PostgreSQL Weekly News – February 05 2012

== PostgreSQL Weekly News – February 05 2012 ==

PGDay France will be in Lyon on June 7, 2012.

PGDay NYC will be held April 2, 2012 at Lighthouse International in
New York City.

== PostgreSQL Product News ==

MyJSQLView Version 3.31 Released.

Slony-I 2.1.1 & 1.2.23 released.

== PostgreSQL Jobs for February ==

== PostgreSQL Local ==

The fifth annual “Prague PostgreSQL Developers Day” conference,
organized by CSPUG (Czech and Slovak PostgreSQL Users Group), will be
held on February 9, 2012 in Prague.

PGDay NYC will be held April 2, 2012 at Lighthouse International in
New York City.

PGCon 2012 will be held 17-18 May 2012, in Ottawa at the University of
Ottawa. It will be preceded by two days of tutorials on 15-16 May 2012.

PGDay France will be in Lyon on June 7, 2012.

== PostgreSQL in the News ==

Planet PostgreSQL:

PostgreSQL Weekly News is brought to you this week by David Fetter

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== Reviews ==

== Applied Patches ==

Heikki Linnakangas pushed:

– Accept a non-existent value in “ALTER USER/DATABASE SET …”
command. When default_text_search_config, default_tablespace, or
temp_tablespaces setting is set per-user or per-database, with an
“ALTER USER/DATABASE SET …” statement, don’t throw an error if the
text search configuration or tablespace does not exist. In case of
text search configuration, even if it doesn’t exist in the current
database, it might exist in another database, where the setting is
intended to have its effect. This behavior is now the same as
search_path’s. Tablespaces are cluster-wide, so the same argument
doesn’t hold for tablespaces, but there’s a problem with pg_dumpall:
it dumps “ALTER USER SET …” statements before the “CREATE
TABLESPACE” statements. Arguably that’s pg_dumpall’s fault – it
should dump the statements in such an order that the tablespace is
created first and then the “ALTER USER SET default_tablespace …”
statements after that – but it seems better to be consistent with
search_path and default_text_search_config anyway. Besides, you
could still create a dump that throws an error, by creating the
tablespace, running “ALTER USER SET default_tablespace”, then
dropping the tablespace and running pg_dumpall on that. Backpatch
to all supported versions.

– Make group commit more effective. When a backend needs to flush the
WAL, and someone else is already flushing the WAL, wait until it
releases the WALInsertLock and check if we still need to do the
flush or if the other backend already did the work for us, before
acquiring WALInsertLock. This helps group commit, because when the
WAL flush finishes, all the backends that were waiting for it can be
woken up in one go, and the can all concurrently observe that
they’re done, rather than waking them up one by one in a cascading
fashion. This is based on a new LWLock function,
LWLockWaitUntilFree(), which has peculiar semantics. If the lock is
immediately free, it grabs the lock and returns true. If it’s not
free, it waits until it is released, but then returns false without
grabbing the lock. This is used in XLogFlush(), so that when the
lock is acquired, the backend flushes the WAL, but if it’s not, the
backend first checks the current flush location before retrying.
Original patch and benchmarking by Peter Geoghegan and Simon Riggs,
although this patch as committed ended up being very different from

– Fix bug in the new wait-until-lwlock-is-free mechanism. If there
was a wait-until-free process in the head of the wait queue,
followed by an exclusive locker, the exclusive locker was not be
woken up as it should.

– Print function signature, not just name, in PL/pgSQL error messages.
This makes it unambiguous which function the message is coming from,
if you have overloaded functions. Pavel Stehule, reviewed by
Abhijit Menon-Sen.

Simon Riggs pushed:

– Various minor comments changes from bgwriter to checkpointer.

– Minor bug fix and cleanup from self-review of sync rep queues patch.

Robert Haas pushed:

– Remove prototype for nonexistent function.

– Built-in JSON data type. Like the XML data type, we simply store
JSON data as text, after checking that it is valid. More complex
operations such as canonicalization and comparison may come later,
but this is enough for not. There are a few open issues here, such
as whether we should attempt to detect UTF-8 surrogate pairs
represented as \uXXXX\uYYYY, but this gets the basic framework in

– Catversion bump for JSON patch. Sigh.

– Adjust expected regression test outputs for PL/python. This got
broken by commit 4c6cedd1b014abf2046886a9a92e10e18f0d658e, which
caused PL/pgsql error messages to print the function signature, not
just the name. Per buildfarm.

– Avoid re-checking for visibility map extension too frequently. When
testing bits (but not when setting or clearing them), we now won’t
check whether the map has been extended. This significantly
improves performance in the case where the visibility map doesn’t
exist yet, by avoiding an extra system call per tuple. To make sure
backends notice eventually, send an smgr inval on VM extension.
Dean Rasheed, with minor modifications by me.

– Allow spgist’s text_ops to handle pattern-matching operators. This
was presumably intended to work this way all along, but a few key
bits of indxpath.c didn’t get the memo. Robert Haas and Tom Lane

Peter Eisentraut pushed:

– Add sequence USAGE privileges to information schema. The sequence
USAGE privilege is sufficiently similar to the SQL standard that it
seems reasonable to show in the information schema. Also add some
compatibility notes about it on the GRANT reference page.

– Use abort() instead of exit() to abort library functions. In some
hopeless situations, certain library functions in libpq and
libpgport quit the program. Use abort() for that instead of exit(),
so we don’t interfere with the normal exit codes the program might
use, we clearly signal the abnormal termination, and the caller has
a chance of catching the termination. This was originally pointed
out by Debian’s Lintian program.

– PL/Python: Add result metadata functions. Add result object
functions .colnames, .coltypes, .coltypmods to obtain information
about the result column names and types, which was previously not
possible in the PL/Python SPI interface. reviewed by Abhijit

– pg_dump: Add GCC noreturn attribute to appropriate functions. This
is a small help to the compiler and static analyzers.

– psql: Reduce the amount of const lies a bit.

– psql: Case preserving completion of SQL key words. Instead of
always completing SQL key words in upper case, look at the word
being completed and match the case. reviewed by Fujii Masao

– initdb: Add options –auth-local and –auth-host. Reviewed by
Robert Haas and Pavel Stehule

– ecpg: Improve test building Further improve on commit
c75e1436467f32a06b5ab9d594d2a390e7f4594d. Instead of building both
.o files and binaries in the same make rule, just rely on the normal
.c -> .o rule. This will ensure that dependency tracking is used
when enabled. To do this, disable the implicit direct .c -> binary
rule globally, which will also prevent the original problem (*.dSYM
junk) from reappearing elsewhere.

Tom Lane pushed:

– Code review for plpgsql fn_signature patch. Don’t quote the output
of format_procedure(); it’s already quoted quite enough. Remove the
fn_name field, which was now just dead weight. Fix remaining
expected-output files.

– Try to be more consistent about accepting denormalized float8
numbers. On some platforms, strtod() reports ERANGE for a
denormalized value (ie, one that can be represented as distinct from
zero, but is too small to have full precision). On others, it
doesn’t. It seems better to try to accept these values
consistently, so add a test to see if the result value indicates a
true out-of-range condition. This should be okay per Single Unix
Spec. On machines where the underlying math isn’t IEEE standard,
the behavior for such small numbers may not be very consistent, but
then it wouldn’t be anyway. Marti Raudsepp, after a proposal by
Jeroen Vermeulen

– Add some regression test cases for denormalized float8 input. This
was submitted with the previous patch, but I’m committing it
separately to ease backing it out if these results prove too
unportable. Marti Raudsepp, after a proposal by Jeroen Vermeulen

– Revert “Add some regression test cases for denormalized float8
input.” This reverts commit
500cf66d5522b39ddfdc26b309f8b5b0e385f42e. As was more or less
expected, a small minority of platforms won’t accept denormalized
input even with the recent changes. It doesn’t seem especially
helpful to test this if we’re going to have to provide an alternate
expected-file to allow failure.

– Allow SQL-language functions to reference parameters by name.
Matthew Draper, reviewed by Hitoshi Harada

– Improve comment.

– Add missing Assert and fix inaccurate elog message in
standby_redo(). All other WAL redo routines either call
RestoreBkpBlocks() or Assert that they haven’t been passed any
backup blocks. Make this one do likewise. Also, fix incorrect
routine name in its failure message.

– Fix transient clobbering of shared buffers during WAL replay.
RestoreBkpBlocks was in the habit of zeroing and refilling the
target buffer; which was perfectly safe when the code was written,
but is unsafe during Hot Standby operation. The reason is that we
have coding rules that allow backends to continue accessing a tuple
in a heap relation while holding only a pin on its buffer. Such a
backend could see transiently zeroed data, if WAL replay had
occasion to change other data on the page. This has been shown to
be the cause of bug #6425 from Duncan Rance (who deserves kudos for
developing a sufficiently-reproducible test case) as well as Bridget
Frey’s re-report of bug #6200. It most likely explains the original
report as well, though we don’t yet have confirmation of that. To
fix, change the code so that only bytes that are supposed to change
will change, even transiently. This actually saves cycles in
RestoreBkpBlocks, since it’s not writing the same bytes twice. Also
fix seq_redo, which has the same disease, though it has to work a
bit harder to meet the requirement. So far as I can tell, no other
WAL replay routines have this type of bug. In particular, the
index-related replay routines, which would certainly be broken if
they had to meet the same standard, are not at risk because we do
not have coding rules that allow access to an index page when not
holding a buffer lock on it. Back-patch to 9.0 where Hot Standby
was added.

Alvaro Herrera pushed:

– Properly free the sslcompression field in PGconn. Marko Kreen

– Implement dry-run mode for pg_archivecleanup. In dry-run mode, just
the name of the file to be removed is printed to stdout; this is so
the user can easily plug it into another program through a pipe. If
debug mode is also specified, a more verbose message is printed to
stderr. Author: Gabriele Bartolini Reviewer: Josh Kupershmidt

Andrew Dunstan pushed:

– Add array_to_json and row_to_json functions. Also move the
escape_json function from explain.c to json.c where it seems to
belong. Andrew Dunstan, Reviewd by Abhijit Menon-Sen.

Michael Meskes pushed:

– Applied Peter’s patch to PQconnectdbParams in ecpglib instead of the
old PQconectdb.

Bruce Momjian pushed:

– Remove tabs in SGML file.

== Rejected Patches (for now) ==

No one was disappointed this week 🙂

== Pending Patches ==

Alexander Korotkov sent in another revision of the patch to add GiST
indexing for range types, per review by Jeff Davis.

Kyotaro HORIGUCHI and Marko Kreen traded patches to speed dblink by
creating and using a new libpq tuple storage method.

Gilles Darold sent in a patch to implement pg_is_in_backup().

Alvaro Herrera sent in another revision of the FOREIGN KEY locks

Robert Haas and Simon Riggs traded patches to implement DROP INDEX

Andrew Dunstan sent in a patch to fix an issue where pg_dump -s could
dump data if it came from an extension.

Shigeru HANADA sent in another revision of the patch to implement a
PostgreSQL FDW.

Heikki Linnakangas sent in another revision of the patch to scale xlog

Peter Eisentraut sent in another revision of the patch to enable
renaming constraints in an ALTER TABLE statement.

Chetan Suttraway sent in a patch to implement SPI_gettypemod().

Simon Riggs sent in a patch refactoring log_newpage.

Alvaro Herrera sent in a patch to fix an issue where heap_tuple_read
could get a false positive.

Alvaro Herrera sent in a patch to make options in pg_hba.conf be

Oleg Bartunov sent in a patch to support NULLs in SP-GiST.

Robert Haas sent in another revision of the patch to allow EXPLAIN
ANALYZE not to include timing information.

Marti Raudsepp sent in another revision of the patch to cache stable
expressions with constant arguments.

KaiGai Kohei sent in another revision of the patch to unify the
permissions checks on DROP.

KaiGai Kohei sent in another revision of the patch to add a
sepgsql.client_label GUC.

Thomas Munro sent in a patch to add an optional SKIP LOCKED DATA to

Jeff Janes sent in another revision of the patch to use less memory
during sorting.

Jeff Davis sent in a patch to fix an issue where it was possible for
things to happen between an initdb call and its actually getting
written out to disk.

Simon Riggs sent in another revision of the patch to fix an issue in

Jan Urbanski sent in a patch to fix a memory leak in PL/PythonU’s
datum->dict transformation.

Jan Urbanski sent in a patch to fix a memory leak in PL/PythonU’s
datum->string transformation.

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