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. 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. 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. 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 index. Implement a truly serializable isolation level Allow foreign key constraints to be added as initially NOT VALID, and validated later Allow multiple collations to be used within a single database Support 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/FROM Allow 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. 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 scans Teach 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 inequality Try to compact the background writer's fsync queue when it overflows, instead of doing an fsync per block written 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_buffers 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 new recovery.conf parameter, recovery_target_name, allowing recovery to proceed to a named restore point Named restore points can be created using a new server function, pg_create_restore_point. Instrument checkpoint sync calls Use the same lexer for recovery.conf that has been used for postgresql.conf 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 view Add a "conflicts" column to pg_stat_database New system view pg_stat_database_conflicts New 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 bgwriter Allow 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. 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. 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. Add pg_is_xlog_replay_paused, pg_xlog_replay_pause, and pg_xlog_replay_resume functions. Change pg_last_xlog_receive_location not to move backwards. 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 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. Support streaming base backups. A new client, pg_basebackup, can be used to perform a streaming base backup. Add a directory output format to pg_dump 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 languages Allow psql to automatically deduce the client encoding from the locale 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. Allow ecpg to accept dynamic cursor names even in WHERE CURRENT OF clauses 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. Allow generic record arguments to PL/Perl functions Convert PostgreSQL arrays passed to PL/perl functions to Perl arrays Fix an error when a set-returning function fails halfway through Skip dropped attributes when converting Python objects to tuples Improve messages for errors in compiling anonymous PL/Python blocks Improve 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. Do not prefix error messages with the string "PL/Python: " It is redundant, given the error context. 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 calls Invalidate PL/python functions with composite type arguments when the type changes Add quoting functions plpy.quote_ident, plpy.quote_literal, and plpy.quote_nullable Support table functions Add a plpy.subtransaction() context manager Provide a separate exception class for each error code the backend defines, and make it possible to get the SQLSTATE from the exception object Assorted 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). 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_fsync In contrib/pageinspect, fix the heap_page_item to return infomasks as 32 bit values In contrib/btree_gist, support KNN GiST searches In contrib/pg_trgm, support LIKE, ILIKE, and KNN GiST searches Several 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. 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 directories Add a make check-world target PGXS support for contrib/hstore