Fix race in SERIALIZABLE READ ONLY.

Fix assert failures in parallel SERIALIZABLE READ ONLY.

Fix assorted missing logic for GroupingFunc nodes.

Avoid crash in rare case of concurrent DROP

doc: mention inheritance's tableoid can be used in partitioning

doc: add example of using pg_dump with GNU split and gzip

Close yet another race condition in replication slot test code

Make new replication slot test code even less racy

Make new replication slot test code less racy

Advance old-segment horizon properly after slot invalidation

Fix range check in ECPG numeric to int conversion

doc: for various substring funcs, document if only first match

Fix check for conflicting session- vs transaction-level locks.

Make printf("%s", NULL) print "(null)" instead of crashing.

Lock the extension during ALTER EXTENSION ADD/DROP.

Doc: improve documentation about exponentiation operator.

Fix corner-case uninitialized-variable issues in plpgsql.