Prevent walsummarizer from getting stuck at a timeline switch.

injection_points: Clear waiter slot on error and exit

Fix failing Memoize test on 32-bit machines

Reduce memory overheads for storing a Memoize tuple

Fix GIN posting tree page deletion with incomplete splits.

Reduce non-leaf keys overlap in GiST indexes produced by a sorted build

Allow IO time to be counted without a matching IO operation in pg_stat_io