Re: Threaded Sorting - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Threaded Sorting
Date
Msg-id 20100.1033739157@sss.pgh.pa.us
Whole thread Raw
In response to Threaded Sorting  (Hans-Jürgen Schönig <postgres@cybertec.at>)
List pgsql-hackers
Hans-Jürgen Schönig <postgres@cybertec.at> writes:
> Did anybody think about threaded sorting so far?
> Assume an SMP machine. In the case of building an index or in the case 
> of sorting a lot of data there is just one backend working. Therefore 
> just one CPU is used.
> What about starting a thread for every temporary file being created? 
> This way CREATE INDEX could use many CPUs.

In my experience, once you have enough data to force a temp file to be
used, the sort algorithm is I/O bound anyway.  Throwing more CPUs at it
won't help much.
        regards, tom lane


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