Fix race in SSI interaction with empty btrees. When predicate-locking btrees, we have a special case for completely empty btrees, since there is no page to lock. This was racy, because, without buffer lock held, a matching key could be inserted between the _bt_search() and the PredicateLockRelation() calls.
Fix, by rechecking _bt_search() after taking the relation-level SIREAD lock, if using SERIALIZABLE isolation and an empty btree is discovered. Back-patch to all supported releases. Fixes one aspect of bug #17949. Reported-by: Artem Anisimov <artem.anisimov....@gmail.com> Reviewed-by: Dmitry Dolgov <9erthali...@gmail.com> Reviewed-by: Heikki Linnakangas <hlinn...@iki.fi> Discussion: https://postgr.es/m/17949-a0f17035294a55e2%40postgresql.org Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/f9b7fc651a99ea518650d8aca661652136b249fc Modified Files -------------- src/backend/access/nbtree/nbtsearch.c | 39 +++++++++++++++++++++++------------ 1 file changed, 26 insertions(+), 13 deletions(-)