PostgreSQL 15 Draft Release Notes

> Allow WAL full page writes to use LZ4 and Zstandard compression

This would affect streaming replication, which is basically WAL shipping, I presume?

Most of the interesting stuff to me that I'm seeing this release are around not streaming, but instead logical replication:

> Allow [ed: logical replicataion] publication of all tables in a schema

> Allow publication content to be filtered using a WHERE clause

> Allow publications to be restricted to specific columns

> Add two-phase information to the logical replication stream

A lot of neat tools for replication, which will all help a lot of the interesting Change-Data-Capture work that's been emerging. Getting on my high horse here: making the database not just a store of data to be queried, but a source of truth that others can subscribe to, adding reactivity to our core data systems, is a big ongoing & interesting work of the decades. A sizable part of what made etcd so popular, I tend to think, is it's somewhat easy to use Watch API[1]. Seems like there's a lot of new tools happening in 15 for this.

Some other random selections:

> Allow SELECT DISTINCT to be parallelized

> Add SQL/JSON-standard JSON constructors. Add SQL/JSON query functions JSON_EXISTS(), JSON_QUERY(), and JSON_VALUE(). Add JSON_TABLE function to cause JSON data to be treated as a table.

[1] https://etcd.io/docs/v3.2/learning/api/#watch-api

We are on Postgres 12 still, I am hoping that foreign data wrappers improve to the point they are more usable. When we last assessed it, we saw highly erratic behavior. The promise of fdw (in lieu of ETL pipelines) for many cases is tremendous, but I got the sense that the query planner needed a lot of work still (as of postgres 12).