Tom Lane [Thu, 19 Nov 2015 19:54:05 +0000 (14:54 -0500)]
Dodge a macro-name conflict with Perl.
Some versions of Perl export a macro named HS_KEY. This creates a
conflict in contrib/hstore_plperl against hstore's macro of the same
name. The most future-proof solution seems to be to rename our macro;
I chose HSTORE_KEY. For consistency, rename HS_VAL and related macros
similarly.
Back-patch to 9.5. contrib/hstore_plperl doesn't exist before that
so there is no need to worry about the conflict in older releases.
Tom Lane [Thu, 19 Nov 2015 19:16:39 +0000 (14:16 -0500)]
Fix thinko: errmsg -> ereport.
Silly mistake in my commit 09cecdf285ea9f51, reported by Erik Rijkers.
The fact that the buildfarm didn't find this implies that we are not
testing Perl builds that lack MULTIPLICITY, which is a bit disturbing
from a coverage standpoint. Until today I'd have said nobody cared
about such configurations anymore; but maybe not.
Robert Haas [Thu, 19 Nov 2015 15:49:25 +0000 (10:49 -0500)]
Make ALTER .. SET SCHEMA do nothing, instead of throwing an ERROR.
This was already true for CREATE EXTENSION, but historically has not
been true for other object types. Therefore, this is a backward
incompatibility. Per discussion on pgsql-hackers, everyone seems to
agree that the new behavior is better.
Marti Raudsepp, reviewed by Haribabu Kommi and myself
Andrew Dunstan [Thu, 19 Nov 2015 03:47:41 +0000 (22:47 -0500)]
Improve vcregress.pl's handling of tap tests for client programs
The target is now named 'bincheck' rather than 'tapcheck' so that it
reflects what is checked instead of the test mechanism. Some of the
logic is improved, making it easier to add further sets of TAP based
tests in future. Also, the environment setting logic is imrpoved.
Andres Freund [Thu, 19 Nov 2015 00:25:58 +0000 (01:25 +0100)]
Remove function names from some elog() calls in heapam.c.
At least one of the names was, due to a function renaming late in the
development of ON CONFLICT, wrong. Since including function names in
error messages is against the message style guide anyway, remove them
from the messages.
Discussion: CAM3SWZT8paz=usgMVHm0XOETkQvzjRtAUthATnmaHQQY0obnGw@mail.gmail.com
Backpatch: 9.5, where ON CONFLICT was introduced
Andres Freund [Mon, 9 Nov 2015 23:02:49 +0000 (00:02 +0100)]
Improve ON CONFLICT documentation.
Author: Peter Geoghegan and Andres Freund
Discussion: CAM3SWZScpWzQ-7EJC77vwqzZ1GO8GNmURQ1QqDQ3wRn7AbW1Cg@mail.gmail.com
Backpatch: 9.5, where ON CONFLICT was introduced
Tom Lane [Wed, 18 Nov 2015 22:45:05 +0000 (17:45 -0500)]
Accept flex > 2.5.x in configure.
Per buildfarm member anchovy, 2.6.0 exists in the wild now.
Hopefully it works with Postgres; if not, we'll have to do something
about that, but in any case claiming it's "too old" is pretty silly.
Robert Haas [Wed, 18 Nov 2015 13:25:33 +0000 (08:25 -0500)]
Fix dumb bug in tqueue.c
When I wrote this code originally, the intention was to recompute the
remapinfo only when the tupledesc changes. This presumably only
happens once per query, but I copied the design pattern from other
DestReceivers. However, due to a silly oversight on my part,
tqueue->tupledesc never got set, leading to recomputation for every
tuple.
This should improve the performance of parallel scans that return a
significant number of tuples.
Report by Amit Kapila; patch by me, reviewed by him.
Tom Lane [Tue, 17 Nov 2015 20:46:47 +0000 (15:46 -0500)]
Fix possible internal overflow in numeric division.
div_var_fast() postpones propagating carries in the same way as mul_var(),
so it has the same corner-case overflow risk we fixed in 246693e5ae8a36f0,
namely that the size of the carries has to be accounted for when setting
the threshold for executing a carry propagation step. We've not devised
a test case illustrating the brokenness, but the required fix seems clear
enough. Like the previous fix, back-patch to all active branches.
Robert Haas [Mon, 16 Nov 2015 23:50:06 +0000 (18:50 -0500)]
Remove volatile qualifiers from bufmgr.c and freelist.c
Prior to commit 0709b7ee72e4bc71ad07b7120acd117265ab51d0, access to
variables within a spinlock-protected critical section had to be done
through a volatile pointer, but that should no longer be necessary.
Tom Lane [Mon, 16 Nov 2015 18:45:17 +0000 (13:45 -0500)]
Speed up ruleutils' name de-duplication code, and fix overlength-name case.
Since commit 11e131854f8231a21613f834c40fe9d046926387, ruleutils.c has
attempted to ensure that each RTE in a query or plan tree has a unique
alias name. However, the code that was added for this could be quite slow,
even as bad as O(N^3) if N identical RTE names must be replaced, as noted
by Jeff Janes. Improve matters by building a transient hash table within
set_rtable_names. The hash table in itself reduces the cost of detecting a
duplicate from O(N) to O(1), and we can save another factor of N by storing
the number of de-duplicated names already created for each entry, so that
we don't have to re-try names already created. This way is probably a bit
slower overall for small range tables, but almost by definition, such cases
should not be a performance problem.
In principle the same problem applies to the column-name-de-duplication
code; but in practice that seems to be less of a problem, first because
N is limited since we don't support extremely wide tables, and second
because duplicate column names within an RTE are fairly rare, so that in
practice the cost is more like O(N^2) not O(N^3). It would be very much
messier to fix the column-name code, so for now I've left that alone.
An independent problem in the same area was that the de-duplication code
paid no attention to the identifier length limit, and would happily produce
identifiers that were longer than NAMEDATALEN and wouldn't be unique after
truncation to NAMEDATALEN. This could result in dump/reload failures, or
perhaps even views that silently behaved differently than before. We can
fix that by shortening the base name as needed. Fix it for both the
relation and column name cases.
In passing, check for interrupts in set_rtable_names, just in case it's
still slow enough to be an issue.
Tom Lane [Sun, 15 Nov 2015 19:41:09 +0000 (14:41 -0500)]
Fix ruleutils.c's dumping of whole-row Vars in ROW() and VALUES() contexts.
Normally ruleutils prints a whole-row Var as "foo.*". We already knew that
that doesn't work at top level of a SELECT list, because the parser would
treat the "*" as a directive to expand the reference into separate columns,
not a whole-row Var. However, Joshua Yanovski points out in bug #13776
that the same thing happens at top level of a ROW() construct; and some
nosing around in the parser shows that the same is true in VALUES().
Hence, apply the same workaround already devised for the SELECT-list case,
namely to add a forced cast to the appropriate rowtype in these cases.
(The alternative of just printing "foo" was rejected because it is
difficult to avoid ambiguity against plain columns named "foo".)
Tom Lane [Sat, 14 Nov 2015 19:55:38 +0000 (14:55 -0500)]
Improve type numeric's calculations for ln(), log(), exp(), pow().
Set the "rscales" for intermediate-result calculations to ensure that
suitable numbers of significant digits are maintained throughout. The
previous coding hadn't thought this through in any detail, and as a result
could deliver results with many inaccurate digits, or in the worst cases
even fail with divide-by-zero errors as a result of losing all nonzero
digits of intermediate results.
In exp_var(), get rid entirely of the logic that separated the calculation
into integer and fractional parts: that was neither accurate nor
particularly fast. The existing range-reduction method of dividing by 2^n
can be applied across the full input range instead of only 0..1, as long as
we are careful to set an appropriate rscale for each step.
Also fix the logic in mul_var() for shortening the calculation when the
caller asks for fewer output digits than an exact calculation would
require. This bug doesn't affect simple multiplications since that code
path asks for an exact result, but it does contribute to accuracy issues
in the transcendental math functions.
In passing, improve performance of mul_var() a bit by forcing the shorter
input to be on the left, thus reducing the number of iterations of the
outer loop and probably also reducing the number of carry-propagation
steps needed.
This is arguably a bug fix, but in view of the lack of field complaints,
it does not seem worth the risk of back-patching.
Alvaro Herrera [Thu, 12 Nov 2015 21:05:23 +0000 (18:05 -0300)]
vacuumdb: don't prompt for passwords over and over
Having the script prompt for passwords over and over was a preexisting
problem when it processed multiple databases or when it processed
multiple analyze stages, but the parallel mode introduced in commit a179232047 made it worse.
Fix the annoyance by keeping a copy of the password used by the first
connection that requires one. Since users can (currently) only have a
single password, there's no need for more complex arrangements (such as
remembering one password per database).
Per bug #13741 reported by Eric Brown. Patch authored and
cross-reviewed by Haribabu Kommi and Michael Paquier, slightly tweaked
by Álvaro Herrera.
Discussion: http://www.postgresql.org/message-id/20151027193919.931.54948@wrigleys.postgresql.org
Backpatch to 9.5, where parallel vacuumdb was introduced.
Robert Haas [Thu, 12 Nov 2015 19:59:09 +0000 (14:59 -0500)]
Move each SLRU's lwlocks to a separate tranche.
This makes it significantly easier to identify these lwlocks in
LWLOCK_STATS or Trace_lwlocks output. It's also arguably better
from a modularity standpoint, since lwlock.c no longer needs to
know anything about the LWLock needs of the higher-level SLRU
facility.
Ildus Kurbangaliev, reviewd by Álvaro Herrera and by me.
Tom Lane [Thu, 12 Nov 2015 18:03:52 +0000 (13:03 -0500)]
Fix unwanted flushing of libpq's input buffer when socket EOF is seen.
In commit 210eb9b743c0645d I centralized libpq's logic for closing down
the backend communication socket, and made the new pqDropConnection
routine always reset the I/O buffers to empty. Many of the call sites
previously had not had such code, and while that amounted to an oversight
in some cases, there was one place where it was intentional and necessary
*not* to flush the input buffer: pqReadData should never cause that to
happen, since we probably still want to process whatever data we read.
This is the true cause of the problem Robert was attempting to fix in c3e7c24a1d60dc6a, namely that libpq no longer reported the backend's final
ERROR message before reporting "server closed the connection unexpectedly".
But that only accidentally fixed it, by invoking parseInput before the
input buffer got flushed; and very likely there are timing scenarios
where we'd still lose the message before processing it.
To fix, pass a flag to pqDropConnection to tell it whether to flush the
input buffer or not. On review I think flushing is actually correct for
every other call site.
Back-patch to 9.3 where the problem was introduced. In HEAD, also improve
the comments added by c3e7c24a1d60dc6a.
Robert Haas [Thu, 12 Nov 2015 14:12:18 +0000 (09:12 -0500)]
libpq: Notice errors a backend may have sent just before dying.
At least since the introduction of Hot Standby, the backend has
sometimes sent fatal errors even when no client query was in
progress, assuming that the client would receive it. However,
pqHandleSendFailure was not in sync with this assumption, and
only tries to catch notices and notifies. Add a parseInput call
to the loop there to fix.
Andres Freund suggested the fix. Comments are by me.
Reviewed by Michael Paquier.
Robert Haas [Thu, 12 Nov 2015 14:00:33 +0000 (09:00 -0500)]
Make idle backends exit if the postmaster dies.
Letting backends continue to run if the postmaster has exited prevents
PostgreSQL from being restarted, which in many environments is
catastrophic. Worse, if some other backend crashes, we no longer have
any protection against shared memory corruption. So, arrange for them
to exit instead. We don't want to expend many cycles on this, but
including postmaster death in the set of things that we wait for when
a backend is idle seems cheap enough.
Tom Lane [Thu, 12 Nov 2015 00:19:14 +0000 (19:19 -0500)]
Do a round of copy-editing on the 9.5 release notes.
Also fill in the previously empty "major enhancements" list. YMMV as to
which items should make the cut, but it's past time we had something more
than a placeholder here.
(I meant to get this done before beta2 was wrapped, but got distracted by
PDF build problems. Better late than never.)
Tom Lane [Wed, 11 Nov 2015 22:13:38 +0000 (17:13 -0500)]
Improve documentation around autovacuum-related storage parameters.
These were discussed in three different sections of the manual, which
unsurprisingly had diverged over time; and the descriptions of individual
variables lacked stylistic consistency even within each section (and
frequently weren't in very good English anyway). Clean up the mess, and
remove some of the redundant information in hopes that future additions
will be less likely to re-introduce inconsistency. For instance I see
no need for maintenance.sgml to include its very own list of all the
autovacuum storage parameters, especially since that list was already
incomplete.
Tom Lane [Wed, 11 Nov 2015 18:39:21 +0000 (13:39 -0500)]
Be more noisy about "wrong number of nailed relations" initfile problems.
In commit 5d1ff6bd559ea8df1b7302e245e690b01b9a4fa4 I added some logic to
relcache.c to try to ensure that the regression tests would fail if we
made a mistake about which relations belong in the relcache init files.
I'm quite sure I tested that, but I must have done so only for the
non-shared-catalog case, because a report from Adam Brightwell showed that
the regression tests still pass just fine if we bollix the shared-catalog
init file in the way this code was supposed to catch. The reason is that
that file gets loaded before we do client authentication, so the WARNING
is not sent to the client, only to the postmaster log, where it's far too
easily missed.
The least Rube Goldbergian answer to this is to put an Assert(false)
after the elog(WARNING). That will certainly get developers' attention,
while not breaking production builds' ability to recover from corner
cases with similar symptoms.
Since this is only of interest to developers, there seems no need for
a back-patch, even though the previous commit went into all branches.
Robert Haas [Wed, 11 Nov 2015 14:02:52 +0000 (09:02 -0500)]
Generate parallel sequential scan plans in simple cases.
Add a new flag, consider_parallel, to each RelOptInfo, indicating
whether a plan for that relation could conceivably be run inside of
a parallel worker. Right now, we're pretty conservative: for example,
it might be possible to defer applying a parallel-restricted qual
in a worker, and later do it in the leader, but right now we just
don't try to parallelize access to that relation. That's probably
the right decision in most cases, anyway.
Using the new flag, generate parallel sequential scan plans for plain
baserels, meaning that we now have parallel sequential scan in
PostgreSQL. The logic here is pretty unsophisticated right now: the
costing model probably isn't right in detail, and we can't push joins
beneath Gather nodes, so the number of plans that can actually benefit
from this is pretty limited right now. Lots more work is needed.
Nevertheless, it seems time to enable this functionality so that all
this code can actually be tested easily by users and developers.
Note that, if you wish to test this functionality, it will be
necessary to set max_parallel_degree to a value greater than the
default of 0. Once a few more loose ends have been tidied up here, we
might want to consider changing the default value of this GUC, but
I'm leaving it alone for now.
Along the way, fix a bug in cost_gather: the previous coding thought
that a Gather node's transfer overhead should be costed on the basis of
the relation size rather than the number of tuples that actually need
to be passed off to the leader.
Patch by me, reviewed in earlier versions by Amit Kapila.
Robert Haas [Wed, 11 Nov 2015 13:57:52 +0000 (08:57 -0500)]
Make sequential scans parallel-aware.
In addition, this path fills in a number of missing bits and pieces in
the parallel infrastructure. Paths and plans now have a parallel_aware
flag indicating whether whatever parallel-aware logic they have should
be engaged. It is believed that we will need this flag for a number of
path/plan types, not just sequential scans, which is why the flag is
generic rather than part of the SeqScan structures specifically.
Also, execParallel.c now gives parallel nodes a chance to initialize
their PlanState nodes from the DSM during parallel worker startup.
Amit Kapila, with a fair amount of adjustment by me. Review of previous
patch versions by Haribabu Kommi and others.
Tom Lane [Wed, 11 Nov 2015 03:11:39 +0000 (22:11 -0500)]
Docs: fix misleading example.
Commit 8457d0beca731bf0 introduced an example which, while not incorrect,
failed to exhibit the behavior it meant to describe, as a result of omitting
an E'' prefix that needed to be there. Noticed and fixed by Peter Geoghegan.
I (tgl) failed to resist the temptation to wordsmith nearby text a bit
while at it.
Tom Lane [Tue, 10 Nov 2015 20:59:59 +0000 (15:59 -0500)]
Improve our workaround for 'TeX capacity exceeded' in building PDF files.
In commit a5ec86a7c787832d28d5e50400ec96a5190f2555 I wrote a quick hack
that reduced the number of TeX string pool entries created while converting
our documentation to PDF form. That held the fort for awhile, but as of
HEAD we're back up against the same limitation. It turns out that the
original coding of \FlowObjectSetup actually results in *three* string pool
entries being generated for every "flow object" (that is, potential
cross-reference target) in the documentation, and my previous hack only got
rid of one of them. With a little more care, we can reduce the string
count to one per flow object plus one per actually-cross-referenced flow
object (about 115000 + 5000 as of current HEAD); that should work until
the documentation volume roughly doubles from where it is today.
As a not-incidental side benefit, this change also causes pdfjadetex to
stop emitting unreferenced hyperlink anchors (bookmarks) into the PDF file.
It had been making one willy-nilly for every flow object; now it's just one
per actually-cross-referenced object. This results in close to a 2X
savings in PDF file size. We will still want to run the output through
"jpdftweak" to get it to be compressed; but we no longer need removal of
unreferenced bookmarks, so we might be able to find a quicker tool for
that step.
Although the failure only affects HEAD and US-format output at the moment,
9.5 cannot be more than a few pages short of failing likewise, so it
will inevitably fail after a few rounds of minor-version release notes.
I don't have a lot of faith that we'll never hit the limit in the older
branches; and anyway it would be nice to get rid of jpdftweak across the
board. Therefore, back-patch to all supported branches.
Andres Freund [Mon, 9 Nov 2015 04:08:56 +0000 (05:08 +0100)]
Add paragraph about ON CONFLICT interaction with partitioning.
Author: Peter Geoghegan and Andres Freund
Discussion: CAM3SWZScpWzQ-7EJC77vwqzZ1GO8GNmURQ1QqDQ3wRn7AbW1Cg@mail.gmail.com,
CAHGQGwFUCWwSU7dtc2aRdRk73ztyr_jY5cPOyts+K8xKJ92X4Q@mail.gmail.com
Backpatch: 9.5, where UPSERT was introduced
Andres Freund [Sun, 8 Nov 2015 22:01:53 +0000 (23:01 +0100)]
Set replication origin when decoding commit records.
By accident the replication origin was not set properly in
DecodeCommit(). That's bad because the origin is passed to the output
plugins origin filter, and accessible from the output plugin via
ReorderBufferTXN->origin_id. Accessing the origin of individual changes
worked before the fix, which is why this wasn't notices earlier.
Reported-By: Craig Ringer
Author: Craig Ringer
Discussion: CAMsr+YFhBJLp=qfSz3-J+0P1zLkE8zNXM2otycn20QRMx380gw@mail.gmail.com
Backpatch: 9.5, where replication origins where introduced
Noah Misch [Sun, 8 Nov 2015 22:28:53 +0000 (17:28 -0500)]
Don't connect() to a wildcard address in test_postmaster_connection().
At least OpenBSD, NetBSD, and Windows don't support it. This repairs
pg_ctl for listen_addresses='0.0.0.0' and listen_addresses='::'. Since
pg_ctl prefers to test a Unix-domain socket, Windows users are most
likely to need this change. Back-patch to 9.1 (all supported versions).
This could change pg_ctl interaction with loopback-interface firewall
rules. Therefore, in 9.4 and earlier (released branches), activate the
change only on known-affected platforms.
Tom Lane [Sat, 7 Nov 2015 21:13:49 +0000 (16:13 -0500)]
Rename PQsslAttributes() to PQsslAttributeNames(), and const-ify fully.
Per discussion, the original name was a bit misleading, and
PQsslAttributeNames() seems more apropos. It's not quite too late to
change this in 9.5, so let's change it while we can.
Also, make sure that the pointer array is const, not only the pointed-to
strings.
Tom Lane [Sat, 7 Nov 2015 17:43:24 +0000 (12:43 -0500)]
Fix enforcement of restrictions inside regexp lookaround constraints.
Lookahead and lookbehind constraints aren't allowed to contain backrefs,
and parentheses within them are always considered non-capturing. Or so
says the manual. But the regexp parser forgot about these rules once
inside a parenthesized subexpression, so that constructs like (\w)(?=(\1))
were accepted (but then not correctly executed --- a case like this acted
like (\w)(?=\w), without any enforcement that the two \w's match the same
text). And in (?=((foo))) the innermost parentheses would be counted as
capturing parentheses, though no text would ever be captured for them.
To fix, properly pass down the "type" argument to the recursive invocation
of parse().
Back-patch to all supported branches; it was agreed that silent
misexecution of such patterns is worse than throwing an error, even though
new errors in minor releases are generally not desirable.
Robert Haas [Fri, 6 Nov 2015 21:58:45 +0000 (16:58 -0500)]
Modify tqueue infrastructure to support transient record types.
Commit 4a4e6893aa080b9094dadbe0e65f8a75fee41ac6, which introduced this
mechanism, failed to account for the fact that the RECORD pseudo-type
uses transient typmods that are only meaningful within a single
backend. Transferring such tuples without modification between two
cooperating backends does not work. This commit installs a system
for passing the tuple descriptors over the same shm_mq being used to
send the tuples themselves. The two sides might not assign the same
transient typmod to any given tuple descriptor, so we must also
substitute the appropriate receiver-side typmod for the one used by
the sender. That adds some CPU overhead, but still seems better than
being unable to pass records between cooperating parallel processes.
Along the way, move the logic for handling multiple tuple queues from
tqueue.c to nodeGather.c; tqueue.c now provides a TupleQueueReader,
which reads from a single queue, rather than a TupleQueueFunnel, which
potentially reads from multiple queues. This change was suggested
previously as a way to make sure that nodeGather.c rather than tqueue.c
had policy control over the order in which to read from queues, but
it wasn't clear to me until now how good an idea it was. typmod
mapping needs to be performed separately for each queue, and it is
much simpler if the tqueue.c code handles that and leaves multiplexing
multiple queues to higher layers of the stack.
Robert Haas [Fri, 6 Nov 2015 17:10:42 +0000 (12:10 -0500)]
Add sort support routine for the UUID data type.
This introduces a simple encoding scheme to produce abbreviated keys:
pack as many bytes of each UUID as will fit into a Datum. On
little-endian machines, a byteswap is also performed; the abbreviated
comparator can therefore just consist of a simple 3-way unsigned integer
comparison.
The purpose of this change is to speed up sorting data on a column
of type UUID.
Stephen Frost [Fri, 6 Nov 2015 16:18:27 +0000 (11:18 -0500)]
Set include_realm=1 default in parse_hba_line
With include_realm=1 being set down in parse_hba_auth_opt, if multiple
options are passed on the pg_hba line, such as:
host all all 0.0.0.0/0 gss include_realm=0 krb_realm=XYZ.COM
We would mistakenly reset include_realm back to 1. Instead, we need to
set include_realm=1 up in parse_hba_line, prior to parsing any of the
additional options.
Tom Lane [Thu, 5 Nov 2015 23:15:48 +0000 (18:15 -0500)]
Fix erroneous hash calculations in gin_extract_jsonb_path().
The jsonb_path_ops code calculated hash values inconsistently in some cases
involving nested arrays and objects. This would result in queries possibly
not finding entries that they should find, when using a jsonb_path_ops GIN
index for the search. The problem cases involve JSONB values that contain
both scalars and sub-objects at the same nesting level, for example an
array containing both scalars and sub-arrays. To fix, reset the current
stack->hash after processing each value or sub-object, not before; and
don't try to be cute about the outermost level's initial hash.
Correcting this means that existing jsonb_path_ops indexes may now be
inconsistent with the new hash calculation code. The symptom is the same
--- searches not finding entries they should find --- but the specific
rows affected are likely to be different. Users will need to REINDEX
jsonb_path_ops indexes to make sure that all searches work as expected.
Per bug #13756 from Daniel Cheng. Back-patch to 9.4 where the faulty
logic was introduced.
Tom Lane [Thu, 5 Nov 2015 18:52:30 +0000 (13:52 -0500)]
Fix memory leaks in PL/Python.
Previously, plpython was in the habit of allocating a lot of stuff in
TopMemoryContext, and it was very slipshod about making sure that stuff
got cleaned up; in particular, use of TopMemoryContext as fn_mcxt for
function calls represents an unfixable leak, since we generally don't
know what the called function might have allocated in fn_mcxt. This
results in session-lifespan leakage in certain usage scenarios, as for
example in a case reported by Ed Behn back in July.
To fix, get rid of all the retail allocations in TopMemoryContext.
All long-lived allocations are now made in sub-contexts that are
associated with specific objects (either pl/python procedures, or
Python-visible objects such as cursors and plans). We can clean these
up when the associated object is deleted.
I went so far as to get rid of PLy_malloc completely. There were a
couple of places where it could still have been used safely, but on
the whole it was just an invitation to bad coding.
Haribabu Kommi, based on a draft patch by Heikki Linnakangas;
some further work by me
Robert Haas [Thu, 5 Nov 2015 17:05:38 +0000 (12:05 -0500)]
Pass extra data to bgworkers, and use this to fix parallel contexts.
Up until now, the total amount of data that could be passed to a
background worker at startup was one datum, which can be a small as
4 bytes on some systems. That's enough to pass a dsm_handle or an
array index, but not much else. Add a bgw_extra flag to the
BackgroundWorker struct, allowing up to 128 bytes to be passed to
a new worker on any platform.
Use this to fix a problem I recently discovered with the parallel
context machinery added in 9.5: the master assigns each worker an
array index, and each worker subsequently assigns itself an array
index, and there's nothing to guarantee that the two sets of indexes
match, leading to chaos.
Normally, I would not back-patch the change to add bgw_extra, since it
is basically a feature addition. However, since 9.5 is still in beta
and there seems to be no other sensible way to repair the broken
parallel context machinery, back-patch to 9.5. Existing background
worker code can ignore the bgw_extra field without a problem, but
might need to be recompiled since the structure size has changed.
Tom Lane [Thu, 5 Nov 2015 15:46:14 +0000 (10:46 -0500)]
Improve implementation of GEQO's init_tour() function.
Rather than filling a temporary array and then copying values to the
output array, we can generate the required random permutation in-place
using the Fisher-Yates shuffle algorithm. This is shorter as well as
more efficient than before. It's pretty unlikely that anyone would
notice a speed improvement, but shorter code is better.
Tom Lane [Wed, 4 Nov 2015 17:03:30 +0000 (12:03 -0500)]
Add regression tests for remote execution of extension operators/functions.
Rather than relying on other extensions to be available for installation,
let's just add some test objects to the postgres_fdw extension itself
within the regression script.
Tom Lane [Tue, 3 Nov 2015 23:42:02 +0000 (18:42 -0500)]
Allow postgres_fdw to ship extension funcs/operators for remote execution.
The user can whitelist specified extension(s) in the foreign server's
options, whereupon we will treat immutable functions and operators of those
extensions as candidates to be sent for remote execution.
Whitelisting an extension in this way basically promises that the extension
exists on the remote server and behaves compatibly with the local instance.
We have no way to prove that formally, so we have to rely on the user to
get it right. But this seems like something that people can usually get
right in practice.
We might in future allow functions and operators to be whitelisted
individually, but extension granularity is a very convenient special case,
so it got done first.
The patch as-committed lacks any regression tests, which is unfortunate,
but introducing dependencies on other extensions for testing purposes
would break "make installcheck" scenarios, which is worse. I have some
ideas about klugy ways around that, but it seems like material for a
separate patch. For the moment, leave the problem open.
Robert Haas [Tue, 3 Nov 2015 17:46:06 +0000 (12:46 -0500)]
postgres_fdw: Add ORDER BY to some remote SQL queries.
If the join problem's entire ORDER BY clause can be pushed to the
remote server, consider a path that adds this ORDER BY clause. If
use_remote_estimate is on, we cost this path using an additional
remote EXPLAIN. If not, we just estimate that the path costs 20%
more, which is intended to be large enough that we won't request a
remote sort when it's not helpful, but small enough that we'll have
the remote side do the sort when in doubt. In some cases, the remote
sort might actually be free, because the remote query plan might
happen to produce output that is ordered the way we need, but without
remote estimates we have no way of knowing that.
It might also be useful to request sorted output from the remote side
if it enables an efficient merge join, but this patch doesn't attempt
to handle that case.
Ashutosh Bapat with revisions by me. Also reviewed by Fabrízio de Royes
Mello and Jeevan Chalke.
Tom Lane [Tue, 3 Nov 2015 16:57:56 +0000 (11:57 -0500)]
Remove obsolete advice about doubling backslashes in regex escapes.
Standard-conforming literals have been the default for long enough that
it no longer seems necessary to go out of our way to tell people to write
regex escapes illegibly.
Tom Lane [Tue, 3 Nov 2015 16:49:21 +0000 (11:49 -0500)]
Code + docs review for unicode linestyle patch.
Fix some brain fade in commit a2dabf0e1dda93c8: erroneous variable names
in docs, rearrangements that made sentences less clear not more so,
undocumented and poorly-chosen-anyway API behaviors of subroutines,
bad grammar in error messages, copy-and-paste faults.
Robert Haas [Tue, 3 Nov 2015 14:12:52 +0000 (09:12 -0500)]
shm_mq: Third attempt at fixing nowait behavior in shm_mq_receive.
Commit a1480ec1d3bacb9acb08ec09f22bc25bc033115b purported to fix the
problems with commit b2ccb5f4e6c81305386edb34daf7d1d1e1ee112a, but it
didn't completely fix them. The problem is that the checks were
performed in the wrong order, leading to a race condition. If the
sender attached, sent a message, and detached after the receiver
called shm_mq_get_sender and before the receiver called
shm_mq_counterparty_gone, we'd incorrectly return SHM_MQ_DETACHED
before all messages were read. Repair by reversing the order of
operations, and add a long comment explaining why this new logic is
(hopefully) correct.
Robert Haas [Mon, 2 Nov 2015 23:11:29 +0000 (18:11 -0500)]
Fix problems with ParamListInfo serialization mechanism.
Commit d1b7c1ffe72e86932b5395f29e006c3f503bc53d introduced a mechanism
for serializing a ParamListInfo structure to be passed to a parallel
worker. However, this mechanism failed to handle external expanded
values, as pointed out by Noah Misch. Repair.
Moreover, plpgsql_param_fetch requires adjustment because the
serialization mechanism needs it to skip evaluating unused parameters
just as we would do when it is called from copyParamList, but params
== estate->paramLI in that case. To fix, make the bms_is_member test
in that function unconditional.
Finally, have setup_param_list set a new ParamListInfo field,
paramMask, to the parameters actually used in the expression, so that
we don't try to fetch those that are not needed when serializing a
parameter list. This isn't necessary for correctness, but it makes
the performance of the parallel executor code comparable to what we
do for cases involving cursors.
Design suggestions and extensive review by Noah Misch. Patch by me.
Kevin Grittner [Sat, 31 Oct 2015 19:43:34 +0000 (14:43 -0500)]
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.
Tom Lane [Fri, 30 Oct 2015 23:14:19 +0000 (19:14 -0400)]
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.)
Robert Haas [Fri, 30 Oct 2015 09:43:00 +0000 (10:43 +0100)]
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.
Tom Lane [Thu, 29 Oct 2015 22:54:35 +0000 (18:54 -0400)]
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.
Robert Haas [Tue, 27 Oct 2015 23:27:58 +0000 (00:27 +0100)]
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.
Alvaro Herrera [Tue, 27 Oct 2015 21:17:55 +0000 (18:17 -0300)]
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
Alvaro Herrera [Tue, 27 Oct 2015 18:06:50 +0000 (15:06 -0300)]
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.
Alvaro Herrera [Tue, 27 Oct 2015 16:20:40 +0000 (13:20 -0300)]
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.
Robert Haas [Fri, 23 Oct 2015 02:01:11 +0000 (22:01 -0400)]
shm_mq: Repair breakage from previous commit.
If the counterparty writes some data into the queue and then detaches,
it's wrong to return SHM_MQ_DETACHED right away. If we do that, we
fail to read whatever was written.
Robert Haas [Thu, 22 Oct 2015 20:33:30 +0000 (16:33 -0400)]
shm_mq: Fix failure to notice a dead counterparty when nowait is used.
The shm_mq mechanism was intended to optionally notice when the process
on the other end of the queue fails to attach to the queue. It does
this by allowing the user to pass a BackgroundWorkerHandle; if the
background worker in question is launched and dies without attaching
to the queue, then we know it never will. This logic works OK in
blocking mode, but when called with nowait = true we fail to notice
that this has happened due to an asymmetry in the logic. Repair.
Tom Lane [Thu, 22 Oct 2015 16:33:51 +0000 (09:33 -0700)]
Remove redundant CREATEUSER/NOCREATEUSER options in CREATE ROLE et al.
Once upon a time we did not have a separate CREATEROLE privilege, and
CREATEUSER effectively meant SUPERUSER. When we invented CREATEROLE
(in 8.1) we also added SUPERUSER so as to have a less confusing keyword
for this role property. However, we left CREATEUSER in place as a
deprecated synonym for SUPERUSER, because of backwards-compatibility
concerns. It's still there and is still confusing people, as for example
in bug #13694 from Justin Catterson. 9.6 will be ten years or so later,
which surely ought to be long enough to end the deprecation and just
remove these old keywords. Hence, do so.