This release focuses on removing limitations that have existed in the PostgreSQL™ code for many years.
Major changes in this release:
To maintain database consistency in case of an operating system crash, previous releases of PostgreSQL™ have forced all data modifications to disk before each transaction commit. With WAL, only one log file must be flushed to disk, greatly improving performance. If you have been using -F in previous releases to disable disk flushes, you might want to consider discontinuing its use.
TOAST - Previous releases had a compiled-in row length limit, typically 8k - 32k. This limit made storage of long text fields difficult. With TOAST, long rows of any length can be stored with good performance.
We now support outer joins. The UNION/NOT IN workaround for outer joins is no longer required. We use the SQL92 outer join syntax.
The previous C function manager did not handle null values properly, nor did it support 64-bit CPU's (Alpha). The new function manager does. You can continue using your old custom functions, but you might want to rewrite them in the future to use the new function manager call interface.
A large number of complex queries that were unsupported in previous releases now work. Many combinations of views, aggregates, UNION, LIMIT, cursors, subqueries, and inherited tables now work properly. Inherited tables are now accessed by default. Subqueries in FROM are now supported.
A dump/restore using pg_dump is required for those wishing to migrate data from any previous release.
Bug Fixes --------- Many multibyte/Unicode/locale fixes (Tatsuo and others) More reliable ALTER TABLE RENAME (Tom) Kerberos V fixes (David Wragg) Fix for INSERT INTO...SELECT where targetlist has subqueries (Tom) Prompt username/password on standard error (Bruce) Large objects inv_read/inv_write fixes (Tom) Fixes for to_char(), to_date(), to_ascii(), and to_timestamp() (Karel, Daniel Baldoni) Prevent query expressions from leaking memory (Tom) Allow UPDATE of arrays elements (Tom) Wake up lock waiters during cancel (Hiroshi) Fix rare cursor crash when using hash join (Tom) Fix for DROP TABLE/INDEX in rolled-back transaction (Hiroshi) Fix psql crash from \l+ if MULTIBYTE enabled (Peter E) Fix truncation of rule names during CREATE VIEW (Ross Reedstrom) Fix PL/perl (Alex Kapranoff) Disallow LOCK on views (Mark Hollomon) Disallow INSERT/UPDATE/DELETE on views (Mark Hollomon) Disallow DROP RULE, CREATE INDEX, TRUNCATE on views (Mark Hollomon) Allow PL/pgSQL accept non-ASCII identifiers (Tatsuo) Allow views to proper handle GROUP BY, aggregates, DISTINCT (Tom) Fix rare failure with TRUNCATE command (Tom) Allow UNION/INTERSECT/EXCEPT to be used with ALL, subqueries, views, DISTINCT, ORDER BY, SELECT...INTO (Tom) Fix parser failures during aborted transactions (Tom) Allow temporary relations to properly clean up indexes (Bruce) Fix VACUUM problem with moving rows in same page (Tom) Modify pg_dump to better handle user-defined items in template1 (Philip) Allow LIMIT in VIEW (Tom) Require cursor FETCH to honor LIMIT (Tom) Allow PRIMARY/FOREIGN Key definitions on inherited columns (Stephan) Allow ORDER BY, LIMIT in subqueries (Tom) Allow UNION in CREATE RULE (Tom) Make ALTER/DROP TABLE rollback-able (Vadim, Tom) Store initdb collation in pg_control so collation cannot be changed (Tom) Fix INSERT...SELECT with rules (Tom) Fix FOR UPDATE inside views and subselects (Tom) Fix OVERLAPS operators conform to SQL92 spec regarding NULLs (Tom) Fix lpad() and rpad() to handle length less than input string (Tom) Fix use of NOTIFY in some rules (Tom) Overhaul btree code (Tom) Fix NOT NULL use in Pl/pgSQL variables (Tom) Overhaul GIST code (Oleg) Fix CLUSTER to preserve constraints and column default (Tom) Improved deadlock detection handling (Tom) Allow multiple SERIAL columns in a table (Tom) Prevent occasional index corruption (Vadim) Enhancements ------------ Add OUTER JOINs (Tom) Function manager overhaul (Tom) Allow ALTER TABLE RENAME on indexes (Tom) Improve CLUSTER (Tom) Improve ps status display for more platforms (Peter E, Marc) Improve CREATE FUNCTION failure message (Ross) JDBC improvements (Peter, Travis Bauer, Christopher Cain, William Webber, Gunnar) Grand Unified Configuration scheme/GUC. Many options can now be set in data/postgresql.conf, postmaster/postgres flags, or SET commands (Peter E) Improved handling of file descriptor cache (Tom) New warning code about auto-created table alias entries (Bruce) Overhaul initdb process (Tom, Peter E) Overhaul of inherited tables; inherited tables now accessed by default; new ONLY key word prevents it (Chris Bitmead, Tom) ODBC cleanups/improvements (Nick Gorham, Stephan Szabo, Zoltan Kovacs, Michael Fork) Allow renaming of temp tables (Tom) Overhaul memory manager contexts (Tom) pg_dumpall uses CREATE USER or CREATE GROUP rather using COPY (Peter E) Overhaul pg_dump (Philip Warner) Allow pg_hba.conf secondary password file to specify only username (Peter E) Allow TEMPORARY or TEMP key word when creating temporary tables (Bruce) New memory leak checker (Karel) New SET SESSION CHARACTERISTICS (Thomas) Allow nested block comments (Thomas) Add WITHOUT TIME ZONE type qualifier (Thomas) New ALTER TABLE ADD CONSTRAINT (Stephan) Use NUMERIC accumulators for INTEGER aggregates (Tom) Overhaul aggregate code (Tom) New VARIANCE and STDDEV() aggregates Improve dependency ordering of pg_dump (Philip) New pg_restore command (Philip) New pg_dump tar output option (Philip) New pg_dump of large objects (Philip) New ESCAPE option to LIKE (Thomas) New case-insensitive LIKE - ILIKE (Thomas) Allow functional indexes to use binary-compatible type (Tom) Allow SQL functions to be used in more contexts (Tom) New pg_config utility (Peter E) New PL/pgSQL EXECUTE command which allows dynamic SQL and utility statements (Jan) New PL/pgSQL GET DIAGNOSTICS statement for SPI value access (Jan) New quote_identifiers() and quote_literal() functions (Jan) New ALTER TABLE table OWNER TO user command (Mark Hollomon) Allow subselects in FROM, i.e. FROM (SELECT ...) [AS] alias (Tom) Update PyGreSQL to version 3.1 (D'Arcy) Store tables as files named by OID (Vadim) New SQL function setval(seq,val,bool) for use in pg_dump (Philip) Require DROP VIEW to remove views, no DROP TABLE (Mark) Allow DROP VIEW view1, view2 (Mark) Allow multiple objects in DROP INDEX, DROP RULE, and DROP TYPE (Tom) Allow automatic conversion to/from Unicode (Tatsuo, Eiji) New /contrib/pgcrypto hashing functions (Marko Kreen) New pg_dumpall --globals-only option (Peter E) New CHECKPOINT command for WAL which creates new WAL log file (Vadim) New AT TIME ZONE syntax (Thomas) Allow location of Unix domain socket to be configurable (David J. MacKenzie) Allow postmaster to listen on a specific IP address (David J. MacKenzie) Allow socket path name to be specified in hostname by using leading slash (David J. MacKenzie) Allow CREATE DATABASE to specify template database (Tom) New utility to convert MySQL schema dumps to SQL92 and PostgreSQL (Thomas) New /contrib/rserv replication toolkit (Vadim) New file format for COPY BINARY (Tom) New /contrib/oid2name to map numeric files to table names (B Palmer) New "idle in transaction" ps status message (Marc) Update to pgaccess 0.98.7 (Constantin Teodorescu) pg_ctl now defaults to -w (wait) on shutdown, new -l (log) option Add rudimentary dependency checking to pg_dump (Philip) Types ----- Fix INET/CIDR type ordering and add new functions (Tom) Make OID behave as an unsigned type (Tom) Allow BIGINT as synonym for INT8 (Peter E) New int2 and int8 comparison operators (Tom) New BIT and BIT VARYING types (Adriaan Joubert, Tom, Peter E) CHAR() no longer faster than VARCHAR() because of TOAST (Tom) New GIST seg/cube examples (Gene Selkov) Improved round(numeric) handling (Tom) Fix CIDR output formatting (Tom) New CIDR abbrev() function (Tom) Performance ----------- Write-Ahead Log (WAL) to provide crash recovery with less performance overhead (Vadim) ANALYZE stage of VACUUM no longer exclusively locks table (Bruce) Reduced file seeks (Denis Perchine) Improve BTREE code for duplicate keys (Tom) Store all large objects in a single table (Denis Perchine, Tom) Improve memory allocation performance (Karel, Tom) Source Code ----------- New function manager call conventions (Tom) SGI portability fixes (David Kaelbling) New configure --enable-syslog option (Peter E) New BSDI README (Bruce) configure script moved to top level, not /src (Peter E) Makefile/configuration/compilation overhaul (Peter E) New configure --with-python option (Peter E) Solaris cleanups (Peter E) Overhaul /contrib Makefiles (Karel) New OpenSSL configuration option (Magnus, Peter E) AIX fixes (Andreas) QNX fixes (Maurizio) New heap_open(), heap_openr() API (Tom) Remove colon and semi-colon operators (Thomas) New pg_class.relkind value for views (Mark Hollomon) Rename ichar() to chr() (Karel) New documentation for btrim(), ascii(), chr(), repeat() (Karel) Fixes for NT/Cygwin (Pete Forman) AIX port fixes (Andreas) New BeOS port (David Reid, Cyril Velter) Add proofreader's changes to docs (Addison-Wesley, Bruce) New Alpha spinlock code (Adriaan Joubert, Compaq) UnixWare port overhaul (Peter E) New Darwin/Mac OS X port (Peter Bierman, Bruce Hartzler) New FreeBSD Alpha port (Alfred) Overhaul shared memory segments (Tom) Add IBM S/390 support (Neale Ferguson) Moved macmanuf to /contrib (Larry Rosenman) Syslog improvements (Larry Rosenman) New template0 database that contains no user additions (Tom) New /contrib/cube and /contrib/seg GIST sample code (Gene Selkov) Allow NetBSD's libedit instead of readline (Peter) Improved assembly language source code format (Bruce) New contrib/pg_logger New --template option to createdb New contrib/pg_control utility (Oliver) New FreeBSD tools ipc_check, start-scripts/freebsd