PostgreSQL 7.4.3 Documentation
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# E.16. Release 7.2

> Release date: 2002-02-04

## E.16.1. Overview

This release improves PostgreSQL for use in high-volume applications.

Major changes in this release:

VACUUM

  Vacuuming no longer locks tables, thus allowing normal user access during the vacuum. A new `VACUUM FULL` command does old-style vacuum by locking the table and shrinking the on-disk copy of the table.

Transactions

  There is no longer a problem with installations that exceed four billion transactions.

OIDs

  OIDs are now optional. Users can now create tables without OIDs for cases where OID usage is excessive.

Optimizer

  The system now computes histogram column statistics during `ANALYZE`, allowing much better optimizer choices.

Security

  A new MD5 encryption option allows more secure storage and transfer of passwords. A new Unix-domain socket authentication option is available on Linux and BSD systems.

Statistics

  Administrators can use the new table access statistics module to get fine-grained information about table and index usage.

Internationalization

  Program and library messages can now be displayed in several languages.

## E.16.2. Migration to version 7.2

A dump/restore using `pg_dump` is required for those wishing to migrate data from any previous release.

Observe the following incompatibilities:

- The semantics of the `VACUUM` command have changed in this release. You may wish to update your maintenance procedures accordingly.

- In this release, comparisons using `= NULL` will always return false (or NULL, more precisely). Previous releases automatically transformed this syntax to `IS NULL`. The old behavior can be re-enabled using a `postgresql.conf` parameter.

- The `pg_hba.conf` and `pg_ident.conf` configuration is now only reloaded after receiving a SIGHUP signal, not with each connection.

- The function `octet_length()` now returns the uncompressed data length.

- The date/time value `'current'` is no longer available. You will need to rewrite your applications.

- The `timestamp()`, `time()`, and `interval()` functions are no longer available. Instead of `timestamp()`, use `timestamp 'string'` or `CAST`.

The `SELECT ... LIMIT #,#` syntax will be removed in the next release. You should change your queries to use separate LIMIT and OFFSET clauses, e.g. `LIMIT 10 OFFSET 20`.

## E.16.3. Changes

### E.16.3.1. Server Operation

- Create temporary files in a separate directory (Bruce)

- Delete orphaned temporary files on postmaster startup (Bruce)

- Added unique indexes to some system tables (Tom)

- System table operator reorganization (Oleg Bartunov, Teodor Sigaev, Tom)

- Renamed pg_log to pg_clog (Tom)

- Enable SIGTERM, SIGQUIT to kill backends (Jan)

- Removed compile-time limit on number of backends (Tom)

- Better cleanup for semaphore resource failure (Tatsuo, Tom)

- Allow safe transaction ID wraparound (Tom)

- Removed OIDs from some system tables (Tom)

- Removed "triggered data change violation" error check (Tom)

- SPI portal creation of prepared/saved plans (Jan)

- Allow SPI column functions to work for system columns (Tom)

- Long value compression improvement (Tom)

- Statistics collector for table, index access (Jan)

- Truncate extra-long sequence names to a reasonable value (Tom)

- Measure transaction times in milliseconds (Thomas)

- Fix TID sequential scans (Hiroshi)

- Superuser ID now fixed at 1 (Peter E)

- New pg_ctl "reload" option (Tom)

### E.16.3.2. Performance

- Optimizer improvements (Tom)

- New histogram column statistics for optimizer (Tom)

- Reuse write-ahead log files rather than discarding them (Tom)

- Cache improvements (Tom)

- IS NULL, IS NOT NULL optimizer improvement (Tom)

- Improve lock manager to reduce lock contention (Tom)

- Keep relcache entries for index access support functions (Tom)

- Allow better selectivity with NaN and infinities in NUMERIC (Tom)

- R-tree performance improvements (Kenneth Been)

- B-tree splits more efficient (Tom)

### E.16.3.3. Privileges

- Change UPDATE, DELETE privileges to be distinct (Peter E)

- New REFERENCES, TRIGGER privileges (Peter E)

- Allow GRANT/REVOKE to/from more than one user at a time (Peter E)

- New has_table_privilege() function (Joe Conway)

- Allow non-superuser to vacuum database (Tom)

- New SET SESSION AUTHORIZATION command (Peter E)

- Fix bug in privilege modifications on newly created tables (Tom)

- Disallow access to pg_statistic for non-superuser, add user-accessible views (Tom)

### E.16.3.4. Client Authentication

- Fork postmaster before doing authentication to prevent hangs (Peter E)

- Add ident authentication over Unix domain sockets on Linux, *BSD (Helge Bahmann, Oliver Elphick, Teodor Sigaev, Bruce)

- Add a password authentication method that uses MD5 encryption (Bruce)

- Allow encryption of stored passwords using MD5 (Bruce)

- PAM authentication (Dominic J. Eidson)

- Load pg_hba.conf and pg_ident.conf only on startup and SIGHUP (Bruce)

### E.16.3.5. Server Configuration

- Interpretation of some time zone abbreviations as Australian rather than North American now settable at run time (Bruce)

- New parameter to set default transaction isolation level (Peter E)

- New parameter to enable conversion of "expr = NULL" into "expr IS NULL", off by default (Peter E)

- New parameter to control memory usage by VACUUM (Tom)

- New parameter to set client authentication timeout (Tom)

- New parameter to set maximum number of open files (Tom)

### E.16.3.6. Queries

- Statements added by INSERT rules now execute after the INSERT (Jan)

- Prevent unadorned relation names in target list (Bruce)

- NULLs now sort after all normal values in ORDER BY (Tom)

- New IS UNKNOWN, IS NOT UNKNOWN Boolean tests (Tom)

- New SHARE UPDATE EXCLUSIVE lock mode (Tom)

- New EXPLAIN ANALYZE command that shows run times and row counts (Martijn van Oosterhout)

- Fix problem with LIMIT and subqueries (Tom)

- Fix for LIMIT, DISTINCT ON pushed into subqueries (Tom)

- Fix nested EXCEPT/INTERSECT (Tom)

### E.16.3.7. Schema Manipulation

- Fix SERIAL in temporary tables (Bruce)

- Allow temporary sequences (Bruce)

- Sequences now use int8 internally (Tom)

- New SERIAL8 creates int8 columns with sequences, default still SERIAL4 (Tom)

- Make OIDs optional using WITHOUT OIDS (Tom)

- Add %TYPE syntax to CREATE TYPE (Ian Lance Taylor)

- Add ALTER TABLE / DROP CONSTRAINT for CHECK constraints (Christopher Kings-Lynne)

- New CREATE OR REPLACE FUNCTION to alter existing function (preserving the function OID) (Gavin Sherry)

- Add ALTER TABLE / ADD [ UNIQUE | PRIMARY ] (Christopher Kings-Lynne)

- Allow column renaming in views

- Make ALTER TABLE / RENAME COLUMN update column names of indexes (Brent Verner)

- Fix for ALTER TABLE / ADD CONSTRAINT ... CHECK with inherited tables (Stephan Szabo)

- ALTER TABLE RENAME update foreign-key trigger arguments correctly (Brent Verner)

- DROP AGGREGATE and COMMENT ON AGGREGATE now accept an aggtype (Tom)

- Add automatic return type data casting for SQL functions (Tom)

- Allow GiST indexes to handle NULLs and multikey indexes (Oleg Bartunov, Teodor Sigaev, Tom)

- Enable partial indexes (Martijn van Oosterhout)

### E.16.3.8. Utility Commands

- Add RESET ALL, SHOW ALL (Marko Kreen)

- CREATE/ALTER USER/GROUP now allow options in any order (Vince)

- Add LOCK A, B, C functionality (Neil Padgett)

- New ENCRYPTED/UNENCRYPTED option to CREATE/ALTER USER (Bruce)

- New light-weight VACUUM does not lock table; old semantics are available as VACUUM FULL (Tom)

- Disable COPY TO/FROM on views (Bruce)

- COPY DELIMITERS string must be exactly one character (Tom)

- VACUUM warning about index tuples fewer than heap now only appears when appropriate (Martijn van Oosterhout)

- Fix privilege checks for CREATE INDEX (Tom)

- Disallow inappropriate use of CREATE/DROP INDEX/TRIGGER/VIEW (Tom)

### E.16.3.9. Data Types and Functions

- SUM(), AVG(), COUNT() now uses int8 internally for speed (Tom)

- Add convert(), convert2() (Tatsuo)

- New function bit_length() (Peter E)

- Make the "n" in CHAR(n)/VARCHAR(n) represents letters, not bytes (Tatsuo)

- CHAR(), VARCHAR() now reject strings that are too long (Peter E)

- BIT VARYING now rejects bit strings that are too long (Peter E)

- BIT now rejects bit strings that do not match declared size (Peter E)

- INET, CIDR text conversion functions (Alex Pilosov)

- INET, CIDR operators << and <<= indexable (Alex Pilosov)

- Bytea \### now requires valid three digit octal number

- Bytea comparison improvements, now supports =, <>, >, >=, <, and <=

- Bytea now supports B-tree indexes

- Bytea now supports LIKE, LIKE...ESCAPE, NOT LIKE, NOT LIKE...ESCAPE

- Bytea now supports concatenation

- New bytea functions: position, substring, trim, btrim, and length

- New encode() function mode, "escaped", converts minimally escaped bytea to/from text

- Add pg_database_encoding_max_length() (Tatsuo)

- Add pg_client_encoding() function (Tatsuo)

- now() returns time with millisecond precision (Thomas)

- New TIMESTAMP WITHOUT TIMEZONE data type (Thomas)

- Add ISO date/time specification with "T", yyyy-mm-ddThh:mm:ss (Thomas)

- New xid/int comparison functions (Hiroshi)

- Add precision to TIME, TIMESTAMP, and INTERVAL data types (Thomas)

- Modify type coercion logic to attempt binary-compatible functions first (Tom)

- New encode() function installed by default (Marko Kreen)

- Improved to_*() conversion functions (Karel Zak)

- Optimize LIKE/ILIKE when using single-byte encodings (Tatsuo)

- New functions in contrib/pgcrypto: crypt(), hmac(), encrypt(), gen_salt() (Marko Kreen)

- Correct description of translate() function (Bruce)

- Add INTERVAL argument for SET TIME ZONE (Thomas)

- Add INTERVAL YEAR TO MONTH (etc.) syntax (Thomas)

- Optimize length functions when using single-byte encodings (Tatsuo)

- Fix path_inter, path_distance, path_length, dist_ppath to handle closed paths (Curtis Barrett, Tom)

- octet_length(text) now returns non-compressed length (Tatsuo, Bruce)

- Handle "July" full name in date/time literals (Greg Sabino Mullane)

- Some datatype() function calls now evaluated differently

- Add support for Julian and ISO time specifications (Thomas)

### E.16.3.10. Internationalization

- National language support in psql, pg_dump, libpq, and server (Peter E)

- Message translations in Chinese (simplified, traditional), Czech, French, German, Hungarian, Russian, Swedish (Peter E, Serguei A. Mokhov, Karel Zak, Weiping He, Zhenbang Wei, Kovacs Zoltan)

- Make trim, ltrim, rtrim, btrim, lpad, rpad, translate multibyte aware (Tatsuo)

- Add LATIN5,6,7,8,9,10 support (Tatsuo)

- Add ISO 8859-5,6,7,8 support (Tatsuo)

- Correct LATIN5 to mean ISO-8859-9, not ISO-8859-5 (Tatsuo)

- Make mic2ascii() non-ASCII aware (Tatsuo)

- Reject invalid multibyte character sequences (Tatsuo)

### E.16.3.11. PL/pgSQL

- Now uses portals for SELECT loops, allowing huge result sets (Jan)

- CURSOR and REFCURSOR support (Jan)

- Can now return open cursors (Jan)

- Add ELSEIF (Klaus Reger)

- Improve PL/pgSQL error reporting, including location of error (Tom)

- Allow IS or FOR key words in cursor declaration, for compatibility (Bruce)

- Fix for SELECT ... FOR UPDATE (Tom)

- Fix for PERFORM returning multiple rows (Tom)

- Make PL/pgSQL use the server's type coercion code (Tom)

- Memory leak fix (Jan, Tom)

- Make trailing semicolon optional (Tom)

### E.16.3.12. PL/Perl

- New untrusted PL/Perl (Alex Pilosov)

- PL/Perl is now built on some platforms even if libperl is not shared (Peter E)

### E.16.3.13. PL/Tcl

- Now reports errorInfo (Vsevolod Lobko)

- Add spi_lastoid function (bob@redivi.com)

### E.16.3.14. PL/Python

- ...is new (Andrew Bosma)

### E.16.3.15. psql

- \d displays indexes in unique, primary groupings (Christopher Kings-Lynne)

- Allow trailing semicolons in backslash commands (Greg Sabino Mullane)

- Read password from /dev/tty if possible

- Force new password prompt when changing user and database (Tatsuo, Tom)

- Format the correct number of columns for Unicode (Patrice)

### E.16.3.16. libpq

- New function PQescapeString() to escape quotes in command strings (Florian Weimer)

- New function PQescapeBytea() escapes binary strings for use as SQL string literals

### E.16.3.17. JDBC

- Return OID of INSERT (Ken K)

- Handle more data types (Ken K)

- Handle single quotes and newlines in strings (Ken K)

- Handle NULL variables (Ken K)

- Fix for time zone handling (Barry Lind)

- Improved Druid support

- Allow eight-bit characters with non-multibyte server (Barry Lind)

- Support BIT, BINARY types (Ned Wolpert)

- Reduce memory usage (Michael Stephens, Dave Cramer)

- Update DatabaseMetaData (Peter E)

- Add DatabaseMetaData.getCatalogs() (Peter E)

- Encoding fixes (Anders Bengtsson)

- Get/setCatalog methods (Jason Davies)

- DatabaseMetaData.getColumns() now returns column defaults (Jason Davies)

- DatabaseMetaData.getColumns() performance improvement (Jeroen van Vianen)

- Some JDBC1 and JDBC2 merging (Anders Bengtsson)

- Transaction performance improvements (Barry Lind)

- Array fixes (Greg Zoller)

- Serialize addition

- Fix batch processing (Rene Pijlman)

- ExecSQL method reorganization (Anders Bengtsson)

- GetColumn() fixes (Jeroen van Vianen)

- Fix isWriteable() function (Rene Pijlman)

- Improved passage of JDBC2 conformance tests (Rene Pijlman)

- Add bytea type capability (Barry Lind)

- Add isNullable() (Rene Pijlman)

- JDBC date/time test suite fixes (Liam Stewart)

- Fix for SELECT 'id' AS xxx FROM table (Dave Cramer)

- Fix DatabaseMetaData to show precision properly (Mark Lillywhite)

- New getImported/getExported keys (Jason Davies)

- MD5 password encryption support (Jeremy Wohl)

- Fix to actually use type cache (Ned Wolpert)

### E.16.3.18. ODBC

- Remove query size limit (Hiroshi)

- Remove text field size limit (Hiroshi)

- Fix for SQLPrimaryKeys in multibyte mode (Hiroshi)

- Allow ODBC procedure calls (Hiroshi)

- Improve boolean handing (Aidan Mountford)

- Most configuration options now settable via DSN (Hiroshi)

- Multibyte, performance fixes (Hiroshi)

- Allow driver to be used with iODBC or unixODBC (Peter E)

- MD5 password encryption support (Bruce)

- Add more compatibility functions to odbc.sql (Peter E)

### E.16.3.19. ECPG

- EXECUTE ... INTO implemented (Christof Petig)

- Multiple row descriptor support (e.g. CARDINALITY) (Christof Petig)

- Fix for GRANT parameters (Lee Kindness)

- Fix INITIALLY DEFERRED bug

- Various bug fixes (Michael, Christof Petig)

- Auto allocation for indicator variable arrays (int *ind_p=NULL)

- Auto allocation for string arrays (char **foo_pp=NULL)

- ECPGfree_auto_mem fixed

- All function names with external linkage are now prefixed by ECPG

- Fixes for arrays of structures (Michael)

### E.16.3.20. Misc. Interfaces

- Python fix fetchone() (Gerhard Haring)

- Use UTF, Unicode in Tcl where appropriate (Vsevolod Lobko, Reinhard Max)

- Add Tcl COPY TO/FROM (ljb)

- Prevent output of default index op class in pg_dump (Tom)

- Fix libpgeasy memory leak (Bruce)

### E.16.3.21. Build and Install

- Configure, dynamic loader, and shared library fixes (Peter E)

- Fixes in QNX 4 port (Bernd Tegge)

- Fixes in Cygwin and Windows ports (Jason Tishler, Gerhard Haring, Dmitry Yurtaev, Darko Prenosil, Mikhail Terekhov)

- Fix for Windows socket communication failures (Magnus, Mikhail Terekhov)

- Hurd compile fix (Oliver Elphick)

- BeOS fixes (Cyril Velter)

- Remove configure --enable-unicode-conversion, now enabled by multibyte (Tatsuo)

- AIX fixes (Tatsuo, Andreas)

- Fix parallel make (Peter E)

- Install SQL language manual pages into OS-specific directories (Peter E)

- Rename config.h to pg_config.h (Peter E)

- Reorganize installation layout of header files (Peter E)

### E.16.3.22. Source Code

- Remove SEP_CHAR (Bruce)

- New GUC hooks (Tom)

- Merge GUC and command line handling (Marko Kreen)

- Remove EXTEND INDEX (Martijn van Oosterhout, Tom)

- New pgjindent utility to indent java code (Bruce)

- Remove define of true/false when compiling under C++ (Leandro Fanzone, Tom)

- pgindent fixes (Bruce, Tom)

- Replace strcasecmp() with strcmp() where appropriate (Peter E)

- Dynahash portability improvements (Tom)

- Add 'volatile' usage in spinlock structures

- Improve signal handling logic (Tom)

### E.16.3.23. Contrib

- New contrib/rtree_gist (Oleg Bartunov, Teodor Sigaev)

- New contrib/tsearch full-text indexing (Oleg, Teodor Sigaev)

- Add contrib/dblink for remote database access (Joe Conway)

- contrib/ora2pg Oracle conversion utility (Gilles Darold)

- contrib/xml XML conversion utility (John Gray)

- contrib/fulltextindex fixes (Christopher Kings-Lynne)

- New contrib/fuzzystrmatch with levenshtein and metaphone, soundex merged (Joe Conway)

- Add contrib/intarray boolean queries, binary search, fixes (Oleg Bartunov)

- New pg_upgrade utility (Bruce)

- Add new pg_resetxlog options (Bruce, Tom)

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