Fix privilege checks for pg_prewarm() on indexes. pg_prewarm() currently checks for SELECT privileges on the target relation. However, indexes do not have access rights of their own, so a role may be denied permission to prewarm an index despite having the SELECT privilege on its parent table. This commit fixes this by locking the parent table before the index (to avoid deadlocks) and checking for SELECT on the parent table. Note that the code is largely borrowed from amcheck_lock_relation_and_check().
An obvious downside of this change is the extra AccessShareLock on the parent table during prewarming, but that isn't expected to cause too much trouble in practice. Author: Ayush Vatsa <[email protected]> Co-authored-by: Nathan Bossart <[email protected]> Reviewed-by: Tom Lane <[email protected]> Reviewed-by: Jeff Davis <[email protected]> Discussion: https://postgr.es/m/CACX%2BKaMz2ZoOojh0nQ6QNBYx8Ak1Dkoko%3DD4FSb80BYW%2Bo8CHQ%40mail.gmail.com Backpatch-through: 13 Branch ------ REL_16_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/fae0ce5e318eea8cd8f7bac936a58ee7cbd10bf8 Modified Files -------------- contrib/pg_prewarm/pg_prewarm.c | 47 ++++++++++++++++++++++++++++++++++++--- contrib/pg_prewarm/t/001_basic.pl | 29 +++++++++++++++++++++++- 2 files changed, 72 insertions(+), 4 deletions(-)
