Release 9.1alpha2
Overview
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.
Changes
SQL Features
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
This is not the hoped-for facility of using
INSERT/UPDATE/DELETE inside a WITH, but rather the other way
around.
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
Performance
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.
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
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
Server 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.
Administration and Monitoring
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
Security
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.
Built-In Functions
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.
Data 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.
psql
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
Procedural Languages
PL/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
Additional Supplied Modules
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()
Source Code, Build Options
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>