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.
Commit 4a4e6893aa, 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.
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.
Peter Geoghegan
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.
Discovered by Jeff McCormick during testing.
Bug introduced by 9a08841.
Back-patch to 9.5
Previously, negative values were always displayed in bytes, regardless
of how large they were.
Adrian Vondendriesch, reviewed by Julien Rouhaud and myself
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.
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.
Report and patch by me. Review by Amit Kapila.
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.
Nathan Wagner, edited a bit by me
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.
Paul Ramsey, hacked up a bit more by me
Commit a1480ec1d3 purported to fix the
problems with commit b2ccb5f4e6, 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.
Commit d1b7c1ffe7 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.
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
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.)
Commit b0b0d84b3d 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.
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.
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 ccc4c07499. 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.
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
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
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.
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.
Reported off-list by Rushabh Lathia. Patch by me.
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.
Commit 816e336f12 added the wrong error
check to async.c; sending restrictions is restricted to the leader,
not altogether unsafe.
Commit 3bd909b220 added ExecShutdownNode
to traverse the planstate tree and call shutdown functions, but made
a Gather node, the only node that actually has such a function, abort
the tree traversal, which is wrong.
Commit bda76c1c8c caused both plus and
minus infinity to be rendered as "infinity", which is not only wrong
but inconsistent with the pre-9.4 behavior of to_json(). Fix that by
duplicating the coding in date_out/timestamp_out/timestamptz_out more
closely. Per bug #13687 from Stepan Perlov. Back-patch to 9.4, like
the previous commit.
In passing, also re-pgindent json.c, since it had gotten a bit messed up by
recent patches (and I was already annoyed by indentation-related problems
in back-patching this fix ...)
Per a report from Shay Rojansky, Npgsql sends ssl_renegotiation_limit=0
in the startup packet because it does not support renegotiation; other
clients which have not attempted to support renegotiation might well
behave similarly. The recent removal of this parameter forces them to
break compatibility with either current PostgreSQL versions, or
previous ones. Per discussion, the best solution is to accept the
parameter but only allow a value of 0.
Shay Rojansky, edited a little by me.
Commit 0e57b4d8bd contained some clever
logic that attempted to make sure that we couldn't get confused about
whether the last thing we cached was a strcoll() result or a strxfrm()
result, but it wasn't quite clever enough, because we can perform
further abbreviations after having already performed some comparisons.
Introduce an explicit flag in the hopes of making this watertight.
Peter Geoghegan, reviewed by me.
pg_regprefix was doing nothing with lookahead constraints, which would
be fine if it were the right kind of nothing, but it isn't: we have to
terminate our search for a fixed prefix, not just pretend the LACON arc
isn't there. Otherwise, if the current state has both a LACON outarc and a
single plain-color outarc, we'd falsely conclude that the color represents
an addition to the fixed prefix, and generate an extracted index condition
that restricts the indexscan too much. (See added regression test case.)
Terminating the search is conservative: we could traverse the LACON arc
(thus assuming that the constraint can be satisfied at runtime) and then
examine the outarcs of the linked-to state. But that would be a lot more
work than it seems worth, because writing a LACON followed by a single
plain character is a pretty silly thing to do.
This makes a difference only in rather contrived cases, but it's a bug,
so back-patch to all supported branches.
Using this API, one backend can set up a ParallelHeapScanDesc to
which multiple backends can then attach. Each tuple in the relation
will be returned to exactly one of the scanning backends. Only
forward scans are supported, and rescans must be carefully
coordinated.
This is not exposed to the planner or executor yet.
The original version of this code was written by me. Amit Kapila
reviewed it, tested it, and improved it, including adding support for
synchronized scans, per review comments from Jeff Davis. Extensive
testing of this and related patches was performed by Haribabu Kommi.
Final cleanup of this patch by me.
This may allow some callers to avoid the overhead involved in tearing
down a parallel context and then setting up a new one, which means
releasing the DSM and then allocating and populating a new one. I
suspect we'll want to revise the Gather node to make use of this new
capability, but even if not it may be useful elsewhere and requires
very little additional code.
Revert our previous addition of "all" flags to copyins() and copyouts();
they're no longer needed, and were never anything but an unsightly hack.
Improve a couple of infelicities in the REG_DEBUG code for dumping
the NFA data structure, including adding code to count the total
number of states and arcs.
Add a couple of missed error checks.
Add some more documentation in the README file, and some regression tests
illustrating cases that exceeded the state-count limit and/or took
unreasonable amounts of time before this set of patches.
Back-patch to all supported branches.
This code previously counted the number of NFA states it created, and
complained if a limit was exceeded, so as to prevent bizarre regex patterns
from consuming unreasonable time or memory. That's fine as far as it went,
but the code paid no attention to how many arcs linked those states. Since
regexes can be contrived that have O(N) states but will need O(N^2) arcs
after fixempties() processing, it was still possible to blow out memory,
and take a long time doing it too. To fix, modify the bookkeeping to count
space used by both states and arcs.
I did not bother with including the "color map" in the accounting; it
can only grow to a few megabytes, which is not a lot in comparison to
what we're allowing for states+arcs (about 150MB on 64-bit machines
or half that on 32-bit machines).
Looking at some of the larger real-world regexes captured in the Tcl
regression test suite suggests that the most that is likely to be needed
for regexes found in the wild is under 10MB, so I believe that the current
limit has enough headroom to make it okay to keep it as a hard-wired limit.
In connection with this, redefine REG_ETOOBIG as meaning "regular
expression is too complex"; the previous wording of "nfa has too many
states" was already somewhat inapropos because of the error code's use
for stack depth overrun, and it was not very user-friendly either.
Back-patch to all supported branches.
The previous coding would create a new intermediate state every time it
wanted to interchange the ordering of two constraint arcs. Certain regex
features such as \Y can generate large numbers of parallel constraint arcs,
and if we needed to reorder the results of that, we created unreasonable
numbers of intermediate states. To improve matters, keep a list of
already-created intermediate states associated with the state currently
being considered by the outer loop; we can re-use such states to place all
the new arcs leading to the same destination or source.
I also took the trouble to redefine push() and pull() to have a less risky
API: they no longer delete any state or arc that the caller might possibly
have a pointer to, except for the specifically-passed constraint arc.
This reduces the risk of re-introducing the same type of error seen in
the failed patch for CVE-2007-4772.
Back-patch to all supported branches.
The previous coding took something like O(N^4) time to fully process a
chain of N EMPTY arcs. We can't really do much better than O(N^2) because
we have to insert about that many arcs, but we can do lots better than
what's there now. The win comes partly from using mergeins() to amortize
de-duplication of arcs across multiple source states, and partly from
exploiting knowledge of the ordering of arcs for each state to avoid
looking at arcs we don't need to consider during the scan. We do have
to be a bit careful of the possible reordering of arcs introduced by
the sort-merge coding of the previous commit, but that's not hard to
deal with.
Back-patch to all supported branches.
Change the singly-linked in-arc and out-arc lists to be doubly-linked,
so that arc deletion is constant time rather than having worst-case time
proportional to the number of other arcs on the connected states.
Modify the bulk arc transfer operations copyins(), copyouts(), moveins(),
moveouts() so that they use a sort-and-merge algorithm whenever there's
more than a small number of arcs to be copied or moved. The previous
method is O(N^2) in the number of arcs involved, because it performs
duplicate checking independently for each copied arc. The new method may
change the ordering of existing arcs for the destination state, but nothing
really cares about that.
Provide another bulk arc copying method mergeins(), which is unused as
of this commit but is needed for the next one. It basically is like
copyins(), but the source arcs might not all come from the same state.
Replace the O(N^2) bubble-sort algorithm used in carcsort() with a qsort()
call.
These changes greatly improve the performance of regex compilation for
large or complex regexes, at the cost of extra space for arc storage during
compilation. The original tradeoff was probably fine when it was made, but
now we care more about speed and less about memory consumption.
Back-patch to all supported branches.
It's possible to construct regular expressions that contain loops of
constraint arcs (that is, ^ $ AHEAD BEHIND or LACON arcs). There's no use
in fully traversing such a loop at execution, since you'd just end up in
the same NFA state without having consumed any input. Worse, such a loop
leads to infinite looping in the pullback/pushfwd stage of compilation,
because we keep pushing or pulling the same constraints around the loop
in a vain attempt to move them to the pre or post state. Such looping was
previously recognized in CVE-2007-4772; but the fix only handled the case
of trivial single-state loops (that is, a constraint arc leading back to
its source state) ... and not only that, it was incorrect even for that
case, because it broke the admittedly-not-very-clearly-stated API contract
of the pull() and push() subroutines. The first two regression test cases
added by this commit exhibit patterns that result in assertion failures
because of that (though there seem to be no ill effects in non-assert
builds). The other new test cases exhibit multi-state constraint loops;
in an unpatched build they will run until the NFA state-count limit is
exceeded.
To fix, remove the code added for CVE-2007-4772, and instead create a
general-purpose constraint-loop-breaking phase of regex compilation that
executes before we do pullback/pushfwd. Since we never need to traverse
a constraint loop fully, we can just break the loop at any chosen spot,
if we add clone states that can replicate any sequence of arc transitions
that would've traversed just part of the loop.
Also add some commentary clarifying why we have to have all these
machinations in the first place.
This class of problems has been known for some time --- we had a report
from Marc Mamin about two years ago, for example, and there are related
complaints in the Tcl bug tracker. I had discussed a fix of this kind
off-list with Henry Spencer, but didn't get around to doing something
about it until the issue was rediscovered by Greg Stark recently.
Back-patch to all supported branches.
Prior to commit 0709b7ee72, access to
variables within a spinlock-protected critical section had to be done
through a volatile pointer, but that should no longer be necessary.
Michael Paquier
Prior to commit 0709b7ee72, access to
variables within a spinlock-protected critical section had to be done
through a volatile pointer, but that should no longer be necessary.
Thomas Munro
In order for this to be safe, the code which hands true serializability
will need to taught that the SIRead locks taken by a parallel worker
pertain to the same transaction as those taken by the parallel leader.
Some further changes may be needed as well. Until the necessary
adaptations are made, don't generate parallel plans in serializable
mode, and if a previously-generated parallel plan is used after
serializable mode has been activated, run it serially.
This fixes a bug in commit 7aea8e4f2d.
In the previous coding, before returning from ExecutorRun, we'd shut
down all parallel workers. This was dead wrong if ExecutorRun was
called with a non-zero tuple count; it had the effect of truncating
the query output. To fix, give ExecutePlan control over whether to
enter parallel mode, and have it refuse to do so if the tuple count
is non-zero. Rewrite the Gather logic so that it can cope with being
called outside parallel mode.
Commit 7aea8e4f2d is largely to blame
for this problem, though this patch modifies some subsequently-committed
code which relied on the guarantees it purported to make.
Commit 7aea8e4f2d was overoptimistic
about the degree of safety associated with running various functions
in parallel mode. Functions that take a table name or OID as an
argument are at least parallel-restricted, because the table might be
temporary, and we currently don't allow parallel workers to touch
temporary tables. Functions that take a query as an argument are
outright unsafe, because the query could be anything, including a
parallel-unsafe query.
Also, the queue of pending notifications is backend-private, so adding
to it from a worker doesn't behave correctly. We could fix this by
transferring the worker's queue of pending notifications to the master
during worker cleanup, but that seems like more trouble than it's
worth for now. In addition to adjusting the pg_proc.h markings, also
add an explicit check for this in async.c.
check_role() tries to verify that the user has permission to become the
requested role, but this is inappropriate in a parallel worker, which
needs to exactly recreate the master's authorization settings. So skip
the check in that case.
This fixes a bug in commit 924bcf4f16.
Starting a parallel worker transaction changes our notion of which XIDs
are in-progress or committed, and our notion of the current command
counter ID. Therefore, our view of these caches prior to starting
this transaction may no longer valid. Defend against that by clearing
them.
This fixes a bug in commit 924bcf4f16.
Commit 924bcf4f16 failed to enforce
parallel mode checks during the commit of a parallel worker, because
we exited parallel mode prior to ending the transaction so that we
could pop the active snapshot. Re-establish parallel mode during
parallel worker commit. Without this, it's far too easy for unsafe
actions during the pre-commit sequence to crash the server instead of
hitting the error checks as intended.
Just to be extra paranoid, adjust a couple of the sanity checks in
xact.c to check not only IsInParallelMode() but also
IsParallelWorker().
Commit 924bcf4f16 correctly forbade
parallel workers to modify the command counter while in parallel mode,
but it inexplicably neglected to actually transfer the current command
counter from leader to workers. This can result in the workers seeing
a different set of tuples from the leader, which is bad. Repair.
Commit 2bd9e412f9 introduced a mechanism
for relaying protocol messages from a background worker to another
backend via a shm_mq. However, there was no provision for shutting
down the communication channel. Therefore, a protocol message sent
late in the shutdown sequence, such as a DEBUG message resulting from
cranking up log_min_messages, could crash the server. To fix, install
an on_dsm_detach callback that disables sending messages to the shm_mq
when the associated DSM is detached.
The function failed to adhere to its specification that the "tcategory"
argument should not be examined when the input value is NULL. This
resulted in a crash in some cases. Per bug #13680 from Boyko Yordanov.
In passing, re-pgindent some recent changes in jsonb.c, and fix a rather
ungrammatical comment.
Diagnosis and patch by Michael Paquier, cosmetic changes by me
This fixes a long-standing bug which was discovered while investigating
the interaction between the new join pushdown code and the EvalPlanQual
machinery: if a ForeignScan appears on the inner side of a paramaterized
nestloop, an EPQ recheck would re-return the original tuple even if
it no longer satisfied the pushed-down quals due to changed parameter
values.
This fix adds a new member to ForeignScan and ForeignScanState and a
new argument to make_foreignscan, and requires changes to FDWs which
push down quals to populate that new argument with a list of quals they
have chosen to push down. Therefore, I'm only back-patching to 9.5,
even though the bug is not new in 9.5.
Etsuro Fujita, reviewed by me and by Kyotaro Horiguchi.
Per Mark Johnston, this resolves a build error on FreeBSD related
to the fact that dtrace is modifying the generated object files
under the hood. Consequently, without this, dtrace gets reinvoked
at install time because the object files have been updated. This
is a pretty hacky fix, but it shouldn't hurt anything, and it's
not clear that it's worth expending any more effort for a feature
that not too many people are using.
Patch by Mark Johnston. This is arguably back-patchable as a bug
fix to the build system, but I'm not certain enough of the
consequences to try that. Let's see what the buildfarm (and
our packagers) think of this change on master first.
Postmaster child processes that aren't supposed to be attached to shared
memory were not bothering to close the shared memory mapping handle they
inherit from the postmaster process. That's mostly harmless, since the
handle vanishes anyway when the child process exits -- but the syslogger
process, if used, doesn't get killed and restarted during recovery from a
backend crash. That meant that Windows doesn't see the shared memory
mapping as becoming free, so it doesn't delete it and the postmaster is
unable to create a new one, resulting in failure to recover from crashes
whenever logging_collector is turned on.
Per report from Dmitry Vasilyev. It's a bit astonishing that we'd not
figured this out long ago, since it's been broken from the very beginnings
of out native Windows support; probably some previously-unexplained trouble
reports trace to this.
A secondary problem is that on Cygwin (perhaps only in older versions?),
exec() may not detach from the shared memory segment after all, in which
case these child processes did remain attached to shared memory, posing
the risk of an unexpected shared memory clobber if they went off the rails
somehow. That may be a long-gone bug, but we can deal with it now if it's
still live, by detaching within the infrastructure introduced here to deal
with closing the handle.
Back-patch to all supported branches.
Tom Lane and Amit Kapila
Many functions stored JsonbIteratorToken values in variables of other
integer types. Also, standardize order relative to other declarations.
Expect compilers to generate the same code before and after this change.
Cache strxfrm() blobs across calls made to the text SortSupport
abbreviation routine. This can speed up sorting if the same string
needs to be abbreviated many times in a row.
Also, cache the result of the previous strcoll() comparison, so that
if we're asked to compare the same strings agin, we do need to call
strcoll() again.
Perhaps surprisingly, these optimizations don't seem to hurt even when
they don't help. memcmp() is really cheap compared to strcoll() or
strxfrm().
Peter Geoghegan, reviewed by me.
If we do some byte-swapping while abbreviating, we can do comparisons
using integer arithmetic rather than memcmp.
Peter Geoghegan, reviewed and slightly revised by me.
This flag has proven to be a recipe for bugs, and it doesn't seem like
it can really buy anything in terms of performance. So let's just
*always* set the process latch when we receive SIGUSR1 instead of
trying to do it only when needed.
Per my recent proposal on pgsql-hackers.
During expand_security_quals, we take the security barrier quals on an
RTE and create a subquery which evaluates the quals. During this, we
have to replace any variables in the outer query which refer to the
original RTE with references to the columns from the subquery.
We need to also perform that replacement for any Vars in the
append_rel_list.
Only backpatching to 9.5 as we only go through this process in 9.4 for
auto-updatable security barrier views, which UNION ALL queries aren't.
Discovered by Haribabu Kommi
Patch by Dean Rasheed
For some reason, neither of the compilers I usually use noticed the
uninitialized-variable problem I introduced in commit 7e2a18a916.
That's hardly a good enough excuse though. Committing with brown paper bag
on head.
In addition to putting the operations in the right order, move the
declaration of "now" inside the loop; there's no need for it to be
outside, and that does wake up older gcc enough to notice any similar
future problem.
Back-patch to 9.4; earlier versions lack the time-to-SIGKILL stanza
so there's no bug.
The postmaster now checks every minute or so (worst case, at most two
minutes) that postmaster.pid is still there and still contains its own PID.
If not, it performs an immediate shutdown, as though it had received
SIGQUIT.
The original goal behind this change was to ensure that failed buildfarm
runs would get fully cleaned up, even if the test scripts had left a
postmaster running, which is not an infrequent occurrence. When the
buildfarm script removes a test postmaster's $PGDATA directory, its next
check on postmaster.pid will fail and cause it to exit. Previously, manual
intervention was often needed to get rid of such orphaned postmasters,
since they'd block new test postmasters from obtaining the expected socket
address.
However, by checking postmaster.pid and not something else, we can provide
additional robustness: manual removal of postmaster.pid is a frequent DBA
mistake, and now we can at least limit the damage that will ensue if a new
postmaster is started while the old one is still alive.
Back-patch to all supported branches, since we won't get the desired
improvement in buildfarm reliability otherwise.
Prior to commit 0709b7ee72, access to
variables within a spinlock-protected critical section had to be done
through a volatile pointer, but that should no longer be necessary.
This continues work begun in df4077cda2
and 6ba4ecbf47.
Thomas Munro and Michael Paquier
For time masks, like HH24, MI, SS, CC, MM, do not count the negative
sign as part of the zero-padding length specified by the mask, e.g. have
to_char('-4 years'::interval, 'YY') return '-04', not '-4'.
Report by Craig Ringer
The tsquery, ltxtquery and query_int data types have a common ancestor.
Having acquired check_stack_depth() calls independently, each was
missing at least one call. Back-patch to 9.0 (all supported versions).
A range type can name another range type as its subtype, and a record
type can bear a column of another record type. Consequently, functions
like range_cmp() and record_recv() are recursive. Functions at risk
include operator family members and referents of pg_type regproc
columns. Treat as recursive any such function that looks up and calls
the same-purpose function for a record column type or the range subtype.
Back-patch to 9.0 (all supported versions).
An array type's element type is never itself an array type, so array
functions are unaffected. Recursion depth proportional to array
dimensionality, found in array_dim_to_jsonb(), is fine thanks to MAXDIM.
Sufficiently-deep recursion heretofore elicited a SIGSEGV. If an
application constructs PostgreSQL json or jsonb values from arbitrary
user input, application users could have exploited this to terminate all
active database connections. That applies to 9.3, where the json parser
adopted recursive descent, and later versions. Only row_to_json() and
array_to_json() were at risk in 9.2, both in a non-security capacity.
Back-patch to 9.2, where the json type was introduced.
Oskari Saarenmaa, reviewed by Michael Paquier.
Security: CVE-2015-5289
Similar to 7d8db3e, given that INSERT+RETURNING requires SELECT rights
on the table, apply the SELECT policies as WCOs to the tuples being
inserted. Apply the same logic to UPDATE+RETURNING.
Back-patch to 9.5 where RLS was added.
The WithCheckOptions list in Query are only populated during rewrite and
do not need to be written out or read in as part of a Query structure.
Further, move WithCheckOptions to the bottom and add comments to clarify
that it is only populated during rewrite.
Back-patch to 9.5 with a catversion bump, as we are still in alpha.
In 020235a575 I lowered the autovacuum_*freeze_max_age minimums to
allow for easier testing of wraparounds. I did not touch the
corresponding per-table limits. While those don't matter for the purpose
of wraparound, it seems more consistent to lower them as well.
It's noteworthy that the previous reloption lower limit for
autovacuum_multixact_freeze_max_age was too high by one magnitude, even
before 020235a575.
Discussion: 26377.1443105453@sss.pgh.pa.us
Backpatch: back to 9.0 (in parts), like the prior patch
To allow users to force RLS to always be applied, even for table owners,
add ALTER TABLE .. FORCE ROW LEVEL SECURITY.
row_security=off overrides FORCE ROW LEVEL SECURITY, to ensure pg_dump
output is complete (by default).
Also add SECURITY_NOFORCE_RLS context to avoid data corruption when
ALTER TABLE .. FORCE ROW SECURITY is being used. The
SECURITY_NOFORCE_RLS security context is used only during referential
integrity checks and is only considered in check_enable_rls() after we
have already checked that the current user is the owner of the relation
(which should always be the case during referential integrity checks).
Back-patch to 9.5 where RLS was added.
On reflection, the submitted patch didn't really work to prevent the
request size from exceeding MaxAllocSize, because of the fact that we'd
happily round nbuckets up to the next power of 2 after we'd limited it to
max_pointers. The simplest way to enforce the limit correctly is to
round max_pointers down to a power of 2 when it isn't one already.
(Note that the constraint to INT_MAX / 2, if it were doing anything useful
at all, is properly applied after that.)
Limit the size of the hashtable pointer array to not more than
MaxAllocSize, per reports from Kouhei Kaigai and others of "invalid memory
alloc request size" failures. There was discussion of allowing the array
to get larger than that by using the "huge" palloc API, but so far no proof
that that is actually a good idea, and at this point in the 9.5 cycle major
changes from old behavior don't seem like the way to go.
Fix a rather serious secondary bug in the new code, which was that it
didn't ensure nbuckets remained a power of 2 when recomputing it for the
multiple-batch case.
Clean up sloppy division of labor between ExecHashIncreaseNumBuckets and
its sole call site.
Null path elements and, where the object is an array, invalid integer
elements now cause an error.
Incorrect behaviour noted by Thom Brown, patch from Dmitry Dolgov.
Backpatch to 9.5 where jsonb_set was introduced
Specifically, make its effect independent from the row_security GUC, and
make it affect permission checks pertinent to views the BYPASSRLS role
owns. The row_security GUC thereby ceases to change successful-query
behavior; it can only make a query fail with an error. Back-patch to
9.5, where BYPASSRLS was introduced.
Without CASCADE, if an extension has an unfullfilled dependency on
another extension, CREATE EXTENSION ERRORs out with "required extension
... is not installed". That is annoying, especially when that dependency
is an implementation detail of the extension, rather than something the
extension's user can make sense of.
In addition to CASCADE this also includes a small set of regression
tests around CREATE EXTENSION.
Author: Petr Jelinek, editorialized by Michael Paquier, Andres Freund
Reviewed-By: Michael Paquier, Andres Freund, Jeff Janes
Discussion: 557E0520.3040800@2ndquadrant.com
The existing hint talked about "may only contain letters", but the
actual requirement is more strict: only lower case letters are allowed.
Reported-By: Rushabh Lathia
Author: Rushabh Lathia
Discussion: AGPqQf2x50qcwbYOBKzb4x75sO_V3g81ZsA8+Ji9iN5t_khFhQ@mail.gmail.com
Backpatch: 9.4-, where replication slots were added
Four related issues:
1) attnos/varnos/resnos for EXCLUDED were out of sync when a column
after one dropped in the underlying relation was referenced.
2) References to whole-row variables (i.e. EXCLUDED.*) lead to errors.
3) It was possible to reference system columns in the EXCLUDED pseudo
relations, even though they would not have valid contents.
4) References to EXCLUDED were rewritten by the RLS machinery, as
EXCLUDED was treated as if it were the underlying relation.
To fix the first two issues, generate the excluded targetlist with
dropped columns in mind and add an entry for whole row
variables. Instead of unconditionally adding a wholerow entry we could
pull up the expression if needed, but doing it unconditionally seems
simpler. The wholerow entry is only really needed for ruleutils/EXPLAIN
support anyway.
The remaining two issues are addressed by changing the EXCLUDED RTE to
have relkind = composite. That fits with EXCLUDED not actually being a
real relation, and allows to treat it differently in the relevant
places. scanRTEForColumn now skips looking up system columns when the
RTE has a composite relkind; fireRIRrules() already had a corresponding
check, thereby preventing RLS expansion on EXCLUDED.
Also add tests for these issues, and improve a few comments around
excluded handling in setrefs.c.
Reported-By: Peter Geoghegan, Geoff Winkless
Author: Andres Freund, Amit Langote, Peter Geoghegan
Discussion: CAEzk6fdzJ3xYQZGbcuYM2rBd2BuDkUksmK=mY9UYYDugg_GgZg@mail.gmail.com,
CAM3SWZS+CauzbiCEcg-GdE6K6ycHE_Bz6Ksszy8AoixcMHOmsA@mail.gmail.com
Backpatch: 9.5, where ON CONFLICT was introduced
Some of the functions in regex compilation and execution recurse, and
therefore could in principle be driven to stack overflow. The Tcl crew
has seen this happen in practice in duptraverse(), though their fix was
to put in a hard-wired limit on the number of recursive levels, which is
not too appetizing --- fortunately, we have enough infrastructure to check
the actually available stack. Greg Stark has also seen it in other places
while fuzz testing on a machine with limited stack space. Let's put guards
in to prevent crashes in all these places.
Since the regex code would leak memory if we simply threw elog(ERROR),
we have to introduce an API that checks for stack depth without throwing
such an error. Fortunately that's not difficult.
In cfindloop(), if the initial call to shortest() reports that a
zero-length match is possible at the current search start point, but then
it is unable to construct any actual match to that, it'll just loop around
with the same start point, and thus make no progress. We need to force the
start point to be advanced. This is safe because the loop over "begin"
points has already tried and failed to match starting at "close", so there
is surely no need to try that again.
This bug was introduced in commit e2bd904955,
wherein we allowed continued searching after we'd run out of match
possibilities, but evidently failed to think hard enough about exactly
where we needed to search next.
Because of the way this code works, such a match failure is only possible
in the presence of backrefs --- otherwise, shortest()'s judgment that a
match is possible should always be correct. That probably explains how
come the bug has escaped detection for several years.
The actual fix is a one-liner, but I took the trouble to add/improve some
comments related to the loop logic.
After fixing that, the submitted test case "()*\1" didn't loop anymore.
But it reported failure, though it seems like it ought to match a
zero-length string; both Tcl and Perl think it does. That seems to be from
overenthusiastic optimization on my part when I rewrote the iteration match
logic in commit 173e29aa5deefd9e71c183583ba37805c8102a72: we can't just
"declare victory" for a zero-length match without bothering to set match
data for capturing parens inside the iterator node.
Per fuzz testing by Greg Stark. The first part of this is a bug in all
supported branches, and the second part is a bug since 9.2 where the
iteration rewrite happened.
Commit 9662143f0c added infrastructure to
allow regular-expression operations to be terminated early in the event
of SIGINT etc. However, fuzz testing by Greg Stark disclosed that there
are still cases where regex compilation could run for a long time without
noticing a cancel request. Specifically, the fixempties() phase never
adds new states, only new arcs, so it doesn't hit the cancel check I'd put
in newstate(). Add one to newarc() as well to cover that.
Some experimentation of my own found that regex execution could also run
for a long time despite a pending cancel. We'd put a high-level cancel
check into cdissect(), but there was none inside the core text-matching
routines longest() and shortest(). Ordinarily those inner loops are very
very fast ... but in the presence of lookahead constraints, not so much.
As a compromise, stick a cancel check into the stateset cache-miss
function, which is enough to guarantee a cancel check at least once per
lookahead constraint test.
Making this work required more attention to error handling throughout the
regex executor. Henry Spencer had apparently originally intended longest()
and shortest() to be incapable of incurring errors while running, so
neither they nor their subroutines had well-defined error reporting
behaviors. However, that was already broken by the lookahead constraint
feature, since lacon() can surely suffer an out-of-memory failure ---
which, in the code as it stood, might never be reported to the user at all,
but just silently be treated as a non-match of the lookahead constraint.
Normalize all that by inserting explicit error tests as needed. I took the
opportunity to add some more comments to the code, too.
Back-patch to all supported branches, like the previous patch.
Tom Lane
Robert Haas
Stephen Frost
Peter Eisentraut
Kevin Grittner
Alvaro Herrera
Noah Misch
Bruce Momjian
Andres Freund
Andrew Dunstan