pgsql: Reap the benefits of not having to avoid leaking PGresults.

Reap the benefits of not having to avoid leaking PGresults.

Remove a bunch of PG_TRY constructs, de-volatilize related
variables, remove some PQclear calls in error paths.
Aside from making the code simpler and shorter, this should
provide some marginal performance gains.

For ease of review, I did not re-indent code within the removed
PG_TRY constructs. That'll be done in a separate patch.

Author: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Reviewed-by: Matheus Alcantara <matheusssilv97(at)gmail(dot)com>
Discussion: https://postgr.es/m/2976982.1748049023@sss.pgh.pa.us

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/80aa9848befc13c188d2775a859deaf172fdd3a2

Modified Files
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contrib/dblink/dblink.c | 96 ++++--------
contrib/postgres_fdw/connection.c | 52 ++-----
contrib/postgres_fdw/postgres_fdw.c | 163 +++++----------------
contrib/postgres_fdw/postgres_fdw.h | 2 +-
.../libpqwalreceiver/libpqwalreceiver.c | 31 +---
src/include/libpq/libpq-be-fe-helpers.h | 13 +-
6 files changed, 83 insertions(+), 274 deletions(-)