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

Tom Lane wrote:
> CVSROOT:    /cvsroot
> Module name:    pgsql-server
> Changes by:    tgl@svr1.postgresql.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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