== PostgreSQL Weekly News - October 10 2010 ==
The deadline for the CfP for MySQL Conf is October 25, 2010. Mail
Selena Deckelman selenamarie <AT> gmail <DOT> com for feedback, help
with submissions, or help generating ideas.
== PostgreSQL Product News ==
Another PostgreSQL Diff Tool 2.2.2, a tool for database diffs, released.
Slony-I 2.0.5, a master-to-multiple-cascading-replica system for
== PostgreSQL Jobs for October ==
== PostgreSQL Local ==
Michael Renner will be doing a talk on Database Replication with PostgreSQL 9.0
on the 12th of October at the Metalab in Vienna, Austria. Link & Info in de_AT:
PgDay.IT 2010 will be in Rome this year December 10th. The Call for
Papers is now open.
Early bird registration for JDCon West 2010 is now open.
Call for Papers for PGDay.EU 2010 held on December 6-8 in Stuttgart,
Germany is open.
== PostgreSQL in the News ==
Planet PostgreSQL: http://planet.postgresql.org/
PostgreSQL Weekly News is brought to you this week by David Fetter
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) Spanish language
== Reviews ==
ITAGAKI Takahiro reviewed the patch to fix some access control leaks
== Applied Patches ==
Tom Lane pushed:
- Undo some poorly-thought-out "proofreading improvements". Per
- Use a separate interpreter for each calling SQL userid in plperl and
pltcl. There are numerous methods by which a Perl or Tcl function
can subvert the behavior of another such function executed later;
for example, by redefining standard functions or operators called by
the target function. If the target function is SECURITY DEFINER, or
is called by such a function, this means that any ordinary SQL user
with Perl or Tcl language usage rights can do essentially anything
with the privileges of the target function's owner. To close this
security hole, create a separate Perl or Tcl interpreter for each
SQL userid under which plperl or pltcl functions are executed within
a session. However, all plperlu or pltclu functions run within a
session still share a single interpreter, since they all execute at
the trust level of a database superuser anyway. Note: this change
results in a functionality loss when libperl has been built without
the "multiplicity" option: it's no longer possible to call plperl
functions under different userids in one session, since such a
libperl can't support multiple interpreters in one process.
However, such a libperl already failed to support concurrent use of
plperl and plperlu, so it's likely that few people use such versions
with Postgres. Security: CVE-2010-3433
- Reduce the memory requirement for large ispell dictionaries. This
patch eliminates per-chunk palloc overhead for most small
allocations needed in the representation of an ispell dictionary.
This saves close to a factor of 2 on the current Czech ispell data.
While it doesn't cover every last small allocation in the ispell
code, we are at the point of diminishing returns, because about 95%
of the allocations are covered already. Pavel Stehule, rather
heavily revised by Tom Lane.
- Clean up temporary-memory management during ispell dictionary
loading. Add explicit initialization and cleanup functions to
spell.c, and keep all working state in the already-existing
ISpellDict struct. This lets us get rid of a static variable along
with some extremely shaky assumptions about usage of child memory
contexts. This commit is just code beautification and has no impact
on functionality or performance, but it opens the way to a
less-grotty implementation of Pavel Stehule's memory-saving hack,
which will follow shortly.
- Teach CLUSTER to use seqscan-and-sort when it's faster than
indexscan. ... or at least, when the planner's cost estimates say
it will be faster. Leonardo Francalanci, reviewed by Itagaki
Takahiro and Tom Lane
- Eliminate some repetitive coding in tuplesort.c. Use a macro
LogicalTapeReadExact() to encapsulate the error check when we want
to read an exact number of bytes from a "tape". Per a suggestion of
- Improve logging in VACUUM FULL VERBOSE and CLUSTER VERBOSE. This
patch resurrects some of the information that could be logged by the
old, now-dead implementation of VACUUM FULL, in particular counts of
live and dead tuples and the time taken for the table rebuild
proper. There's still no logging about the ensuing index rebuilds,
though. Itagaki Takahiro.
- Fix sloppy usage of TRIGGER_FIRED_BEFORE/TRIGGER_FIRED_AFTER.
Various places were testing TRIGGER_FIRED_BEFORE() where what they
really meant was !TRIGGER_FIRED_AFTER(), or vice versa. This needs
to be cleaned up because there are about to be more than two
possible states. We might want to note this in the 9.1 release
notes as something for trigger authors to double-check. For
consistency's sake I also changed some places that assumed that
TRIGGER_FIRED_FOR_ROW and TRIGGER_FIRED_FOR_STATEMENT are
necessarily mutually exclusive; that's not in immediate danger of
breaking, but it's still sloppier than it should be. Extracted from
Dean Rasheed's patch for triggers on views. I'm committing this
separately since it's an identifiable separate issue, and is the
only reason for the patch to touch most of these particular files.
- Support triggers on views. This patch 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. In passing, this patch
corrects the names of some columns in the
information_schema.triggers view. It seems the SQL committee
renamed them somewhere between SQL:99 and SQL:2003. Dean Rasheed,
reviewed by Bernd Helmle; some additional hacking by me.
- Teach psql to do tab completion for names of psql variables.
Completion is supported in the context of \set and when
interpolating a variable value using :foo etc. In passing, fix some
places in tab-complete.c that weren't following project style for
comment formatting. Pavel Stehule, reviewed by Itagaki Takahiro.
- Improve the planner's simplification of NOT constructs. This patch
merges the responsibility for NOT-flattening into
eval_const_expressions' processing. It wasn't done that way
originally because prepqual.c is far older than
eval_const_expressions. But putting this work into
eval_const_expressions saves one pass over the qual trees, and in
fact saves even more than that because we can exploit the knowledge
that the subexpressions have already been recursively simplified.
Doing it this way also lets us do it uniformly over all expressions,
whereas prepqual.c formerly just did it at top level to save cycles.
That should improve the planner's ability to recognize
logically-equivalent constructs. While at it, also add the ability
to fold a NOT into BooleanTest and NullTest constructs (the latter
only for the scalar-datatype case). Per discussion of bug #5702.
Simon Riggs pushed:
- Correct docs for behaviour of ALTER DATABASE .. RENAME during Hot
Standby. Actual behaviour did not match documented behaviour and we
have agreed that it should be the docs that change. Spotted by
Robert Haas pushed:
- Improve WAL reliability documentation, and add more cross-references
to it. In particular, we are now more explicit about the fact that
you may need wal_sync_method=fsync_writethrough for crash-safety on
some platforms, including MaxOS X. There's also now an explicit
caution against assuming that the default setting of wal_sync_method
is either crash-safe or best for performance.
- Warn that views can be safely used to hide columns, but not rows.
Bruce Momjian pushed:
- Single-word clarification in postgresql.conf
Peter Eisentraut pushed:
- Extensive ECPG documentation improvements. Satoshi Nagayasu,
reviewed and revised by Peter Eisentraut. Since this introduces new
refentries that we probably don't want to publish as man pages,
tweak man page stylesheet to omit man pages without manvolnum
element. Peter Eisentraut.
== Rejected Patches (for now) ==
No one was disappointed this week :-)
== Pending Patches ==
Dean Rasheed sent in three revsisions of a patch to implement median
and percentile aggregates.
Marko (johto) Tiikkaja sent in two revisions of a patch to fix
snapshot-taking inconsistencies, in the process deprecating
KaiGai Kohei sent in a patch to fix some of the access control leaks
in views, and Robert Haas sent in two revisions of a patch documenting
Marko (johto) Tiikkaja and Hitoshi Harada traded patches to allow
top-level DML (INSERT, UPDATE, DELETE) in CTEs.
Bernd Helmle sent in another revision of the patch to extend NOT NULL
Alexander Korotkov sent in two more revisions of the patch to improve
the Levenshtein functions to work with multi-byte character sets.
Craig Ringer sent in two revisions of a patch to enable crash dumps on
Windows. Crash dumps are a Windows-specific debugging feature.
Gurjeet Singh sent in two revisions of a patch to allow labeling an
existing unique index, which could, for example, be created
concurrently, as a primary key.
Simon Riggs sent in a WIP patch to implement synchronous replication
with user-controlled durability specified on the master.
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|Subject: Another PostgreSQL Diff Tool 2.2.2 released|