Peter, Since I'd need to install haskell on my system before installing pandoc, I've attached my "final" edit of the RST file so that I don't hold things up.
-- Josh Berkus PostgreSQL Experts Inc. www.pgexperts.com
.. -*- mode: rst -*- ================= Release 8.5alpha1 ================= 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 ------- SQL Features ~~~~~~~~~~~~ - 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" - Allows 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 ANSI/ISO standard. - Changes 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. Performance ~~~~~~~~~~~ - 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. - Makes 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(). - 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. Administration and Monitoring ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - 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. Security ~~~~~~~~ - New has_sequence_privilege() functions allow you to check sequence privileges for a given ROLE. Built-In Functions ~~~~~~~~~~~~~~~~~~ - 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. Datatypes ~~~~~~~~~ - 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. Server Tools ~~~~~~~~~~~~ - pg_dump/pg_restore --clean now drops large objects. - Modifies parallel pg_restore ordering logic to avoid a potential O(N^2) slowdown for some complex databases. psql ~~~~ - Have \\d show child tables that inherit from the specified parent - psql now shows the index methods in \\di Procedural Languages ~~~~~~~~~~~~~~~~~~~~ - PL/pgSQL functions using RETURNS QUERY or RECORD types no longer always need to be rebuilt after adding or dropping a column for the related tables. - Improves error context reporting in PL/Python, for easier debugging. - Greatly expands the regression testing for PL/Python. Additional Supplied Modules ~~~~~~~~~~~~~~~~~~~~~~~~~~~ - 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. Development ~~~~~~~~~~~ - 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. Source code, build options ~~~~~~~~~~~~~~~~~~~~~~~~~~ - 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/. - 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. - Make the core scanner re-entrant, along with additional fixes that will let it be used directly by PL/pgSQL. - Fix backend startup to not depend on the flat-file copy of pg_database. This is a first step towards eliminating the flat files altogether. - Add s_lock support for SuperH architecture (not well tested).
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