Alpha 5 is now available for testing

The fifth alpha release for PostgreSQL version 9.1, 9.1alpha5, is now available. There are no new major features in this alpha release as compared to 9.1alpha4, but there are many minor bug fixes and improvements to features added in 9.1alpha4 and earlier alpha releases. It is expected that no major new features will be added before final release; this is likely to be the final alpha release for PostgreSQL 9.1.

Please download, install, and test Alpha5. We depend on your bug reports and feedback in order to proceed to 9.1beta and to final release. The more testing you do, the sooner 9.1 will be available. Thank you to the many users who reported bugs in earlier alphas.

Most of the 148 changes and fixes between Alpha4 and Alpha5 were around two major features, per-column collations and synchronous replication. Work on per-column collations included some major refactoring, adding support for it in all features of PostgreSQL, and changes to the column collations API and system catalogs. Multiple reported bugs were fixed in synchronous replication including lockups, issues with recovery mode, and replication being very slow with fsync = off. If you tested either of these features, please retest as the code has changed significantly since Alpha4.

Other changes included:
* add post-creation hook for extensions
* numerous additions and corrections to documentation and release notes
* allow valid-on-creation foreign keys as column constraints
* refactor of min/max aggregate optimization
* fix potential race condition with pg_basebackup
* fix PL/Python array memory leak
* raise maximum value for many timeout configuration settings
* fix handling of "unknown" literals in UNION queries
* fix some division-by-zero issues in the code
* cleanup some variable handling in ECPG
* fix some makefile problems introduced in Alpha4
* make permissions for COMMENT ON ROLE consistent

The new features which are expected to be available in PostgreSQL 9.1 are documented in the release notes, at http://developer.postgresql.org/pgdocs/postgres/release-9-1.html. If you are able to help with organized alpha testing, please see the Alpha/Beta testing page: http://wiki.postgresql.org/wiki/HowToBetaTest

Alpha releases are not stable and should never be used in production; they are for testing new features only. There is no guarantee that any features or APIs present in the alphas will be present, or the
same, in the final release.

Alpha release information page: http://www.postgresql.org/developer/alpha

Download the alpha release here:
http://www.postgresql.org/ftp/source/v9.1alpha5/

Alpha releases are primarily made in source code form only. Binary packages for some operating systems will be prepared in the coming days.

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Josh Berkus