Postgres is very nice when it comes to extending with custom plugins, with many set of facilities available, like:

A lot of work has been put into making Postgres 12 an excellent release to come, and in some of the features introduced, there is one which found its way into the tree and has been first proposed to community at the end of 2012. Here is the commit which has introduced it:

pg_checksums is a renaming of the tool called pg_verify_checksums which has been introduced in Postgres 11. Version 12 is introducing new options and possibilities which explain the renaming, as the tool has become much more multi-purpose.

The maximum number of connections a PostgreSQL can accept is configured using max_connections. When attempting to connect to a server already at full capacity, logically the server complains:

Postgres 12 is bringing a game-changer regarding common table expressions (named also CTE, defined by WITH clauses in SELECT queries) with the following commit:

Partitions in Postgres are a recent concept, being introduced as of version 10 and improved a lot over the last years. It is complicated, and doable, to gather information about them with specific queries working on the system catalogs, still these may not be straight-forward. For example, getting a full partition tree leads to the use of WITH RECURSIVE when working on partitions with multiple layers.

A couple of weeks ago a bug has popped up on the community mailing lists about the use of temporary objects in two-phase commit. After discussions, the result is the following commit:

The following commit has been merged into Postgres 12, adding a new option for VACUUM and ANALYZE:

The following commit has been merged into Postgres 12 a couple of months ago, easing failover control flow:

The following bug fix has been committed to the PostgreSQL code tree, addressing an issue visibly since ON COMMIT support for CREATE TABLE has been added back in commit ebb5318 from 2002: