pgsql: Avoid race in RelationBuildDesc() affecting CREATE INDEX CONCURR

Avoid race in RelationBuildDesc() affecting CREATE INDEX CONCURRENTLY.

CIC and REINDEX CONCURRENTLY assume backends see their catalog changes
no later than each backend's next transaction start. That failed to
hold when a backend absorbed a relevant invalidation in the middle of
running RelationBuildDesc() on the CIC index. Queries that use the
resulting index can silently fail to find rows. Fix this for future
index builds by making RelationBuildDesc() loop until it finishes
without accepting a relevant invalidation. It may be necessary to
reindex to recover from past occurrences; REINDEX CONCURRENTLY suffices.
Back-patch to 9.6 (all supported versions).

Noah Misch and Andrey Borodin, reviewed (in earlier versions) by Andres
Freund.

Discussion: https://postgr.es/m/[email protected]

Branch
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REL_13_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/2e33b43599ad3868ee180f149050444bf0a7ca15

Modified Files
--------------
contrib/amcheck/Makefile | 2 +
contrib/amcheck/t/002_cic.pl | 78 +++++++++++++++++++++
src/backend/utils/cache/inval.c | 12 +++-
src/backend/utils/cache/relcache.c | 115 +++++++++++++++++++++++++++++--
src/include/utils/inval.h | 1 +
src/include/utils/relcache.h | 2 +-
src/test/perl/PostgresNode.pm | 135 +++++++++++++++++++++++++++++++++++++
src/tools/pgindent/typedefs.list | 1 +
8 files changed, 336 insertions(+), 10 deletions(-)