== PostgreSQL Weekly News - December 20 2009 ==
Commitfest 2009-11 is now closed. Kudos to Greg Smith for managing
this one, and to all who reviewed, patched, and otherwise
The Call for Papers for East is open until January 30, 2010. Details at:
PgUS 2009 Board Elections are happening now.
Seeking booth staffers for Open Day Linux Conf AU in Wellington, NZ
January 23, 2009, 11-2pm, Contact selena -at- postgresql.org to
== PostgreSQL Product News ==
Alerce 1.0.0, a synchronous replication system for Python, released.
Gluster Storage Platform 3.0 released.
pgpool-II 2.3.1, a connection pooler and more, released.
pg_rman 1.1.1, an online backup and restore tool for PostgreSQL, released.
Devrim GUNDUZ has created a new LiveCD based on Fedora 12 and
== PostgreSQL 8.5 Feature of the Week ==
WHEN clauses on Triggers. In 8.5Alpha3, you will be able to create
triggers with a WHEN clause so that they will only execute if specific
values or conditions occur. Thanks Itagaki Takahiro and the NTT team.
== PostgreSQL Tip of the Week ==
Tip Of The Week: PostgreSQL comes with 3 ways to handle trees: WITH
RECURSIVE queries, the ltree contrib module, and the connect_by()
function in the tablefunc supplied module.
== PostgreSQL Jobs for December ==
== PostgreSQL Local ==
The New York Capital District PUG's first meeting will be January 7,
Stefan Keller will be teach a course called, "Introducion to
PostGIS/PostgreSQL" at the University of Applied Sciences Rapperswil
(HSR) on January 14, 2010 in Zurich, Switzerland.
PGDay-Cuba 2010 will be held 4-6 February 2010, in La Havana at the
University of Science Informatic. Attendees from Cuba, the Dominican
Republic and Venezuela are invited.
FOSDEM 2010 will be in Brussels, Belgium on February 6-7, 2010.
Chemnitzer Linuxtage will be in Chemnitz, Germany on March 13-14, 2010.
PgCon 2010 will be held May 20-21 2010 in Ottawa with tutorials before
on the 18th and 19th. The RfP is open!
== PostgreSQL in the News ==
Planet PostgreSQL: http://planet.postgresql.org/
PostgreSQL Weekly News is brought to you this week by David Fetter
and Josh Berkus.
Submit news and announcements by Sunday at 3:00pm Pacific time.
Please send English language ones to david(at)fetter(dot)org, German language
to pwn(at)pgug(dot)de, Italian language to pwn(at)itpug(dot)org(dot)
== Reviews ==
Greg Smith reviewed ITAGAKI Takahiro's latest patch to enable pgbench
to launch shell commands.
Marko Kreen reviewed Kurt Harriman's patch to remove the gcc
dependency in the definition of inline functions.
Hiroyuki Yamada found a bug in hot standby where it can freeze when
the startup process calls LockBufferForCleanup(), complete with repro.
== Applied Patches ==
ITAGAKI Takahiro committed:
- In pgsql/src/bin/pg_ctl/pg_ctl.c, fix pg_ctl initdb without options.
Passing NULL string to snprintf is avoided.
- Add \shell and \setshell meta commands to pgbench. \shell command
runs an external shell command. \setshell also does the same and
sets the result to a variable. Original patch by Michael Paquier
with some editorialization by ITAGAKI Takahiro, and reviewed by Greg
- In pgsql/doc/src/sgml/ref/alter_large_object.sgml, add missing Id
keyword to alter_large_object.sgml.
- Add a whitespace to fix the query to dump large objects.
PL/pgSQL-by-default patch broke the code for 8.3 <= server_version <
Robert Haas committed:
- Add an EXPLAIN (BUFFERS) option to show buffer-usage statistics.
This patch also removes buffer-usage statistics from the
track_counts output, since this (or the global server statistics) is
deemed to be a better interface to this information. Itagaki
Takahiro, reviewed by Euler Taveira de Oliveira.
- Several fixes for EXPLAIN (FORMAT YAML), plus one for EXPLAIN
(FORMAT JSON). ExplainSeparatePlans() was busted for both JSON and
YAML output - the present code is a holdover from the original
version of my machine-readable explain patch, which didn't have the
grouping_stack machinery. Also, fix an odd distribution of labor
between ExplainBeginGroup() and ExplainYAMLLineStarting() when
marking lists with "- ", with each providing one character. This
broke the output format for multi-query statements. Also, fix
ExplainDummyGroup() for the YAML output format. Along the way, make
the YAML format use escape_yaml() in situations where the JSON
format uses escape_json(). Right now, it doesn't matter because all
the values are known not to need escaping, but it seems safer this
way. Finally, I added some comments to better explain what the YAML
output format is doing. Greg Sabino Mullane reported the issues
with multi-query statements. Analysis and remaining cleanups by
- Improve documentation for pg_largeobject changes. Rewrite the
documentation in more idiomatic English, and in the process make it
somewhat more succinct. Move the discussion of specific large
object privileges out of the "server-side functions" section, where
it certainly doesn't belong, and into "implementation features".
That might not be exactly right either, but it doesn't seem worth
creating a new section for this amount of information. Fix a few
spelling and layout problems, too.
- Fix a few typos in the latest 8.5alpha3 release notes.
- In pgsql/doc/src/sgml/backup.sgml, fix two small typos in Hot
Standby docs. John Naylor.
- More cleanups for the recent large object permissions patch.
Rewrite or adjust various comments for clarity. Remove one bogus
comment that doesn't reflect what the code actually does. Improve
the description of the lo_compat_privileges option.
Tom Lane committed:
- In pgsql/doc/src/sgml/pgbench.sgml, fix broken markup.
- Support ORDER BY within aggregate function calls, at long last
providing a non-kluge method for controlling the order in which
values are fed to an aggregate function. At the same time eliminate
the old implementation restriction that DISTINCT was only supported
for single-argument aggregates. Possibly release-notable behavioral
change: formerly, agg(DISTINCT x) dropped null values of x
unconditionally. Now, it does so only if the agg transition
function is strict; otherwise nulls are treated as DISTINCT normally
would, ie, you get one copy. Andrew Gierth, reviewed by Hitoshi
- Add a hook to let loadable modules get control at ProcessUtility
execution, and use it to extend contrib/pg_stat_statements to track
utility commands. Itagaki Takahiro, reviewed by Euler Taveira de
- In pgsql/src/backend/tsearch/wparser_def.c, avoid unnecessary
copying of source string when generating a cloned TParser. For long
source strings the copying results in O(N^2) behavior, and the
multiplier can be significant if wide-char conversion is involved.
Andres Freund, reviewed by Kevin Grittner.
- Avoid a premature coercion failure in transformSetOperationTree()
when presented with an UNKNOWN-type Var, which can happen in cases
where an unknown literal appeared in a subquery. While many such
cases will fail later on anyway in the planner, there are some cases
where the planner is able to flatten the query and replace the Var
by the constant before it has to coerce the union column to the
final type. I had added this check in 8.4 to provide earlier/better
error detection, but it causes a regression for some cases that
worked OK before. Fix by not making the check if the input node is
UNKNOWN type and not a Const or Param. If it isn't going to work,
it will fail anyway at plan time, with the only real loss being
inability to provide an error cursor. Per gripe from Britt Piehler.
In passing, rename a couple of variables to remove confusion from an
inner scope masking the same variable names in an outer scope.
- Force the TZ environment variable to be set during initdb. This is
to short-circuit the rather expensive identify_system_timezone()
procedure, which we have no real need for during initdb since
nothing done here depends on the timezone setting. Since we launch
quite a few standalone backends during the initdb sequence, this
adds up to a significant savings, and seems worth doing to save
developer time even though it will hardly matter to end users. Per
my report today on pgsql-hackers.
- Fix link that doesn't work in standalone INSTALL document.
- Bump catversion to reflect the fact that Hiroshi Saito patch changed
pg_proc contents, and PG_CONTROL_VERSION to reflect the fact that it
changed pg_control contents. (I see we did at least remember to
change XLOG_PAGE_MAGIC for the WAL contents changes.)
- Adjust some more places in the documentation to match the fact that
plpgsql is now installed by default.
- Join in the fun of editorializing on the alpha release notes.
- plpgsql patch broke the MSVC build, too.
- Sigh, I managed to break the no-links-in-plain-text-docs rule too...
- There is no good reason for the CREATE TABLE LIKE INCLUDING COMMENTS
code to have hard-wired knowledge of the rules for naming index
columns. It can just look at the actual names in the source index,
instead. Do some minor formatting cleanup too.
Peter Eisentraut committed:
- Python 3 support in PL/Python. Behaves more or less unchanged
compared to Python 2, but the new language variant is called
plpython3u. Documentation describing the naming scheme is included.
- If there is no sigdelset(), define it as a macro. This removes some
duplicate code that recreated the identical workaround when the
newer signal API is missing.
- Don't unblock SIGQUIT in the SIGQUIT handler. This was possibly
linked to a deadlock-like situation in glibc syslog code invoked by
the ereport call in quickdie(). In any case, a signal handler
should not unblock its own signal unless there is a specific reason
- 8.5alpha3 release notes up to Fri Dec 18 21:37:38 2009 +0000
- Translation updates
- Add hot standby to release notes
- Add documentation why reassigning PL/Python function parameters in
the function body can have undesirable outcomes. (bug #5232)
Michael Meskes committed:
- Fixed auto-prepare to not try preparing statements that are not
preparable. Bug found and solved by Zoltan Boszormenyi some small
adjustments by Michael Meskes.
- Reverting accidently commited changes.
Magnus Hagander committed:
- In pgsql/doc/src/sgml/hstore.sgml, remove spurious '22' that clearly
shouldn't be there. David E. Wheeler.
Bruce Momjian committed:
- Install server-side language PL/pgSQL by default.
- Add comments about places where system oids have to be preserved for
- Convert tabs to spaces in SGML.
Alvaro Herrera committed:
- In pgsql/doc/src/sgml/start.sgml, update tutorial on the fact that
backslash commands are no longer listed in psql's startup banner.
- Update ecpg regression tests to plpgsql installed by default.
Simon Riggs committed:
- Allow read only connections during recovery, known as Hot Standby.
Enabled by recovery_connections = on (default) and forcing archive
recovery using a recovery.conf. Recovery processing now emulates the
original transactions as they are replayed, providing full locking
and MVCC behaviour for read only queries. Recovery must enter
consistent state before connections are allowed, so there is a
delay, typically short, before connections succeed. Replay of
recovering transactions can conflict and in some cases deadlock with
queries during recovery; these result in query cancellation after
max_standby_delay seconds have expired. Infrastructure changes have
minor effects on normal running, though introduce four new types of
WAL record. New test mode "make standbycheck" allows regression
tests of static command behaviour on a standby server while in
recovery. Typical and extreme dynamic behaviours have been checked
via code inspection and manual testing. Few port specific behaviours
have been utilised, though primary testing has been on Linux only so
far. This commit is the basic patch. Additional changes will follow
in this release to enhance some aspects of behaviour, notably
improved handling of conflicts, deadlock detection and query
cancellation. Changes to VACUUM FULL are also required. Simon
Riggs, with significant and lengthy review by Heikki Linnakangas,
including streamlined redesign of snapshot creation and two-phase
commit. Important contributions from Florian Pflug, Mark Kirkwood,
Merlin Moncure, Greg Stark, Gianni Ciolli, Gabriele Bartolini, Hannu
Krosing, Robert Haas, Tatsuo Ishii, Hiroyuki Yamada plus support and
feedback from many other community members.
== Rejected Patches (for now) ==
No one was disappointed this week :-)
== Pending Patches ==
Zoltan Boszormenyi sent in four more revisions of the ECPG patch for
SQLDA, this time as an ECPG native feature rather than
Michael Paquier sent in another revision of the patch to enable
pgbench to launch shell commands.
Robert Haas sent in a patch to fix explain output for multi-plan
ITAGAKI Takahiro sent in another revision of the patch which reworks
Kurt Harriman sent in another revision of the patch to remove the gcc
dependency in definitions of inline functions.
Zoltan Boszormenyi sent in another revision of the ECPG patch to
support DESCRIBE [OUTPUT].
Zoltan Boszormenyi sent in four more revisions of the ECPG patch to
support out-of-scope cursor support in Informix mode.
Peter Eisentraut sent in three patches to fix a bug where recovery
gets stuck when children are not processing SIGQUIT from a previous
crash. The first defines sigdelset as a macro if it's not already there.
The second moves the operation of unblocking SIGQUIT out of the
SIGQUIT handler. The third times out the ereport call in quickdie
after 60 seconds.
KaiGai Kohei sent in a patch to clean up existing privilege checks and
KaiGai Kohei sent in a patch to make EnableDisableRule() check the
ownership of the relation which owns the rule.
KaiGai Kohei sent in a patch which removes obscure permission checks
David Wheeler sent in a patch to add hstore_to_json().
KaiGai Kohei sent in a patch to fix an issue with ALTER TABLE...ALTER
COLUMN...RENAME TO which happened in situations where the table in
question is the child, via table inheritance, of multiple tables.
KaiGai Kohei sent in a patch to remove redundant ownership checks.
Robert Haas sent in a patch to clean up comments with non-standard
KaiGai Kohei sent in a patch to help pg_dump work with the new large
object (lo) ACLs.
James Pye sent in a patch to add some new SPI functions to
Martin Pihlak sent in a patch to fix a bug in foreign data wrappers.
Florian Pflug sent in a WIP patch that allows easier introspection of
composite types from SQL and PL/pgsql.
John Naylor sent in another patch to revamp the BKI infrastructure.
Tom Lane sent in a WIP patch to choose better default names for
indexes, per discussion.
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