== PostgreSQL Weekly News – October 21 2012 ==
== PostgreSQL Weekly News – October 21 2012 ==
The 6th annual Highload++ conference will be on October 22-23, 2012 in
== PostgreSQL Product News ==
pgBadger 2.1, a PostgreSQL log analyzer written in Perl, released:
pgpool-HA 2.0 released. It helps manage high availability of pgpool.
pg_stat_plans 1.0 beta 1, an enhanced SQL monitoring and tuning tool, released.
== PostgreSQL 9.3 Feature of the Week ==
== PostgreSQL Tip of the Week ==
== PostgreSQL Jobs for October ==
== PostgreSQL Local ==
The 6th annual Highload++ conference will be on October 22-23, 2012 in
PostgreSQL Conference Europe 2012 will be in Prague, Czech Republic
on October 23-26.
There will be a PGDay November 9, 2012 at USP, São Paulo
PostgreSQL Day Argentina 2012 will be held on November 13th in Bernal,
Buenos Aires, at the National University of Quilmes. It will cover
topics for PostgreSQL users, developers and contributors, as well as
decision and policy makers. For more information about the
conference, please see the website at
This year Ecuador’s PGDay will be held at Quito city on November 17th,
2012. The Call for Papers is open until October 10. Send proposals
to Jaime Casanova jaime <AT> 2ndquadrant <DOT> com.
The sixth edition of the Italian PostgreSQL Day (PGDay.IT 2012) will
be held on November 23, 2012 in Prato, Tuscany. The International
Call for Papers is now open. Talks and presentations in English are
accepted. Information in English for papers submission is available
== PostgreSQL in the News ==
Planet PostgreSQL: http://planet.postgresql.org/
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== Applied Patches ==
Heikki Linnakangas pushed:
– Fix race condition in pg_ctl reading postmaster.pid. If postmaster
changed postmaster.pid while pg_ctl was reading it, pg_ctl could
overrun the buffer it allocated for the file. Fix by reading the
whole file to memory with one read() call. initdb contains an
identical copy of the readfile() function, but the files that initdb
reads are static, not modified concurrently. Nevertheless, add a
simple bounds-check there, if only to silence static analysis tools.
Per report from Dave Vitek. Backpatch to all supported branches.
– Remove comment that is no longer true. AddToDataDirLockFile()
supports out-of-order updates of the lockfile nowadays.
– Fix typo in comment. Fujii Masao
– Further tweaking of the readfile() function in pg_ctl. Don’t leak a
file descriptor if the file is empty or we can’t read its size.
Expect there to be a newline at the end of the last line, too. If
there isn’t, ignore anything after the last newline. This makes it a
tiny bit more robust in case the file is appended to concurrently,
so that we don’t return the last line if it hasn’t been fully
written yet. And this makes the code a bit less obscure, anyway. Per
Tom Lane’s suggestion. Backpatch to all supported branches.
Tom Lane pushed:
– alter_generic regression test cannot run concurrently with
privileges test. … because the latter plays games with the
privileges for language SQL. It looks like running alter_generic in
parallel with “misc” is OK though. Also, adjust serial_schedule to
maintain the same test ordering (up to parallelism) as
– Close un-owned SMgrRelations at transaction end. If an SMgrRelation
is not “owned” by a relcache entry, don’t allow it to live past
transaction end. This design allows the same SMgrRelation to be
used for blind writes of multiple blocks during a transaction, but
ensures that we don’t hold onto such an SMgrRelation indefinitely.
Because an SMgrRelation typically corresponds to open file
descriptors at the fd.c level, leaving it open when there’s no
corresponding relcache entry can mean that we prevent the kernel
from reclaiming deleted disk space. (While CacheInvalidateSmgr
messages usually fix that, there are cases where they’re not issued,
such as DROP DATABASE. We might want to add some more sinval
messaging for that, but I’d be inclined to keep this type of logic
anyway, since allowing VFDs to accumulate indefinitely for
blind-written relations doesn’t seem like a good idea.) This code
replaces a previous attempt towards the same goal that proved to be
unreliable. Back-patch to 9.1 where the previous patch was added.
– Revert “Use “transient” files for blind writes, take 2″. This
reverts commit fba105b1099f4f5fa7283bb17cba6fed2baa8d0c. That
approach had problems with the smgr-level state not tracking what we
really want to happen, and with the VFD-level state not tracking the
smgr-level state very well either. In consequence, it was still
possible to hold kernel file descriptors open for long-gone tables
(as in recent report from Tore Halset), and yet there were also
cases of FDs being closed undesirably soon. A replacement
implementation will follow.
– Fix planning of non-strict equivalence clauses above outer joins.
If a potential equivalence clause references a variable from the
nullable side of an outer join, the planner needs to take care that
derived clauses are not pushed to below the outer join; else they
may use the wrong value for the variable. (The problem arises only
with non-strict clauses, since if an upper clause can be proven
strict then the outer join will get simplified to a plain join.)
The planner attempted to prevent this type of error by checking that
potential equivalence clauses aren’t outerjoin-delayed as a whole,
but actually we have to check each side separately, since the two
sides of the clause will get moved around separately if it’s treated
as an equivalence. Bugs of this type can be demonstrated as far
back as 7.4, even though releases before 8.3 had only a very ad-hoc
notion of equivalence clauses. In addition, we neglected to account
for the possibility that such clauses might have nonempty
nullable_relids even when not outerjoin-delayed; so the
equivalence-class machinery lacked logic to compute correct
nullable_relids values for clauses it constructs. This oversight
was harmless before 9.2 because we were only using
RestrictInfo.nullable_relids for OR clauses; but as of 9.2 it could
result in pushing constructed equivalence clauses to incorrect
places. (This accounts for bug #7604 from Bill MacArthur.) Fix the
first problem by adding a new test check_equivalence_delay() in
distribute_qual_to_rels, and fix the second one by adding code in
equivclass.c and called functions to set correct nullable_relids for
generated clauses. Although I believe the second part of this is
not currently necessary before 9.2, I chose to back-patch it anyway,
partly to keep the logic similar across branches and partly because
it seems possible we might find other reasons why we need valid
values of nullable_relids in the older branches. Add regression
tests illustrating these problems. In 9.0 and up, also add test
cases checking that we can push constants through outer joins, since
we’ve broken that optimization before and I nearly broke it again
with an overly simplistic patch for this problem.
– Code review for inline-list patch. Make foreach macros less
syntactically dangerous, and fix some typos in
evidently-never-tested ones. Add missing slist_next_node and
slist_head_node functions. Fix broken dlist_check code. Assorted
– Remove unnecessary “head” arguments from some dlist/slist functions.
dlist_delete, dlist_insert_after, dlist_insert_before,
slist_insert_after do not need access to the list header, and indeed
insisting on that negates one of the main advantages of a
doubly-linked list. In consequence, revert addition of
“cache_bucket” field to CatCTup.
– Further cleanup of catcache.c ilist changes. Remove useless
duplicate initialization of bucket headers, don’t use a
dlist_mutable_iter in a performance-critical path that doesn’t need
it, make some other cosmetic changes for consistency’s sake.
– Provide some static-assertion functionality on all compilers. On
reflection (especially after noticing how many buildfarm critters
have __builtin_types_compatible_p but not _Static_assert), it seems
like we ought to try a bit harder to make these macros do something
everywhere. The initial cut at it would have been no help to code
that is compiled only on platforms without _Static_assert, for
instance; and in any case not all our contributors do their initial
coding on the latest gcc version. Some googling about static
assertions turns up quite a bit of prior art for making it work in
compilers that lack _Static_assert. The method that seems closest
to our needs involves defining a struct with a bit-field that has
negative width if the assertion condition fails. There seems no
reliable way to get the error message string to be output, but
throwing a compile error with a confusing message is better than
missing the problem altogether. In the same spirit, if we don’t
have __builtin_types_compatible_p we can at least insist that the
variable have the same width as the type. This won’t catch errors
such as “wrong pointer type”, but it’s far better than nothing. In
addition to changing the macro definitions, adjust a
compile-time-constant Assert in contrib/hstore to use
StaticAssertStmt, so we can get some buildfarm coverage on whether
that macro behaves sanely or not. There’s surely more places that
could be converted, but this is the first one I came across.
– Fix ruleutils to print “INSERT INTO foo DEFAULT VALUES” correctly.
Per bug #7615 from Marko Tiikkaja. Apparently nobody ever tried
this case before …
– Fix hash_search to avoid corruption of the hash table on
out-of-memory. An out-of-memory error during expand_table() on a
palloc-based hash table would leave a partially-initialized entry in
the table. This would not be harmful for transient hash tables,
since they’d get thrown away anyway at transaction abort. But for
long-lived hash tables, such as the relcache hash, this would
effectively corrupt the table, leading to crash or other misbehavior
later. To fix, rearrange the order of operations so that table
enlargement is attempted before we insert a new entry, rather than
after adding it to the hash table. Problem discovered by Hitoshi
Harada, though this is a bit different from his proposed patch.
– Fix UtilityContainsQuery() to handle CREATE TABLE Alexander Shulgin
EXECUTE correctly. The code seems to have been written to handle
the pre-parse-analysis representation, where an ExecuteStmt would
appear directly under CreateTableAsStmt. But in reality the
function is only run on already-parse-analyzed statements, so there
will be a Query node in between. We’d not noticed the bug because
the function is generally not used at all except in extended query
protocol. Per report from Robert Haas and Rushabh Lathia.
– Prevent overflow in pgbench’s percent-done display. Per Thom Brown.
– Fix pg_dump’s handling of DROP DATABASE commands in –clean mode.
In commit 4317e0246c645f60c39e6572644cff1cb03b4c65, I accidentally
broke this behavior while rearranging code to ensure that –create
wouldn’t affect whether a DATABASE entry gets put into
archive-format output. Thus, 9.2 would issue a DROP DATABASE
command in –clean mode, which is either useless or dangerous
depending on the usage scenario. It should not do that, and no
longer does. A bright spot is that this refactoring makes it easy
to allow the combination of –clean and –create to work sensibly,
ie, emit DROP DATABASE then CREATE DATABASE before reconnecting.
Ordinarily we’d consider that a feature addition and not back-patch
it, but it seems silly to not include the extra couple of lines
required in the 9.2 version of the code. Per report from Guillaume
Lelarge, though this is slightly more extensive than his proposed
Bruce Momjian pushed:
– When outputting the session id in log_line_prefix (%c) or in CSV log
output mode, cause the hex digits after the period to always be at
least four hex digits, with zero-padding.
Simon Riggs pushed:
– Clarify hash index caution and copy to CREATE INDEX docs
– Fix typo in previous commit
– Add isolation tests for DROP INDEX CONCURRENTLY. Backpatch to 9.2
to ensure bugs are fixed. Abhijit Menon-Sen
– Revert tests for drop index concurrently.
– Re-think guts of DROP INDEX CONCURRENTLY. Concurrent behaviour was
flawed when using a two-step process, so add an additional phase of
processing to ensure concurrency for both SELECTs and
INSERT/UPDATE/DELETEs. Backpatch to 9.2. Andres Freund, tweaked by
– Isolation test for DROP INDEX CONCURRENTLY for recent concurrent
changes. Abhijit Menon-Sen
– Fix orphan on cancel of drop index concurrently. Canceling DROP
INDEX CONCURRENTLY during wait could allow an orphaned index to be
left behind which could not be dropped. Backpatch to 9.2 Andres
Freund, tested by Abhijit Menon-Sen
Alvaro Herrera pushed:
– Embedded list interface. Provide a common implementation of
embedded singly-linked and doubly-linked lists. “Embedded” in the
sense that the nodes’ next/previous pointers exist within some
larger struct; this design choice reduces memory allocation
overhead. Most of the implementation uses inlineable functions
(where supported), for performance. Some existing uses of both
types of lists have been converted to the new code, for
demonstration purposes. Other uses can (and probably will) be
converted in the future. Since dllist.c is unused after this
conversion, it has been removed. Author: Andres Freund Some tweaks
by me Reviewed by Tom Lane, Peter Geoghegan
– pg_dump: Output functions deterministically sorted. Implementation
idea from Tom Lane Author: Joel Jacobson Reviewed by Joachim Wieland
Andrew Dunstan pushed:
– Use a more portable platform test.
http://git.postgresql.org/pg/commitdiff/2f2be7473ba28d1e5c96a0a52b30c831d1c0d203== Rejected Patches (for now) ==
Jeremy Evans patch to always include encoding of database in
== Pending Patches ==
Zoltan Boszormenyi sent in another revision of the patch to allow
pg_basebackup to configure and start standby.
Andrew Dunstan sent in another revision of the patch to add parallel
Pavel Stehule and Shigeru HANADA traded patches to implement \gset in
Amit Kapila sent in another revision of the patch to truncate trailing
nulls from heap rows to reduce the size of the null bitmap.
KaiGai Kohei sent in another revision of the patch implementing
row-level access control.
Amit Kapila sent in another revision of the patch to reduce the amount
of WAL used in update operations.
Karl O. Pinc sent in a patch to add –truncate-tables to pg_restore.
Karl O. Pinc sent in a doc patch to fix an punctuation error for
Karl O. Pinc sent in a word-smithing doc patch for pg_restore.
Peter Geoghegan sent in another revision of the patch to use
grow_memtuples with sort_mem.
Shigeru HANADA sent in another revision of the patch to make dropping
multiple tables in a single transaction faster.
Kevin Grittner sent in three revisions of a patch to fix CREATE/DROP
Claudio Freire sent in two revisions of a patch to prefetch index
pages for B-Tree index scans.
Kyotaro HORIGUCHI sent in three revisions of a patch to fix an issue
in pg_stat_replication where sync_state is not being properly set.
Alvaro Herrera sent in another revision of the patch implementing
foreign key locks.
Will Leinweber sent in a patch to add \watch to psql.
Tom Lane sent in a bug to fix the -c option in pg_dump/pg_restore.
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