The PostgreSQL Global Development Group announces that the first beta release of PostgreSQL 12 is now available for download. This release contains previews of all features that will be available in the final release of PostgreSQL 12, though some details of the release could change before then.
In the spirit of the open source PostgreSQL community, we strongly encourage you to test the new features of PostgreSQL 12 in your database systems to help us eliminate any bugs or other issues that may exist. While we do not advise you to run PostgreSQL 12 Beta 1 in your production environments, we encourage you to find ways to run your typical application workloads against this beta release.
Your testing and feedback will help the community ensure that the PostgreSQL 12 release upholds our standards of providing a stable, reliable release of the world's most advanced open source relational database.
PostgreSQL 12 improves the overall performance of the standard B-tree indexes with improvements to the space management of these indexes as well. These improvements also provide a reduction of index size for B-tree indexes that are frequently modified, in addition to a performance gain.
Additionally, PostgreSQL 12 adds the ability to rebuild indexes concurrently,
which lets you perform a REINDEX operation
without blocking any writes to the index. This feature should help with lengthy
index rebuilds that could cause downtime when managing a PostgreSQL database
in a production environment.
PostgreSQL 12 extends the abilities of several of the specialized indexing
mechanisms. The ability to create covering indexes, i.e. the INCLUDE clause
that was introduced in PostgreSQL 11, has now been added to GiST indexes.
SP-GiST indexes now support the ability to perform K-nearest neighbor (K-NN)
queries for data types that support the distance (<->) operation.
The amount of write-ahead log (WAL) overhead generated when creating a GiST, GIN, or SP-GiST index is also significantly reduced in PostgreSQL 12, which provides several benefits to the disk utilization of a PostgreSQL cluster and features such as continuous archiving and streaming replication.
Common table expressions (aka WITH queries) can now be automatically inlined
in a query if they a) are not recursive, b) do not have any side-effects and
c) are only referenced once in a later part of a query. This removes an
"optimization fence" that has existed since the introduction of the WITH
clause in PostgreSQL 8.4
If need be, you can force a WITH query to materialize using the MATERIALIZED
clause, e.g.
WITH c AS MATERIALIZED (
SELECT * FROM a WHERE a.x % 4 = 0
)
SELECT * FROM c JOIN d ON d.y = a.x;
PostgreSQL 12 improves on the performance when processing tables with thousands of partitions for operations that only need to use a small number of partitions.
PostgreSQL 12 also provides improvements to the performance of both INSERT and
COPY into a partitioned table. ATTACH PARTITION can now be performed
without blocking concurrent queries on the partitioned table. Additionally, the
ability to use foreign keys to reference partitioned tables is now permitted in
PostgreSQL 12.
PostgreSQL 12 now allows execution of JSON path queries per the SQL/JSON specification in the SQL:2016 standard. Similar to XPath expressions for XML, JSON path expressions let you evaluate a variety of arithmetic expressions and functions in addition to comparing values within JSON documents.
A subset of these expressions can be accelerated with GIN indexes, allowing the execution of highly performant lookups across sets of JSON data.
PostgreSQL 12 now supports case-insensitive and accent-insensitive comparisons for ICU provided collations, also known as "nondeterministic collations". When used, these collations can provide convenience for comparisons and sorts, but can also lead to a performance penalty as a collation may need to make additional checks on a string.
CREATE STATISTICS,
introduced in PostgreSQL 10 to help collect more complex statistics over multiple
columns to improve query planning, now supports most-common value statistics.
This leads to improved query plans for distributions that are non-uniform.
PostgreSQL 12 allows the creation of generated columns that compute their values with an expression using the contents of other columns. This feature provides stored generated columns, which are computed on inserts and updates and are saved on disk. Virtual generated columns, which are computed only when a column is read as part of a query, are not implemented yet.
PostgreSQL 12 introduces the pluggable table storage interface that allows for
the creation and use of different methods for table storage. New access methods
can be added to a PostgreSQL cluster using the CREATE ACCESS METHOD
command and subsequently added to tables with the new USING clause on
CREATE TABLE.
A table storage interface can be defined by creating a new table access method.
In PostgreSQL 12, the storage interface that is used by default is the heap
access method, which is currently is the only built-in method.
The pg_verify_checkums command has been renamed to pg_checksums
and now supports the ability to enable and disable page checksums across a
PostgreSQL cluster that is offline. Previously, page checksums could only be
enabled during the initialization of a cluster with initdb.
GSSAPI now supports client-side and server-side encryption and can be specified in
the pg_hba.conf
file using the hostgssenc and hostnogssenc record types. PostgreSQL 12 also
allows for discovery of LDAP servers based on DNS SRV records if PostgreSQL
was compiled with OpenLDAP.
There are several changes introduced in PostgreSQL 12 that can affect the behavior as well as management of your ongoing operations. A few of these are noted below; for information about other changes, please review the "Migrating to Version 12" section of the release notes.
recovery.conf configuration file is now merged into the main
postgresql.conf file. PostgreSQL will not start if it detects that
recovery.conf is present. To put PostgreSQL into a non-primary mode, you can
use the recovery.signal and the standby.signal files.You can read more about archive recovery here:
https://www.postgresql.org/docs/12/runtime-config-wal.html#RUNTIME-CONFIG-WAL-ARCHIVE-RECOVERY
Just-in-Time (JIT) compilation is now enabled by default.
OIDs can no longer be added to user created tables using the WITH OIDs
clause. Operations on tables that have columns that were created using
WITH OIDS (i.e. columns named "OID") will need to be adjusted.
Running a SELECT * command on a system table will now also output the OID for
the rows in the system table as well, instead of the old behavior which required
the OID column to be specified explicitly.
Many other new features and improvements have been added to PostgreSQL 12, some of which may be as or more important to specific users than what is mentioned above. Please see the Release Notes for a complete list of new and changed features.
The stability of each PostgreSQL release greatly depends on you, the community, to test the upcoming version with your workloads and testing tools in order to find bugs and regressions before the general availability of PostgreSQL 12. As this is a Beta, minor changes to database behaviors, feature details, and APIs are still possible. Your feedback and testing will help determine the final tweaks on the new features, so please test in the near future. The quality of user testing helps determine when we can make a final release.
A list of open issues is publicly available in the PostgreSQL wiki. You can report bugs using this form on the PostgreSQL website:
https://www.postgresql.org/account/submitbug/
This is the first beta release of version 12. The PostgreSQL Project will release additional betas as required for testing, followed by one or more release candidates, until the final release in late 2019. For further information please see the Beta Testing page.