Re: Sort performance - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Sort performance
Date
Msg-id 5444.1157126236@sss.pgh.pa.us
Whole thread Raw
In response to Sort performance  (Gregory Stark <stark@enterprisedb.com>)
List pgsql-hackers
Gregory Stark <stark@enterprisedb.com> writes:
>     Mem     Runs    Time
>     ----    ----    ----
>     1MB    18    8.25s
>     10MB    3    5.6s
>     100MB    qsort    6.1s

I'm confused what this means exactly?  Are you saying that in the first
two cases, there were 18 and 3 sorted runs generated in the initial
pass, and in the third case we just did the sort in memory using qsort?

How many items are being sorted, exactly?  Since it's text, it probably
also makes a big difference what LC_COLLATE setting you are using.
Non-C sort locale could mean that the strcoll() calls swamp all else.

How long does it take sort(1) to do the same task?
        regards, tom lane


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