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. The release notes are cumulative over all alpha releases. Items that are new in the latest alpha release are emphasized. 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. Modify the definition of window-function PARTITION BY and ORDER BY clauses so that their elements are always taken as simple expressions over the query's input columns. Fix bug with WITH RECURSIVE immediately inside WITH RECURSIVE. Define a new, more extensible syntax for COPY options. Add ALTER DEFAULT PRIVILEGES command, which allows users to adjust the privileges that will be applied to subsequently-created objects. Support use of function argument names to identify which actual arguments match which function parameters. The syntax uses AS, for example funcname(value AS arg1, anothervalue AS arg2). Add CREATE LIKE INCLUDING COMMENTS and STORAGE, and INCLUDING ALL shortcut. Add GRANT/REVOKE ON ALL TABLES/SEQUENCES/FUNCTIONS IN SCHEMA. Add SQL-compliant triggers on columns, ie fire only if certain columns are named in the UPDATE's SET list. Add surrogate pair support for U& string and identifier syntax. Add Unicode escapes in E'...' strings. DROP COLUMN and DROP CONSTRAINT now support an IF EXISTS clause so that users can avoid fatal errors when running repeatable scripts. UNIQUE constraints can now be DEFERRABLE. This is primarily useful for incremental updates of numerical keys, e.g. "ID = ID + 1" Allow parentheses around the query expression that follows a WITH clause. INFORMATION_SCHEMA, a catalog of standard views of database objects, has been updated to the SQL:2008 standard. Change character_octet_length to more sensible values in INFORMATION_SCHEMA. Allow * as parameter for FORCE QUOTE for COPY CSV, so that all columns will be quoted. Make TRUNCATE do truncate-in-place when processing a relation that was created or previously truncated in the current (sub)transaction. Implement "join removal" for cases where the inner side of a left join is unique and is not referenced above the join. EXPLAIN allows output of plans in XML or JSON format for automated processing of explain plans by analysis or visualization tools. EXPLAIN now supports the use of generic options in EXPLAIN ( option value, ... ) format, which permits the creation of additional EXPLAIN options. ALTER TABLE ... ALTER COLUMN ... SET STATISTICS DISTINCT allows users to manually tweak the number of distinct values estimated for a column, to fix cases where ANALYZE estimates are incorrect. 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. 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). Simplify the forms foo <> true and foo <> false to foo = false and foo = true during query optimization. Avoid per-send() system calls to manage SIGPIPE in libpq, if the platform provides either sockopt(SO_NOSIGPIPE) or the MSG_NOSIGNAL flag to send(). Add a Boolean server configuration parameter "bonjour" to control whether a Bonjour-enabled build actually attempts to advertise itself via Bonjour. When reloading postgresql.conf, log what parameters actually changed. Make it possibly to specify server configuration parameters per user and per database. psql has gained a drds command to display the settings. Allow the collection of statistics on sequences. Add the ability to include the SQLSTATE error code of any error messages in the PostgreSQL activity log with the new log_line_prefix placeholder %e. Show the exact value being complained of in unique-constraint-violation error messages, including unique-index build failures. Increase the maximum value of extra_float_digits to 3, and have pg_dump use that value when the backend is new enough to allow it, because it is possible to need 3 extra digits for float4 values (but not for float8 values). Support "samehost" and "samenet" specifications in pg_hba.conf. New has_sequence_privilege() functions allow you to check sequence privileges for a given ROLE. Support POSIX-compatible interpretation of ? as well as {m,n} and related constructs in SIMILAR TO, per SQL:2008. The to_char() formatting functions now supports EEEE (scientific notation). Use floor() not rint() when reducing precision of fractional seconds in timestamp_trunc, timestamptz_trunc, and interval_trunc() for the float-datetime case. This improves accuracy of time calculations. Fix ancient bug in handling of to_char() modifier 'TH', when used with HH. Fix encoding handling in binary input function of xml type. Tighten binary receive functions so that they reject values that the text input functions don't accept either. New hex-string input and output format options for type bytea. Hex output format is enabled by default, which is an incompatible change. See the new bytea_output parameter if you need to restore compatibility. Adds prefix support for text search synonym dictionary, allowing creation of synonyms on partial matches. It is now reasonably safe to use pg_ctl to start the postmaster from a boot-time script. Remove the use of the flat files pg_auth and pg_database. (At least pgbouncer currently suggests referring to the pg_auth file for its user database. Such schemes will no longer work.) pg_dump/pg_restore --clean now drops large objects. Modify parallel pg_restore ordering logic to avoid a potential O(N^2) slowdown for some complex databases. Implement significantly saner behavior when two or more psql sessions overlap in their use of the history file. Add "pset linestyle ascii/unicode" option to psql, allowing our traditional ASCII-art style of table output to be upgraded to use Unicode box drawing characters if desired. By default, psql will use the Unicode characters whenever client_encoding is UTF8. Have \d show child tables that inherit from the specified parent psql now shows the index methods in \di Add DO statement to support execution of procedural language code without having to create a function for it. Fix/improve bytea and boolean support in PL/Python. Data type conversion into and out of PL/Python previously went through an intermediate string representation, which caused various discrepancies especially with bytea and boolean data. This is now fixed by converting the values directly. PL/Python now accepts Unicode objects where it previously only accepted string objects (for example, as return value). Unicode objects are converted to the PostgreSQL server encoding as necessary. Improve error context reporting in PL/Perl, for easier debugging. Allow plpgsql IN parameters to be assigned to. Convert a Perl array to a PostgreSQL array when returned by set-returning functions as well as non-SRFs. Allow MOVE FORWARD n, MOVE BACKWARD n, MOVE FORWARD ALL, MOVE BACKWARD ALL in PL/pgSQL. PL/pgSQL functions can now better cope with row types containing dropped columns. Improve error context reporting in PL/Python, for easier debugging. Greatly expand the regression testing for PL/Python. Assorted improvements in contrib/hstore. pgbench is now multi-threaded, allowing it to use multiple CPU's for its client connections, and to do more realistic workload testing. Added the ability to retrieve asynchronous notifications using dblink, via the addition of the function dblink_get_notify(). Added matchorig, matchsynonyms, and keepsynonyms options to contrib/dict_xsyn. Added contrib/unaccent. Add ECPG function that returns the current transaction status. Make ECPG more robust against applications freeing strings. Make libpq reject non-numeric and out-of-range port numbers with a suitable error message. Functions which conflict with C++ reserved words have been renamed, making backend header files now safe to use with C++ libraries. Add man pages for SPI functions. ECPG now includes a STRING datatype for Informix compatibility mode. Change the WIN32 API version to be 5.01 (Windows XP), to bring in the proper IPv6 headers in newer SDKs. Write to the Windows eventlog in UTF-16, converting the message encoding as necessary. Replace use of the long-deprecated Bonjour API DNSServiceRegistrationCreate with the not-so-deprecated DNSServiceRegister. The new code will fail on Mac OS X releases before 10.3. Install a hopefully-temporary workaround for Mac OS X Snow Leopard readdir() bug. 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. Add s_lock support for SuperH architecture (not well tested). Fix inclusions of readline/editline header files so that we only attempt to #include the version of history.h that is in the same directory as the readline.h we are using. This avoids problems in some scenarios where both readline and editline are installed. Derived files that are shipped in the distribution used to be built in the source directory even for out-of-tree builds. They are now also built in the build tree. This should be more convenient for certain developers' workflows. Translations were updated. Upgrade to Autoconf 2.63 (not relevant to users of distribution tarballs). 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. The generated documentation files are now shipped "loose", not in sub-tarballs. New toolchain to generate man pages. From now on, the man pages will be current in every release. Code-coverage testing support now extends to the entire source tree, not only src/backend/. Make the core scanner re-entrant, along with additional fixes that will let it be used directly by PL/pgSQL.