== PostgreSQL Weekly News – July 29 2012 ==
== PostgreSQL Weekly News – July 29 2012 ==
== PostgreSQL Product News ==
Barman 1.0.0, a backup and recovery manager for PostgreSQL, released.
Repmgr 1.2.0 and 2.0beta, an HA and replication cluster management
software for PostgreSQL, released.
== PostgreSQL Jobs for July ==
== PostgreSQL Local ==
PostgreSQL Session will be held on October 4th, 2012, in Paris,
France. More information at:
PostgreSQL Conference Europe 2012 will be in Prague, Czech Republic
on October 23-26. The call for papers is open.
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
== PostgreSQL in the News ==
Planet PostgreSQL: http://planet.postgresql.org/
PostgreSQL Weekly News is brought to you this week by David Fetter
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== Applied Patches ==
Robert Haas pushed:
– Make pgbench vacuum before building indexes. This is apparently
faster than doing things the other way around when the scale factor
is large. Along the way, adjust -n to suppress vacuuming during
initialization as well as during test runs. Jeff Janes, with some
small changes by me.
– Log a better message when canceling autovacuum. The old message was
at DEBUG2, so typically it didn’t show up in the log at all. As a
result, in most cases where autovacuum was canceled, the only
information that was logged was the table being vacuumed, with no
indication as to what problem caused the cancel. Crank up the level
to LOG and add some more details to assist with debugging.
Back-patch all the way, per discussion on pgsql-hackers.
– Tab complete table names after ALTER TABLE x [NO] INHERIT. Jeff
Peter Eisentraut pushed:
– Update information schema to SQL:2011. This is just a section
renumbering for now. Some details might be filled in later.
– Document that pg_basebackup will create its output directory
Alvaro Herrera pushed:
– Change syntax of new CHECK NO INHERIT constraints. The initially
implemented syntax, “CHECK NO INHERIT (expr)” was not deemed very
good, so switch to “CHECK (expr) NO INHERIT” instead. This way it
looks similar to SQL-standards compliant constraint attribute.
Backport to 9.2 where the new syntax and feature was introduced.
– Add translator comments to module names
Tom Lane pushed:
– Fix longstanding crash-safety bug with newly-created-or-reset
sequences. If a crash occurred immediately after the first
nextval() call for a serial column, WAL replay would restore the
sequence to a state in which it appeared that no nextval() had been
done, thus allowing the first sequence value to be returned again by
the next nextval() call; as reported in bug #6748 from Xiangming
Mei. More generally, the problem would occur if an ALTER SEQUENCE
was executed on a freshly created or reset sequence. (The
manifestation with serial columns was introduced in 8.2 when we
added an ALTER SEQUENCE OWNED BY step to serial column creation.)
The cause is that sequence creation attempted to save one WAL entry
by writing out a WAL record that made it appear that the first
nextval() had already happened (viz, with is_called = true), while
marking the sequence’s in-database state with log_cnt = 1 to show
that the first nextval() need not emit a WAL record. However, ALTER
SEQUENCE would emit a new WAL entry reflecting the actual
in-database state (with is_called = false). Then, nextval would
allocate the first sequence value and set is_called = true, but it
would trust the log_cnt value and not emit any WAL record. A crash
at this point would thus restore the sequence to its post-ALTER
state, causing the next nextval() call to return the first sequence
value again. To fix, get rid of the idea of logging an is_called
status different from reality. This means that the first
nextval-driven WAL record will happen at the first nextval call not
the second, but the marginal cost of that is pretty negligible. In
addition, make sure that ALTER SEQUENCE resets log_cnt to zero in
any case where it touches sequence parameters that affect future
nextval results. This will result in some user-visible changes in
the contents of a sequence’s log_cnt column, as reflected in the
patch’s regression test changes; but no application should be
depending on that anyway, since it was already true that log_cnt
changes rather unpredictably depending on checkpoint timing. In
addition, make some basically-cosmetic improvements to get rid of
sequence.c’s undesirable intimacy with page layout details. It was
always really trying to WAL-log the contents of the sequence tuple,
so we should have it do that directly using a HeapTuple’s t_data and
t_len, rather than backing into it with some magic assumptions about
where the tuple would be on the sequence’s page. Back-patch to all
– Only allow autovacuum to be auto-canceled by a directly blocked
process. In the original coding of the autovacuum cancel feature,
commit acac68b2bcae818bc8803b8cb8cbb17eee8d5e2b, an autovacuum
process was considered a target for cancellation if it was found to
hard-block any process examined in the deadlock search. This patch
tightens the test so that the autovacuum must directly hard-block
the current process. This should make the behavior more predictable
in general, and in particular it ensures that an autovacuum will not
be canceled with less than deadlock_timeout grace period. In the
old coding, it was possible for an autovacuum to be canceled almost
instantly, given unfortunate timing of two or more other processes’
lock attempts. This also justifies the logging methodology in the
recent commit d7318d43d891bd63e82dcfc27948113ed7b1db80; without this
restriction, that patch isn’t providing enough information to see
the connection of the canceling process to the autovacuum. Like
that one, patch all the way back.
– 8.3 doesn’t have errdetail_log().
– Improve reporting of error situations in find_other_exec(). This
function suppressed any stderr output from the called program, which
is unnecessary in the normal case and unhelpful in error cases. It
also gave a rather opaque message along the lines of “fgets failure:
Success” in case the called program failed to return anything on
stdout. Since we’ve seen multiple reports of people not
understanding what’s wrong when pg_ctl reports this, improve the
message. Back-patch to all active branches.
Bruce Momjian pushed:
– Simplify pg_upgrade’s handling when returning directory listings.
Backpatch to 9.2.
– Document that the pg_upgrade user of rsync might want to skip some
files, like postmaster.pid. Backpatch to 9.2.
– Update doc mention of diskchecker.pl to add URL for script; retain
URL for description. Patch to 9.0 and later, where script is
== Rejected Patches (for now) ==
No one was disappointed this week
== Pending Patches ==
Alexander Korotkov and Heikki Linnakangas traded patches implementing
SP-GiST indexing based on 2-D mapping an quad-trees.
Marko Kreen sent in two more revisions of the row-at-a-time patch for
KaiGai Kohei sent in another revision of the refactoring of the ALTER
Alvaro Herrera sent in a patch to clarify some file names used by
Pavel Stehule sent in a patch to add \gset to psql, which assigns the
target list of the query, which must return exactly one row, to a list
of psql variables named with commas separating them after \gset.
Fujii Masao sent in another pair of revisions of the patch to prevent
restored WAL files from being archived again: one for git master; the
other for 9.2.
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