There are many new features and improvements in this release. Thanks to our developers and maintainers, nearly every aspect of the system has received some attention since the previous release. Here is a brief, incomplete summary:
Views and rules are now functional thanks to extensive new code in the rewrite rules system from Jan Wieck. He also wrote a chapter on it for the Programmer's Guide.
Jan also contributed a second procedural language, PL/pgSQL, to go with the original PL/pgTCL procedural language he contributed last release.
We have optional multiple-byte character set support from Tatsuo Iishi to complement our existing locale support.
Client/server communications has been cleaned up, with better support for asynchronous messages and interrupts thanks to Tom Lane.
The parser will now perform automatic type coercion to match arguments to available operators and functions, and to match columns and expressions with target columns. This uses a generic mechanism which supports the type extensibility features of Postgres. There is a new chapter in the User's Guide which covers this topic.
Three new data types have been added. Two types, inet and cidr, support various forms of IP network, subnet, and machine addressing. There is now an 8-byte integer type available on some platforms. See the chapter on data types in the User's Guide for details. A fourth type, serial, is now supported by the parser as an amalgam of the int4 type, a sequence, and a unique index.
Several more SQL92-compatible syntax features have been added, including INSERT DEFAULT VALUES
The automatic configuration and installation system has received some attention, and should be more robust for more platforms than it has ever been.
A dump/restore using pg_dump or pg_dumpall is required for those wishing to migrate data from any previous release of Postgres.
Bug Fixes --------- Fix for a tiny memory leak in PQsetdb/PQfinish(Bryan) Remove char2-16 data types, use char/varchar(Darren) Pqfn not handles a NOTICE message(Anders) Reduced busywaiting overhead for spinlocks with many backends (dg) Stuck spinlock detection (dg) Fix up "ISO-style" timespan decoding and encoding(Thomas) Fix problem with table drop after rollback of transaction(Vadim) Change error message and remove non-functional update message(Vadim) Fix for COPY array checking Fix for SELECT 1 UNION SELECT NULL Fix for buffer leaks in large object calls(Pascal) Change owner from oid to int4 type(Bruce) Fix a bug in the oracle compatibility functions btrim() ltrim() and rtrim() Fix for shared invalidation cache overflow(Massimo) Prevent file descriptor leaks in failed COPY's(Bruce) Fix memory leak in libpgtcl's pg_select(Constantin) Fix problems with username/passwords over 8 characters(Tom) Fix problems with handling of asynchronous NOTIFY in backend(Tom) Fix of many bad system table entries(Tom) Enhancements ------------ Upgrade ecpg and ecpglib,see src/interfaces/ecpc/ChangeLog(Michael) Show the index used in an EXPLAIN(Zeugswetter) EXPLAIN invokes rule system and shows plan(s) for rewritten queries(Jan) Multi-byte awareness of many data types and functions, via configure(Tatsuo) New configure --with-mb option(Tatsuo) New initdb --pgencoding option(Tatsuo) New createdb -E multibyte option(Tatsuo) Select version(); now returns PostgreSQL version(Jeroen) Libpq now allows asynchronous clients(Tom) Allow cancel from client of backend query(Tom) Psql now cancels query with Control-C(Tom) Libpq users need not issue dummy queries to get NOTIFY messages(Tom) NOTIFY now sends sender's PID, so you can tell whether it was your own(Tom) PGresult struct now includes associated error message, if any(Tom) Define "tz_hour" and "tz_minute" arguments to date_part()(Thomas) Add routines to convert between varchar and bpchar(Thomas) Add routines to allow sizing of varchar and bpchar into target columns(Thomas) Add bit flags to support timezonehour and minute in data retrieval(Thomas) Allow more variations on valid floating point numbers (e.g. ".1", "1e6")(Thomas) Fixes for unary minus parsing with leading spaces(Thomas) Implement TIMEZONE_HOUR, TIMEZONE_MINUTE per SQL92 specs(Thomas) Check for and properly ignore FOREIGN KEY column constraints(Thomas) Define USER as synonym for CURRENT_USER per SQL92 specs(Thomas) Enable HAVING clause but no fixes elsewhere yet. Make "char" type a synonym for "char(1)" (actually implemented as bpchar)(Thomas) Save string type if specified for DEFAULT clause handling(Thomas) Coerce operations involving different data types(Thomas) Allow some index use for columns of different types(Thomas) Add capabilities for automatic type conversion(Thomas) Cleanups for large objects, so file is truncated on open(Peter) Readline cleanups(Tom) Allow psql \f \ to make spaces as delimiter(Bruce) Pass pg_attribute.atttypmod to the frontend for column field lengths(Tom,Bruce) Msql compatibility library in /contrib(Aldrin) Remove the requirement that ORDER/GROUP BY clause identifiers be included in the target list(David) Convert columns to match columns in UNION clauses(Thomas) Remove fork()/exec() and only do fork()(Bruce) Jdbc cleanups(Peter) Show backend status on ps command line(only works on some platforms)(Bruce) Pg_hba.conf now has a sameuser option in the database field Make lo_unlink take oid param, not int4 New DISABLE_COMPLEX_MACRO for compilers that can't handle our macros(Bruce) Libpgtcl now handles NOTIFY as a Tcl event, need not send dummy queries(Tom) libpgtcl cleanups(Tom) Add -error option to libpgtcl's pg_result command(Tom) New locale patch, see docs/README/locale(Oleg) Fix for pg_dump so CONSTRAINT and CHECK syntax is correct(ccb) New contrib/lo code for large object orphan removal(Peter) New psql command "SET CLIENT_ENCODING TO 'encoding'" for multi-bytes feature, see /doc/README.mb(Tatsuo) /contrib/noupdate code to revoke update permission on a column Libpq can now be compiled on win32(Magnus) Add PQsetdbLogin() in libpq New 8-byte integer type, checked by configure for OS support(Thomas) Better support for quoted table/column names(Thomas) Surround table and column names with double-quotes in pg_dump(Thomas) PQreset() now works with passwords(Tom) Handle case of GROUP BY target list column number out of range(David) Allow UNION in subselects Add auto-size to screen to \d? commands(Bruce) Use UNION to show all \d? results in one query(Bruce) Add \d? field search feature(Bruce) Pg_dump issues fewer \connect requests(Tom) Make pg_dump -z flag work better, document it in manual page(Tom) Add HAVING clause with full support for subselects and unions(Stephan) Full text indexing routines in contrib/fulltextindex(Maarten) Transaction ids now stored in shared memory(Vadim) New PGCLIENTENCODING when issuing COPY command(Tatsuo) Support for SQL92 syntax "SET NAMES"(Tatsuo) Support for LATIN2-5(Tatsuo) Add UNICODE regression test case(Tatsuo) Lock manager cleanup, new locking modes for LLL(Vadim) Allow index use with OR clauses(Bruce) Allows "SELECT NULL ORDER BY 1;" Explain VERBOSE prints the plan, and now pretty-prints the plan to the postmaster log file(Bruce) Add Indices display to \d command(Bruce) Allow GROUP BY on functions(David) New pg_class.relkind for large objects(Bruce) New way to send libpq NOTICE messages to a different location(Tom) New \w write command to psql(Bruce) New /contrib/findoidjoins scans oid columns to find join relationships(Bruce) Allow binary-compatible indices to be considered when checking for valid indices for restriction clauses containing a constant(Thomas) New ISBN/ISSN code in /contrib/isbn_issn Allow NOT LIKE, IN, NOT IN, BETWEEN, and NOT BETWEEN constraint(Thomas) New rewrite system fixes many problems with rules and views(Jan) * Rules on relations work * Event qualifications on insert/update/delete work * New OLD variable to reference CURRENT, CURRENT will be remove in future * Update rules can reference NEW and OLD in rule qualifications/actions * Insert/update/delete rules on views work * Multiple rule actions are now supported, surrounded by parentheses * Regular users can create views/rules on tables they have RULE permits * Rules and views inherit the permissions on the creator * No rules at the column level * No UPDATE NEW/OLD rules * New pg_tables, pg_indexes, pg_rules and pg_views system views * Only a single action on SELECT rules * Total rewrite overhaul, perhaps for 6.5 * handle subselects * handle aggregates on views * handle insert into select from view works System indexes are now multi-key(Bruce) Oidint2, oidint4, and oidname types are removed(Bruce) Use system cache for more system table lookups(Bruce) New backend programming language PL/pgSQL in backend/pl(Jan) New SERIAL data type, auto-creates sequence/index(Thomas) Enable assert checking without a recompile(Massimo) User lock enhancements(Massimo) New setval() command to set sequence value(Massimo) Auto-remove unix socket file on startup if no postmaster running(Massimo) Conditional trace package(Massimo) New UNLISTEN command(Massimo) Psql and libpq now compile under win32 using win32.mak(Magnus) Lo_read no longer stores trailing NULL(Bruce) Identifiers are now truncated to 31 characters internally(Bruce) Createuser options now availble on the command line Code for 64-bit integer supported added, configure tested, int8 type(Thomas) Prevent file descriptor leaf from failed COPY(Bruce) New pg_upgrade command(Bruce) Updated /contrib directories(Massimo) New CREATE TABLE DEFAULT VALUES statement available(Thomas) New INSERT INTO TABLE DEFAULT VALUES statement available(Thomas) New DECLARE and FETCH feature(Thomas) libpq's internal structures now not exported(Tom) Allow up to 8 key indexes(Bruce) Remove ARCHIVE keyword, that is no longer used(Thomas) pg_dump -n flag to supress quotes around indentifiers disable system columns for views(Jan) new INET and CIDR types for network addresses(TomH, Paul) no more double quotes in psql output pg_dump now dumps views(Terry) new SET QUERY_LIMIT(Tatsuo,Jan) Source Tree Changes ------------------- /contrib cleanup(Jun) Inline some small functions called for every row(Bruce) Alpha/linux fixes Hp/UX cleanups(Tom) Multi-byte regression tests(Soonmyung.) Remove --disabled options from configure Define PGDOC to use POSTGRESDIR by default Make regression optional Remove extra braces code to pgindent(Bruce) Add bsdi shared library support(Bruce) New --without-CXX support configure option(Brook) New FAQ_CVS Update backend flowchart in tools/backend(Bruce) Change atttypmod from int16 to int32(Bruce, Tom) Getrusage() fix for platforms that do not have it(Tom) Add PQconnectdb, PGUSER, PGPASSWORD to libpq man page NS32K platform fixes(Phil Nelson, John Buller) Sco 7/UnixWare 2.x fixes(Billy,others) Sparc/Solaris 2.5 fixes(Ryan) Pgbuiltin.3 is obsolete, move to doc files(Thomas) Even more documention(Thomas) Nextstep support(Jacek) Aix support(David) pginterface manual page(Bruce) shared libraries all have version numbers merged all OS-specific shared library defines into one file smarter TCL/TK configuration checking(Billy) smarter perl configuration(Brook) configure uses supplied install-sh if no install script found(Tom) new Makefile.shlib for shared library configuration(Tom)