Release date: 2005-11-08
Major changes in this release:
Access to the shared buffer cache was identified as a significant scalability problem, particularly on multi-CPU systems. In this release, the way that locking is done in the buffer manager has been overhauled to reduce lock contention and improve scalability. The buffer manager has also been changed to use a “clock sweep” replacement policy.
       In previous releases, only a single index could be used to do
       lookups on a table. With this feature, if a query has
       WHERE tab.col1 = 4 and tab.col2 = 9, and there is
       no multicolumn index on col1 and col2,
       but there is an index on col1 and another on
       col2, it is possible to search both indexes and
       combine the results in memory, then do heap fetches for only
       the rows matching both the col1 and
       col2 restrictions. This is very useful in
       environments that have a lot of unstructured queries where it
       is impossible to create indexes that match all possible access
       conditions.  Bitmap scans are useful even with a single index,
       as they reduce the amount of random access needed; a bitmap
       index scan is efficient for retrieving fairly large fractions
       of the complete table, whereas plain index scans are not.
      
       Two-phase commit allows transactions to be "prepared" on several
       computers, and once all computers have successfully prepared
       their transactions (none failed), all transactions can be
       committed. Even if a machine crashes after a prepare, the
       prepared transaction can be committed after the machine is
       restarted. New syntax includes PREPARE TRANSACTION and
       COMMIT/ROLLBACK PREPARED. A new system view
       pg_prepared_xacts has also been added.
      
Roles are a combination of users and groups. Like users, they can have login capability, and like groups, a role can have other roles as members. Roles basically remove the distinction between users and groups. For example, a role can:
Have login capability (optionally)
Own objects
Hold access permissions for database objects
Inherit permissions from other roles it is a member of
       Once a user logs into a role, she obtains capabilities of
       the login role plus any inherited roles, and can use
       SET ROLE to switch to other roles she is a member of.
       This feature is a generalization of the SQL standard's concept of
       roles.
       This change also replaces pg_shadow and
       pg_group by new role-capable catalogs
       pg_authid and pg_auth_members. The old
       tables are redefined as read-only views on the new role tables.
      
MIN() and
      MAX() (Tom)
            In previous releases, the only way to use an index for
       MIN() or MAX() was to rewrite the
       query as SELECT col FROM tab ORDER BY col LIMIT 1.
       Index usage now happens automatically.
      
/contrib/pg_autovacuum into the main server
      (Alvaro)
            Integrating autovacuum into the server allows it to be
       automatically started and stopped in sync with the database
       server, and allows autovacuum to be configured from
       postgresql.conf.
      
SELECT ... FOR SHARE
      (Alvaro)
            While PostgreSQL's MVCC locking
       allows SELECT to never be blocked by writers and
       therefore does not need shared row locks for typical operations,
       shared locks are useful for applications that require shared row
       locking.  In particular this reduces the locking requirements
       imposed by referential integrity checks.
      
This extension of the dependency mechanism prevents roles from being dropped while there are still database objects they own. Formerly it was possible to accidentally “orphan” objects by deleting their owner. While this could be recovered from, it was messy and unpleasant.
       The new constraint_exclusion configuration
       parameter avoids lookups on child tables where constraints indicate
       that no matching rows exist in the child table.
      
       This allows for a basic type of table partitioning. If child tables
       store separate key ranges and this is enforced using appropriate
       CHECK constraints, the optimizer will skip child
       table accesses when the constraint guarantees no matching rows
       exist in the child table.
      
A dump/restore using pg_dump is required for those wishing to migrate data from any previous release.
    The 8.0 release announced that the to_char() function
    for intervals would be removed in 8.1. However, since no better API
    has been suggested, to_char(interval) has been enhanced in
    8.1 and will remain in the server.
   
Observe the following incompatibilities:
      add_missing_from is now false by default (Neil)
     
      By default, we now generate an error if a table is used in a query
      without a FROM reference.  The old behavior is still
      available, but the parameter must be set to 'true' to obtain it.
     
      It might be necessary to set add_missing_from to true
      in order to load an existing dump file, if the dump contains any
      views or rules created using the implicit-FROM syntax.
      This should be a one-time annoyance, because
      PostgreSQL 8.1 will convert
      such views and rules to standard explicit-FROM syntax.
      Subsequent dumps will therefore not have the problem.
     
      Cause input of a zero-length string ('') for
      float4/float8/oid
      to throw an error, rather than treating it as a zero (Neil)
     
This change is consistent with the current handling of zero-length strings for integers. The schedule for this change was announced in 8.0.
      default_with_oids is now false by default (Neil)
     
      With this option set to false, user-created tables no longer
      have an OID column unless WITH OIDS is specified in
      CREATE TABLE. Though OIDs have existed in all
      releases of PostgreSQL, their use is limited
      because they are only four bytes long and the counter is shared
      across all installed databases. The preferred way of uniquely
      identifying rows is via sequences and the SERIAL type,
      which have been supported since PostgreSQL 6.4.
     
      Add E'' syntax so eventually ordinary strings can
      treat backslashes literally (Bruce)
     
      Currently PostgreSQL processes a
      backslash in a string literal as introducing a special escape sequence,
      e.g. \n or \010.
      While this allows easy entry of special values, it is
      nonstandard and makes porting of applications from other
      databases more difficult. For this reason, the
      PostgreSQL project is planning to
      remove the special meaning of backslashes in strings. For
      backward compatibility and for users who want special backslash
      processing, a new string syntax has been created. This new string
      syntax is formed by writing an E immediately preceding the
      single quote that starts the string, e.g. E'hi\n'. While
      this release does not change the handling of backslashes in strings, it
      does add new configuration parameters to help users migrate applications
      for future releases:
     
        standard_conforming_strings — does this release
        treat backslashes literally in ordinary strings?
       
       escape_string_warning — warn about backslashes in
       ordinary (non-E) strings
      
      The standard_conforming_strings value is read-only.
      Applications can retrieve the value to know how backslashes are
      processed.  (Presence of the parameter can also be taken as an
      indication that E'' string syntax is supported.)
      In a future release, standard_conforming_strings
      will be true, meaning backslashes will be treated literally in
      non-E strings. To prepare for this change, use E''
      strings in places that need special backslash processing, and
      turn on escape_string_warning to find additional
      strings that need to be converted to use E''.
      Also, use two single-quotes ('') to embed a literal
      single-quote in a string, rather than the
      PostgreSQL-supported syntax of
      backslash single-quote (\').  The former is
      standards-conforming and does not require the use of the
      E'' string syntax.  You can also use the
      $$ string syntax, which does not treat backslashes
      specially.
     
      Make REINDEX DATABASE reindex all indexes in the
      database (Tom)
     
      Formerly, REINDEX DATABASE reindexed only
      system tables. This new behavior seems more intuitive. A new
      command REINDEX SYSTEM provides the old functionality
      of reindexing just the system tables.
     
Read-only large object descriptors now obey MVCC snapshot semantics
      When a large object is opened with INV_READ (and not
      INV_WRITE), the data read from the descriptor will now
      reflect a “snapshot” of the large object's state at the
      time of the transaction snapshot in use by the query that called
      lo_open().  To obtain the old behavior of always
      returning the latest committed data, include INV_WRITE
      in the mode flags for lo_open().
     
Add proper dependencies for arguments of sequence functions (Tom)
      In previous releases, sequence names passed to nextval(),
      currval(), and setval() were stored as
      simple text strings, meaning that renaming or dropping a
      sequence used in a DEFAULT clause made the clause
      invalid. This release stores all newly-created sequence function
      arguments as internal OIDs, allowing them to track sequence
      renaming, and adding dependency information that prevents
      improper sequence removal. It also makes such DEFAULT
      clauses immune to schema renaming and search path changes.
     
      Some applications might rely on the old behavior of
      run-time lookup for sequence names. This can still be done by
      explicitly casting the argument to text, for example
      nextval('myseq'::text).
     
      Pre-8.1 database dumps loaded into 8.1 will use the old text-based
      representation and therefore will not have the features of
      OID-stored arguments. However, it is possible to update a
      database containing text-based DEFAULT clauses.
      First, save this query into a file, such as fixseq.sql:
SELECT  'ALTER TABLE ' ||
   pg_catalog.quote_ident(n.nspname) || '.' ||
   pg_catalog.quote_ident(c.relname) ||
   ' ALTER COLUMN ' || pg_catalog.quote_ident(a.attname) ||
   ' SET DEFAULT ' ||
   regexp_replace(d.adsrc,
                  $$val\(\(('[^']*')::text\)::regclass$$,
                  $$val(\1$$,
                  'g') ||
   ';'
FROM    pg_namespace n, pg_class c, pg_attribute a, pg_attrdef d
WHERE   n.oid = c.relnamespace AND
   c.oid = a.attrelid AND
   a.attrelid = d.adrelid AND
   a.attnum = d.adnum AND
   d.adsrc ~ $$val\(\('[^']*'::text\)::regclass$$;
      Next, run the query against a database to find what
      adjustments are required, like this for database db1:
psql -t -f fixseq.sql db1
      This will show the ALTER TABLE commands needed to
      convert the database to the newer OID-based representation.
      If the commands look reasonable, run this to update the database:
psql -t -f fixseq.sql db1 | psql -e db1
This process must be repeated in each database to be updated.
      In psql, treat unquoted
      \{digit}+ sequences as octal (Bruce)
     
      In previous releases, \{digit}+ sequences were
      treated as decimal, and only \0{digit}+ were treated
      as octal. This change was made for consistency.
     
      Remove grammar productions for prefix and postfix %
      and ^ operators
      (Tom)
     
      These have never been documented and complicated the use of the
      modulus operator (%) with negative numbers.
     
      Make &< and &> for polygons
      consistent with the box "over" operators (Tom)
     
      CREATE LANGUAGE can ignore the provided arguments
      in favor of information from pg_pltemplate
      (Tom)
     
      A new system catalog pg_pltemplate has been defined
      to carry information about the preferred definitions of procedural
      languages (such as whether they have validator functions).  When
      an entry exists in this catalog for the language being created,
      CREATE LANGUAGE will ignore all its parameters except the
      language name and instead use the catalog information.  This measure
      was taken because of increasing problems with obsolete language
      definitions being loaded by old dump files.  As of 8.1,
      pg_dump will dump procedural language definitions as
      just CREATE LANGUAGE , relying
      on a template entry to exist at load time.  We expect this will be a
      more future-proof representation.
     name
      Make pg_cancel_backend(int) return a
      boolean rather than an integer (Neil)
     
      Some users are having problems loading UTF-8 data into 8.1.X.
      This is because previous versions allowed invalid UTF-8 byte
      sequences to be entered into the database, and this release
      properly accepts only valid UTF-8 sequences. One way to correct a
      dumpfile is to run the command iconv -c -f UTF-8 -t
      UTF-8 -o cleanfile.sql dumpfile.sql. The -c option
      removes invalid character sequences. A diff of the two files will
      show the sequences that are invalid. iconv reads the
      entire input file into memory so it might be necessary to use
      split to break up the dump into multiple smaller
      files for processing.
     
Below you will find a detailed account of the additional changes between PostgreSQL 8.1 and the previous major release.
Improve GiST and R-tree index performance (Neil)
Improve the optimizer, including auto-resizing of hash joins (Tom)
Overhaul internal API in several areas
Change WAL record CRCs from 64-bit to 32-bit (Tom)
We determined that the extra cost of computing 64-bit CRCs was significant, and the gain in reliability too marginal to justify it.
Prevent writing large empty gaps in WAL pages (Tom)
Improve spinlock behavior on SMP machines, particularly Opterons (Tom)
Allow nonconsecutive index columns to be used in a multicolumn index (Tom)
       For example, this allows an index on columns a,b,c to be used in
       a query with WHERE a = 4 and c = 10.
      
       Skip WAL logging for CREATE TABLE AS /
       SELECT INTO (Simon)
      
       Since a crash during CREATE TABLE AS would cause the
       table to be dropped during recovery, there is no reason to WAL
       log as the table is loaded.  (Logging still happens if WAL
       archiving is enabled, however.)
      
Allow concurrent GiST index access (Teodor, Oleg)
       Add configuration parameter full_page_writes to
       control writing full pages to WAL (Bruce)
      
To prevent partial disk writes from corrupting the database, PostgreSQL writes a complete copy of each database disk page to WAL the first time it is modified after a checkpoint. This option turns off that functionality for more speed. This is safe to use with battery-backed disk caches where partial page writes cannot happen.
       Use O_DIRECT if available when using
       O_SYNC for wal_sync_method
       (Itagaki Takahiro)
      
       O_DIRECT causes disk writes to bypass the kernel
       cache, and for WAL writes, this improves performance.
      
       Improve COPY FROM performance (Alon Goldshuv)
      
       This was accomplished by reading COPY input in
       larger chunks, rather than character by character.
      
       Improve the performance of COUNT(),
       SUM, AVG(),
       STDDEV(), and
       VARIANCE() (Neil, Tom)
      
Prevent problems due to transaction ID (XID) wraparound (Tom)
The server will now warn when the transaction counter approaches the wraparound point. If the counter becomes too close to wraparound, the server will stop accepting queries. This ensures that data is not lost before needed vacuuming is performed.
Fix problems with object IDs (OIDs) conflicting with existing system objects after the OID counter has wrapped around (Tom)
       Add warning about the need to increase
       max_fsm_relations and max_fsm_pages
       during VACUUM (Ron Mayer)
      
       Add temp_buffers configuration parameter to allow
       users to determine the size of the local buffer area for
       temporary table access (Tom)
      
       Add session start time and client IP address to
       pg_stat_activity (Magnus)
      
       Adjust pg_stat views for bitmap scans (Tom)
      
The meanings of some of the fields have changed slightly.
       Enhance pg_locks view (Tom)
      
       Log queries for client-side PREPARE and
       EXECUTE (Simon)
      
       Allow Kerberos name and user name case sensitivity to be
       specified in postgresql.conf (Magnus)
      
       Add configuration parameter krb_server_hostname so
       that the server host name can be specified as part of service
       principal (Todd Kover)
      
If not set, any service principal matching an entry in the keytab can be used. This is new Kerberos matching behavior in this release.
       Add log_line_prefix options for millisecond
       timestamps (%m) and remote host (%h) (Ed
       L.)
      
Add WAL logging for GiST indexes (Teodor, Oleg)
GiST indexes are now safe for crash and point-in-time recovery.
       Remove old *.backup files when we do
       pg_stop_backup() (Bruce)
      
       This prevents a large number of *.backup files from
       existing in pg_xlog/.
      
Add configuration parameters to control TCP/IP keep-alive times for idle, interval, and count (Oliver Jowett)
These values can be changed to allow more rapid detection of lost client connections.
Add per-user and per-database connection limits (Petr Jelinek)
       Using ALTER USER and ALTER DATABASE,
       limits can now be enforced on the maximum number of sessions that
       can concurrently connect as a specific user or to a specific database.
       Setting the limit to zero disables user or database connections.
      
Allow more than two gigabytes of shared memory and per-backend work memory on 64-bit machines (Koichi Suzuki)
       New system catalog pg_pltemplate allows overriding
       obsolete procedural-language definitions in dump files (Tom)
      
Add temporary views (Koju Iijima, Neil)
       Fix HAVING without any aggregate functions or
       GROUP BY so that the query returns a single group (Tom)
      
       Previously, such a case would treat the HAVING
       clause the same as a WHERE clause.  This was not per spec.
      
       Add USING clause to allow additional tables to be
       specified to DELETE (Euler Taveira de Oliveira, Neil)
      
       In prior releases, there was no clear method for specifying
       additional tables to be used for joins in a DELETE
       statement. UPDATE already has a FROM
       clause for this purpose.
      
       Add support for \x hex escapes in backend and ecpg
       strings (Bruce)
      
       This is just like the standard C \x escape syntax.
       Octal escapes were already supported.
      
       Add BETWEEN SYMMETRIC query syntax (Pavel Stehule)
      
       This feature allows BETWEEN comparisons without
       requiring the first value to be less than the second. For
       example, 2 BETWEEN [ASYMMETRIC] 3 AND 1 returns
       false, while 2 BETWEEN SYMMETRIC 3 AND 1 returns
       true. BETWEEN ASYMMETRIC was already supported.
      
       Add NOWAIT option to SELECT ... FOR
       UPDATE/SHARE (Hans-Juergen Schoenig)
      
       While the statement_timeout configuration
       parameter allows a query taking more than a certain amount of
       time to be canceled, the NOWAIT option allows a
       query to be canceled as soon as a SELECT ... FOR
       UPDATE/SHARE command cannot immediately acquire a row lock.
      
Track dependencies of shared objects (Alvaro)
PostgreSQL allows global tables (users, databases, tablespaces) to reference information in multiple databases. This addition adds dependency information for global tables, so, for example, user ownership can be tracked across databases, so a user who owns something in any database can no longer be removed. Dependency tracking already existed for database-local objects.
       Allow limited ALTER OWNER commands to be performed
       by the object owner (Stephen Frost)
      
Prior releases allowed only superusers to change object owners. Now, ownership can be transferred if the user executing the command owns the object and would be able to create it as the new owner (that is, the user is a member of the new owning role and that role has the CREATE permission that would be needed to create the object afresh).
       Add ALTER object SET SCHEMA capability
       for some object types (tables, functions, types) (Bernd Helmle)
      
This allows objects to be moved to different schemas.
       Add ALTER TABLE ENABLE/DISABLE TRIGGER to
       disable triggers (Satoshi Nagayasu)
      
       Allow TRUNCATE to truncate multiple tables in a
       single command (Alvaro)
      
       Because of referential integrity checks, it is not allowed to
       truncate a table that is part of a referential integrity
       constraint. Using this new functionality, TRUNCATE
       can be used to truncate such tables, if both tables involved in
       a referential integrity constraint are truncated in a single
       TRUNCATE command.
      
       Properly process carriage returns and line feeds in
       COPY CSV mode (Andrew)
      
       In release 8.0, carriage returns and line feeds in CSV
       COPY TO were processed in an inconsistent manner. (This was
       documented on the TODO list.)
      
       Add COPY WITH CSV HEADER to allow a header line as
       the first line in COPY (Andrew)
      
       This allows handling of the common CSV usage of
       placing the column names on the first line of the data file. For
       COPY TO, the first line contains the column names,
       and for COPY FROM, the first line is ignored.
      
       On Windows, display better sub-second precision in
       EXPLAIN ANALYZE (Magnus)
      
       Add trigger duration display to EXPLAIN ANALYZE
       (Tom)
      
Prior releases included trigger execution time as part of the total execution time, but did not show it separately. It is now possible to see how much time is spent in each trigger.
       Add support for \x hex escapes in COPY
       (Sergey Ten)
      
Previous releases only supported octal escapes.
       Make SHOW ALL include variable descriptions
       (Matthias Schmidt)
      
       SHOW varname still only displays the variable's
       value and does not include the description.
      
       Make initdb create a new standard
       database called postgres, and convert utilities to
       use postgres rather than template1 for
       standard lookups (Dave)
      
       In prior releases, template1 was used both as a
       default connection for utilities like
       createuser, and as a template for
       new databases. This caused CREATE DATABASE to
       sometimes fail, because a new database cannot be created if
       anyone else is in the template database. With this change, the
       default connection database is now postgres,
       meaning it is much less likely someone will be using
       template1 during CREATE DATABASE.
      
       Create new reindexdb command-line
       utility by moving /contrib/reindexdb into the
       server (Euler Taveira de Oliveira)
      
       Add MAX() and MIN() aggregates for
       array types (Koju Iijima)
      
       Fix to_date() and to_timestamp() to
       behave reasonably when CC and YY fields
       are both used (Karel Zak)
      
       If the format specification contains CC and a year
       specification is YYY or longer, ignore the
       CC. If the year specification is YY or
       shorter, interpret CC as the previous century.
      
       Add md5(bytea) (Abhijit Menon-Sen)
      
       md5(text) already existed.
      
       Add support for numeric ^ numeric based on
       power(numeric, numeric)
      
The function already existed, but there was no operator assigned to it.
       Fix NUMERIC modulus by properly truncating the quotient
       during computation (Bruce)
      
In previous releases, modulus for large values sometimes returned negative results due to rounding of the quotient.
       Add a function lastval() (Dennis Björklund)
      
       lastval() is a simplified version of
       currval(). It automatically determines the proper
       sequence name based on the most recent nextval() or
       setval() call performed by the current session.
      
       Add to_timestamp(DOUBLE PRECISION) (Michael Glaesemann)
      
       Converts Unix seconds since 1970 to a TIMESTAMP WITH
       TIMEZONE.
      
       Add pg_postmaster_start_time() function (Euler
       Taveira de Oliveira, Matthias Schmidt)
      
       Allow the full use of time zone names in AT TIME
       ZONE, not just the short list previously available (Magnus)
      
       Previously, only a predefined list of time zone names were
       supported by AT TIME ZONE. Now any supported time
       zone name can be used, e.g.:
SELECT CURRENT_TIMESTAMP AT TIME ZONE 'Europe/London';
In the above query, the time zone used is adjusted based on the daylight saving time rules that were in effect on the supplied date.
       Add GREATEST() and LEAST() variadic
       functions (Pavel Stehule)
      
These functions take a variable number of arguments and return the greatest or least value among the arguments.
       Add pg_column_size() (Mark Kirkwood)
      
This returns storage size of a column, which might be compressed.
       Add regexp_replace() (Atsushi Ogawa)
      
This allows regular expression replacement, like sed. An optional flag argument allows selection of global (replace all) and case-insensitive modes.
Fix interval division and multiplication (Bruce)
       Previous versions sometimes returned unjustified results, like
       '4 months'::interval / 5 returning '1 mon
       -6 days'.
      
Fix roundoff behavior in timestamp, time, and interval output (Tom)
       This fixes some cases in which the seconds field would be shown as
       60 instead of incrementing the higher-order fields.
      
       Add a separate day field to type interval so a one day
       interval can be distinguished from a 24 hour interval (Michael
       Glaesemann)
      
       Days that contain a daylight saving time adjustment are not 24
       hours long, but typically 23 or 25 hours.  This change creates a
       conceptual distinction between intervals of “so many days”
       and intervals of “so many hours”.  Adding
       1 day to a timestamp now gives the same local time on
       the next day even if a daylight saving time adjustment occurs
       between, whereas adding 24 hours will give a different
       local time when this happens.  For example, under US DST rules:
'2005-04-03 00:00:00-05' + '1 day' = '2005-04-04 00:00:00-04' '2005-04-03 00:00:00-05' + '24 hours' = '2005-04-04 01:00:00-04'
       Add justify_days() and justify_hours()
       (Michael Glaesemann)
      
These functions, respectively, adjust days to an appropriate number of full months and days, and adjust hours to an appropriate number of full days and hours.
       Move /contrib/dbsize into the backend, and rename
       some of the functions (Dave Page, Andreas Pflug)
      
           pg_tablespace_size()
         
          pg_database_size()
         
          pg_relation_size()
         
          pg_total_relation_size()
         
          pg_size_pretty()
         
       pg_total_relation_size() includes indexes and TOAST
       tables.
      
Add functions for read-only file access to the cluster directory (Dave Page, Andreas Pflug)
          pg_stat_file()
         
          pg_read_file()
         
          pg_ls_dir()
         
       Add pg_reload_conf() to force reloading of the
       configuration files (Dave Page, Andreas Pflug)
      
       Add pg_rotate_logfile() to force rotation of the
       server log file (Dave Page, Andreas Pflug)
      
       Change pg_stat_* views to include TOAST tables (Tom)
      
Rename some encodings to be more consistent and to follow international standards (Bruce)
          UNICODE is now UTF8
         
          ALT is now WIN866
         
          WIN is now WIN1251
         
         TCVN is now WIN1258
         
The original names still work.
       Add support for WIN1252 encoding (Roland Volkmann)
      
       Add support for four-byte UTF8 characters (John
       Hansen)
      
       Previously only one, two, and three-byte UTF8 characters
       were supported. This is particularly important for support for
       some Chinese character sets.
      
       Allow direct conversion between EUC_JP and
       SJIS to improve performance (Atsushi Ogawa)
      
Allow the UTF8 encoding to work on Windows (Magnus)
This is done by mapping UTF8 to the Windows-native UTF16 implementation.
       Fix ALTER LANGUAGE RENAME (Sergey Yatskevich)
      
       Allow function characteristics, like strictness and volatility,
       to be modified via ALTER FUNCTION (Neil)
      
Increase the maximum number of function arguments to 100 (Tom)
       Allow SQL and PL/pgSQL functions to use OUT and
       INOUT parameters (Tom)
      
       OUT is an alternate way for a function to return
       values. Instead of using RETURN, values can be
       returned by assigning to parameters declared as OUT or
       INOUT.  This is notationally simpler in some cases,
       particularly so when multiple values need to be returned.
       While returning multiple values from a function
       was possible in previous releases, this greatly simplifies the
       process.  (The feature will be extended to other server-side
       languages in future releases.)
      
       Move language handler functions into the pg_catalog schema
      
This makes it easier to drop the public schema if desired.
       Add SPI_getnspname() to SPI (Neil)
      
Overhaul the memory management of PL/pgSQL functions (Neil)
The parsetree of each function is now stored in a separate memory context. This allows this memory to be easily reclaimed when it is no longer needed.
       Check function syntax at CREATE FUNCTION time,
       rather than at runtime (Neil)
      
Previously, most syntax errors were reported only when the function was executed.
       Allow OPEN to open non-SELECT queries
       like EXPLAIN and SHOW (Tom)
      
       No longer require functions to issue a RETURN
       statement (Tom)
      
       This is a byproduct of the newly added OUT and
       INOUT functionality.  RETURN can
       be omitted when it is not needed to provide the function's
       return value.
      
       Add support for an optional INTO clause to
       PL/pgSQL's EXECUTE statement (Pavel Stehule, Neil)
      
       Make CREATE TABLE AS set ROW_COUNT (Tom)
      
       Define SQLSTATE and SQLERRM to return
       the SQLSTATE and error message of the current
       exception (Pavel Stehule, Neil)
      
These variables are only defined inside exception blocks.
       Allow the parameters to the RAISE statement to be
       expressions (Pavel Stehule, Neil)
      
       Add a loop CONTINUE statement (Pavel Stehule, Neil)
      
Allow block and loop labels (Pavel Stehule)
Allow large result sets to be returned efficiently (Abhijit Menon-Sen)
       This allows functions to use return_next() to avoid
       building the entire result set in memory.
      
Allow one-row-at-a-time retrieval of query results (Abhijit Menon-Sen)
       This allows functions to use spi_query() and
       spi_fetchrow() to avoid accumulating the entire
       result set in memory.
      
       Force PL/Perl to handle strings as UTF8 if the
       server encoding is UTF8 (David Kamholz)
      
Add a validator function for PL/Perl (Andrew)
This allows syntax errors to be reported at definition time, rather than execution time.
Allow PL/Perl to return a Perl array when the function returns an array type (Andrew)
This basically maps PostgreSQL arrays to Perl arrays.
       Allow Perl nonfatal warnings to generate NOTICE
       messages (Andrew)
      
       Allow Perl's strict mode to be enabled (Andrew)
      
       Add \set ON_ERROR_ROLLBACK to allow statements in
       a transaction to error without affecting the rest of the
       transaction (Greg Sabino Mullane)
      
This is basically implemented by wrapping every statement in a sub-transaction.
       Add support for \x hex strings in
       psql variables (Bruce)
      
Octal escapes were already supported.
       Add support for troff -ms output format (Roger
       Leigh)
      
       Allow the history file location to be controlled by
       HISTFILE (Andreas Seltenreich)
      
This allows configuration of per-database history storage.
       Prevent \x (expanded mode) from affecting
       the output of \d tablename (Neil)
      
       Add -L option to psql to
       log sessions (Lorne Sunley)
      
This option was added because some operating systems do not have simple command-line activity logging functionality.
       Make \d show the tablespaces of indexes (Qingqing
       Zhou)
      
       Allow psql help (\h) to
       make a best guess on the proper help information (Greg Sabino
       Mullane)
      
       This allows the user to just add \h to the front of
       the syntax error query and get help on the supported syntax.
       Previously any additional query text beyond the command name
       had to be removed to use \h.
      
       Add \pset numericlocale to allow numbers to be
       output in a locale-aware format (Eugen Nedelcu)
      
       For example, using C locale 100000 would
       be output as 100,000.0 while a European locale might
       output this value as 100.000,0.
      
Make startup banner show both server version number and psql's version number, when they are different (Bruce)
Also, a warning will be shown if the server and psql are from different major releases.
       Add -n / --schema switch to
       pg_restore (Richard van den Berg)
      
This allows just the objects in a specified schema to be restored.
Allow pg_dump to dump large objects even in text mode (Tom)
       With this change, large objects are now always dumped; the former
       -b switch is a no-op.
      
Allow pg_dump to dump a consistent snapshot of large objects (Tom)
Dump comments for large objects (Tom)
       Add --encoding to pg_dump
       (Magnus Hagander)
      
This allows a database to be dumped in an encoding that is different from the server's encoding. This is valuable when transferring the dump to a machine with a different encoding.
       Rely on pg_pltemplate for procedural languages (Tom)
      
       If the call handler for a procedural language is in the
       pg_catalog schema, pg_dump does not
       dump the handler.  Instead, it dumps the language using just
       CREATE LANGUAGE ,
       relying on the namepg_pltemplate catalog to provide
       the language's creation parameters at load time.
      
       Add a PGPASSFILE environment variable to specify the
       password file's filename (Andrew)
      
       Add lo_create(), that is similar to
       lo_creat() but allows the OID of the large object
       to be specified (Tom)
      
       Make libpq consistently return an error
       to the client application on malloc()
       failure (Neil)
      
Fix pgxs to support building against a relocated installation
Add spinlock support for the Itanium processor using Intel compiler (Vikram Kalsi)
Add Kerberos 5 support for Windows (Magnus)
Add Chinese FAQ (laser@pgsqldb.com)
Rename Rendezvous to Bonjour to match OS/X feature renaming (Bruce)
       Add support for fsync_writethrough on
       macOS (Chris Campbell)
      
Streamline the passing of information within the server, the optimizer, and the lock system (Tom)
Allow pg_config to be compiled using MSVC (Andrew)
This is required to build DBD::Pg using MSVC.
Remove support for Kerberos V4 (Magnus)
Kerberos 4 had security vulnerabilities and is no longer maintained.
Code cleanups (Coverity static analysis performed by EnterpriseDB)
       Modify postgresql.conf to use documentation defaults
       on/off rather than
       true/false (Bruce)
      
Enhance pg_config to be able to report more build-time values (Tom)
Allow libpq to be built thread-safe on Windows (Dave Page)
Allow IPv6 connections to be used on Windows (Andrew)
Add Server Administration documentation about I/O subsystem reliability (Bruce)
       Move private declarations from gist.h to
       gist_private.h (Neil)
      
       In previous releases, gist.h contained both the
       public GiST API (intended for use by authors of GiST index
       implementations) as well as some private declarations used by
       the implementation of GiST itself. The latter have been moved
       to a separate file, gist_private.h. Most GiST
       index implementations should be unaffected.
      
Overhaul GiST memory management (Neil)
       GiST methods are now always invoked in a short-lived memory
       context. Therefore, memory allocated via palloc()
       will be reclaimed automatically, so GiST index implementations
       do not need to manually release allocated memory via
       pfree().
      
       Add /contrib/pg_buffercache contrib module (Mark
       Kirkwood)
      
This displays the contents of the buffer cache, for debugging and performance tuning purposes.
       Remove /contrib/array because it is obsolete (Tom)
      
       Clean up the /contrib/lo module (Tom)
      
       Move /contrib/findoidjoins to
       /src/tools (Tom)
      
       Remove the <<, >>,
       &<, and &> operators from
       /contrib/cube
      
These operators were not useful.
       Improve /contrib/btree_gist (Janko Richter)
      
       Improve /contrib/pgbench (Tomoaki Sato, Tatsuo)
      
There is now a facility for testing with SQL command scripts given by the user, instead of only a hard-wired command sequence.
       Improve /contrib/pgcrypto (Marko Kreen)
      
Implementation of OpenPGP symmetric-key and public-key encryption
Both RSA and Elgamal public-key algorithms are supported.
Stand alone build: include SHA256/384/512 hashes, Fortuna PRNG
OpenSSL build: support 3DES, use internal AES with OpenSSL < 0.9.7
         Take build parameters (OpenSSL, zlib) from configure result
        
         There is no need to edit the Makefile anymore.
        
         Remove support for libmhash and libmcrypt