== PostgreSQL Weekly News - October 05 2014 ==

== PostgreSQL Weekly News - October 05 2014 ==

PGCon 2015 will be in June, a few weeks later than previous years.
The website will be updated soon. In the meantime, please see:
https://plus.google.com/109158564828766727391/posts/5VrpSxoZDAa

Federico Campoli will talk about PostgreSQL and Big Data at the
Italian Linux Day in Ferrara the October 25th, 2014. Details:
http://www.pgdba.co.uk/2014/10/postgresql-and-big-data-talk.html

Mark your calendars. The second Swiss Postgres Conference will be
held June 25-26, 2015 at HSR Rapperswil. There will be one day of
tutorials, and one day of "regular" presentations. Details to follow.

== PostgreSQL Product News ==

pgtoolkit v1.0.2, a maintenance toolkit for PostgreSQL, released
https://github.com/grayhemp/pgtoolkit

== PostgreSQL Jobs for October ==

http://archives.postgresql.org/pgsql-jobs/2014-10/threads.php

== PostgreSQL Local ==

The fifth edition of the Argentinian PostgreSQL Day will be held on
November 28th, 2014 in Santa Fe, Argentina. The International CfP is
open through September 28th, 2014.
http://www.postgresql.org.ar/pgday2014

The 4th PgDay Ecuador will be held on Tuesday 7th in October at the
city of Quito, as part of the 5th International Congress of Free
Software. Send talk proposals to ecpug AT postgresql DOT org.

The sixth PGDay Cubano be held on 13 and 14 October 2014 in Habana.
https://postgresql.uci.cu/?p=380

PGConf.EU 2014 in Madrid, Spain on October 21-24 is now open for
registration.
http://2014.pgconf.eu/registration/

PGDay.IT 2014 will take place in Prato on November the 7th 2014. The
International Call For Papers is now open:
http://2014.pgday.it/call-for-papers-en/

== 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 ==

Stephen Frost pushed:

- Revert 95d737ff to add 'ignore_nulls'. Per discussion, revert the
commit which added 'ignore_nulls' to row_to_json. This capability
would be better added as an independent function rather than being
bolted on to row_to_json. Additionally, the implementation didn't
address complex JSON objects, and so was incomplete anyway. Pointed
out by Tom and discussed with Andrew and Robert.
http://git.postgresql.org/pg/commitdiff/c8a026e4f15e2063cd7fe6cb9ffe44f2a81398bd

- Also revert e3ec0728, JSON regression tests. Managed to forget to
update the other JSON regression test output, again. Revert the
commit which fixed it before. Per buildfarm.
http://git.postgresql.org/pg/commitdiff/08da8947f4b52ad41770f260a3962b032de77120

- Correct stdin/stdout usage in COPY .. PROGRAM The COPY documentation
incorrectly stated, for the PROGRAM case, that we read from stdin
and wrote to stdout. Fix that, and improve consistency by referring
to the 'PostgreSQL' user instead of the 'postgres' user, as is done
in the rest of the COPY documentation. Pointed out by Peter van
Dijk. Back-patch to 9.3 where COPY .. PROGRAM was introduced.
http://git.postgresql.org/pg/commitdiff/8492d86342915cb466eeb2d896d9b49887f59350

- Fix CreatePolicy, pg_dump -v; psql and doc updates. Peter Geoghegan
pointed out that valgrind was, rightfully, complaining about
CreatePolicy() ending up copying beyond the end of the parsed policy
name. Name is a fixed-size type and we need to use namein (through
DirectFunctionCall1()) to flush out the entire array before we pass
it down to heap_form_tuple. Michael Paquier pointed out that
pg_dump --verbose was missing a newline and Fabrízio de Royes Mello
further pointed out that the schema was also missing from the
messages, so fix those also. Also, based on an off-list comment
from Kevin, rework the psql \d output to facilitate copy/pasting
into a new CREATE or ALTER POLICY command. Lastly, improve the
pg_policies view and update the documentation for it, along with a
few other minor doc corrections based on an off-list discussion with
Adam Brightwell.
http://git.postgresql.org/pg/commitdiff/78d72563ef141ddc507ddd5ae77db613a309041a

Tom Lane pushed:

- Change JSONB's on-disk format for improved performance. The
original design used an array of offsets into the variable-length
portion of a JSONB container. However, such an array is basically
uncompressible by simple compression techniques such as TOAST's LZ
compressor. That's bad enough, but because the offset array is at
the front, it tended to trigger the give-up-after-1KB heuristic in
the TOAST code, so that the entire JSONB object was stored
uncompressed; which was the root cause of bug #11109 from Larry
White. To fix without losing the ability to extract a random array
element in O(1) time, change this scheme so that most of the JEntry
array elements hold lengths rather than offsets. With data that's
compressible at all, there tend to be fewer distinct element
lengths, so that there is scope for compression of the JEntry array.
Every N'th entry is still an offset. To determine the length or
offset of any specific element, we might have to examine up to N
preceding JEntrys, but that's still O(1) so far as the total
container size is concerned. Testing shows that this cost is
negligible compared to other costs of accessing a JSONB field, and
that the method does largely fix the incompressible-data problem.
While at it, rearrange the order of elements in a JSONB object so
that it's "all the keys, then all the values" not alternating keys
and values. This doesn't really make much difference right at the
moment, but it will allow providing a fast path for extracting
individual object fields from large JSONB values stored EXTERNAL
(ie, uncompressed), analogously to the existing optimization for
substring extraction from large EXTERNAL text values. Bump
catversion to denote the incompatibility in on-disk format. We will
need to fix pg_upgrade to disallow upgrading jsonb data stored with
9.4 betas 1 and 2. Heikki Linnakangas and Tom Lane
http://git.postgresql.org/pg/commitdiff/def4c28cf9147472ba4cfc5b68a098d7a29fb0fb

- Fix some more problems with nested append relations. As of commit
a87c72915 (which later got backpatched as far as 9.1), we're
explicitly supporting the notion that append relations can be
nested; this can occur when UNION ALL constructs are nested, or when
a UNION ALL contains a table with inheritance children. Bug #11457
from Nelson Page, as well as an earlier report from Elvis
Pranskevichus, showed that there were still nasty bugs associated
with such cases: in particular the EquivalenceClass mechanism could
try to generate "join" clauses connecting an appendrel child to some
grandparent appendrel, which would result in assertion failures or
bogus plans. Upon investigation I concluded that all current
callers of find_childrel_appendrelinfo() need to be fixed to
explicitly consider multiple levels of parent appendrels. The most
complex fix was in processing of "broken" EquivalenceClasses, which
are ECs for which we have been unable to generate all the derived
equality clauses we would like to because of missing cross-type
equality operators in the underlying btree operator family. That
code path is more or less entirely untested by the regression tests
to date, because no standard opfamilies have such holes in them. So
I wrote a new regression test script to try to exercise it a bit,
which turned out to be quite a worthwhile activity as it exposed
existing bugs in all supported branches. The present patch is
essentially the same as far back as 9.2, which is where
parameterized paths were introduced. In 9.0 and 9.1, we only need
to back-patch a small fragment of commit 5b7b5518d, which fixes
failure to propagate out the original WHERE clauses when a broken
Emmanuel Cecchet contains constant members. (The regression test
case results show that these older branches are noticeably stupider
than 9.2+ in terms of the quality of the plans generated; but we
don't really care about plan quality in such cases, only that the
plan not be outright wrong. A more invasive fix in the older
branches would not be a good idea anyway from a plan-stability
standpoint.)
http://git.postgresql.org/pg/commitdiff/5a6c168c7859e150c61e30b7519471045bab065e

- Fix bogus logic for zic -P option. The quick hack I added to zic to
dump out currently-in-use timezone abbreviations turns out to have a
nasty bug: within each zone, it was printing the last "struct
ttinfo" to be *defined*, not necessarily the last one in use. This
was mainly a problem in zones that had changed the meaning of their
zone abbreviation (to another GMT offset value) and later changed it
back. As a result of this error, we'd missed out updating the
tznames/ files for some jurisdictions that have changed their zone
abbreviations since the tznames/ files were originally created.
I'll address the missing data updates in a separate commit.
http://git.postgresql.org/pg/commitdiff/596857043023738099d6d16f8edbe6b7353876c0

- Update time zone abbreviations lists. This updates
known_abbrevs.txt to be what it should have been already, were my -P
patch not broken; and updates some tznames/ entries that missed
getting any love in previous timezone data updates because zic
failed to flag the change of abbreviation. The non-cosmetic
updates: * Remove references to "ADT" as "Arabia Daylight Time", an
* abbreviation that's been out of use since 2007; therefore,
claiming there is a conflict with "Atlantic Daylight Time" doesn't
seem especially helpful. (We have left obsolete entries in the
files when they didn't conflict with anything, but that seems like a
different situation.) * Fix entirely incorrect GMT offsets for CKT
(Cook Islands), FJT, FJST (Fiji); we didn't even have them on the
proper side of the date line. (Seems to have been aboriginal errors
in our tznames data; there's no evidence anything actually changed
recently.) * FKST (Falkland Islands Summer Time) is now used all
year round, so don't mark it as a DST abbreviation. * Update SAKT
(Sakhalin) to mean GMT+11 not GMT+10. In cosmetic changes, I fixed
a bunch of wrong (or at least obsolete) claims about abbreviations
not being present in the zic files, and tried to be consistent about
how obsolete abbreviations are labeled. Note the underlying
timezone/data files are still at release 2014e; this is just trying
to get us in sync with what those files actually say before we go to
the next update.
http://git.postgresql.org/pg/commitdiff/4f499eee9d4b30e761b04fa28406578c10b4badf

- Update time zone data files to tzdata release 2014h. Most zones in
the Russian Federation are subtracting one or two hours as of
2014-10-26. Update the meanings of the abbreviations IRKT, KRAT,
MAGT, MSK, NOVT, OMST, SAKT, VLAT, YAKT, YEKT to match. The IANA
timezone database has adopted abbreviations of the form AxST/AxDT
for all Australian time zones, reflecting what they believe to be
current majority practice Down Under. These names do not conflict
with usage elsewhere (other than ACST for Acre Summer Time, which
has been in disuse since 1994). Accordingly, adopt these names into
our "Default" timezone abbreviation set. The "Australia"
abbreviation set now contains only CST,EAST,EST,SAST,SAT,WST, all of
which are thought to be mostly historical usage. Note that SAST has
also been changed to be South Africa Standard Time in the "Default"
abbreviation set. Add zone abbreviations SRET (Asia/Srednekolymsk)
and XJT (Asia/Urumqi), and use WSST/WSDT for western Samoa. Also a
DST law change in the Turks & Caicos Islands (America/Grand_Turk),
and numerous corrections for historical time zone data.
http://git.postgresql.org/pg/commitdiff/513d06ded1b44206903b87dabefee5a97243ba67

- Update 9.4 release notes for commits through today. Add entries for
recent changes, including noting the JSONB format change and the
recent timezone data changes. We should remove those two items
before 9.4 final: the JSONB change will be of no interest in the
long run, and it's not normally our habit to mention timezone
updates in major-release notes. But it seems important to document
them temporarily for beta testers. I failed to resist the
temptation to wordsmith a couple of existing entries, too.
http://git.postgresql.org/pg/commitdiff/f706f2c1a06dfd3fe69194a93d417ca4be8951b1

Andres Freund pushed:

- doc fix for pg_recvlogical: --create doesn't immediately exit.
Author: Michael Paquier
http://git.postgresql.org/pg/commitdiff/445d262852f7aa83f9973a13bd56320d3a63842c

- Rename CACHE_LINE_SIZE to PG_CACHE_LINE_SIZE. As noted in
http://bugs.debian.org/763098 there is a conflict between postgres'
definition of CACHE_LINE_SIZE and the definition by various *bsd
platforms. It's debatable who has the right to define such a name,
but postgres' use was only introduced in 375d8526f290 (9.4), so it
seems like a good idea to rename it. Discussion:
20140930195756(dot)GC27407(at)msg(dot)df7cb(dot)de Per complaint of Christoph Berg
in the above email, although he's not the original bug reporter.
Backpatch to 9.4 where the define was introduced.
http://git.postgresql.org/pg/commitdiff/ef8863844bb0b0dab7b92c5f278302a42b4bf05a

- Improve documentation about binary/textual output mode for output
plugins. Also improve related error message as it contributed to
the confusion. Discussion:
CAB7nPqQrqFzjqCjxu4GZzTrD9kpj6HMn9G5aOOMwt1WZ8NfqeA(at)mail(dot)gmail(dot)com,
CAB7nPqQXc_+g95zWnqaa=mVQ4d3BVRs6T41frcEYi2ocUrR3+A(at)mail(dot)gmail(dot)com
Per discussion between Michael Paquier, Robert Haas and Andres
Freund. Backpatch to 9.4 where logical decoding was introduced.
http://git.postgresql.org/pg/commitdiff/0ef3c29a4b43e72d93cff65a17a9ccccff87618d

- Block signals while computing the sleep time in postmaster's main
loop. DetermineSleepTime() was previously called without blocked
signals. That's not good, because it allows signal handlers to
interrupt its workings. DetermineSleepTime() was added in 9.3 with
the addition of background workers (da07a1e856511), where it only
read from BackgroundWorkerList. Since 9.4, where dynamic background
workers were added (7f7485a0cde), the list is also manipulated in
DetermineSleepTime(). That's bad because the list now can be
persistently corrupted if modified by both a signal handler and
DetermineSleepTime(). This was discovered during the investigation
of hangs on buildfarm member anole. It's unclear whether this bug is
the source of these hangs or not, but it's worth fixing either way.
I have confirmed that it can cause crashes. It luckily looks like
this only can cause problems when bgworkers are actively used.
Discussion: 20140929193733(dot)GB14400(at)awork2(dot)anarazel(dot)de Backpatch to
9.3 where background workers were introduced.
http://git.postgresql.org/pg/commitdiff/a39e78b710eb588e102aedd2828611d7bc74714b

- pg_recvlogical.c code review. Several comments still referred to
'initiating', 'freeing', 'stopping' replication slots. These were
terms used during different phases of the development of logical
decoding, but are no long accurate. Also rename StreamLog() to
StreamLogicalLog() and add 'void' to the prototype. Author: Michael
Paquier, with some editing by me. Backpatch to 9.4 where
pg_recvlogical was introduced.
http://git.postgresql.org/pg/commitdiff/fdf81c9a6cf94921084e52c8d2ff903bae362620

- Install all headers for the new atomics API. Previously, by
mistake, only atomics.h was installed. Kohei KaiGai
http://git.postgresql.org/pg/commitdiff/952872698d9443fdf9b808a1376017f00c91065a

- Refactor replication connection code of various pg_basebackup
utilities. Move some more code to manage replication connection
command to streamutil.c. A later patch will introduce replication
slot via pg_receivexlog and this avoid duplicating relevant code
between pg_receivexlog and pg_recvlogical. Author: Michael Paquier,
with some editing by me.
http://git.postgresql.org/pg/commitdiff/0c013e08cfbebd35ec982c4df15d44b521094d52

Bruce Momjian pushed:

- pg_upgrade: have pg_upgrade fail for old 9.4 JSONB format.
Backpatch through 9.4
http://git.postgresql.org/pg/commitdiff/35419aeb8356e3d6973816846cb6ca64a0f736bf

Álvaro Herrera pushed:

- Fix pg_dump's --if-exists for large objects. This was born broken in
9067310cc5dd590e36c2c3219dbf3961d7c9f8cb. Per trouble report from
Joachim Wieland. Pavel Stěhule and Álvaro Herrera
http://git.postgresql.org/pg/commitdiff/fd02931a6c83bf3beb2d03f65700600787d569a3

- Don't balance vacuum cost delay when per-table settings are in
effect. When there are cost-delay-related storage options set for a
table, trying to make that table participate in the autovacuum
cost-limit balancing algorithm produces undesirable results: instead
of using the configured values, the global values are always used,
as illustrated by Mark Kirkwood in
http://www.postgresql.org/message-id/52FACF15.8020507@catalyst.net.nz
Since the mechanism is already complicated, just disable it for
those cases rather than trying to make it cope. There are
undesirable side-effects from this too, namely that the total I/O
impact on the system will be higher whenever such tables are
vacuumed. However, this is seen as less harmful than slowing down
vacuum, because that would cause bloat to accumulate. Anyway, in
the new system it is possible to tweak options to get the precise
behavior one wants, whereas with the previous system one was simply
hosed. This has been broken forever, so backpatch to all supported
branches. This might affect systems where cost_limit and cost_delay
have been set for individual tables.
http://git.postgresql.org/pg/commitdiff/1021bd6a89bc756c2a72b29eeee1a7a5c25f64f5

Heikki Linnakangas pushed:

- Add functions for dealing with PGP armor header lines to pgcrypto.
This add a new pgp_armor_headers function to extract armor headers
from an ASCII-armored blob, and a new overloaded variant of the
armor function, for constructing an ASCII-armor with extra headers.
Marko Tiikkaja and me.
http://git.postgresql.org/pg/commitdiff/32984d8fc3dbb90a3fafb69fece0134f1ea790f9

- Remove num_xloginsert_locks GUC, replace with a #define. I left the
GUC in place for the beta period, so that people could experiment
with different values. No-one's come up with any data that a
different value would be better under some circumstances, so rather
than try to document to users what the GUC, let's just hard-code the
current value, 8.
http://git.postgresql.org/pg/commitdiff/5fa6c81a43d047a070eff1f711b90c084c6d3e31

- Refactor pgbench log-writing code to a separate function. The
doCustom function was incredibly long, this makes it a little bit
more readable.
http://git.postgresql.org/pg/commitdiff/84f0ea3f68aed5e5b9cc1ef8599a7c28b0b97b0f

- Fix typo in error message.
http://git.postgresql.org/pg/commitdiff/86f809088c2c4f931b2a7554f4be92cd3f33ba13

- Fix documentation for CREATE SEQUENCE IF NOT EXISTS. The [ IF NOT
EXISTS ] was put in wrong place in the syntax. Pointed out by Marti
Raudsepp.
http://git.postgresql.org/pg/commitdiff/7a08e21f35454ced4050598b09be571a98bdb104

- Check for GiST index tuples that don't fit on a page. The page
splitting code would go into infinite recursion if you try to insert
an index tuple that doesn't fit even on an empty page. Per analysis
and suggested fix by Andrew Gierth. Fixes bug #11555, reported by
Bryan Seitz (analysis happened over IRC). Backpatch to all supported
versions.
http://git.postgresql.org/pg/commitdiff/7690ddea0c1f6d16584b3e90010a9933ca7134e0

Robert Haas pushed:

- Increase the number of buffer mapping partitions to 128. Testing by
Amit Kapila, Andres Freund, and myself, with and without other
patches that also aim to improve scalability, seems to indicate that
this change is a significant win over the current value and over
smaller values such as 64. It's not clear how high we can push this
value before it starts to have negative side-effects elsewhere, but
going this far looks OK.
http://git.postgresql.org/pg/commitdiff/3acc10c997f916f6a741d0b4876126b7b08e3892

- Still another typo fix for 0709b7ee72e4bc71ad07b7120acd117265ab51d0.
Buildfarm member anole caught this one.
http://git.postgresql.org/pg/commitdiff/9019264f2e2f87c879855449f57aeeb336ee3c88

- Fix typos in comments. Etsuro Fujita
http://git.postgresql.org/pg/commitdiff/017b2e9822cf6c28fc5024a5f9a6f0d3dde885a4

- Eliminate one background-worker-related flag variable. Teach
sigusr1_handler() to use the same test for whether a worker might
need to be started as ServerLoop(). Aside from being perhaps a bit
simpler, this prevents a potentially-unbounded delay when starting a
background worker. On some platforms, select() doesn't return when
interrupted by a signal, but is instead restarted, including a reset
of the timeout to the originally-requested value. If signals arrive
often enough, but no connection requests arrive, sigusr1_handler()
will be executed repeatedly, but the body of ServerLoop() won't be
reached. This change ensures that, even in that case, background
workerw will eventually get launched. This is far from a perfect
fix; really, we need select() to return control to ServerLoop()
after an interrupt, either via the self-pipe trick or some other
mechanism. But that's going to require more work and discussion, so
let's do this for now to at least mitigate the damage. Per
investigation of test_shm_mq failures on buildfarm member anole.
http://git.postgresql.org/pg/commitdiff/d0410d66037c2f3f9bee45e0a2db9e47eeba2bb4

Peter Eisentraut pushed:

- Translation updates
http://git.postgresql.org/pg/commitdiff/1ec4a970fe6b996cba765a7e9c1897c00bf6c968

== Rejected Patches (for now) ==

No one was disappointed this week :-)

== Pending Patches ==

Bogdan Pilch sent in a patch to allow trailing commas in SELECT
statements.

Heikki Linnakangas sent in a patch to use a plain memcmp() to compare
the Datums while building the red-black tree for GIN.

Peter Eisentraut sent in a patch to correct the documentation for
effective_io_concurrency.

Peter Geoghegan sent in another revision of a patch to add a new
infrastructure to sortsupport, and add a single client of this new
infrastructure, the text sortsupport routine.

Herwin Weststrate sent in two revisions of a patch to allow format
0000-0000-0000 in the MAC parser.

Kaigai Kouhei sent in two more revisions of a patch to create a custom
scan API.

Michael Paquier and Ali Akbar traded patches to add a
generate_series(numeric, numeric) function.

Fabrízio de Royes Mello and Marti Raudsepp traded patches to implement
CINE for indexes.

Michael Paquier sent in another revision of a patch to implement
REINDEX CONCURRENTLY.

Adam Brightwell sent in three revisions of a patch to clean up
superuser().

Ilya Kosmodemiansky sent in a patch to to trace LWLocks with the
lowest possible performance impact.

Thomas Munro sent in two revisions of a patch to implement NEXT VALUE
FOR <sequence>.

Kaigai Kouhei sent in a patch to insure that the new port/atomics/*.h
files are included when installing.

Marti Raudsepp sent in a patch to allow semijoin/antijoin/hashed
SubPlan optimization when an EXISTS subquery contains a LIMIT clause
with a positive constant.

Fabrízio de Royes Mello sent in a patch to ensure that the CREATE
SEQUENCE syntax correctly summarizes the options for CREATE SEQUENCE.

Kaigai Kouhei sent in a patch to make ResourceOwnerForgetBuffer()
O(1) instead of O(N^2).

Michael Banck sent in a patch to allow logging to notice that a
checkpoint is to be written on shutdown.

Heikki Linnakangas sent in another revision of a patch to create a
pgbench throttling latency limit.

Shigeru HANADA sent in a WIP patch to add join push-down support for
foreign tables.

Andrew Dunstan sent in a patch to implement json[b]_strip_nulls.

Marco Nenciarini sent in a patch to add an optional backup profile to
pg_basebackup in service of the eventual feature, incremental backup.

Heikki Linnakangas sent in another revision of a patch to change the
WAL format and API.