pgsql: Avoid syscache lookup while building a WAIT FOR tuple descriptor

Avoid syscache lookup while building a WAIT FOR tuple descriptor

Use TupleDescInitBuiltinEntry instead of TupleDescInitEntry when building
the result tuple descriptor for the WAIT FOR command. This avoids a syscache
access that could re-establish a catalog snapshot after we've explicitly
released all snapshots before the wait.

Discussion: https://postgr.es/m/CABPTF7U%2BSUnJX_woQYGe%3D%3DR9Oz%2B-V6X0VO2stBLPGfJmH_LEhw%40mail.gmail.com
Author: Xuneng Zhou <xunengzhou@gmail.com>
Reviewed-by: Alexander Korotkov <aekorotkov@gmail.com>

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/834038c1f8d52f51666c60ec774bbbf590f4e8c6

Modified Files
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src/backend/commands/wait.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)