pgsql: Fix dumb bug in tqueue.c

Fix dumb bug in tqueue.c

When I wrote this code originally, the intention was to recompute the
remapinfo only when the tupledesc changes. This presumably only
happens once per query, but I copied the design pattern from other
DestReceivers. However, due to a silly oversight on my part,
tqueue->tupledesc never got set, leading to recomputation for every
tuple.

This should improve the performance of parallel scans that return a
significant number of tuples.

Report by Amit Kapila; patch by me, reviewed by him.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/adeee974866085db84b860c1f397dd7c6b136a0a

Modified Files
--------------
src/backend/executor/tqueue.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)