== PostgreSQL Weekly News - November 01 2015 ==

== PostgreSQL Weekly News - November 01 2015 ==

== PostgreSQL Product News ==

PGroonga 1.0.0, a fast full text search platform for all languages,
released.
http://groonga.org/en/blog/2015/10/29/pgroonga-1.0.0.html

tds_fdw 1.0.6, a foreign data wrapper for MS-SQL Server and Sybase, released.
https://github.com/GeoffMontee/tds_fdw/releases

== PostgreSQL Jobs for November ==

http://archives.postgresql.org/pgsql-jobs/2015-11/

== PostgreSQL Local ==

Highload++2015 is November 2-3, 2015 in Moscow, Russia. Information in
Russian and English, respectively:
http://highload.ru/
http://highload.co/

PGConf Silicon Valley 2015 is November 17-18 at the South San
Francisco Convention Center.
http://www.pgconfsv.com

PGBR2015 (The Brazilian PostgreSQL Conference) will take place in Porto
Alegre, Rio Grande do Sul, on November 18, 19 and 20. Registration is
open.
http://pgbr.postgresql.org.br/2015/en/

Postgres Conference China 2015 will be on November 20-22, 2015 in
Beijing.
http://postgres2015.eventdove.com/ (Chinese)
http://postgrescluster2015.eventdove.com/ (English)

PGConf.DE will be held on November 26-27, 2015 in Hamburg, Germany, at
the Lindner Hotel am Michel.
http://2015.pgconf.de/

PostgreSQL(at)SCaLE is a two day, two track event which takes place on Jan.
21-22, 2016, at Pasadena Convention Center, as part of SCaLE 14X.
The CfP is open until Oct 30, 2015.
https://www.socallinuxexpo.org/scale/14x/cfp

== 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
to pwn(at)arpug(dot)com(dot)ar(dot)

== Applied Patches ==

Álvaro Herrera pushed:

- Measure string lengths only once. Bernd Helmle complained that
CreateReplicationSlot() was assigning the same value to the same
variable twice, so we could remove one of them. Code inspection
reveals that we can actually remove both assignments: according to
the author the assignment was there for beauty of the strlen line
only, and another possible fix to that is to put the strlen in its
own line, so do that. To be consistent within the file, refactor
all duplicated strlen() calls, which is what we do elsewhere in the
backend anyway. In basebackup.c, snprintf already returns the right
length; no need for strlen afterwards. Backpatch to 9.4, where
replication slots were introduced, to keep code identical. Some of
this is older, but the patch doesn't apply cleanly and it's only of
cosmetic value anyway. Discussion:
http://www.postgresql.org/message-id/BE2FD71DEA35A2287EA5F018@eje.credativ.lan
http://git.postgresql.org/pg/commitdiff/0cd836a4e818f049716e47fe81bf5d4800509c57

- Cleanup commit timestamp module activaction, again Further tweak
commit_ts.c so that on a standby the state is completely consistent
with what that in the master, rather than behaving differently in
the cases that the settings differ. Now in standby and master the
module should always be active or inactive in lockstep. Author:
Petr Jelínek, with some further tweaks by Álvaro Herrera. Backpatch
to 9.5, where commit timestamps were introduced. Discussion:
http://www.postgresql.org/message-id/5622BF9D.2010409@2ndquadrant.com
http://git.postgresql.org/pg/commitdiff/531d21b75ff6b18ea8638c736a05326ebd519f49

- Fix BRIN free space computations A bug in the original free space
computation made it possible to return a page which wasn't actually
able to fit the item. Since the insertion code isn't prepared to
deal with PageAddItem failing, a PANIC resulted ("failed to add BRIN
tuple [to new page]"). Add a macro to encapsulate the correct
computation, and use it in brin_getinsertbuffer's callers before
calling that routine, to raise an early error. I became aware of
the possiblity of a problem in this area while working on
ccc4c074994d734. There's no archived discussion about it, but it's
easy to reproduce a problem in the unpatched code with something
like CREATE TABLE t (a text); CREATE INDEX ti ON t USING brin (a)
WITH (pages_per_range=1); for length in `seq 8000 8196` do psql -f -
<<EOF TRUNCATE TABLE t; INSERT INTO t VALUES ('z'), (repeat('a',
$length)); EOF done Backpatch to 9.5, where BRIN was introduced.
http://git.postgresql.org/pg/commitdiff/21a4e4a4c9fe417e2462b6f90f6b0e49e32ceba6

- Document BRIN's inclusion opclass framework Backpatch to 9.5 -- this
should have been part of b0b7be61337, but we didn't have
38b03caebc5de either at the time. Author: Emre Hasegeli Revised by:
Ian Barwick Discussion:
http://www.postgresql.org/message-id/CAE2gYzyB39Q9up_-TO6FKhH44pcAM1x6n_Cuj15qKoLoFihUVg@mail.gmail.com
http://www.postgresql.org/message-id/562DA711.3020305@2ndquadrant.com
http://git.postgresql.org/pg/commitdiff/c15898c1d5d53602de097905a90f3dd176e8e7fd

- Fix secondary expected output for commit_ts test Per red wall in
buildfarm
http://git.postgresql.org/pg/commitdiff/dbe6f434ee1852f08c011065467a6cfc5ce10864

Robert Haas pushed:

- Make Gather node projection-capable. The original Gather code
failed to mark a Gather node as not able to do projection, but it
couldn't, even though it did call initialize its projection info via
ExecAssignProjectionInfo. There doesn't seem to be any good reason
for this node not to have projection capability, so clean things up
so that it does. Without this, plans using Gather nodes might need
to carry extra Result nodes to do projection.
http://git.postgresql.org/pg/commitdiff/8538a6307049590ddb5ba127b2ecac6308844d60

- Fix incorrect message in ATWrongRelkindError. Mistake introduced by
commit 3bf3ab8c563699138be02f9dc305b7b77a724307. Etsuro Fujita
http://git.postgresql.org/pg/commitdiff/9dcce7123e1b0012fcf7f8b8761b34aebb66986d

- Add missing serial comma, for consistency. Amit Langote, per Etsuro
Fujita
http://git.postgresql.org/pg/commitdiff/d45565162494c75eae91481eda17dc0c8ecab5db

- Fix typo in bgworker.c
http://git.postgresql.org/pg/commitdiff/c6baec92fc48387da8164d50f5699a7162267718

- Update parallel executor support to reuse the same DSM. Commit
b0b0d84b3d663a148022e900ebfc164284a95f55 purported to make it
possible to relaunch workers using the same parallel context, but it
had an unpleasant race condition: we might reinitialize after the
workers have sent their last control message but before they have
dettached the DSM, leaving to crashes. Repair by introducing a new
ParallelContext operation, ReinitializeParallelDSM. Adjust
execParallel.c to use this new support, so that we can rescan a
Gather node by relaunching workers but without needing to recreate
the DSM. Amit Kapila, with some adjustments by me. Extracted from
latest parallel sequential scan patch.
http://git.postgresql.org/pg/commitdiff/3a1f8611f2582df0a16bcd35caed2e1526387643

- doc: security_barrier option is a Boolean, not a string. Mistake
introduced by commit 5bd91e3a835b5d5499fee5f49fc7c0c776fe63dd. Hari
Babu
http://git.postgresql.org/pg/commitdiff/c5057b2b34813ca114bc808cb56b7a7fcde64393

Peter Eisentraut pushed:

- Message style improvements. Message style, plurals, quoting,
spelling, consistency with similar messages
http://git.postgresql.org/pg/commitdiff/a8d585c0915939a42acdb529d8e0eb832935d45f

- Remove some remains from Alpha support removal
http://git.postgresql.org/pg/commitdiff/c5130e8ee09e5ae605f3aa944a31dd9021c1d3dd

Tom Lane pushed:

- Docs: add example clarifying use of nested JSON containment. Show
how this can be used in practice to make queries simpler and more
flexible. Also, draw an explicit contrast to the existence
operator, which doesn't work that way. Peter Geoghegan and Tom Lane
http://git.postgresql.org/pg/commitdiff/23937a4253490bf0c06aef0b8658270176f52de4

- Implement lookbehind constraints in our regular-expression engine.
A lookbehind constraint is like a lookahead constraint in that it
consumes no text; but it checks for existence (or nonexistence) of a
match *ending* at the current point in the string, rather than one
*starting* at the current point. This is a long-requested feature
since it exists in many other regex libraries, but Henry Spencer had
never got around to implementing it in the code we use. Just making
it work is actually pretty trivial; but naive copying of the logic
for lookahead constraints leads to code that often spends O(N^2)
time to scan an N-character string, because we have to run the match
engine from string start to the current probe point each time the
constraint is checked. In typical use-cases a lookbehind constraint
will be written at the start of the regex and hence will need to be
checked at every character --- so O(N^2) work overall. To fix that,
I introduced a third copy of the core DFA matching loop, paralleling
the existing longest() and shortest() loops. This version,
matchuntil(), can suspend and resume matching given a couple of
pointers' worth of storage space. So we need only run it across the
string once, stopping at each interesting probe point and then
resuming to advance to the next one. I also put in an optimization
that simplifies one-character lookahead and lookbehind constraints,
such as "(?=x)" or "(?<!\w)", into AHEAD and BEHIND constraints,
which already existed in the engine. This avoids the overhead of
the LACON machinery entirely for these rather common cases. The net
result is that lookbehind constraints run a factor of three or so
slower than Perl's for multi-character constraints, but faster than
Perl's for one-character constraints ... and they work fine for
variable-length constraints, which Perl gives up on entirely. So
that's not bad from a competitive perspective, and there's room for
further optimization if anyone cares. (In reality, raw scan rate
across a large input string is probably not that big a deal for
Postgres usage anyway; so I'm happy if it's linear.)
http://git.postgresql.org/pg/commitdiff/12c9a04008870c283931d6b3b648ee21bbc2cfda

Kevin Grittner pushed:

- Fix serialization anomalies due to race conditions on INSERT. On
insert the CheckForSerializableConflictIn() test was performed
before the page(s) which were going to be modified had been locked
(with an exclusive buffer content lock). If another process
acquired a relation SIReadLock on the heap and scanned to a page on
which an insert was going to occur before the page was so locked, a
rw-conflict would be missed, which could allow a serialization
anomaly to be missed. The window between the check and the page
lock was small, so the bug was generally not noticed unless there
was high concurrency with multiple processes inserting into the same
table. This was reported by Peter Bailis as bug #11732, by Sean
Chittenden as bug #13667, and by others. The race condition was
eliminated in heap_insert() by moving the check down below the
acquisition of the buffer lock, which had been the very next
statement. Because of the loop locking and unlocking multiple
buffers in heap_multi_insert() a check was added after all inserts
were completed. The check before the start of the inserts was left
because it might avoid a large amount of work to detect a
serialization anomaly before performing the all of the inserts and
the related WAL logging. While investigating this bug, other SSI
bugs which were even harder to hit in practice were noticed and
fixed, an unnecessary check (covered by another check, so redundant)
was removed from heap_update(), and comments were improved.
Back-patch to all supported branches. Kevin Grittner and Thomas
Munro
http://git.postgresql.org/pg/commitdiff/585e2a3b1a57cd7f763a9203e77563c729d6104e

== Rejected Patches (for now) ==

No one was disappointed this week :-)

== Pending Patches ==

Zeus Kronion sent in a patch to fix an issue with parallel workers in
pg_dump.

Haribabu Kommi sent in another revision of a patch to implement
multi-tenancy with RLS.

Victor Wagner sent in another revision of a patch to implement
failover at the libpq connect level.

Ashutosh Bapat sent in three more revisions of a patch to get sorted
data from a foreign server.

Nathan Wagner and David Fetter sent in two revisions of a patch to add
fortnights as a unit of time measurement.

Robert Haas sent in a patch to modify tqueue infrastructure to
support transient record types.

Valery Popov sent in a patch to add a max_recursion_depth parameter to
blunt the effects of out-of-control WITH RECURSIVE queries.

Michael Paquier sent in another revision of a patch to allow showing
tuple data in the pageinspect contrib extension.

David Rowley sent in a patch to make tlist_matches_tupdesc() more
efficient.

Marko Tiikkaja sent in a patch to add \pset true/false to psql.

Marko Tiikkaja sent in a patch to add a new aggregate, onlyvalue,
which returns the single distinct non-NULL value from the input values
and raises an exception if some number other than one distinct
non-NULL value exists.

Rahila Syed sent in another revision of a patch to implement a vacuum
progress checker.

Pavel Stěhule sent in another revision of a patch to implement
ereport() in PL/PythonU.

Stas Kelvich sent in another revision of a patch to add KNN support to
the cube contrib extension.

Alexander Korotkov sent in two more revisions of a patch to move
PinBuffer and UnpinBuffer to atomics.

SAWADA Masahiko sent in two more revisions of a patch to add a
"frozen" bit to the visibility map.

Amit Langote sent in another revision of a patch to implement
declarative partitioning.

Pavel Stěhule sent in another revision of a patch to enhance the types
usable in PL/pgsql.

Fabien COELHO sent in another revision of a patch to extend pgbench
expressions with functions.

Jim Nasby sent in a patch to install config/missing.

Konstantin Knizhnik sent in a patch to add an extensible transaction
manager API.

Marko Tiikkaja sent in a patch to allow COPY (query) to use
INSERT/UPDATE/DELETE...RETURNING in addition to SELECT, TABLE, and
VALUES.

Pavel Stěhule sent in another revision of a patch to add an optional
--group-command parameter to psql, which lets it execute multiple
commands from the shell command line.

Peter Geoghegan sent in a patch to correct a comment in strxfrm cache.

Alexander Lebedev sent in a patch to add support for box type in
SP-GiST index.

Dean Rasheed sent in a patch to add trigonometric functions that take
degree measurements as inputs.