Re: pgsql-server/src/backend/utils/sort tuplesort.c

Tom Lane wrote:
> CVSROOT: /cvsroot
> Module name: pgsql-server
> Changes by: tgl(at)svr1(dot)postgresql(dot)org 04/03/17 18:24:58
>
> Modified files:
> src/backend/utils/sort: tuplesort.c
>
> Log message:
> During btree index build, sort equal-keyed tuples according to their
> TID (heap position). This doesn't do anything to the validity of the
> finished index, but by pretending to qsort() that there are no really
> equal keys in the sort, we can avoid performance problems with qsort
> implementations that have trouble with large numbers of equal keys.
> Patch from Manfred Koizar.

I think there is also the advantage that many equal keys will access the
heap in a more sequential, rather than random, order, which is the part
that really excited me.

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