PostgreSQL 12: Feature Highlights

Hi,

Now that a draft of the release notes are available[1] this seems like a
good time to begin determining what features we want to highlight prior
to the Beta 1 announcement. First, a small editorial :)

Reading through the list a few times, it is quite impressive the breadth
of features that are available for PostgreSQL 12 and the impact they can
have on our user workloads. I think this is very exciting and I think
our users will be very impressed with this release :) It also presents
some challenges for coming up with features to highlight, but I call
this a "good problem."

(I am less inclined to "trim the list" for the sake of doing so for a
Beta 1 announcement, as based on an analysis of the data, often what
people read are the announcements itself and not the release notes, so
trying to get as much info in front of people without making it too
tedious is the goal.)

Knowing that the target audience of the announcements are users of
PostgreSQL, and knowing the main goals of the beta announcement is to
both make people aware of features and to encourage testing, I think we
need to divide things into a few groups:

- Feature Highlights
- Changes that could affect existing operating environments

Also note below that the way I am listing them out does not constitute a
rank order as this list is just an initial compilation.

With further ado...

# Feature Highlights

1. Partitioning Improvements

- Performance, e.g. enhanced partition pruning, COPY performance, ATTACH
PARTITION
- Foreign Keys
- Partition bounds now support expressions

2. Query parallelism is now supported in SERIALIZABLE transaction mode

3. Indexing

- Improvements overall performance to standard (B-tree) indexes with
writes as well as with bloat
- REINDEX CONCURRENTLY
- GiST indexes now support covering indexes (INCLUDE clause)
- SP-GiST indexes now support K-NN queries
- WAL overhead reduced on GiST, GIN, & SP-GiST index creation

4. CREATE STATISTICS now supports most-common value statistics, which
leads to improved query plans for distributions that are non-uniform

5. WITH queries (CTEs) can now be inlined, subject to certain restrictions

6. Support for JSON path queries per the SQL/JSON standard as well as
support for indexing on equality expressions

7. Introduction of generated columns that compute and store an
expression as a value on the table

8. Enable / disable page checksums for an offline cluster

9. Authentication

- GSSAPI client/server encryption support
- LDAP server discovery

10. Introduction of CREATE ACCESS METHOD that permits the addition of
new table storage types

# Changes That Can Affect Existing Operating Environments

1. recovery.conf merged into postgresql.conf;
recovery.signal/standby.signal being used for switching into non-primary
mode

2. JIT enabled by default

As always, constructive feedback welcome. With the goal in mind that
this will be turned into a Beta 1 announcement, please indicate if you
believe something is missing or if something does not belong on this list.

Thanks!

Jonathan

[1] https://www.postgresql.org/docs/devel/release-12.html