Changes Since Beta 3
--------------------
-Fixes and changes in PostgreSQL 15 Beta 3 include:
+Fixes and changes in PostgreSQL 15 Beta 4 include:
* The SQL/JSON features proposed for this release have been removed.
-* [`MERGE`](https://www.postgresql.org/docs/15/sql-merge.html) statements are
-explicitly rejected inside of a
+* Avoid crash with [`MERGE`](https://www.postgresql.org/docs/15/sql-merge.html)
+when called inside COPY or a
[common-table expression](https://www.postgresql.org/docs/15/queries-with.html)
-(aka `WITH` query) and
+(aka `WITH` query).
[`COPY`](https://www.postgresql.org/docs/15/sql-copy.html) statements.
* Enable `table_rewrite` event triggers for `ALTER MATERIALIZED VIEW`.
* Fix crash in `CREATE DATABASE ... STRATEGY WAL_LOG`.
* Fix issue with
[recovery prefeteching](https://www.postgresql.org/docs/15/runtime-config-wal.html#GUC-RECOVERY-PREFETCH)
that could cause a crash on standby promotion.
-* Adjust costing to force parallelism with partition aggregates.
* Fix LSN returned for error reports of WAL read failures from the
[`pg_walinspect`](https://www.postgresql.org/docs/15/pgwalinspect.html) extension.