## Appendix E. Release Notes

The release notes contain the significant changes in each Postgres Pro Standard release, with major features and migration issues listed at the top. The release notes do not contain changes that affect only a few users or changes that are internal and therefore not user-visible. For example, the optimizer is improved in almost every release, but the improvements are usually observed by users as simply faster queries.

## E.1. Postgres Pro Standard 11.2.1

Release Date: 2019-03-26

### E.1.1. Overview

This release is based on PostgreSQL 11.2 and Postgres Pro Standard 11.1.1. All improvements inherited from PostgreSQL 11.2 are listed in PostgreSQL 11.2 Release Notes.

Major enhancements over Postgres Pro Standard 11.1.1 include:

- Fixed processing of queries with multiple `OR` clauses to eliminate duplicate results and ensure the correct sort order.

- Fixed an issue that could cause server failures when using non-strict aggregate functions.

- Changed delivery model for pg_probackup utility:

  - On Linux, pg_probackup is now provided in the `pg-probackup-std-11` package. On ALT Linux and Debian-based systems, when upgrading from Postgres Pro Standard 11.1.1, run `apt dist-upgrade` (or `apt-get dist-upgrade`) to ensure that all new dependencies are handled correctly.

  - On Windows, pg_probackup now has a separate installer. You have to install core components of the current Postgres Pro version before installing pg_probackup.

- Added new options to Postgres Pro interactive installer for Windows. Now you can:

  - Choose `icu` or `libc` as the default collation provider. Previously, Postgres Pro Standard always used `icu` by default.

  - Select a Windows user that starts Postgres Pro service. By default, Postgres Pro service is started on behalf of `NT AUTHORITY\NetworkService`.

- On SUSE Linux Enterprise Server and RHEL-based systems, moved several utilities to different packages for consistency with other Linux distributions: pg_recievewal and pg_recvlogical are delivered as part of the `postgrespro-std-11-client` package, while pg_rewind, pg_waldump, pg_upgrade are now located in the `postgrespro-std-11-server` package.

- Backported the patch that addresses `dsm_attach()` race condition when DSM handles are reused; in vanilla PostgreSQL, this fix is targeted for the future updates only. The patch is hoped to resolve issues when the server reports the following error message: `ERROR: dsa_area could not attach to segment`.

- Fixed pg_upgrade to avoid issues with domain constraints that depend on collations. Such constraints are now validated during the upgrade, while in the the previous Postgres Pro versions they were always marked as invalid in the new cluster.

- Fixed pg_dump to correctly work with databases of the previous Postgres Pro major version.

- Fixed the pg-setup script so that it can initialize a cluster in a non-default location when run with the `-D` option.

- Improved selectivity estimation for indexes on boolean columns.

- Fixed performance degradation for index-only scans over wide indexes.

- Accelerated index creation and minimized undesired eviction of relation pages from shared buffers while an index is being built.

- Ended support for ALT Linux SPT 6.0 and Windows 7 SP1.

- Updated `pg_pathman` module to version 1.5.5. As compared to version 1.5.2 provided in the previous Postgres Pro releases, the following enhancements were introduced:

  - Fixed `pg_pathman` upgrade scripts to avoid issues caused by a different the number of `pg_config` attributes in `pg_pathman` 1.4 and 1.5 major versions.

  - Improved `pg_pathman` stability:

    - Trying to call `pg_pathman` functions when this extension is disabled does not cause server failures anymore; now an error is raised instead.

    - Different partitioning strategies can now be successfully applied to the same table.

- Updated `pg_variables` module to version 1.2:

  - Added support for array types.

  - Improved module stability.

  - Changed empty package handling. An empty package is now removed only after the transaction that emptied it has ended.

  (See Section F.42.)

### E.1.2. Migration to Version 11.2.1

If you are upgrading from Postgres Pro Standard based on the same PostgreSQL major version, it is enough to install the new version into your current installation directory.

Since pg_probackup delivery model changed in Postgres Pro Standard 11.2.1, when upgrading from a lower version on ALT Linux and Debian-based systems, run `apt dist-upgrade` (or `apt-get dist-upgrade`) to ensure that all new dependencies are handled correctly. On Windows, you have to run a separate pg_probackup installer to complete the upgrade.

To migrate from PostgreSQL or a Postgres Pro Standard release based on a previous PostgreSQL major version, see the instructions in Postgres Pro Standard 11.1.1 Release Notes. If you are opting for a dump/restore, make sure to use the `--add-collprovider` option to correctly choose the collation provider for the migrated database.