.. -*- mode: rst -*-
=================
Release 8.5alpha1
=================
.. last commit: Simplify and speed up man page installation

Overview
--------

PostgreSQL alpha releases are snapshots of development code.  They are
intended to preview and test upcoming features and to provide the
possibility for early feedback.  They should not be used in production
installations or active development projects.  While the PostgreSQL
code is continuously subject to a number of automated and manual
tests, alpha releases might have serious bugs.  Also features may be
changed incompatibly or removed at any time during the development
cycle.

The development cycle of a PostgreSQL major release alternates between
periods of development and periods of integration work, called commit
fests, normally one month each.  Alpha releases are planned to be
produced at the end of every commit fest, thus every two months.
Since the first commit fest starts within a month from the beginning
of development altogether, early alpha releases are not indicative of
the likely feature set of the final release.

The release notes below highlight user visible changes and new
features.  There are normally numerous bug fixes and performance
improvements in every new snapshot of PostgreSQL, and it would be too
bulky to attempt to list them all.  Note that many bug fixes are also
backported to stable releases of PostgreSQL, and you should be using
those if you are looking for bug-fix-only upgrades for your current
installations.

Migration
---------

To upgrade from any release to an alpha release or from an alpha
release to any other release will most likely require a dump/restore
upgrade procedure.  It may happen that this is not necessary in
particular cases, but that is not verified beforehand.  (The server
will warn you in any case when a dump/restore is necessary if you
attempt to use it with an old data directory.)  Note, however, that
the dump/restore upgrade procedure is expected to work for alpha
releases, and problems in this area should be reported.

Changes
-------

Server
~~~~~~

- Added log_line_prefix placeholder %e to contain the current SQL
  state

- Allow parentheses around the query expression that follows a WITH
  clause.

- Fixed ancient bug in handling of to_char modifier 'TH', when used
  with HH.

- Use floor() not rint() when reducing precision of fractional seconds
  in timestamp_trunc, timestamptz_trunc, and interval_trunc() for the
  float-datetime case.

- More sensible values for character_octet_length column in
  information schema.

- Information schema updated to SQL:2008

- Backend header files are now safe to use with C++.

- Make GEQO's planning deterministic by having it start from a
  predictable random number seed each time.

- Rewrite GEQO's gimme_tree function so that it always finds a legal
  join sequence.  Previously, it could have failed to produce a plan
  in some cases.

- Simplify the forms foo <> true and foo <> false to foo = true and
  foo = false.

- DROP IF EXISTS for columns and constraints

- Tweak TOAST code so that columns marked with MAIN storage strategy
  are not forced out-of-line unless that is necessary to make the row
  fit on a page.  Previously, they were forced out-of-line if needed
  to get the row down to the default target size (1/4th page).

- EXPLAIN can now take generic options

- EXPLAIN allows output of plans in XML or JSON format.

- Support EEEE (scientific notation) in to_char().

- Allow * as parameter for FORCE QUOTE for COPY CSV

- Support deferrable uniqueness constraints.

- Added ALTER TABLE ... ALTER COLUMN ... SET STATISTICS DISTINCT

- has_sequence_privilege()

- New hex-string input and output for type BYTEA.

- Fast shutdown stop should forcibly disconnect any active backends,
  even if a smart shutdown is already in progress. Backpatched to 8.3.

pg_dump
~~~~~~~

- Fixed up --binary-upgrade option so that it behaves properly with
  inherited columns and check constraints.

- Properly restore pg_largeobject.relfozenxid in binary upgrade mode.

- Make pg_dump/pg_restore --clean options drop large objects too.

- Modify parallel pg_restore logic to avoid potential O(N^2) slowdown
  in extreme cases.

psql
~~~~

- Have \\d show child tables that inherit from the specified parent

- Show definition of index columns in \\d on index

ecpg
~~~~

- Added STRING datatype for Informix compatibility mode.

Procedural Languages
~~~~~~~~~~~~~~~~~~~~

- Improve plpgsql's ability to cope with rowtypes containing dropped
  columns,

Contrib
~~~~~~~

- Multi-threaded version of pgbench

- Adds the ability to retrieve async notifications using dblink, via
  the addition of the function dblink_get_notify().

- Add matchorig, matchsynonyms, and keepsynonyms options to
  contrib/dict_xsyn.

Source code, build options
~~~~~~~~~~~~~~~~~~~~~~~~~~

- Upgrade to Autoconf 2.63

- Minimum version of Flex is now 2.5.31, to support reentrant scanners
  (not relevant to users of distribution tarballs).

- Documentation build rules have been improved

- New toolchain to generate man pages.  From now on, the man pages
  will be current in every release.

- Added man pages for SPI functions.

- Reserve the shared memory region during backend startup on Windows,
  so that memory allocated by starting third party DLLs doesn't end up
  conflicting with it.  Hopefully this solves the long-time issue with
  "could not reattach to shared memory" errors on Win32.

- Added s_lock support for SuperH architecture.

- Test coverage support now extends to the entire source tree, not
  only src/backend/.