== PostgreSQL Weekly News - March 17 2013 ==
Save The Date!
Postgres Open 2013 will be in Chicago, IL, USA, September 16-18.
Early Bird registration:
== PostgreSQL Product News ==
E-Maj 1.0.2 released. E-Maj is a PostgreSQL extension that offers the
capability to log updates performed on one or several sets of tables,
and cancel these updates if needed, resettting the table set to a
predefined stable state.
== PostgreSQL Jobs for March ==
== PostgreSQL Local ==
PGDay NYC 2013 will be held on March 22, 2013 in New York City.
PG Day France is the major French-speaking PostgreSQL community event.
The deadline for sending proposals is Saturday, March 24, 2013 at
PostgreSQL Session will be held on March 28th, 2013 in Paris,
France. The Call for Papers is open.
PGCon 2013 will be held May 23-24 2013, in Ottawa at the University of
The 6th annual "Prague PostgreSQL Developers Day" conference,
organized by CSPUG (Czech and Slovak PostgreSQL Users Group), will be
held on May 30, 2013 at Faculty of Mathematics and Physics, Charles
University (Malostranske namesti 25, Prague). The CfP is open until
April 14, 2013 . More information in Czech is at
The Call for Papers for PostgreSQL Brazil, to be held August 15-17,
2013 in Porto Velho, RO, Brazil, is open. Proposals are due by March
== PostgreSQL in the News ==
Planet PostgreSQL: http://planet.postgresql.org/
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== Applied Patches ==
Tom Lane pushed:
- Fix thinko in matview patch. "break" instead of "continue"
suppressed view expansion for views appearing later in the range
table. Per report from Erikjan Rijkers. While at it, improve the
associated comment a bit.
- Avoid generating bad remote SQL for INSERT ... DEFAULT VALUES.
"INSERT INTO foo() VALUES ()" is invalid syntax, so don't do that.
- Fix postgres_fdw's issues with inconsistent interpretation of data
values. For datatypes whose output formatting depends on one or
more GUC settings, we have to worry about whether the other server
will interpret the value the same way it was meant. pg_dump has
been aware of this hazard for a long time, but postgres_fdw needs to
deal with it too. To fix data retrieval from the remote server, set
the necessary remote GUC settings at connection startup. (We were
already assuming that settings made then would persist throughout
the remote session.) To fix data transmission to the remote server,
temporarily force the relevant GUCs to the right values when we're
about to convert any data values to text for transmission. This is
all pretty grotty, and not very cheap either. It's tempting to
think of defining one uber-GUC that would override any settings that
might render printed data values unportable. But of course, older
remote servers wouldn't know any such thing and would still need
this logic. While at it, revert commit
f7951eef89be78c50ea2241f593d76dfefe176c9, since this provides a real
fix. (The timestamptz given in the error message returned from the
"remote" server will now reliably be shown in UTC.)
- Avoid row-processing-order dependency in postgres_fdw regression
test. A test intended to provoke an error on the remote side was
coded in such a way that multiple rows should be updated, so the
output would vary depending on which one was processed first. Per
- Allow default expressions to be attached to columns of foreign
tables. There's still some discussion about exactly how
postgres_fdw ought to handle this case, but there seems no debate
that we want to allow defaults to be used for inserts into foreign
tables. So remove the core-code restrictions that prevented it.
While at it, get rid of the special grammar productions for CREATE
FOREIGN TABLE, and instead add explicit FEATURE_NOT_SUPPORTED error
checks for the disallowed cases. This makes the grammar a shade
smaller, and more importantly results in much more intelligible
error messages for unsupported cases. It's also one less thing to
fix if we ever start supporting constraints on foreign tables.
- Fix contrib/postgres_fdw's handling of column defaults. Adopt the
position that only locally-defined defaults matter. Any defaults
defined in the remote database do not affect insertions performed
through a foreign table (unless they are for columns not known to
the foreign table). While it'd arguably be more useful to permit
remote defaults to be used, making that work in a consistent fashion
requires far more work than seems possible for 9.3.
- Fix documentation oversight. Mention that PlanForeignModify's
result must be copiable by copyObject.
- Introduce less-bogus handling of collations in contrib/postgres_fdw.
Treat expressions as being remotely executable only if all
collations used in them are determined by Vars of the foreign table.
This means that, if the foreign server gets different answers than
we do, it's the user's fault for not having marked the foreign table
columns with collations equivalent to the remote table's. This rule
allows most simple expressions such as "var < 'constant'" to be sent
to the remote side, because the constant isn't determining the
collation (the Var's collation would win). There's still room for
improvement, but it's hard to see how to do it without a lot more
knowledge and/or assumptions about what the remote side will do.
- Avoid inserting Result nodes that only compute identity projections.
The planner sometimes inserts Result nodes to perform column
projections (ie, arbitrary scalar calculations) above plan nodes
that lack projection logic of their own. However, we did that even
if the lower plan node was in fact producing the required column set
already; which is a pretty common case given the popularity of
"SELECT * FROM ...". Measurements show that the useless plan node
adds non-negligible overhead, especially when there are many columns
in the result. So add a check to avoid inserting a Result node
unless there's something useful for it to do. There are a couple of
remaining places where unnecessary Result nodes could get inserted,
but they are (a) much less performance-critical, and (b) coded in
such a way that it's hard to avoid inserting a Result, because the
desired tlist is changed on-the-fly in subsequent logic. We'll
leave those alone for now. Kyotaro Horiguchi; reviewed and further
hacked on by Amit Kapila and Tom Lane.
- Minor fixes for hstore_to_json_loose(). Fix unportable use of
isdigit(), get rid of useless calculations.
- Avoid inserting no-op Limit plan nodes. This was discussed in
connection with the patch to avoid inserting no-op Result nodes, but
not actually implemented therein.
- Extend format() to handle field width and left/right alignment.
This change adds some more standard sprintf() functionality to
format(). Pavel Stehule, reviewed by Dean Rasheed and Kyotaro
- Improve error reporting in code that checks for buffer refcount
leaks. Formerly we just Assert'ed that each refcount was zero,
which was quick and easy but failed to provide a good overview of
what was wrong. Change the code so that we'll call
PrintBufferLeakWarning() for each buffer with a nonzero refcount,
and then Assert at the end of the loop. This costs nothing in
runtime and might ease diagnosis of some bugs. Greg Smith, reviewed
by Satoshi Nagayasu, further tweaked by me
- Improve the documentation about commit_delay. Clarify the docs
explaining what commit_delay does, and add a recommendation about a
useful value for it, namely half of the single-page fsync time
reported by pg_test_fsync. This is informed by testing of the
new-in-9.3 implementation of commit_delay; in prior versions it was
far harder to arrive at a useful setting. In passing, do some
wordsmithing and markup-fixing in the same general area. Also,
change pg_test_fsync's default time-per-test from 2 seconds to 5.
The old value was about the minimum at which the results could be
taken seriously at all, and so seems a tad optimistic as a default.
Peter Geoghegan, reviewed by Noah Misch; some additional editing by
- Add lock_timeout configuration parameter. This GUC allows limiting
the time spent waiting to acquire any one heavyweight lock. In
support of this, improve the recently-added timeout infrastructure
to permit efficiently enabling or disabling multiple timeouts at
once. That reduces the performance hit from turning on
lock_timeout, though it's still not zero. Zoltán Böszörményi,
reviewed by Tom Lane, Stephen Frost, and Hari Babu
- Move pqsignal() to libpgport. We had two copies of this function in
the backend and libpq, which was already pretty bogus, but it turns
out that we need it in some other programs that don't use libpq
(such as pg_test_fsync). So put it where it probably should have
been all along. The signal-mask-initialization support in
src/backend/libpq/pqsignal.c stays where it is, though, since we
only need that in the backend.
- Fix inclusions in pg_receivexlog.c. Apparently this was depending
on pqsignal.h for . Not sure why I didn't see the failure
on my other machine.
- Fix inclusions in pgbench.c. Apparently this was depending on
pqsignal.h for . Not sure why I didn't see the failure on
my other machine.
- Re-include pqsignal() in libpq. We need this in
non-ENABLE_THREAD_SAFETY builds, and also to satisfy the exports.txt
entry; while it might be a good idea to remove the latter, I'm
hesitant to do so except in the context of an intentional ABI break.
At least we don't have a separately maintained source file for it
- initdb needs pqsignal() even on Windows. I had thought we weren't
using this version of pqsignal() at all on Windows, but that's wrong
--- initdb is using it (and coping with the POSIX-ish semantics of
bare signal() :-(). So allow the file to be built in WIN32+FRONTEND
case, and add it to the MSVC build logic.
- Use pqsignal() in contrib programs rather than calling signal(2)
directly. The semantics of signal(2) are more variable than one
could wish; in particular, on strict-POSIX platforms the signal
handler will be reset to SIG_DFL when the signal is delivered. This
demonstrably breaks pg_test_fsync's use of SIGALRM. The other
changes I made are not absolutely necessary today, because the
called handlers all exit the program anyway. But it seems like a
good general practice to use pqsignal() exclusively in Postgres
code, now that we have it available everywhere.
- Improve signal-handler lockout mechanism in timeout.c. Rather than
doing a fairly-expensive setitimer() call to prevent interrupts from
happening, let's just invent a simple boolean flag that the signal
handler is required to check. This is not only faster but
considerably more robust than before, since the previous code
effectively assumed that only ITIMER_REAL events would ever fire the
SIGALRM handler, which is obviously something that can be broken
easily by third-party code. Zoltán Böszörményi and Tom Lane
- Increase timeout delays in new timeouts isolation test. Buildfarm
member friarbird doesn't like this test as-committed, evidently
because it's so slow that the test framework doesn't reliably notice
that the backend is waiting before the timeout goes off. (This is
not totally surprising, since friarbird builds with
-DCLOBBER_CACHE_ALWAYS.) Increase the timeout delay from 1 second to
2 in hopes of resolving that problem.
Alvaro Herrera pushed:
- Fix orthotypographical mistake. Apparently I lost some of the edits
I had done on this page for commit 0ac5ad5134. Per note from Etsuro
Fujita, although I didn't use his patch. Make some of the wording
in the affected section a bit more complete, too.
Kevin Grittner pushed:
- Fix bug in dumping prior releases due to MV REFRESH dependency
checking. Reports and suggested patches from Fujii Masao and Andrew
Dunstan. Andrew Dunstan
- Add regression test for MV join to view. This would have caught a
bug in the initial patch, and seems like a good thing to test going
forward. Per bug report by Erik Rijkers and fix by Tom Lane
- Revert unnecessary change in MV call to checkRuleResultList(). Due
to a misreading of the function's comment block, there was an
unneeded change to a call in rewriteDefine.c. There is, in fact no
reason to pass false for a MV; it should be true just like a view.
Fixes issue pointed out by Tom Lane
Peter Eisentraut pushed:
- Add regression tests for XML mapping of domains. Pavel Stěhule
- pg_controldata: Undo message spelling change
- pg_resetxlog: Capitalize placeholder in --help output
Heikki Linnakangas pushed:
- Add cost estimation of range @> and <@ operators. The estimates are
based on the existing lower bound histogram, and a new histogram of
range lengths. Bump catversion, because the range length histogram
now needs to be present in statistic slot kind 6, or you get an
error on @> and <@ queries. (A re-ANALYZE would be enough to fix
that, though) Alexander Korotkov, with some refactoring by me.
- Change the way UESCAPE is lexed, to reduce the size of the flex
tables. The error rule used to avoid backtracking with the U&'...'
UESCAPE 'x' syntax bloated the flex tables, so refactor that. This
patch makes the error rule shorter, by introducing a new exclusive
flex state that's entered after parsing U&'...'. This shrinks the
postgres binary by about 220kB.
- Also update psqlscan.l with the UESCAPE error rule changes. Even
though this patch had no user-visible difference, better keep the
code in psqlscan.l sync with the backend lexer. And of course it's
nice to shrink the psql binary, too. Ecpg's version of the lexer
doesn't have the error rule, it doesn't try to avoid backing up, so
it doesn't need to be modified. As reminded by Tom Lane
Robert Haas pushed:
- Extend object-access hook machinery to support post-alter events.
This also slightly widens the scope of what we support in terms of
post-create events. KaiGai Kohei, with a few changes, mostly to the
comments, by me
== Rejected Patches (for now) ==
No one was disappointed this week :-)
== Pending Patches ==
robins sent in three revisions of a patch to test sequences in the
Jeff Davis and Ants Aasma traded patches to add page checksums.
Michael Paquier sent in another revision of a patch to overhaul
Amit Kapila sent in another revision of a patch to micro-optimize
Michael Paquier sent in two more revisions of a patch to add REINDEX
Joe Conway sent in a patch to ensure that an extension's tables' data
is only dumped in the extension's absence if named explicitly in
Michael Paquier sent in a patch to fix an assertion failure during
promotion of a replica to master.
Zoltan Boszormenyi and Amit Kapila traded patches to allow
postgresql.conf values to be changed via SQL.
Pavel Stehule sent in a patch to detect orphaned locks.
Alvaro Herrera sent in another revision of a patch to add sql_drop
Alvaro Herrera sent in another revision of a patch to add in-catalog
Extension Scripts and Control parameters.
Kevin Grittner sent in two revisions of a patch to fix an assertion
failure in materialized views.
Hadi Moshayedi sent in a patch to improve the performance of NUMERIC's
Marti Raudsepp sent in a patch to fix the fact that version() mixes
host and target architectures in cross-compiles.
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