E.294. Release 7.4

Allow IPv6 server connections (Nigel Kukard, Johan Jordaan, Bruce, Tom, Kurt Roeckx, Andrew Dunstan)

Fix SSL to handle errors cleanly (Nathan Mueller)

In prior releases, certain SSL API error reports were not handled correctly. This release fixes those problems.

SSL protocol security and performance improvements (Sean Chittenden)

SSL key renegotiation was happening too frequently, causing poor SSL performance. Also, initial key handling was improved.

Print lock information when a deadlock is detected (Tom)

This allows easier debugging of deadlock situations.

Update /tmp socket modification times regularly to avoid their removal (Tom)

This should help prevent /tmp directory cleaner administration scripts from removing server socket files.

Enable PAM for macOS (Aaron Hillegass)

Make B-tree indexes fully WAL-safe (Tom)

In prior releases, under certain rare cases, a server crash could cause B-tree indexes to become corrupt. This release removes those last few rare cases.

Allow B-tree index compaction and empty page reuse (Tom)

Fix inconsistent index lookups during split of first root page (Tom)

In prior releases, when a single-page index split into two pages, there was a brief period when another database session could miss seeing an index entry. This release fixes that rare failure case.

Improve free space map allocation logic (Tom)

Preserve free space information between server restarts (Tom)

In prior releases, the free space map was not saved when the postmaster was stopped, so newly started servers had no free space information. This release saves the free space map, and reloads it when the server is restarted.

Add start time to pg_stat_activity (Neil)

New code to detect corrupt disk pages; erase with zero_damaged_pages (Tom)

New client/server protocol: faster, no username length limit, allow clean exit from COPY (Tom)

Add transaction status, table ID, column ID to client/server protocol (Tom)

Add binary I/O to client/server protocol (Tom)

Remove autocommit server setting; move to client applications (Tom)

New error message wording, error codes, and three levels of error detail (Tom, Joe, Peter)

Add hashing for GROUP BY aggregates (Tom)

Make nested-loop joins be smarter about multicolumn indexes (Tom)

Allow multikey hash joins (Tom)

Improve constant folding (Tom)

Add ability to inline simple SQL functions (Tom)

Reduce memory usage for queries using complex functions (Tom)

In prior releases, functions returning allocated memory would not free it until the query completed. This release allows the freeing of function-allocated memory when the function call completes, reducing the total memory used by functions.

Improve GEQO optimizer performance (Tom)

This release fixes several inefficiencies in the way the GEQO optimizer manages potential query paths.

Allow IN / NOT IN to be handled via hash tables (Tom)

Improve NOT IN ( subquery ) performance (Tom)

Allow most IN subqueries to be processed as joins (Tom)

Pattern matching operations can use indexes regardless of locale (Peter)

There is no way for non-ASCII locales to use the standard indexes for LIKE comparisons. This release adds a way to create a special index for LIKE .

Allow the postmaster to preload libraries using preload_libraries (Joe)

For shared libraries that require a long time to load, this option is available so the library can be preloaded in the postmaster and inherited by all database sessions.

Improve optimizer cost computations, particularly for subqueries (Tom)

Avoid sort when subquery ORDER BY matches upper query (Tom)

Deduce that WHERE a.x = b.y AND b.y = 42 also means a.x = 42 (Tom)

Allow hash/merge joins on complex joins (Tom)

Allow hash joins for more data types (Tom)

Allow join optimization of explicit inner joins, disable with join_collapse_limit (Tom)

Add parameter from_collapse_limit to control conversion of subqueries to joins (Tom)

Use faster and more powerful regular expression code from Tcl (Henry Spencer, Tom)

Use bit-mapped relation sets in the optimizer (Tom)

Improve connection startup time (Tom)

The new client/server protocol requires fewer network packets to start a database session.

Improve trigger/constraint performance (Stephan)

Improve speed of col IN (const, const, const, ...) (Tom)

Fix hash indexes which were broken in rare cases (Tom)

Improve hash index concurrency and speed (Tom)

Prior releases suffered from poor hash index performance, particularly for high concurrency situations. This release fixes that, and the development group is interested in reports comparing B-tree and hash index performance.

Align shared buffers on 32-byte boundary for copy speed improvement (Manfred Spraul)

Certain CPU's perform faster data copies when addresses are 32-byte aligned.

Data type numeric reimplemented for better performance (Tom)

numeric used to be stored in base 100. The new code uses base 10000, for significantly better performance.

Rename server parameter server_min_messages to log_min_messages (Bruce)

This was done so most parameters that control the server logs begin with log_ .

Rename show_*_stats to log_*_stats (Bruce)

Rename show_source_port to log_source_port (Bruce)

Rename hostname_lookup to log_hostname (Bruce)

Add checkpoint_warning to warn of excessive checkpointing (Bruce)

In prior releases, it was difficult to determine if checkpoint was happening too frequently. This feature adds a warning to the server logs when excessive checkpointing happens.

New read-only server parameters for localization (Tom)

Change debug server log messages to output as DEBUG rather than LOG (Bruce)

Prevent server log variables from being turned off by non-superusers (Bruce)

This is a security feature so non-superusers cannot disable logging that was enabled by the administrator.

log_min_messages / client_min_messages now controls debug_* output (Bruce)

This centralizes client debug information so all debug output can be sent to either the client or server logs.

Add macOS Rendezvous server support (Chris Campbell)

This allows macOS hosts to query the network for available PostgreSQL servers.

Add ability to print only slow statements using log_min_duration_statement (Christopher)

This is an often requested debugging feature that allows administrators to see only slow queries in their server logs.

Allow pg_hba.conf to accept netmasks in CIDR format (Andrew Dunstan)

This allows administrators to merge the host IP address and netmask fields into a single CIDR field in pg_hba.conf .

New read-only parameter is_superuser (Tom)

New parameter log_error_verbosity to control error detail (Tom)

This works with the new error reporting feature to supply additional error information like hints, file names and line numbers.

postgres --describe-config now dumps server config variables (Aizaz Ahmed, Peter)

This option is useful for administration tools that need to know the configuration variable names and their minimums, maximums, defaults, and descriptions.

Add new columns in pg_settings : context , type , source , min_val , max_val (Joe)

Make default shared_buffers 1000 and max_connections 100, if possible (Tom)

Prior versions defaulted to 64 shared buffers so PostgreSQL would start on even very old systems. This release tests the amount of shared memory allowed by the platform and selects more reasonable default values if possible. Of course, users are still encouraged to evaluate their resource load and size shared_buffers accordingly.

New pg_hba.conf record type hostnossl to prevent SSL connections (Jon Jensen)

In prior releases, there was no way to prevent SSL connections if both the client and server supported SSL. This option allows that capability.

Remove parameter geqo_random_seed (Tom)

Add server parameter regex_flavor to control regular expression processing (Tom)

Make pg_ctl better handle nonstandard ports (Greg)

New SQL-standard information schema (Peter)

Add read-only transactions (Peter)

Print key name and value in foreign-key violation messages (Dmitry Tkach)

Allow users to see their own queries in pg_stat_activity (Kevin Brown)

In prior releases, only the superuser could see query strings using pg_stat_activity . Now ordinary users can see their own query strings.

Fix aggregates in subqueries to match SQL standard (Tom)

The SQL standard says that an aggregate function appearing within a nested subquery belongs to the outer query if its argument contains only outer-query variables. Prior PostgreSQL releases did not handle this fine point correctly.

Add option to prevent auto-addition of tables referenced in query (Nigel J. Andrews)

By default, tables mentioned in the query are automatically added to the FROM clause if they are not already there. This is compatible with historic POSTGRES behavior but is contrary to the SQL standard. This option allows selecting standard-compatible behavior.

Allow UPDATE ... SET col = DEFAULT (Rod)

This allows UPDATE to set a column to its declared default value.

Allow expressions to be used in LIMIT / OFFSET (Tom)

In prior releases, LIMIT / OFFSET could only use constants, not expressions.

Implement CREATE TABLE AS EXECUTE (Neil, Peter)

Make CREATE SEQUENCE grammar more conforming to SQL:2003 (Neil)

Add statement-level triggers (Neil)

While this allows a trigger to fire at the end of a statement, it does not allow the trigger to access all rows modified by the statement. This capability is planned for a future release.

Add check constraints for domains (Rod)

This greatly increases the usefulness of domains by allowing them to use check constraints.

Add ALTER DOMAIN (Rod)

This allows manipulation of existing domains.

Fix several zero-column table bugs (Tom)

PostgreSQL supports zero-column tables. This fixes various bugs that occur when using such tables.

Have ALTER TABLE ... ADD PRIMARY KEY add not-null constraint (Rod)

In prior releases, ALTER TABLE ... ADD PRIMARY would add a unique index, but not a not-null constraint. That is fixed in this release.

Add ALTER TABLE ... WITHOUT OIDS (Rod)

This allows control over whether new and updated rows will have an OID column. This is most useful for saving storage space.

Add ALTER SEQUENCE to modify minimum, maximum, increment, cache, cycle values (Rod)

Add ALTER TABLE ... CLUSTER ON (Alvaro Herrera)

This command is used by pg_dump to record the cluster column for each table previously clustered. This information is used by database-wide cluster to cluster all previously clustered tables.

Improve automatic type casting for domains (Rod, Tom)

Allow dollar signs in identifiers, except as first character (Tom)

Disallow dollar signs in operator names, so x=$1 works (Tom)

Allow copying table schema using LIKE subtable , also SQL:2003 feature INCLUDING DEFAULTS (Rod)

Add WITH GRANT OPTION clause to GRANT (Peter)

This enabled GRANT to give other users the ability to grant privileges on an object.

Add ON COMMIT clause to CREATE TABLE for temporary tables (Gavin)

This adds the ability for a table to be dropped or all rows deleted on transaction commit.

Allow cursors outside transactions using WITH HOLD (Neil)

In previous releases, cursors were removed at the end of the transaction that created them. Cursors can now be created with the WITH HOLD option, which allows them to continue to be accessed after the creating transaction has committed.

FETCH 0 and MOVE 0 now do nothing (Bruce)

In previous releases, FETCH 0 fetched all remaining rows, and MOVE 0 moved to the end of the cursor.

Cause FETCH and MOVE to return the number of rows fetched/moved, or zero if at the beginning/end of cursor, per SQL standard (Bruce)

In prior releases, the row count returned by FETCH and MOVE did not accurately reflect the number of rows processed.

Properly handle SCROLL with cursors, or report an error (Neil)

Allowing random access (both forward and backward scrolling) to some kinds of queries cannot be done without some additional work. If SCROLL is specified when the cursor is created, this additional work will be performed. Furthermore, if the cursor has been created with NO SCROLL , no random access is allowed.

Implement SQL-compatible options FIRST , LAST , ABSOLUTE n , RELATIVE n for FETCH and MOVE (Tom)

Allow EXPLAIN on DECLARE CURSOR (Tom)

Allow CLUSTER to use index marked as pre-clustered by default (Alvaro Herrera)

Allow CLUSTER to cluster all tables (Alvaro Herrera)

This allows all previously clustered tables in a database to be reclustered with a single command.

Prevent CLUSTER on partial indexes (Tom)

Allow DOS and Mac line-endings in COPY files (Bruce)

Disallow literal carriage return as a data value, backslash-carriage-return and \r are still allowed (Bruce)

COPY changes (binary, \. ) (Tom)

Recover from COPY failure cleanly (Tom)

Prevent possible memory leaks in COPY (Tom)

Make TRUNCATE transaction-safe (Rod)

TRUNCATE can now be used inside a transaction. If the transaction aborts, the changes made by the TRUNCATE are automatically rolled back.

Allow prepare/bind of utility commands like FETCH and EXPLAIN (Tom)

Add EXPLAIN EXECUTE (Neil)

Improve VACUUM performance on indexes by reducing WAL traffic (Tom)

Functional indexes have been generalized into indexes on expressions (Tom)

In prior releases, functional indexes only supported a simple function applied to one or more column names. This release allows any type of scalar expression.

Have SHOW TRANSACTION ISOLATION match input to SET TRANSACTION ISOLATION (Tom)

Have COMMENT ON DATABASE on nonlocal database generate a warning, rather than an error (Rod)

Database comments are stored in database-local tables so comments on a database have to be stored in each database.

Improve reliability of LISTEN / NOTIFY (Tom)

Allow REINDEX to reliably reindex nonshared system catalog indexes (Tom)

This allows system tables to be reindexed without the requirement of a standalone session, which was necessary in previous releases. The only tables that now require a standalone session for reindexing are the global system tables pg_database , pg_shadow , and pg_group .

New server parameter extra_float_digits to control precision display of floating-point numbers (Pedro Ferreira, Tom)

This controls output precision which was causing regression testing problems.

Allow +1300 as a numeric time-zone specifier, for FJST (Tom)

Remove rarely used functions oidrand , oidsrand , and userfntest functions (Neil)

Add md5() function to main server, already in contrib/pgcrypto (Joe)

An MD5 function was frequently requested. For more complex encryption capabilities, use contrib/pgcrypto .

Increase date range of timestamp (John Cochran)

Change EXTRACT(EPOCH FROM timestamp) so timestamp without time zone is assumed to be in local time, not GMT (Tom)

Trap division by zero in case the operating system doesn't prevent it (Tom)

Change the numeric data type internally to base 10000 (Tom)

New hostmask() function (Greg Wickham)

Fixes for to_char() and to_timestamp() (Karel)

Allow functions that can take any argument data type and return any data type, using anyelement and anyarray (Joe)

This allows the creation of functions that can work with any data type.

Arrays can now be specified as ARRAY[1,2,3] , ARRAY[['a','b'],['c','d']] , or ARRAY[ARRAY[ARRAY[2]]] (Joe)

Allow proper comparisons for arrays, including ORDER BY and DISTINCT support (Joe)

Allow indexes on array columns (Joe)

Allow array concatenation with || (Joe)

Allow WHERE qualification expr op ANY/SOME/ALL ( array_expr ) (Joe)

This allows arrays to behave like a list of values, for purposes like SELECT * FROM tab WHERE col IN (array_val) .

New array functions array_append , array_cat , array_lower , array_prepend , array_to_string , array_upper , string_to_array (Joe)

Allow user defined aggregates to use polymorphic functions (Joe)

Allow assignments to empty arrays (Joe)

Allow 60 in seconds fields of time , timestamp , and interval input values (Tom)

Sixty-second values are needed for leap seconds.

Allow cidr data type to be cast to text (Tom)

Disallow invalid time zone names in SET TIMEZONE

Trim trailing spaces when char is cast to varchar or text (Tom)

Make float( p ) measure the precision p in binary digits, not decimal digits (Tom)

Add IPv6 support to the inet and cidr data types (Michael Graff)

Add family() function to report whether address is IPv4 or IPv6 (Michael Graff)

Have SHOW datestyle generate output similar to that used by SET datestyle (Tom)

Make EXTRACT(TIMEZONE) and SET/SHOW TIME ZONE follow the SQL convention for the sign of time zone offsets, i.e., positive is east from UTC (Tom)

Fix date_trunc('quarter', ...) (Böjthe Zoltán)

Prior releases returned an incorrect value for this function call.

Make initcap() more compatible with Oracle (Mike Nolan)

initcap() now uppercases a letter appearing after any non-alphanumeric character, rather than only after whitespace.

Allow only datestyle field order for date values not in ISO-8601 format (Greg)

Add new datestyle values MDY , DMY , and YMD to set input field order; honor US and European for backward compatibility (Tom)

String literals like 'now' or 'today' will no longer work as a column default. Use functions such as now() , current_timestamp instead. (change required for prepared statements) (Tom)

Treat NaN as larger than any other value in min() / max() (Tom)

NaN was already sorted after ordinary numeric values for most purposes, but min() and max() didn't get this right.

Prevent interval from suppressing :00 seconds display

New functions pg_get_triggerdef(prettyprint) and pg_conversion_is_visible() (Christopher)

Allow time to be specified as 040506 or 0405 (Tom)

Input date order must now be YYYY-MM-DD (with 4-digit year) or match datestyle

Make pg_get_constraintdef support unique, primary-key, and check constraints (Christopher)

Prevent PL/pgSQL crash when RETURN NEXT is used on a zero-row record variable (Tom)

Make PL/Python's spi_execute interface handle null values properly (Andrew Bosma)

Allow PL/pgSQL to declare variables of composite types without %ROWTYPE (Tom)

Fix PL/Python's _quote() function to handle big integers

Make PL/Python an untrusted language, now called plpythonu (Kevin Jacobs, Tom)

The Python language no longer supports a restricted execution environment, so the trusted version of PL/Python was removed. If this situation changes, a version of PL/Python that can be used by non-superusers will be readded.

Allow polymorphic PL/pgSQL functions (Joe, Tom)

Allow polymorphic SQL functions (Joe)

Improved compiled function caching mechanism in PL/pgSQL with full support for polymorphism (Joe)

Add new parameter $0 in PL/pgSQL representing the function's actual return type (Joe)

Allow PL/Tcl and PL/Python to use the same trigger on multiple tables (Tom)

Fixed PL/Tcl's spi_prepare to accept fully qualified type names in the parameter type list (Jan)

Add \pset pager always to always use pager (Greg)

This forces the pager to be used even if the number of rows is less than the screen height. This is valuable for rows that wrap across several screen rows.

Improve tab completion (Rod, Ross Reedstrom, Ian Barwick)

Reorder \? help into groupings (Harald Armin Massa, Bruce)

Add backslash commands for listing schemas, casts, and conversions (Christopher)

\encoding now changes based on the server parameter client_encoding (Tom)

In previous versions, \encoding was not aware of encoding changes made using SET client_encoding .

Save editor buffer into readline history (Ross)

When \e is used to edit a query, the result is saved in the readline history for retrieval using the up arrow.

Improve \d display (Christopher)

Enhance HTML mode to be more standards-conforming (Greg)

New \set AUTOCOMMIT off capability (Tom)

This takes the place of the removed server parameter autocommit .

New \set VERBOSITY to control error detail (Tom)

This controls the new error reporting details.

New prompt escape sequence %x to show transaction status (Tom)

Long options for psql are now available on all platforms

Multiple pg_dump fixes, including tar format and large objects

Allow pg_dump to dump specific schemas (Neil)

Make pg_dump preserve column storage characteristics (Christopher)

This preserves ALTER TABLE ... SET STORAGE information.

Make pg_dump preserve CLUSTER characteristics (Christopher)

Have pg_dumpall use GRANT / REVOKE to dump database-level privileges (Tom)

Allow pg_dumpall to support the options -a , -s , -x of pg_dump (Tom)

Prevent pg_dump from lowercasing identifiers specified on the command line (Tom)

pg_dump options --use-set-session-authorization and --no-reconnect now do nothing, all dumps use SET SESSION AUTHORIZATION

pg_dump no longer reconnects to switch users, but instead always uses SET SESSION AUTHORIZATION . This will reduce password prompting during restores.

Long options for pg_dump are now available on all platforms

PostgreSQL now includes its own long-option processing routines.

Add function PQfreemem for freeing memory on Windows, suggested for NOTIFY (Bruce)

Windows requires that memory allocated in a library be freed by a function in the same library, hence free() doesn't work for freeing memory allocated by libpq. PQfreemem is the proper way to free libpq memory, especially on Windows, and is recommended for other platforms as well.

Document service capability, and add sample file (Bruce)

This allows clients to look up connection information in a central file on the client machine.

Make PQsetdbLogin have the same defaults as PQconnectdb (Tom)

Allow libpq to cleanly fail when result sets are too large (Tom)

Improve performance of function PQunescapeBytea (Ben Lamb)

Allow thread-safe libpq with configure option --enable-thread-safety (Lee Kindness, Philip Yarra)

Allow function pqInternalNotice to accept a format string and arguments instead of just a preformatted message (Tom, Sean Chittenden)

Control SSL negotiation with sslmode values disable , allow , prefer , and require (Jon Jensen)

Allow new error codes and levels of text (Tom)

Allow access to the underlying table and column of a query result (Tom)

This is helpful for query-builder applications that want to know the underlying table and column names associated with a specific result set.

Allow access to the current transaction status (Tom)

Add ability to pass binary data directly to the server (Tom)

Add function PQexecPrepared and PQsendQueryPrepared functions which perform bind/execute of previously prepared statements (Tom)

Allow setNull on updateable result sets

Allow executeBatch on a prepared statement (Barry)

Support SSL connections (Barry)

Handle schema names in result sets (Paul Sorenson)

Add refcursor support (Nic Ferrier)

Prevent possible memory leak or core dump during libpgtcl shutdown (Tom)

Add Informix compatibility to ECPG (Michael)

This allows ECPG to process embedded C programs that were written using certain Informix extensions.

Add type decimal to ECPG that is fixed length, for Informix (Michael)

Allow thread-safe embedded SQL programs with configure option --enable-thread-safety (Lee Kindness, Bruce)

This allows multiple threads to access the database at the same time.

Moved Python client PyGreSQL to http://www.pygresql.org (Marc)

Prevent need for separate platform geometry regression result files (Tom)

Improved PPC locking primitive (Reinhard Max)

New function palloc0 to allocate and clear memory (Bruce)

Fix locking code for s390x CPU (64-bit) (Tom)

Allow OpenBSD to use local ident credentials (William Ahern)

Make query plan trees read-only to executor (Tom)

Add macOS startup scripts (David Wheeler)

Allow libpq to compile with Borland C++ compiler (Lester Godwin, Karl Waclawek)

Use our own version of getopt_long() if needed (Peter)

Convert administration scripts to C (Peter)

Bison >= 1.85 is now required to build the PostgreSQL grammar, if building from CVS

Merge documentation into one book (Peter)

Add Windows compatibility functions (Bruce)

Allow client interfaces to compile under MinGW (Bruce)

New ereport() function for error reporting (Tom)

Support Intel compiler on Linux (Peter)

Improve Linux startup scripts (Slawomir Sudnik, Darko Prenosil)

Add support for AMD Opteron and Itanium (Jeffrey W. Baker, Bruce)

Remove --enable-recode option from configure

This was no longer needed now that we have CREATE CONVERSION .

Generate a compile error if spinlock code is not found (Bruce)

Platforms without spinlock code will now fail to compile, rather than silently using semaphores. This failure can be disabled with a new configure option.

Change dbmirror license to BSD

Improve earthdistance (Bruno Wolff III)

Portability improvements to pgcrypto (Marko Kreen)

Prevent crash in xml (John Gray, Michael Richards)

Update oracle

Update mysql

Update cube (Bruno Wolff III)

Update earthdistance to use cube (Bruno Wolff III)

Update btree_gist (Oleg)

New tsearch2 full-text search module (Oleg, Teodor)

Add hash-based crosstab function to tablefuncs (Joe)

Add serial column to order connectby() siblings in tablefuncs (Nabil Sayegh,Joe)

Add named persistent connections to dblink (Shridhar Daithanka)

New pg_autovacuum allows automatic VACUUM (Matthew T. O'Connor)

Make pgbench honor environment variables PGHOST , PGPORT , PGUSER (Tatsuo)

Improve intarray (Teodor Sigaev)

Improve pgstattuple (Rod)

Fix bug in metaphone() in fuzzystrmatch

Improve adddepend (Rod)

Update spi/timetravel (Böjthe Zoltán)

Fix dbase -s option and improve non-ASCII handling (Thomas Behr, Márcio Smiderle)

Remove array module because features now included by default (Joe)