 9100.940342626@sss.pgh.pa.us
Whole thread Raw
In response to Re: [HACKERS] sort on huge table  (Tatsuo Ishii <t-ishii@sra.co.jp>)
Responses Re: [HACKERS] sort on huge table  (Tatsuo Ishii <t-ishii@sra.co.jp>)
List pgsql-hackers
Tatsuo Ishii <t-ishii@sra.co.jp> writes:
> It worked with 2GB+ table but was much slower than before.
> Before(with 8MB sort memory): 22 minutes
> After(with 8MB sort memory): 1 hour and 5 minutes
> After(with 80MB sort memory): 42 minutes.

Oh dear.  I had tested it with smaller files and concluded that it was
no slower than before ... I guess there is some effect I'm not seeing
here.  Can you tell whether the extra time is computation or I/O (how
much does the runtime of the backend change between old and new code)?
        regards, tom lane


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