Release 9.1Release Date2011-??-??Overview
This release of
PostgreSQL> adds ... Major enhancements include:
The above items are explained in more detail in the sections below.
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 ...
Observe the following incompatibilities:
Strings
Change the default value of standard_conforming_strings>
to on (Robert Haas)
This removes a long-standing incompatibility with the SQL
standard; escape_string_warning>
has produced warnings about this usage for years. E''>
strings the proper way to embed escapes in strings and is
unaffected by this change.
Casting
Disallow function-style and attribute-style data type casts for
composite types (Tom Lane)
For example, disallow composite_name.text and text(composite_name).
CAST> and ::> are still available for
casting.
Tighten casting checks for domains based on arrays (Tom Lane)
**Details?
Arrays
Change string_to_array()>
to return an empty array for a zero-length string (Pavel
Stehule)
Previously this returned NULL>.
Change string_to_array()>
so a NULL> separator splits the string into characters
(Pavel Stehule)
Previously this returned NULL>.
Object Modification
Fix improper checks for before/after triggers (Tom Lane)
**Tom, I need more details on the impact of this for existing
installs.
Require superuser or CREATEROLE> permissions in order to
set role comments (Tom Lane)
Server Settings
Change pg_last_xlog_receive_location()>
so it never moves backwards (Fujii Masao)
Previously 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.
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 always scoped to
an attached exception block, so it was uncatchable at the same
scope.
Adjust PL/pgSQL's error line reporting code to be consistent
with SQL error line reporting (Pavel Stehule)
Previously error numbering was off by one.
Other Incompatibilities
Have pg_stat_reset()>
reset all database-level statistics (Tom Lane)
Some counters were not being reset.
Fix some information_schema.triggers>
column names to match the new SQL-standard names (Dean Rasheed)
Treat ECPG> cursor names as case-insensitive (Zoltan Boszormenyi)
Changes, current as of 2011-03-15
Version 9.1 has ...
ServerPerformance
Allow unlogged tables using UNLOGGED>
during CREATE
TABLE> (Robert Haas)
These tables are optimized for performance but are cleared in
case of a server crash.
Allow FULL OUTER JOIN to be implemented as a
hash join, and allow either side of a LEFT OUTER JOIN>
or RIGHT OUTER JOIN> to be hashed (Tom Lane)
Previously FULL OUTER JOIN could only be
implemented as a merge join, and LEFT OUTER JOIN
and RIGHT OUTER JOIN could has only the nullable
side of the join. These changes provide additional query optimization
possibilities.
Merge duplicate fsync requests on busy systems (Robert Haas,
Greg Smith)
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)
Optimizer
Allow inheritance table queries to return meaningfully-sorted
results (Greg Stark, Hans-Jurgen Schonig, Robert Haas, Tom
Lane)
This allows optimization of ORDER BY> and
LIMIT> clauses in inheritance table queries.
Allow optimizations of MIN>/MAX> for
inheritance table queries (Tom Lane)
Allow hash joins for array values (Tom Lane)
This provides additional query optimization possibilities.
Improve GIN index scan cost estimation (Teodor Sigaev)
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 keyword all> in the host column of pg_hba.conf>
(Peter Eisentraut)
Previously people used 0.0.0.0/0> or ::/0>
for this.
Allow GSSAPI>
to be used to authenticate to servers via SSPI> (Christian Ullrich)
Specifically this allows Unix-based GSSAPI> clients
to SSPI> authenticate to Windows servers.
Monitoring
Add details to the logging of restartpoints and checkpoints,
which is controlled by log_checkpoints>
(Fujii Masao, Greg Smith)
New details show WAL> file and sync activity.
Add log_file_mode>
which controls the permissions on log files created by the
logging_collector (Martin Pihlak)
Statistical Views
Add client_hostname field to pg_stat_activity>
(Peter Eisentraut)
Previously only the client address was reported.
Add pg_stat_xact_*>
statistic functions and views (Joel Jacobson)
These are like the database-wide statistics counter views but
reflect counts for only the current transaction.
Add the pg_stat_database_conflicts>
system view to show queries that have been canceled and the
reason (Magnus Hagander)
Cancelations 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.
Add record of last reset in database and background writer-level
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 field to pg_stat_bgwriter>
(Greg Smith)
This new field counts the number of times a backend fsyncs a
buffer.
Server Settings
Allow auto-tuning of wal_buffers> (Greg
Smith)
wal_buffers is now auto-tuned by default based on the size of
shared_buffers.
Add restart_after_crash>
which disables server restart after a backend crash (Robert
Haas)
This is designed for cluster managers that want to control
restarts.
Streaming Replication and Continuous Archiving
Allow synchronous replication (Simon Riggs, Fujii Masao)
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_replication>
setting. This allows the primary to wait for a standby to write the
transaction information to disk before acknowledging the commit.
Add variable hot_standby_feedback>
to enable standbys to postpone cleanup of old row versions on the
primary (Simon Riggs)
This helps avoid cancelling long-running queries on the standby.
Add support for sending file system backups to standbys using
the streaming replication network connection (Magnus Hagander,
Heikki Linnakangas)
This avoids the requirement of manually transferring a file
system backup when creating a standby server.
Add command-line tool pg_basebackup>
for creating a new standby server or database backup (Magnus
Hagander)
Add replication permission
for roles (Magnus Hagander)
This is a read-only permission used for streaming replication
and allows non-superusers to initiate replication connections.
Previously only superusers could initiate replication
connections; superusers have this permission by default.
Monitoring
Add system view pg_stat_replication>
which displays activity of WAL> 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 on the primary that generated the most
recent commit or abort record applied on the standby.
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 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>
Add recovery.conf> setting pause_at_recovery_target>
to pause recovery at target (Simon Riggs)
This allows a recovery server to be queried to check if the
recovery point is the one desired.
Allow standby recovery to switch to a new timeline automatically
(Heikki Linnakangas)
Now standby servers scan the archive directory for new
timelines periodically.
Allow recovery.conf>
to use the same quoting behavior as postgresql.conf>
(Dimitri Fontaine)
Previously all values had to be quoted.
Queries
Allow data-modification commands
(INSERT>/UPDATE>/DELETE)> in
WITH> clauses
(Marko Tiikkaja, Hitoshi Harada)
This allows INSERT>/UPDATE>/DELETE>
RETURNING> in WITH> clauses to pass rows
to outer queries.
Allow WITH>
clauses to be fed into INSERT>, 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)
Some other database system already allowed this behavior, and
because of the primary key, the result is unambiguous.
Allow the use of the keyword DISTINCT> in
UNION>/INTERSECT>/EXCEPT>
clauses (Tom Lane)
DISTINCT> is the default behavior so use of this
keyword is redundant.
Fix ordinary queries with rules to use the same snapshot behavior
as EXPLAIN ANALYZE> (Marko Tiikkaja)
Previously EXPLAIN ANALYZE> used a slightly different
snapshot for queries involving rules. The EXPLAIN ANALYZE>
behavior was judged to be more logical.
Strings
Add per-column collation support
(Peter Eisentraut, Tom Lane)
Previously collation could only be set at the database level.
Collation can now be set per column, domain, index, or
expression.
Object Manipulation
Add support for foreign
tables (Shigeru Hanada, Robert Haas, Jan Urbanski,
Heikki Linnakangas)
This allows data stored in foreign sources to be used like
native PostgreSQL>-stored data.
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.
ALTER> Object
Add RESTRICT>/CASCADE> to ALTER TYPE> operations
on typed tables (Peter Eisentraut)
This controls
ADD>/DROP>/ALTER>/RENAME
ATTRIBUTE> cascading behavior.
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, and text search
dictionaries, text search parsers, and text search templates.
CREATE/ALTER TABLE>
Add ALTER TABLE ...
ADD UNIQUE/PRIMARY KEY USING INDEX
(Gurjeet Singh)
This allows a primary key or unique constraint to be added 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>, which can
later be modified to VALIDATED> and validation
checks performed.
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 a varchar 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.
Object Permissions
Add a SECURITY
LABEL> command (KaiGai Kohei)
This allows security labels to be assigned to objects.
Utility Operations
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 level is still accessible by
requesting the REPEATABLE
READ> isolation level.
Add transaction-level advisory
locks (Marko Tiikkaja)
This is similar to the existing session-level advisory locks,
but are freed 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.
COPY>
Add ENCODING> option to COPY 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.
EXPLAIN>
Have EXPLAIN VERBOSE>
show the function call expression (Tom Lane)
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 lock (Robert Haas)
It will try to vacuum later.
CLUSTER>
Allow CLUSTER to sort the table rather than scanning the index
when it seems likely to be cheaper (Leonardo Francalanci)
Indexes
Add nearest-neighbor (order-by-operator) searching to GiST> indexes (Teodor Sigaev, Tom Lane)
This allows GiST> indexes to quickly return
LIMIT>-specified closest values.
Allow GIN> indexes to index null
and empty values (Tom Lane)
This allows full GIN> index scans.
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).
Data Types
Allow numeric> to use a more compact, two-byte header
in many cases (Robert Haas)
Previously all numeric> values had four-byte headers;
this 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.
Casting
Add support for casting between money> and numeric>
(Andy Balholm)
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.
XML>
Add XML> function XMLEXISTS> and xpath_exists()>
functions (Mike Fowler)
These are used for xpath matching.
Add XML> functions xml_is_well_formed()>,
xml_is_well_formed_document()>,
xml_is_well_formed_content()>
(Mike Fowler)
These check whether the input is properly-formed XML>.
They supersede functionality that was previously available only using
contrib/xml2.
Functions
Add SQL function format(text)>, which
behaves like 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> processing control (Pavel Stehule)
Object Information Functions
Add the pg_describe_object()>
function (Alvaro Herrera)
This function is used to obtain comments on objects.
Update comments for built-in operators and their underlying
functions (Tom Lane)
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 fields to the information_schema.sequences>
system view (Peter Eisentraut)
Previously, though the view existed, all of these view fields
were unimplemented.
Allow public> as a pseudo-role name in has_table_privilege()>
and related functions (Alvaro Herrera)
This allows checking for public permissions.
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.
Function and Trigger Creation
Allow INSTEAD
OF> triggers on views (Dean Rasheed)
This feature can be used to implement updatable views.
Reduce lock levels for CREATE TRIGGER>
and some ALTER
TABLE> and CREATE
RULE> operations (Simon Riggs)
This improves concurrency.
Server-Side LanguagesPL/pgSQL Server-Side Language
Add FOREACH IN
ARRAY> to PL/pgSQL to
allow array iteration (Pavel Stehule)
This is more efficient than previous methods.
Add FOREACH IN
ARRAY> to PL/pgSQL to
allow array iteration (Pavel Stehule)
This is more efficient than previous methods.
Allow RAISE without parameters to be caught in
the same places that could catch a RAISE ERROR
from the same location.
The new behavior is more consistent.
PL/Perl Server-Side Language
Allow generic record arguments to PL/Perl functions (Andrew
Dunstan)
**Andrew, I need details on this.
Convert PL/Perl input arguments to Perl arrays (Alexey Klyukin,
Alex Hunsaker)
String representations are still available.
Convert PL/Perl row and composite type arguments to Perl hashes
(Alexey Klyukin, Alex Hunsaker)
String representations are still available.
PL/Python Server-Side Language
Add table function support for PL/Python (Jan Urbanski)
PL/Python now can return multiple OUT> parameters
and record sets.
Add validator to PL/Python (Jan Urbanski)
This allows PL/Python functions to be validated 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.
Allow PL/Python to access SQLSTATE> exception values
(Jan Urbanski)
**Is this the same as the item above?
Add PL/Python explicit subtransactions (Jan Urbanski)
Add PL/Python functions for quoting strings (Jan Urbanski)
The functions are plpy.quote_ident>,
plpy.quote_literal>,
and plpy.quote_nullable>.
Report PL/Python errors from iterators with PLy_elog> (Jan
Urbanski)
plpy.Fatal now raises FATAL>, rather
than ERROR (Jan Urbanski)
The old behavior was incorrect.
Overhaul of PL/Python (Jan Urbanski)
This includes exception support for Python 3. **More?
Client Applications
Mark createlang>
and droplang>
as deprecated now that they use the extension framework (Tom
Lane)
psql>
Add the \conninfo> command to psql>,
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 system table \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 using the
EDITOR_LINENUMBER_SWITCH> 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 psql distinguish between unique
indices and unique constraints (Josh Kupershmidt)
Additional tab completion of psql> variables (Pavel
Stehule)
More psql> tab completion support (Itagaki
Takahiro)
pg_dump>
Add pg_dump>
and pg_dumpall>
option
Add directory> format to pg_dump>
(Joachim Wieland, Heikki Linnakangas)
This is internally similar to the tar>
pg_dump> format.
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" (
Add promote> option to pg_ctl> to
switch a standby server to primary (Fujii Masao)
Development Tools>libpq>
Add a libpq connection option client_encoding>
which behaves like the PGCLIENTENCODING> 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 database clients to use Unix-domain sockets to
check the user name of the server process using requirepeer>
(Peter Eisentraut)
PostgreSQL> already allowed servers to determine
the client user name via Unix-domain sockets.
Add PQping()>
and PQpingParams()>
to libpq (Bruce Momjian, Tom Lane)
The allow detection of the server's status without creating
a new session.
ECPG>
Allow ecpg to accept dynamic cursor names even in
WHERE CURRENT OF clauses
Build Options
Add extensions which simplify
packaging of additions to PostgreSQL> (Dimitri
Fontaine, Tom Lane)
This is controlled by the new CREATE>/ALTER>/DROP EXTENSION >
command; this replaces a more manual method of adding features
to PostgreSQL>.
Makefiles
Require GNU> make>
3.80 or newer (Peter Eisentraut)
Improved parallel make support (Peter Eisentraut)
This allows for faster compiles. Also, make 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 with cross-compiling.
Source Code
Add latches to the source code to wait 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 backend compiles by removing
conflicting keywords (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 with
SQL_ASCII> encoding.
Add src/tools/git_changelog> to replace
cvs2cl> 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.
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)
Contrib
Modify /contrib> modules and stored procedure
languages to install via the new extension mechanism (Tom Lane,
Dimitri Fontaine)
This replaces a more manual method of installation.
Add contrib/file_fdw>
foreign-data wrapper (Shigeru Hanada)
Foreign tables using this foreign data wrapper will read flat files
in a matter very similar to COPY>.
Add nearest-neighbor support to contrib/pg_trgm> and contrib/btree_gist>
(Teodor Sigaev)
Add contrib/btree_gist>
support for searching on not equals (Jeff Davis)
Allow contrib/fuzzystrmatch>'s
levenshtein()> function handle multi-byte characters
(Alexander Korotkov)
Add ssl_cipher()> and ssl_version()>
functions to contrib/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 multi-dimensional arrays (Tom Lane)
In
contrib/intarray>,
avoid errors complaining about the presence 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.
In contrib/xml2>, remove
arbitrary limit on the number of parameter=value pairs that
can be handled by xslt_process()> (Pavel Stehule)
The previous limit was 20.
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.
Security
Add contrib/sepgsql>
to interface permission checks with SE>-Linux (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.
Performance
Add support for LIKE> and ILIKE> index
searches to contrib/pg_trgm> (Alexander
Korotkov)
Add levenshtein_less_equal()> function to contrib/fuzzystrmatch>,
which is optimized for small distances (Alexander Korotkov)
Improve performance of index lookups on contrib/seg> columns (Alexander
Korotkov)
**Confirm this does not affect pg_upgrade>
Improve performance of pg_upgrade> for
databases with many relations (Bruce Momjian)
Add flag to contrib/pgbench> to
report per-statement latencies (Florian Pflug)
Fsync Testing
Move src/tools/test_fsync> to contrib/pg_test_fsync>
(Bruce Momjian, Tom Lane)
Add O_DIRECT> support to contrib/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)
Documentation
Extensive ECPG> documentation
improvements (Satoshi Nagayasu)
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 parameter shows table storage options.
Document that it is possible to access all composite fields
using (compositeval).*
syntax> (Peter Eisentraut)
**Is this syntax new in 9.1?
Document that translate()>
removes characters in from> that don't have a
corresponding to> character (Josh Kupershmidt)
Merge docs for CREATE CONSTRAINT TRIGGER> and CREATE TRIGGER>
(Alvaro Herrera)
Centralize permission and upgrade documentation (Bruce Momjian)
Add kernel tuning
documentation for Solaris 10 (Josh Berkus)
Previously only Solaris 9 kernel tuning was documented.
Release 9.1alpha4Overview
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.
These notes are cumulative over all alpha releases of the current
development cycle. Items that are new in the latest alpha release are
emphasized.
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.
Testing
The primary reason we release alphas is to get users to test new
features as early as possible. If you are interested in helping
with organized testing, please see
the
testing information page.
ChangesReplication and RecoverySupport named restore points
Named restore points can be created using a new server function,
pg_create_restore_point. A new recovery.conf parameter,
recovery_target_name, allows recovery to stop at a named restore
point.
Add new recovery.conf> parameter, pause_at_recovery_target,
which defaults to on
This is a behavior change from previous releases, which entered normal
running upon reaching the recovery target.
Add pg_is_xlog_replay_paused, pg_xlog_replay_pause, and
pg_xlog_replay_resume functionsAllow standby servers to send information on running
transactions back to the master
When enabled, this prevents most recovery conflicts on the slave,
but may cause MVCC bloat on the master.
Support streaming base backups
A new client, pg_basebackup, can be used to perform a streaming base
backup.
Synchronous replication
When enabled, transaction commit will wait for WAL records to be
replicated before informing the client that a transaction has
successfully committed.
When recovery_target_timeline='latest', periodically
rescan the archive for new timelinesSQL Features
Add ALTER ... SET SCHEMA support for conversions,
operators, operator classes, operator families, text search
configurations, text search dictionaries, text search
parsers, and text search templates
Make TRUNCATE ... RESTART IDENTITY restart sequences transactionally
Previously, the sequence restart did not roll back on error.
This meant that an error between truncating and committing
left the sequences out of sync with the table contents, with
potentially bad consequences as were noted in a Warning on
the TRUNCATE man page.
Prevent invoking I/O conversion casts via
functional/attribute notation
This was found to be confusing in some cases. The
functionality is still available via cast syntax.
Add ALTER TYPE ... ADD/DROP/ALTER/RENAME ATTRIBUTE
Support triggers on views
This adds the SQL-standard concept of an INSTEAD OF trigger,
which is fired instead of performing a physical
insert/update/delete. The trigger function is passed the
entire old and/or new rows of the view, and must figure out
what to do to the underlying tables to implement the update.
So this feature can be used to implement updatable views
using trigger programming style rather than rule hacking.
Allow WITH clauses to be attached to INSERT, UPDATE, DELETE
statements
Allow INSERT/UPDATE/DELETE to be used inside a WITH
clause
Allow new values to be added to an existing enum type
Recognize functional dependency on primary
keys
This allows a table's other columns to be referenced without listing
them in GROUP BY, so long as the primary key column(s) are listed in
GROUP BY.
Add CREATE TABLE IF NOT EXISTS
Allow a table's row type to be cast to the table's supertype
if it's a type table
This is analagous to the existing facility that allows casting a row
type to a supertable's row type.
Make foreign data wrappers functional, and support FOREIGN
TABLEs
Foreign tables are component of SQL/MED, and provide a framework to
allow data stored outside the database to be accessed via SQL.
contrib/file_fdw is provided as a sample foreign data wrapper.
Allow a unique or primary key constraint to be created
using an existing indexImplement Serializable Snapshot Isolation, in order to
provide a more robust serializable transaction mode
In previous releases, the REPEATABLE READ and SERIALIZABLE isolation
levels were identical. The historical behavior of REPEATABLE READ is
unchanged in this release, but SERIALIZABLE now provides stronger
guarantees.
Allow foreign key constraints to be added as initially
NOT VALID, and validated laterAllow multiple collations to be used within a single
databaseSupport extensions, which provide a cleaner method for
installing and upgrading add-on modules, such as those in contrib
Teach ALTER TABLE ... SET DATA TYPE to avoid a table write
in some cases where it isn't necessary
Add ENCODING option to COPY TO/FROMAllow binary I/O of type "void"Rearrange snapshot handlling to make rule expansion more
consistent
Portals, SQL functions, and SPI all now agree that a completely new
MVCC snapshot should be obtained only after fully executing each
original query. This is equivalent to the prior behavior of EXPLAIN
ANALYZE. It eliminates one source of concurrency hazards for
rules, and should also be marginally faster.
Performance
Optimize the commit_siblings configuration parameter
KNN GiST, otherwise known as order-by-operator support for GiST
This can be used to optimize nearest-neighbor searches.
Improve process shutdown speed
Speed up conversion of signed integers to C strings
Support MergeAppend plans, to allow sorted output
from append relations
This eliminates the former need to sort the output of an
Append scan when an ordered scan of an inheritance tree is
wanted. This should be particularly useful for fast-start
cases such as queries with LIMIT.
Support unlogged tables
The contents of an unlogged table are not WAL-logged; thus, they
are not replicated and are truncated whenever the database system
enters recovery. Indexes on unlogged tables are also unlogged, but
GIST indexes on unlogged tables are not currently supported.
Hash joins now support right and full outer joins
Previously, full joins could be implemented only as a merge join,
and left and right outer joins could only hash the table on the
nullable side of the join. This optimization is particularly
advantageous when the non-nullable side of a left or right outer
join is much smaller than the nullable side.
Reduce the memory requirement for large ispell dictionaries
Teach CLUSTER to use seqscan-and-sort when it's faster than
indexscan
Improve GIN indexscan cost estimation
Fix GIN to support null keys, empty and null items, and
full index scansTeach GIN to combine duplicate keys even across different
quals
Performance improvements in pg_upgrade for uses with many tables
Reduce lock levels of CREATE TRIGGER and some ALTER
TABLE, CREATE RULE actions
Add some knowledge about prefix matches to
tsmatchsel()
Replace the naive HYPOT() macro with a
standards-conformant hypotenuse function
Avoid unnecessary detoast when comparing unequal-length text
or bytea values for equality or inequalityTry to compact the background writer's fsync queue when
it overflows, instead of doing an fsync per block writtenServer Settings
Change the default value of
standard_conforming_strings> to
on>
This is a significant incompatibility with previous releases,
because it may break unwary applications in security-critical ways.
Add log_file_mode> parameter
This allows control of the file permissions set on log files created
by the syslogger process.
Add restart_after_crash> parameter
Normally, we automatically restart after a backend crash, but in
some cases when PostgreSQL is invoked by clusterware it may be
desirable to suppress this behavior, so we now provide an option which
does that.
Teach replication connections to respect the value of
log_connections
Previously, they were always logged.
Log restartpoints in the same fashion as
checkpoints
Previously, less information was logged for restartpoints.
By default, set wal_buffers to a reasonable value, based
on the setting for shared_buffersAdministration and Monitoring
Instrument checkpoint sync calls
Use the same lexer for recovery.conf that has been used for
postgresql.conf> (Dimitri Fontaine)
Among other things, this allows values in recovery.conf to be unquoted.
Add column buffers_backend_fsync to pg_stat_bgwriter
Add monitoring function pg_last_xact_replay_timestamp()
Allow pg_ctl to register the service in either AUTO or DEMAND start
type
Support host names and host key word all
in pg_hba.conf
Make EXPLAIN show the function call expression of a
FunctionScan plan node, but only in VERBOSE mode
Make EXPLAIN print PARAM_EXEC Params as
the referenced expressions, rather than just $N
Add vacuum and analyze counters to pg_stat_*_tables
views
Add stats functions and views to provide access to a
transaction's own statistics counts
Implement remaining fields of
information_schema.sequences viewAdd a "conflicts" column to pg_stat_databaseNew system view pg_stat_database_conflictsNew system view pg_stat_replication
This view shows which replication slaves are connected to the master,
and reports their status and replication progress.
When an autovacuum worker (other than one performing an
anti-wraparound vacuum) is unable to obtain a lock on the target
relation without blocking, skip the relation
This avoids pinning down an autovacuum worker. The next autovacuum
cycle will try again.
Track time of last statistics reset on databases and
bgwriterSecurity
Add SECURITY LABEL command
This is intended as infrastructure to support integration
with label-based mandatory access control systems such as
SE-Linux.
Add server authentication over Unix-domain
sockets
This adds a libpq connection parameter requirepeer> that
specifies the user name that the server process is expected to run
under.
Add REPLICATION privilege for ROLEs
This makes it possible for replication to be performed by a
non-superuser account.
Built-in Functions
Add pg_read_binary_file() and whole-file-at-once
versions of pg_read_file()
Add new function format(), for sprintf-like string formatting
Add pg_describe_object() function to obtain textual
descriptions of objects as stored in pg_depend
Accept public as a pseudo-role
name in has_table_privilege() and friends
to see if a particular privilege has been granted to
PUBLIC
Add string functions: concat(), concat_ws(), left(),
right(), and reverse()
Add three-parameter forms of array_to_string and
string_to_array
Add XMLEXISTS function
Add xpath_exists() function
This is equivalent to XMLEXISTS except that it offers support for
namespace mapping.
Add xml_is_well_formed, xml_is_well_formed_document,
xml_is_well_formed_content functions to the core XML
code
These supersede a version previously offered by contrib/xml2.
Change pg_last_xlog_receive_location not to move
backwardsData Types
Allow numeric to use a more compact, 2-byte header in
many cases
Add support for dividing money by money (yielding a
float8 result) and for casting between money and numeric
Server Tools
Add options to force quoting of all
identifiers
This includes a quote_all_identifiers parameter which affects the
behavior of the backend, and a --quote-all-identifiers argument to
pg_dump and pg_dumpall which sets the parameter and also affects the
quoting done internally by those applications.
Add a directory output format to pg_dumppsql>
Add S option to \dn command in psql>
System schemas are now hidden by default by \dn.
Add \conninfo command to psql>, to show current connection
info
Extend psql>'s \e and \ef commands so that a line number
can be specified, and the editor's cursor will be initially placed
on that line
To avoid assumptions about what switch the user's editor takes for
this purpose, there is a new psql> variable EDITOR_LINENUMBER_SWITCH
with (at present) no default value.
Add a \sf (show function) command to psql>, for those
times when you need to look at a function but don't wish to fire up
an editor
Make psql> distinguish between unique indices and unique
constraints in \d printout
Add a \dL command to psql>, to list procedural
languagesAllow psql> to automatically deduce the client encoding from
the localelibpq
Add PQlibVersion() function
When reporting the server as not responding, if the
hostname was supplied, also print the IP address
This allows IPv4 and IPv6 failures to be distinguished. Also
useful when a hostname resolves to multiple IP addresses.
Add functions PQping and PQpingParams to allow
detection of the server's status, including a status where
the server is running but refuses ordinary connections
pg_ctl uses the new function. This fixes the case where
pg_ctl reports that the server is not running (cannot
connect) but in fact it is running.
ecpgAllow ecpg to accept dynamic cursor names even in WHERE
CURRENT OF clausesProcedural LanguagesPL/pgSQL
Modify the handling of RAISE without parameters so that
the error it throws can be caught in the same places that could
catch an ordinary RAISE ERROR in the same location
The previous coding insisted on throwing the error from the block
containing the active exception handler; which is arguably more
surprising, and definitely unlike Oracle's behavior.
Remove ancient PL/pgSQL line numbering hack
PL/pgSQL used to count the second line of the function body as
line 1>, if the first line was zero-length.
While this hack arguably has some benefit in terms of making
PL/pgsql's line numbering match the programmer's expectations, it
also makes PL/pgsql inconsistent with the remaining PLs, making it
difficult for clients to reliably determine where the error
actually is. On balance, it seems better to be consistent.
PL/Perl
Allow generic record arguments to PL/Perl functions
Convert PostgreSQL arrays passed to PL/perl functions to
Perl arraysPL/PythonFix an error when a set-returning function fails halfway
throughMake plpy.Fatal() raise FATAL, rather than ERRORSkip dropped attributes when converting Python objects to
tuplesImprove the handling of exceptions
Fix the way that exceptions are handled by the plpy module for Python
3. Get rid of the global variable holding the error state, and
instead arrange to report PostgreSQL errors to Python immediately.
Call PLy_spi_execute_fetch_result inside the try/catch block, so that
errors from fetching tuples are correct reported as errors in the
SPI call. Use the built-in TypeError, not SPIError, for errors
having to do with argument counts or types. Use SPIError, not simply
plpy.Error, for errors in PLy_spi_execute_plan. Do not set
a Python exception if PyArg_ParseTuple failed, as it already sets
the correct exception.
Improve error reportingBetter error messages for errors in compiling anonymous
PL/Python blocks. Avoid prefixing error messages with the string
"PL/Python: ", which is redundant, given the error
context. Provide a separate exception class for each error code
the backend defines, and make it possible to get the SQLSTATE from
the exception object. Report Python errors from iterators
using PLy_elog, so that the Python exception is included in the
exception, and to avoid setting the errcode to
ERRCODE_DATA_EXCEPTION.
Check PL/Python functions for syntax errors at creation
time
Previously, even gross syntax errors would not be detected until
the function was executed.
Allow Python try/catch blocks to catch exceptions arising
from SPI callsInvalidate PL/python functions with composite type
arguments when the type changesAdd quoting functions plpy.quote_ident, plpy.quote_literal,
and plpy.quote_nullableSupport table functionsAdd a plpy.subtransaction() context managerAssorted code cleanup
We now use HTABs instead of Python dictionary objects to cache
procedures. palloc is used in TopMemoryContext instead of malloc.
Avoid use of undocumented API PyObject_NEW. Free plan values in
the PlyPlanObject dealloc function. Add braces around an if block,
for readability. Refactor PLy_spi_prepare to save two levels of
indentation. Avoid palloc(0).
Additional Supplied Modules
New module contrib/auth_delay
New module contrib/sepgsql, an SE-Linux integration for
PostgreSQL
Updates to contrib/isn ISBN tables
Add the ability to compute per-statement latencies (ie,
average execution times) to pgbench
Teach levenshtein() about multi-byte
characters
Add btree_gist support for searching on not
equals
Add ssl_cipher() and ssl_version() functions to
contrib/sslinfo
Remove the arbitrary (and undocumented) limit on the
number of parameter=value pairs that can be handled by
xslt_process()
New module contrib/pg_test_fsync, replacing
src/tools/test_fsyncIn contrib/pageinspect, fix the heap_page_item to return
infomasks as 32 bit valuesIn contrib/btree_gist, support KNN GiST searchesIn contrib/pg_trgm, support LIKE, ILIKE, and KNN GiST
searchesSeveral improvements to contrib/intarray
Correct the behavior of array containment operators, so that an empty
array is contained in any other array. Fix bogus failures where
operators would claim that nulls were present when they really
weren't. Remove arbitrary restriction to 1-D arrays.
Fix pg_upgrade not to insist on pg_dumpall and psql in the
old cluster, since we don't need them, but do check for pg_resetxlog
in the old and new clusters, since we do. Avoid a useless attempt
to call pg_config in the old cluster.Source Code, Build Options
Rewrite the GiST insertion logic so that the
post-recovery cleanup stage to finish incomplete inserts or
splits is not needed anymore
Add support for collecting minidump-style crash dumps
on Windows
Replace pg_class.relistemp column with relpersistence
This is for upcoming work on unlogged and global temporary tables.
GNU make 3.80 or newer is now required
Improved support for parallel make, make -k, and make -q
Include the backend ID in the relpath of temporary
relations
This allows us to reliably remove all leftover temporary relation
files on cluster startup without reference to system catalogs or
WAL; therefore, we no longer include temporary relations in
XLOG_XACT_COMMIT and XLOG_XACT_ABORT WAL records.
Rewrite COMMENT ON object> code for better
modularity, and add necessary locking
Add a hook in ExecCheckRTPerms() for eventual use by
external security-checking modules
Standardize names and calling conventions of
get_whatever_oid functions
Make NestLoop plan nodes pass outer-relation variables
into their inner relation using the general PARAM_EXEC executor
parameter mechanism, rather than the ad-hoc kluge of passing the
outer tuple down through ExecReScan
Make details of the Numeric representation private to
numeric.c
Suppress some compiler warnings from
clang>
Allow make check in PL directoriesAdd a make check-world targetPGXS support for contrib/hstore