This is the first ever alpha release done by the PostgreSQL project. We've started doing alpha releases on the "release early, release often"
principle, so that our advanced users will try new features and new code as early as possible and get back to us with adjustments and problems.
These alphas are not stable and should never be used in production; they are for developers to try new features only. Therefore we are releasing
8.5Alpha1 in source code form only.

There will be three to four more alphas, about every 2 months, before an 8.5 beta release. There is no guarantee that any features or APIs
present in the alphas will be present, or the same, in the final release. Included in the current alpha are:

* Deferrable Unique Constraints
* DROP COLUMN/CONSTRAINT IF EXISTS
* EXPLAIN can output in XML and JSON
* Hex-string input and output for BYTEA
* Multi-threaded pgbench
* Build improvements for code and docs

More detail is available in the Release Notes included with each alpha:
http://developer.postgresql.org/pgdocs/postgres/release-8.5.html

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

Download the first alpha here:
http://www.postgresql.org/ftp/source/8.5alpha1/

Alpha1 is currently available in source code form only. Binary packages for some operating systems will be prepared in the coming days.