Release 9.1 (original) (raw)

E.25.1. Overview

This release shows PostgreSQL moving beyond the traditional relational-database feature set with new, ground-breaking functionality that is unique to PostgreSQL. The streaming replication feature introduced in release 9.0 is significantly enhanced by adding a synchronous-replication option, streaming backups, and monitoring improvements. Major enhancements include:

• Allow synchronous replication
• Add support for foreign tables
• Add per-column collation support
• Add extensions which simplify packaging of additions to PostgreSQL
• Add a true serializable isolation level
• Support unlogged tables using the UNLOGGED option in CREATE TABLE
• Allow data-modification commands (INSERT/UPDATE/DELETE) inWITH clauses
• Add nearest-neighbor (order-by-operator) searching toGiST indexes
• Add a SECURITY LABEL command and support forSELinux permissions control
• Update the PL/Python server-side language

The above items are explained in more detail in the sections below.

E.25.2. Migration to Version 9.1

A dump/restore using pg_dump, or use of pg_upgrade, is required for those wishing to migrate data from any previous release.

Version 9.1 contains a number of changes that may affect compatibility with previous releases. Observe the following incompatibilities:

E.25.2.1. Strings

• Change the default value of standard_conforming_strings to on (Robert Haas)
  By default, backslashes are now ordinary characters in string literals, not escape characters. This change removes a long-standing incompatibility with the SQL standard. escape_string_warning has produced warnings about this usage for years. E'' strings are the proper way to embed backslash escapes in strings and are unaffected by this change.

  Warning
  This change can break applications that are not expecting it and do their own string escaping according to the old rules. The consequences could be as severe as introducing SQL-injection security holes. Be sure to test applications that are exposed to untrusted input, to ensure that they correctly handle single quotes and backslashes in text strings.

E.25.2.2. Casting

• Disallow function-style and attribute-style data type casts for composite types (Tom Lane)
  For example, disallow composite_value.text andtext(composite_value). Unintentional uses of this syntax have frequently resulted in bug reports; although it was not a bug, it seems better to go back to rejecting such expressions. The CAST and :: syntaxes are still available for use when a cast of an entire composite value is actually intended.
• Tighten casting checks for domains based on arrays (Tom Lane)
  When a domain is based on an array type, it is allowed to "look through" the domain type to access the array elements, including subscripting the domain value to fetch or assign an element. Assignment to an element of such a domain value, for instance via UPDATE ... SET domaincol[5] = ..., will now result in rechecking the domain type's constraints, whereas before the checks were skipped.

E.25.2.3. Arrays

• Change string_to_array() to return an empty array for a zero-length string (Pavel Stehule)
  Previously this returned a null value.
• Change string_to_array() so a NULL separator splits the string into characters (Pavel Stehule)
  Previously this returned a null value.

E.25.2.4. Object Modification

• Fix improper checks for before/after triggers (Tom Lane)
  Triggers can now be fired in three cases: BEFORE, AFTER, orINSTEAD OF some action. Trigger function authors should verify that their logic behaves sanely in all three cases.
• Require superuser or CREATEROLE permissions in order to set comments on roles (Tom Lane)

E.25.2.5. Server Settings

• Change pg_last_xlog_receive_location() so it never moves backwards (Fujii Masao)
  Previously, the value of pg_last_xlog_receive_location() could move backward when streaming replication is restarted.
• Have logging of replication connections honor log_connections (Magnus Hagander)
  Previously, replication connections were always logged.

E.25.2.6. PL/pgSQL Server-Side Language

• Change PL/pgSQL's RAISE command without parameters to be catchable by the attached exception block (Piyush Newe)
  Previously RAISE in a code block was always scoped to an attached exception block, so it was uncatchable at the same scope.
• Adjust PL/pgSQL's error line numbering code to be consistent with other PLs (Pavel Stehule)
  Previously, PL/pgSQL would ignore (not count) an empty line at the start of the function body. Since this was inconsistent with all other languages, the special case was removed.
• Make PL/pgSQL complain about conflicting IN and OUT parameter names (Tom Lane)
  Formerly, the collision was not detected, and the name would just silently refer to only the OUT parameter.
• Type modifiers of PL/pgSQL variables are now visible to the SQL parser (Tom Lane)
  A type modifier (such as a varchar length limit) attached to a PL/pgSQL variable was formerly enforced during assignments, but was ignored for all other purposes. Such variables will now behave more like table columns declared with the same modifier. This is not expected to make any visible difference in most cases, but it could result in subtle changes for some SQL commands issued by PL/pgSQL functions.

E.25.2.7. Contrib

• All contrib modules are now installed with CREATE EXTENSION rather than by manually invoking their SQL scripts (Dimitri Fontaine, Tom Lane)
  To update an existing database containing the 9.0 version of a contrib module, use CREATE EXTENSION ... FROM unpackaged to wrap the existing contrib module's objects into an extension. When updating from a pre-9.0 version, drop the contrib module's objects using its old uninstall script, then use CREATE EXTENSION.

E.25.3. Changes

Below you will find a detailed account of the changes between PostgreSQL 9.1 and the previous major release.

E.25.3.1. Server

E.25.3.1.1. Performance

• Support unlogged tables using the UNLOGGED option in CREATE TABLE (Robert Haas)
  Such tables provide better update performance than regular tables, but are not crash-safe: their contents are automatically cleared in case of a server crash. Their contents do not propagate to replication slaves, either.
• Allow FULL OUTER JOIN to be implemented as a hash join, and allow either side of aLEFT OUTER JOIN or RIGHT OUTER JOIN to be hashed (Tom Lane)
  Previously FULL OUTER JOIN could only be implemented as a merge join, andLEFT OUTER JOIN and RIGHT OUTER JOIN could hash only the nullable side of the join. These changes provide additional query optimization possibilities.
• Merge duplicate fsync requests (Robert Haas, Greg Smith)
  This greatly improves performance under heavy write loads.
• Improve performance of commit_siblings (Greg Smith)
  This allows the use of commit_siblings with less overhead.
• Reduce the memory requirement for large ispell dictionaries (Pavel Stehule, Tom Lane)
• Avoid leaving data files open after "blind writes" (Alvaro Herrera)
  This fixes scenarios in which backends might hold files open long after they were deleted, preventing the kernel from reclaiming disk space.

E.25.3.1.2. Optimizer

• Allow inheritance table scans to return meaningfully-sorted results (Greg Stark, Hans-Jurgen Schonig, Robert Haas, Tom Lane)
  This allows better optimization of queries that useORDER BY, LIMIT, or MIN/MAX with inherited tables.
• Improve GIN index scan cost estimation (Teodor Sigaev)
• Improve cost estimation for aggregates and window functions (Tom Lane)

E.25.3.1.3. Authentication

• Support host names and host suffixes (e.g..example.com) in pg_hba.conf (Peter Eisentraut)
  Previously only host IP addresses and CIDR values were supported.
• Support the key word all in the host column of pg_hba.conf (Peter Eisentraut)
  Previously people used 0.0.0.0/0 or ::/0 for this.
• Reject local lines inpg_hba.conf on platforms that don't support Unix-socket connections (Magnus Hagander)
  Formerly, such lines were silently ignored, which could be surprising. This makes the behavior more like other unsupported cases.
• Allow GSSAPI to be used to authenticate to servers via SSPI (Christian Ullrich)
  Specifically this allows Unix-based GSSAPI clients to doSSPI authentication with Windows servers.
• ident authentication over local sockets is now known as peer (Magnus Hagander)
  The old term is still accepted for backward compatibility, but since the two methods are fundamentally different, it seemed better to adopt different names for them.
• Rewrite peer authentication to avoid use of credential control messages (Tom Lane)
  This change makes the peer authentication code simpler and better-performing. However, it requires the platform to provide the getpeereid function or an equivalent socket operation. So far as is known, the only platform for which peer authentication worked before and now will not is pre-5.0 NetBSD.

E.25.3.1.4. Monitoring

• Add details to the logging of restartpoints and checkpoints, which is controlled by log_checkpoints (Fujii Masao, Greg Smith)
  New details include WAL file and sync activity.
• Add log_file_mode which controls the permissions on log files created by the logging collector (Martin Pihlak)
• Reduce the default maximum line length forsyslog logging to 900 bytes plus prefixes (Noah Misch)
  This avoids truncation of long log lines on syslog implementations that have a 1KB length limit, rather than the more common 2KB.

E.25.3.1.5. Statistical Views

• Add client_hostname column to pg_stat_activity (Peter Eisentraut)
  Previously only the client address was reported.
• Add pg_stat_xact_* statistics functions and views (Joel Jacobson)
  These are like the database-wide statistics counter views, but reflect counts for only the current transaction.
• Add time of last reset in database-level and background writer statistics views (Tomas Vondra)
• Add columns showing the number of vacuum and analyze operations in pg_stat_*_tables views (Magnus Hagander)
• Add buffers_backend_fsync column to pg_stat_bgwriter (Greg Smith)
  This new column counts the number of times a backend fsyncs a buffer.

E.25.3.1.6. Server Settings

• Provide auto-tuning of wal_buffers (Greg Smith)
  By default, the value of wal_buffers is now chosen automatically based on the value of shared_buffers.
• Increase the maximum values for deadlock_timeout, log_min_duration_statement, and log_autovacuum_min_duration (Peter Eisentraut)
  The maximum value for each of these parameters was previously only about 35 minutes. Much larger values are now allowed.

E.25.3.2. Replication and Recovery

E.25.3.2.1. Streaming Replication and Continuous Archiving

• Allow synchronous replication (Simon Riggs, Fujii Masao)
  This allows the primary server to wait for a standby to write a transaction's information to disk before acknowledging the commit. One standby at a time can take the role of the synchronous standby, as controlled by the synchronous_standby_names setting. Synchronous replication can be enabled or disabled on a per-transaction basis using the synchronous_commit setting.
• Add protocol support for sending file system backups to standby servers using the streaming replication network connection (Magnus Hagander, Heikki Linnakangas)
  This avoids the requirement of manually transferring a file system backup when setting up a standby server.
• Add replication_timeout setting (Fujii Masao, Heikki Linnakangas)
  Replication connections that are idle for more than the replication_timeout interval will be terminated automatically. Formerly, a failed connection was typically not detected until the TCP timeout elapsed, which is inconveniently long in many situations.
• Add command-line tool pg_basebackup for creating a new standby server or database backup (Magnus Hagander)
• Add a replication permission for roles (Magnus Hagander)
  This is a read-only permission used for streaming replication. It allows a non-superuser role to be used for replication connections. Previously only superusers could initiate replication connections; superusers still have this permission by default.

E.25.3.2.2. Replication Monitoring

• Add system view pg_stat_replication which displays activity ofWAL sender processes (Itagaki Takahiro, Simon Riggs)
  This reports the status of all connected standby servers.
• Add monitoring function pg_last_xact_replay_timestamp() (Fujii Masao)
  This returns the time at which the primary generated the most recent commit or abort record applied on the standby.

E.25.3.2.3. Hot Standby

• Add configuration parameter hot_standby_feedback to enable standbys to postpone cleanup of old row versions on the primary (Simon Riggs)
  This helps avoid canceling long-running queries on the standby.
• Add the pg_stat_database_conflicts system view to show queries that have been canceled and the reason (Magnus Hagander)
  Cancellations can occur because of dropped tablespaces, lock timeouts, old snapshots, pinned buffers, and deadlocks.
• Add a conflicts count to pg_stat_database (Magnus Hagander)
  This is the number of conflicts that occurred in the database.
• Increase the maximum values for max_standby_archive_delay and max_standby_streaming_delay
  The maximum value for each of these parameters was previously only about 35 minutes. Much larger values are now allowed.
• Add ERRCODE_T_R_DATABASE_DROPPED error code to report recovery conflicts due to dropped databases (Tatsuo Ishii)
  This is useful for connection pooling software.

E.25.3.2.4. Recovery Control

• Add functions to control streaming replication replay (Simon Riggs)
  The new functions are pg_xlog_replay_pause(), pg_xlog_replay_resume(), and the status function pg_is_xlog_replay_paused().
• Add recovery.conf settingpause_at_recovery_target to pause recovery at target (Simon Riggs)
  This allows a recovery server to be queried to check whether the recovery point is the one desired.
• Add the ability to create named restore points using pg_create_restore_point() (Jaime Casanova)
  These named restore points can be specified as recovery targets using the new recovery.conf setting recovery_target_name.
• Allow standby recovery to switch to a new timeline automatically (Heikki Linnakangas)
  Now standby servers scan the archive directory for new timelines periodically.
• Add restart_after_crash setting which disables automatic server restart after a backend crash (Robert Haas)
  This allows external cluster management software to control whether the database server restarts or not.
• Allow recovery.conf to use the same quoting behavior as postgresql.conf (Dimitri Fontaine)
  Previously all values had to be quoted.

E.25.3.3. Queries

• Add a true serializable isolation level (Kevin Grittner, Dan Ports)
  Previously, asking for serializable isolation guaranteed only that a single MVCC snapshot would be used for the entire transaction, which allowed certain documented anomalies. The old snapshot isolation behavior is still available by requesting the REPEATABLE READ isolation level.
• Allow data-modification commands (INSERT/UPDATE/DELETE) inWITH clauses (Marko Tiikkaja, Hitoshi Harada)
  These commands can use RETURNING to pass data up to the containing query.
• Allow WITH clauses to be attached toINSERT, UPDATE, DELETE statements (Marko Tiikkaja, Hitoshi Harada)
• Allow non-GROUP BY columns in the query target list when the primary key is specified in the GROUP BY clause (Peter Eisentraut)
  The SQL standard allows this behavior, and because of the primary key, the result is unambiguous.
• Allow use of the key word DISTINCT in UNION/INTERSECT/EXCEPT clauses (Tom Lane)
  DISTINCT is the default behavior so use of this key word is redundant, but the SQL standard allows it.
• Fix ordinary queries with rules to use the same snapshot behavior as EXPLAIN ANALYZE (Marko Tiikkaja)
  Previously EXPLAIN ANALYZE used slightly different snapshot timing for queries involving rules. The EXPLAIN ANALYZE behavior was judged to be more logical.

E.25.3.3.1. Strings

• Add per-column collation support (Peter Eisentraut, Tom Lane)
  Previously collation (the sort ordering of text strings) could only be chosen at database creation. Collation can now be set per column, domain, index, or expression, via the SQL-standard COLLATE clause.

E.25.3.4. Object Manipulation

• Add extensions which simplify packaging of additions to PostgreSQL (Dimitri Fontaine, Tom Lane)
  Extensions are controlled by the new CREATE/ALTER/DROP EXTENSION commands. This replaces ad-hoc methods of grouping objects that are added to a PostgreSQL installation.
• Add support for foreign tables (Shigeru Hanada, Robert Haas, Jan Urbanski, Heikki Linnakangas)
  This allows data stored outside the database to be used like native PostgreSQL-stored data. Foreign tables are currently read-only, however.
• Allow new values to be added to an existing enum type via ALTER TYPE (Andrew Dunstan)
• Add ALTER TYPE ... ADD/DROP/ALTER/RENAME ATTRIBUTE (Peter Eisentraut)
  This allows modification of composite types.

E.25.3.4.1. ALTER Object

• Add RESTRICT/CASCADE to ALTER TYPE operations on typed tables (Peter Eisentraut)
  This controls ADD/DROP/ALTER/RENAME ATTRIBUTE cascading behavior.
• Support ALTER TABLE name {OF | NOT OF} type (Noah Misch)
  This syntax allows a standalone table to be made into a typed table, or a typed table to be made standalone.
• Add support for more object types in ALTER ... SET SCHEMA commands (Dimitri Fontaine)
  This command is now supported for conversions, operators, operator classes, operator families, text search configurations, text search dictionaries, text search parsers, and text search templates.

E.25.3.4.2. CREATE/ALTER TABLE

• Add ALTER TABLE ... ADD UNIQUE/PRIMARY KEY USING INDEX (Gurjeet Singh)
  This allows a primary key or unique constraint to be defined using an existing unique index, including a concurrently created unique index.
• Allow ALTER TABLE to add foreign keys without validation (Simon Riggs)
  The new option is called NOT VALID. The constraint's state can later be modified to VALIDATED and validation checks performed. Together these allow you to add a foreign key with minimal impact on read and write operations.
• Allow ALTER TABLE ... SET DATA TYPE to avoid table rewrites in appropriate cases (Noah Misch, Robert Haas)
  For example, converting a varchar column to text no longer requires a rewrite of the table. However, increasing the length constraint on avarchar column still requires a table rewrite.
• Add CREATE TABLE IF NOT EXISTS syntax (Robert Haas)
  This allows table creation without causing an error if the table already exists.
• Fix possible "tuple concurrently updated" error when two backends attempt to add an inheritance child to the same table at the same time (Robert Haas)
  ALTER TABLE now takes a stronger lock on the parent table, so that the sessions cannot try to update it simultaneously.

E.25.3.5. Utility Operations

• Add transaction-level advisory locks (Marko Tiikkaja)
  These are similar to the existing session-level advisory locks, but such locks are automatically released at transaction end.
• Make TRUNCATE ... RESTART IDENTITY restart sequences transactionally (Steve Singer)
  Previously the counter could have been left out of sync if a backend crashed between the on-commit truncation activity and commit completion.

E.25.3.5.1. COPY

• Add ENCODING option toCOPY TO/FROM (Hitoshi Harada, Itagaki Takahiro)
  This allows the encoding of the COPY file to be specified separately from client encoding.
• Add bidirectional COPY protocol support (Fujii Masao)
  This is currently only used by streaming replication.

E.25.3.5.2. EXPLAIN

• Make EXPLAIN VERBOSE show the function call expression in a FunctionScan node (Tom Lane)

E.25.3.5.3. VACUUM

• Add additional details to the output of VACUUM FULL VERBOSE and CLUSTER VERBOSE (Itagaki Takahiro)
  New information includes the live and dead tuple count and whether CLUSTER is using an index to rebuild.
• Prevent autovacuum from waiting if it cannot acquire a table lock (Robert Haas)
  It will try to vacuum that table later.

E.25.3.5.4. CLUSTER

• Allow CLUSTER to sort the table rather than scanning the index when it seems likely to be cheaper (Leonardo Francalanci)

E.25.3.5.5. Indexes

• Add nearest-neighbor (order-by-operator) searching to GiST indexes (Teodor Sigaev, Tom Lane)
  This allows GiST indexes to quickly return the N closest values in a query withLIMIT. For example
  SELECT * FROM places ORDER BY location <-> point '(101,456)' LIMIT 10;
  finds the ten places closest to a given target point.
• Allow GIN indexes to index null and empty values (Tom Lane)
  This allows full GIN index scans, and fixes various corner cases in which GIN scans would fail.
• Allow GIN indexes to better recognize duplicate search entries (Tom Lane)
  This reduces the cost of index scans, especially in cases where it avoids unnecessary full index scans.
• Fix GiST indexes to be fully crash-safe (Heikki Linnakangas)
  Previously there were rare cases where a REINDEX would be required (you would be informed).

E.25.3.6. Data Types

• Allow numeric to use a more compact, two-byte header in common cases (Robert Haas)
  Previously all numeric values had four-byte headers; this change saves on disk storage.
• Add support for dividing money by money (Andy Balholm)
• Allow binary I/O on type void (Radoslaw Smogura)
• Improve hypotenuse calculations for geometric operators (Paul Matthews)
  This avoids unnecessary overflows, and may also be more accurate.
• Support hashing array values (Tom Lane)
  This provides additional query optimization possibilities.
• Don't treat a composite type as sortable unless all its column types are sortable (Tom Lane)
  This avoids possible "could not identify a comparison function" failures at runtime, if it is possible to implement the query without sorting. Also, ANALYZE won't try to use inappropriate statistics-gathering methods for columns of such composite types.

E.25.3.6.1. Casting

• Add support for casting between money and numeric (Andy Balholm)
• Add support for casting from int4 and int8 tomoney (Joey Adams)
• Allow casting a table's row type to the table's supertype if it's a typed table (Peter Eisentraut)
  This is analogous to the existing facility that allows casting a row type to a supertable's row type.

E.25.3.6.2. XML

• Add XML functionXMLEXISTS and xpath_exists() functions (Mike Fowler)
  These are used for XPath matching.
• Add XML functionsxml_is_well_formed(), xml_is_well_formed_document(),xml_is_well_formed_content() (Mike Fowler)
  These check whether the input is properly-formedXML. They provide functionality that was previously available only in the deprecated contrib/xml2 module.

E.25.3.7. Functions

• Add SQL function format(text, ...), which behaves analogously to C's printf() (Pavel Stehule, Robert Haas)
  It currently supports formats for strings, SQL literals, and SQL identifiers.
• Add string functions concat(), concat_ws(), left(), right(), and reverse() (Pavel Stehule)
  These improve compatibility with other database products.
• Add function pg_read_binary_file() to read binary files (Dimitri Fontaine, Itagaki Takahiro)
• Add a single-parameter version of function pg_read_file() to read an entire file (Dimitri Fontaine, Itagaki Takahiro)
• Add three-parameter forms of array_to_string() and string_to_array() for null value processing control (Pavel Stehule)

E.25.3.7.1. Object Information Functions

• Add the pg_describe_object() function (Alvaro Herrera)
  This function is used to obtain a human-readable string describing an object, based on the pg_class OID, object OID, and sub-object ID. It can be used to help interpret the contents of pg_depend.
• Update comments for built-in operators and their underlying functions (Tom Lane)
  Functions that are meant to be used via an associated operator are now commented as such.
• Add variable quote_all_identifiers to force the quoting of all identifiers in EXPLAIN and in system catalog functions like pg_get_viewdef() (Robert Haas)
  This makes exporting schemas to tools and other databases with different quoting rules easier.
• Add columns to the information_schema.sequences system view (Peter Eisentraut)
  Previously, though the view existed, the columns about the sequence parameters were unimplemented.
• Allow public as a pseudo-role name in has_table_privilege() and related functions (Alvaro Herrera)
  This allows checking for public permissions.

E.25.3.8. Server-Side Languages

E.25.3.8.1. PL/pgSQL Server-Side Language

• Add FOREACH IN ARRAY to PL/pgSQL (Pavel Stehule)
  This is more efficient and readable than previous methods of iterating through the elements of an array value.
• Allow RAISE without parameters to be caught in the same places that could catch a RAISE ERROR from the same location (Piyush Newe)
  The previous coding threw the error from the block containing the active exception handler. The new behavior is more consistent with other DBMS products.

E.25.3.8.2. PL/Perl Server-Side Language

• Allow generic record arguments to PL/Perl functions (Andrew Dunstan)
  PL/Perl functions can now be declared to accept typerecord. The behavior is the same as for any named composite type.
• Convert PL/Perl array arguments to Perl arrays (Alexey Klyukin, Alex Hunsaker)
  String representations are still available.
• Convert PL/Perl composite-type arguments to Perl hashes (Alexey Klyukin, Alex Hunsaker)
  String representations are still available.

E.25.3.8.3. PL/Python Server-Side Language

• Add table function support for PL/Python (Jan Urbanski)
  PL/Python can now return multiple OUT parameters and record sets.
• Add a validator to PL/Python (Jan Urbanski)
  This allows PL/Python functions to be syntax-checked at function creation time.
• Allow exceptions for SQL queries in PL/Python (Jan Urbanski)
  This allows access to SQL-generated exception error codes from PL/Python exception blocks.
• Add explicit subtransactions to PL/Python (Jan Urbanski)
• Add PL/Python functions for quoting strings (Jan Urbanski)
  These functions are plpy.quote_ident, plpy.quote_literal, and plpy.quote_nullable.
• Add traceback information to PL/Python errors (Jan Urbanski)
• Report PL/Python errors from iterators withPLy_elog (Jan Urbanski)
• Fix exception handling with Python 3 (Jan Urbanski)
  Exception classes were previously not available inplpy under Python 3.

E.25.3.9. Client Applications

• Mark createlang and droplang as deprecated now that they just invoke extension commands (Tom Lane)

E.25.3.9.1. psql

• Add psql command\conninfo to show current connection information (David Christensen)
• Add psql command\sf to show a function's definition (Pavel Stehule)
• Add psql command\dL to list languages (Fernando Ike)
• Add the S ("system") option to psql's \dn (list schemas) command (Tom Lane)
  \dn without S now suppresses system schemas.
• Allow psql's\e and \ef commands to accept a line number to be used to position the cursor in the editor (Pavel Stehule)
  This is passed to the editor according to thePSQL_EDITOR_LINENUMBER_ARG environment variable.
• Have psql set the client encoding from the operating system locale by default (Heikki Linnakangas)
  This only happens if the PGCLIENTENCODING environment variable is not set.
• Make \d distinguish between unique indexes and unique constraints (Josh Kupershmidt)
• Make \dt+ reportpg_table_size instead ofpg_relation_size when talking to 9.0 or later servers (Bernd Helmle)
  This is a more useful measure of table size, but note that it is not identical to what was previously reported in the same display.
• Additional tab completion support (Itagaki Takahiro, Pavel Stehule, Andrey Popp, Christoph Berg, David Fetter, Josh Kupershmidt)

E.25.3.9.2. pg_dump

• Add pg_dump and pg_dumpall option --quote-all-identifiers to force quoting of all identifiers (Robert Haas)
• Add directory format topg_dump (Joachim Wieland, Heikki Linnakangas)
  This is internally similar to the tar pg_dump format.

E.25.3.9.3. pg_ctl

• Fix pg_ctl so it no longer incorrectly reports that the server is not running (Bruce Momjian)
  Previously this could happen if the server was running but pg_ctl could not authenticate.
• Improve pg_ctl start's "wait" (-w) option (Bruce Momjian, Tom Lane)
  The wait mode is now significantly more robust. It will not get confused by non-default postmaster port numbers, non-default Unix-domain socket locations, permission problems, or stale postmaster lock files.
• Add promote option topg_ctl to switch a standby server to primary (Fujii Masao)

E.25.3.10. Development Tools

E.25.3.10.1. libpq

• Add a libpq connection option client_encoding which behaves like thePGCLIENTENCODING environment variable (Heikki Linnakangas)
  The value auto sets the client encoding based on the operating system locale.
• Add PQlibVersion() function which returns the libpq library version (Magnus Hagander)
  libpq already had PQserverVersion() which returns the server version.
• Allow libpq-using clients to check the user name of the server process when connecting via Unix-domain sockets, with the new requirepeer connection option (Peter Eisentraut)
  PostgreSQL already allowed servers to check the client user name when connecting via Unix-domain sockets.
• Add PQping() and PQpingParams() to libpq (Bruce Momjian, Tom Lane)
  These functions allow detection of the server's status without trying to open a new session.

E.25.3.10.2. ECPG

• Allow ECPG to accept dynamic cursor names even inWHERE CURRENT OF clauses (Zoltan Boszormenyi)
• Make ecpglib writedouble values with a precision of 15 digits, not 14 as formerly (Akira Kurosawa)

E.25.3.11. Build Options

• Use +Olibmerrno compile flag with HP-UX C compilers that accept it (Ibrar Ahmed)
  This avoids possible misbehavior of math library calls on recent HP platforms.

E.25.3.11.1. Makefiles

• Improved parallel make support (Peter Eisentraut)
  This allows for faster compiles. Also, make -k now works more consistently.
• Require GNU make 3.80 or newer (Peter Eisentraut)
  This is necessary because of the parallel-make improvements.
• Add make maintainer-check target (Peter Eisentraut)
  This target performs various source code checks that are not appropriate for either the build or the regression tests. Currently: duplicate_oids, SGML syntax and tabs check, NLS syntax check.
• Support make check incontrib (Peter Eisentraut)
  Formerly only make installcheck worked, but now there is support for testing in a temporary installation. The top-levelmake check-world target now includes testing contrib this way.

E.25.3.11.2. Windows

• On Windows, allow pg_ctl to register the service as auto-start or start-on-demand (Quan Zongliang)
• Add support for collecting crash dumps on Windows (Craig Ringer, Magnus Hagander)
  minidumps can now be generated by non-debug Windows binaries and analyzed by standard debugging tools.
• Enable building with the MinGW64 compiler (Andrew Dunstan)
  This allows building 64-bit Windows binaries even on non-Windows platforms via cross-compiling.

E.25.3.12. Source Code

• Revise the API for GUC variable assign hooks (Tom Lane)
  The previous functions of assign hooks are now split between check hooks and assign hooks, where the former can fail but the latter shouldn't. This change will impact add-on modules that define custom GUC parameters.
• Add latches to the source code to support waiting for events (Heikki Linnakangas)
• Centralize data modification permissions-checking logic (KaiGai Kohei)
• Add missing get_object_oid() functions, for consistency (Robert Haas)
• Improve ability to use C++ compilers for compiling add-on modules by removing conflicting key words (Tom Lane)
• Add support for DragonFly BSD (Rumko)
• Expose quote_literal_cstr() for backend use (Robert Haas)
• Run regression tests in the default encoding (Peter Eisentraut)
  Regression tests were previously always run withSQL_ASCII encoding.
• Add src/tools/git_changelog to replacecvs2cl and pgcvslog (Robert Haas, Tom Lane)
• Add git-external-diff script to src/tools (Bruce Momjian)
  This is used to generate context diffs from git.
• Improve support for building with Clang (Peter Eisentraut)

E.25.3.12.1. Server Hooks

• Add source code hooks to check permissions (Robert Haas, Stephen Frost)
• Add post-object-creation function hooks for use by security frameworks (KaiGai Kohei)
• Add a client authentication hook (KaiGai Kohei)

E.25.3.13. Contrib

• Modify contrib modules and procedural languages to install via the new extension mechanism (Tom Lane, Dimitri Fontaine)
• Add contrib/file_fdw foreign-data wrapper (Shigeru Hanada)
  Foreign tables using this foreign data wrapper can read flat files in a manner very similar to COPY.
• Add nearest-neighbor search support to contrib/pg_trgm and contrib/btree_gist (Teodor Sigaev)
• Add contrib/btree_gist support for searching on not-equals (Jeff Davis)
• Fix contrib/fuzzystrmatch's levenshtein() function to handle multibyte characters (Alexander Korotkov)
• Add ssl_cipher() andssl_version() functions tocontrib/sslinfo (Robert Haas)
• Fix contrib/intarray and contrib/hstore to give consistent results with indexed empty arrays (Tom Lane)
  Previously an empty-array query that used an index might return different results from one that used a sequential scan.
• Allow contrib/intarray to work properly on multidimensional arrays (Tom Lane)
• In contrib/intarray, avoid errors complaining about the presence of nulls in cases where no nulls are actually present (Tom Lane)
• In contrib/intarray, fix behavior of containment operators with respect to empty arrays (Tom Lane)
  Empty arrays are now correctly considered to be contained in any other array.
• Remove contrib/xml2's arbitrary limit on the number of parameter=value pairs that can be handled byxslt_process() (Pavel Stehule)
  The previous limit was 10.
• In contrib/pageinspect, fix heap_page_item to return infomasks as 32-bit values (Alvaro Herrera)
  This avoids returning negative values, which was confusing. The underlying value is a 16-bit unsigned integer.

E.25.3.13.1. Security

• Add contrib/sepgsql to interface permission checks with SELinux (KaiGai Kohei)
  This uses the new SECURITY LABEL facility.
• Add contrib module auth_delay (KaiGai Kohei)
  This causes the server to pause before returning authentication failure; it is designed to make brute force password attacks more difficult.
• Add dummy_seclabel contrib module (KaiGai Kohei)
  This is used for permission regression testing.

E.25.3.13.2. Performance

• Add support for LIKE andILIKE index searches tocontrib/pg_trgm (Alexander Korotkov)
• Add levenshtein_less_equal() function tocontrib/fuzzystrmatch, which is optimized for small distances (Alexander Korotkov)
• Improve performance of index lookups on contrib/seg columns (Alexander Korotkov)
• Improve performance of pg_upgrade for databases with many relations (Bruce Momjian)
• Add flag to contrib/pgbench to report per-statement latencies (Florian Pflug)

E.25.3.13.3. Fsync Testing

• Move src/tools/test_fsync to contrib/pg_test_fsync (Bruce Momjian, Tom Lane)
• Add O_DIRECT support tocontrib/pg_test_fsync (Bruce Momjian)
  This matches the use of O_DIRECT by wal_sync_method.
• Add new tests to contrib/pg_test_fsync (Bruce Momjian)

E.25.3.14. Documentation

• Extensive ECPG documentation improvements (Satoshi Nagayasu)
• Extensive proofreading and documentation improvements (Thom Brown, Josh Kupershmidt, Susanne Ebrecht)
• Add documentation for exit_on_error (Robert Haas)
  This parameter causes sessions to exit on any error.
• Add documentation for pg_options_to_table() (Josh Berkus)
  This function shows table storage options in a readable form.
• Document that it is possible to access all composite type fields using (compositeval).* syntax (Peter Eisentraut)
• Document that translate() removes characters in from that don't have a correspondingto character (Josh Kupershmidt)
• Merge documentation for CREATE CONSTRAINT TRIGGER and CREATE TRIGGER (Alvaro Herrera)
• Centralize permission andupgrade documentation (Bruce Momjian)
• Add kernel tuning documentation for Solaris 10 (Josh Berkus)
  Previously only Solaris 9 kernel tuning was documented.
• Handle non-ASCII characters consistently in HISTORY file (Peter Eisentraut)
  While the HISTORY file is in English, we do have to deal with non-ASCII letters in contributor names. These are now transliterated so that they are reasonably legible without assumptions about character set.