pgsql: Avoid redundant checks in partition_bounds_copy().

Avoid redundant checks in partition_bounds_copy().

Previously, partition_bounds_copy() checked whether the strategy for the
given partition bounds was hash or not, and then determined the number of
elements in the datums in the datums array for the partition bounds, on
each iteration of the loop for copying the datums array, but there is no
need to do that. Perform the checks only once before the loop iteration.

Author: Etsuro Fujita
Reported-by: Amit Langote and Julien Rouhaud
Discussion: https://postgr.es/m/CAPmGK14Rvxrm8DHWvCjdoks6nwZuHBPvMnWZ6rkEx2KhFeEoPQ@mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/032f9ae012d87c730be0e261a6bae9323c2b2d6c

Modified Files
--------------
src/backend/partitioning/partbounds.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)