Re: Releasing memory during External sorting? - Mailing list pgsql-performance

From Tom Lane
Subject Re: Releasing memory during External sorting?
Date
Msg-id 5021.1127495844@sss.pgh.pa.us
Whole thread Raw
In response to Re: Releasing memory during External sorting?  (Ron Peacetree <rjpeace@earthlink.net>)
Responses Re: Releasing memory during External sorting?
List pgsql-performance
Ron Peacetree <rjpeace@earthlink.net> writes:
> 2= No optimal external sorting algorithm should use more than 2 passes.
> 3= Optimal external sorting algorithms should use 1 pass if at all possible.

A comparison-based sort must use at least N log N operations, so it
would appear to me that if you haven't got approximately log N passes
then your algorithm doesn't work.

            regards, tom lane

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