When REASSIGN and ALTER OWNER TO are used, both the object owner and ACL
list should be changed from the old owner to the new owner. This patch
fixes types, foreign data wrappers, and foreign servers to change their
ACL list properly; they already changed owners properly.
Report by Alexey Bashtanov
This is a backpatch of commit 59367fdf97 (for bug #9923) by Bruce
Momjian to branches 9.1 - 9.4; it wasn't backpatched originally out of
concerns that it would create a backwards compatibility problem, but per
discussion related to bug #13666 that turns out to have been misguided.
(Therefore, the entry in the 9.5 release notes should be removed.)
Note that 9.1 didn't have privileges on types (which were introduced by
commit 729205571e), so this commit only changes foreign-data related
objects in that branch.
Discussion: http://www.postgresql.org/message-id/20151216224004.GL2618@alvherre.pgsqlhttp://www.postgresql.org/message-id/10227.1450373793@sss.pgh.pa.us
Rather than expect the Query returned by get_view_query() to be
read-only and then copy bits and pieces of it out, simply copy the
entire structure when we get it. This addresses an issue where
AcquireRewriteLocks, which is called by acquireLocksOnSubLinks(),
scribbles on the parsetree passed in, which was actually an entry
in relcache, leading to segfaults with certain view definitions.
This also future-proofs us a bit for anyone adding more code to this
path.
The acquireLocksOnSubLinks() was added in commit c3e0ddd40.
Back-patch to 9.3 as that commit was.
psql offered USING, WHERE, and SET in this context, but SET is not a valid
possibility here. Seems to have been a thinko in commit f5ab0a14ea
which added DELETE's USING option.
Previously the completion used the wrong word to match 'BY'. This was
introduced brokenly, in b2de2a. While at it, also add completion of
IN TABLESPACE ... OWNED BY and fix comments referencing nonexistent
syntax.
Reported-By: Michael Paquier
Author: Michael Paquier and Andres Freund
Discussion: CAB7nPqSHDdSwsJqX0d2XzjqOHr==HdWiubCi4L=Zs7YFTUne8w@mail.gmail.com
Backpatch: 9.4, like the commit introducing the bug
Turns out we must set rl_basic_word_break_characters *before* we call
rl_initialize() the first time, because it will quietly copy that value
elsewhere --- but only on the first call. (Love these undocumented
dependencies.) I broke this yesterday in commit 2ec477dc8108339d;
like that commit, back-patch to all active branches. Per report from
Pavel Stehule.
It emerges that libreadline doesn't notice terminal window size change
events unless they occur while collecting input. This is easy to stumble
over if you resize the window while using a pager to look at query output,
but it can be demonstrated without any pager involvement. The symptom is
that queries exceeding one line are misdisplayed during subsequent input
cycles, because libreadline has the wrong idea of the screen dimensions.
The safest, simplest way to fix this is to call rl_reset_screen_size()
just before calling readline(). That causes an extra ioctl(TIOCGWINSZ)
for every command; but since it only happens when reading from a tty, the
performance impact should be negligible. A more valid objection is that
this still leaves a tiny window during entry to readline() wherein delivery
of SIGWINCH will be missed; but the practical consequences of that are
probably negligible. In any case, there doesn't seem to be any good way to
avoid the race, since readline exposes no functions that seem safe to call
from a generic signal handler --- rl_reset_screen_size() certainly isn't.
It turns out that we also need an explicit rl_initialize() call, else
rl_reset_screen_size() dumps core when called before the first readline()
call.
rl_reset_screen_size() is not present in old versions of libreadline,
so we need a configure test for that. (rl_initialize() is present at
least back to readline 4.0, so we won't bother with a test for it.)
We would need a configure test anyway since libedit's emulation of
libreadline doesn't currently include such a function. Fortunately,
libedit seems not to have any corresponding bug.
Merlin Moncure, adjusted a bit by me
Apparently, there are bugs in this code that cause it to loop endlessly.
That bug still needs more research, but in the meantime it's clear that
the loop is missing a check for interrupts so that it can be cancelled
timely.
Backpatch to 9.1 -- this has been missing since 49475aab8d.
If libpq ran out of memory while constructing the result set, it would hang,
waiting for more data from the server, which might never arrive. To fix,
distinguish between out-of-memory error and not-enough-data cases, and give
a proper error message back to the client on OOM.
There are still similar issues in handling COPY start messages, but let's
handle that as a separate patch.
Michael Paquier, Amit Kapila and me. Backpatch to all supported versions.
e3f4cfc7 introduced a LWLockHeldByMe() call, without the corresponding
Assert() surrounding it.
Spotted by Coverity.
Backpatch: 9.1+, like the previous commit
This has worked that way for a long time, maybe always, but you would
not have known it from the documentation. Also back-patch the notes
I added to HEAD earlier today about behavior of the "-f -" switch,
which likewise have been valid for many releases.
These would leak random xlog positions if a walsender used for backup would
a walsender slot previously used by a replication walsender.
In passing also fix a couple of cases where the xlog pointer is directly
compared to zero instead of using XLogRecPtrIsInvalid, noted by
Michael Paquier.
Changing the tablespace of an unlogged relation did not WAL log the
creation and content of the init fork. Thus, after a standby is
promoted, unlogged relation cannot be accessed anymore, with errors
like:
ERROR: 58P01: could not open file "pg_tblspc/...": No such file or directory
Additionally the init fork was not synced to disk, independent of the
configured wal_level, a relatively small durability risk.
Investigation of that problem also brought to light that, even for
permanent relations, the creation of !main forks was not WAL logged,
i.e. no XLOG_SMGR_CREATE record were emitted. That mostly turns out not
to be a problem, because these files were created when the actual
relation data is copied; nonexistent files are not treated as an error
condition during replay. But that doesn't work for empty files, and
generally feels a bit haphazard. Luckily, outside init and main forks,
empty forks don't occur often or are not a problem.
Add the required WAL logging and syncing to disk.
Reported-By: Michael Paquier
Author: Michael Paquier and Andres Freund
Discussion: 20151210163230.GA11331@alap3.anarazel.de
Backpatch: 9.1, where unlogged relations were introduced
Recent releases of libxml2 do not provide error context reports for errors
detected at the very end of the input string. This appears to be a bug, or
at least an infelicity, introduced by the fix for libxml2's CVE-2015-7499.
We can hope that this behavioral change will get undone before too long;
but the security patch is likely to spread a lot faster/further than any
follow-on cleanup, which means this behavior is likely to be present in the
wild for some time to come. As a stopgap, add a variant regression test
expected-file that matches what you get with a libxml2 that acts this way.
As reported in bug #13809 by Alexander Ashurkov, the code for REASSIGN
OWNED hadn't gotten word about user mappings. Deal with them in the
same way default ACLs do, which is to ignore them altogether; they are
handled just fine by DROP OWNED. The other foreign object cases are
already handled correctly by both commands.
Also add a REASSIGN OWNED statement to foreign_data test to exercise the
foreign data objects. (The changes are just before the "cleanup" phase,
so it shouldn't remove any existing live test.)
Reported by Alexander Ashurkov, then independently by Jaime Casanova.
More fuzz testing by Andreas Seltenreich exposed that the planner did not
cope well with chains of lateral references. If relation X references Y
laterally, and Y references Z laterally, then we will have to scan X on the
inside of a nestloop with Z, so for all intents and purposes X is laterally
dependent on Z too. The planner did not understand this and would generate
intermediate joins that could not be used. While that was usually harmless
except for wasting some planning cycles, under the right circumstances it
would lead to "failed to build any N-way joins" or "could not devise a
query plan" planner failures.
To fix that, convert the existing per-relation lateral_relids and
lateral_referencers relid sets into their transitive closures; that is,
they now show all relations on which a rel is directly or indirectly
laterally dependent. This not only fixes the chained-reference problem
but allows some of the relevant tests to be made substantially simpler
and faster, since they can be reduced to simple bitmap manipulations
instead of searches of the LateralJoinInfo list.
Also, when a PlaceHolderVar that is due to be evaluated at a join contains
lateral references, we should treat those references as indirect lateral
dependencies of each of the join's base relations. This prevents us from
trying to join any individual base relations to the lateral reference
source before the join is formed, which again cannot work.
Andreas' testing also exposed another oversight in the "dangerous
PlaceHolderVar" test added in commit 85e5e222b1. Simply rejecting
unsafe join paths in joinpath.c is insufficient, because in some cases
we will end up rejecting *all* possible paths for a particular join, again
leading to "could not devise a query plan" failures. The restriction has
to be known also to join_is_legal and its cohort functions, so that they
will not select a join for which that will happen. I chose to move the
supporting logic into joinrels.c where the latter functions are.
Back-patch to 9.3 where LATERAL support was introduced.
At the end of crash recovery, unlogged relations are reset to the empty
state, using their init fork as the template. The init fork is copied to
the main fork without going through shared buffers. Unfortunately WAL
replay so far has not necessarily flushed writes from shared buffers to
disk at that point. In normal crash recovery, and before the
introduction of 'fast promotions' in fd4ced523 / 9.3, the
END_OF_RECOVERY checkpoint flushes the buffers out in time. But with
fast promotions that's not the case anymore.
To fix, force WAL writes targeting the init fork to be flushed
immediately (using the new FlushOneBuffer() function). In 9.5+ that
flush can centrally be triggered from the code dealing with restoring
full page writes (XLogReadBufferForRedoExtended), in earlier releases
that responsibility is in the hands of XLOG_HEAP_NEWPAGE's replay
function.
Backpatch to 9.1, even if this currently is only known to trigger in
9.3+. Flushing earlier is more robust, and it is advantageous to keep
the branches similar.
Typical symptoms of this bug are errors like
'ERROR: index "..." contains unexpected zero page at block 0'
shortly after promoting a node.
Reported-By: Thom Brown
Author: Andres Freund and Michael Paquier
Discussion: 20150326175024.GJ451@alap3.anarazel.de
Backpatch: 9.1-
While convincing myself that commit 7e19db0c09 would solve both of
the problems recently reported by Andreas Seltenreich, I realized that
add_paths_to_joinrel's handling of LATERAL restrictions could be made
noticeably simpler and faster if we were to retain the minimum possible
parameterization for each joinrel (that is, the set of relids supplying
unsatisfied lateral references in it). We already retain that for
baserels, in RelOptInfo.lateral_relids, so we can use that field for
joinrels too.
This is a back-port of commit edca44b152.
I originally intended not to back-patch that, but additional hacking
in this area turns out to be needed, making it necessary not optional
to compute lateral_relids for joinrels. In preparation for those fixes,
sync the relevant code with HEAD as much as practical. (I did not risk
rearranging fields of RelOptInfo in released branches, however.)
For unclear reasons, this function doesn't always read the expected data
in some old Perl versions. Rewriting it to avoid use of ARGV seems to
dodge the problem, and this version is clearer anyway if you ask me.
In passing, also improve error message in adjacent append_to_file function.
It was possible for the planner to decide to join a LATERAL subquery to
the outer side of an outer join before the outer join itself is completed.
Normally that's fine because of the associativity rules, but it doesn't
work if the subquery contains a lateral reference to the inner side of the
outer join. In such a situation the outer join *must* be done first.
join_is_legal() missed this consideration and would allow the join to be
attempted, but the actual path-building code correctly decided that no
valid join path could be made, sometimes leading to planner errors such as
"failed to build any N-way joins".
Per report from Andreas Seltenreich. Back-patch to 9.3 where LATERAL
support was added.
This way, existing .gitignore entries and makefile clean actions will
automatically apply to the tempdir, should it survive a TAP test run
(which can happen if the user control-C's out of the run, for example).
Michael Paquier, per a complaint from me
In commit 1ea0c73c2 I added a section to user-manag.sgml about how to drop
roles that own objects; but as pointed out by Stephen Frost, I neglected
that shared objects (databases or tablespaces) may need special treatment.
Fix that. Back-patch to supported versions, like the previous patch.
We tried to fetch statistics data from the index metapage, which does not
work if the index isn't actually present. If the index is hypothetical,
instead extrapolate some plausible internal statistics based on the index
page count provided by the index-advisor plugin.
There was already some code in gincostestimate() to invent internal stats
in this way, but since it was only meant as a stopgap for pre-9.1 GIN
indexes that hadn't been vacuumed since upgrading, it was pretty crude.
If we want it to support index advisors, we should try a little harder.
A small amount of testing says that it's better to estimate the entry pages
as 90% of the index, not 100%. Also, estimating the number of entries
(keys) as equal to the heap tuple count could be wildly wrong in either
direction. Instead, let's estimate 100 entries per entry page.
Perhaps someday somebody will want the index advisor to be able to provide
these numbers more directly, but for the moment this should serve.
Problem report and initial patch by Julien Rouhaud; modified by me to
invent less-bogus internal statistics. Back-patch to all supported
branches, since we've supported index advisors since 9.0.
The previous coding could overrun the provided buffer size for a very large
input, or lose precision for a very small input. Adopt the methodology
that's been in use in the equivalent backend code for a long time.
Per private report from Bas van Schaik. Back-patch to all supported
branches.
Failure to initially palloc the comboCids array, or to realloc it bigger
when needed, left combocid's data structures in an inconsistent state that
would cause trouble if the top transaction continues to execute. Noted
while examining a user complaint about the amount of memory used for this.
(There's not much we can do about that, but it does point up that repalloc
failure has a non-negligible chance of occurring here.)
In HEAD/9.5, also avoid possible invocation of memcpy() with a null pointer
in SerializeComboCIDState; cf commit 13bba0227.
PQhost() can return NULL in non-error situations, namely when a Unix-socket
connection has been selected by default. That behavior is a tad debatable
perhaps, but for the moment we should make sure that psql copes with it.
Unfortunately, do_connect() failed to: it could pass a NULL pointer to
strcmp(), resulting in crashes on most platforms. This was reported as a
security issue by ChenQin of Topsec Security Team, but the consensus of
the security list is that it's just a garden-variety bug with no security
implications.
For paranoia's sake, I made the keep_password test not trust PQuser or
PQport either, even though I believe those will never return NULL given
a valid PGconn.
Back-patch to all supported branches.
Also fix getErrorText() to return the right error string on failure.
This behavior now matches that of other operating systems.
Report by Noah Misch
Backpatch through 9.1
The POSIX standard for tar headers requires archive member sizes to be
printed in octal with at most 11 digits, limiting the representable file
size to 8GB. However, GNU tar and apparently most other modern tars
support a convention in which oversized values can be stored in base-256,
allowing any practical file to be a tar member. Adopt this convention
to remove two limitations:
* pg_dump with -Ft output format failed if the contents of any one table
exceeded 8GB.
* pg_basebackup failed if the data directory contained any file exceeding
8GB. (This would be a fatal problem for installations configured with a
table segment size of 8GB or more, and it has also been seen to fail when
large core dump files exist in the data directory.)
File sizes under 8GB are still printed in octal, so that no compatibility
issues are created except in cases that would have failed entirely before.
In addition, this patch fixes several bugs in the same area:
* In 9.3 and later, we'd defined tarCreateHeader's file-size argument as
size_t, which meant that on 32-bit machines it would write a corrupt tar
header for file sizes between 4GB and 8GB, even though no error was raised.
This broke both "pg_dump -Ft" and pg_basebackup for such cases.
* pg_restore from a tar archive would fail on tables of size between 4GB
and 8GB, on machines where either "size_t" or "unsigned long" is 32 bits.
This happened even with an archive file not affected by the previous bug.
* pg_basebackup would fail if there were files of size between 4GB and 8GB,
even on 64-bit machines.
* In 9.3 and later, "pg_basebackup -Ft" failed entirely, for any file size,
on 64-bit big-endian machines.
In view of these potential data-loss bugs, back-patch to all supported
branches, even though removal of the documented 8GB limit might otherwise
be considered a new feature rather than a bug fix.
The previous way of reconstructing check constraints was to do a separate
"ALTER TABLE ONLY tab ADD CONSTRAINT" for each table in an inheritance
hierarchy. However, that way has no hope of reconstructing the check
constraints' own inheritance properties correctly, as pointed out in
bug #13779 from Jan Dirk Zijlstra. What we should do instead is to do
a regular "ALTER TABLE", allowing recursion, at the topmost table that
has a particular constraint, and then suppress the work queue entries
for inherited instances of the constraint.
Annoyingly, we'd tried to fix this behavior before, in commit 5ed6546cf,
but we failed to notice that it wasn't reconstructing the pg_constraint
field values correctly.
As long as I'm touching pg_get_constraintdef_worker anyway, tweak it to
always schema-qualify the target table name; this seems like useful backup
to the protections installed by commit 5f173040.
In HEAD/9.5, get rid of get_constraint_relation_oids, which is now unused.
(I could alternatively have modified it to also return conislocal, but that
seemed like a pretty single-purpose API, so let's not pretend it has some
other use.) It's unused in the back branches as well, but I left it in
place just in case some third-party code has decided to use it.
In HEAD/9.5, also rename pg_get_constraintdef_string to
pg_get_constraintdef_command, as the previous name did nothing to explain
what that entry point did differently from others (and its comment was
equally useless). Again, that change doesn't seem like material for
back-patching.
I did a bit of re-pgindenting in tablecmds.c in HEAD/9.5, as well.
Otherwise, back-patch to all supported branches.
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.
As discussed on -hackers a couple of months ago.
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.
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 246693e5ae,
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.
Dean Rasheed
This back-ports commit 13d856e177 and assorted followon patches
into 9.4 and 9.5. 9.5 and HEAD are now substantially identical in all
the files touched by this commit, except that 010_pg_basebackup.pl has
a few more tests related to the new --slot option. 9.4 has many fewer
TAP tests, but the test infrastructure files are substantially the same,
with the exception that 9.4 lacks the single-tmp-install infrastructure
introduced in 9.5 (commit dcae5facca).
The primary motivation for this patch is to ensure that TAP test case
fixes can be back-patched without hazards of the kind seen in commits
34557f544/06dd4b44f. In principle it should also make the world safe
for running the TAP tests in the buildfarm in these branches; although
we might want to think about back-porting dcae5facca to 9.4 if
we're going to do that for real, because the TAP tests are quite disk
space hungry without it.
Michael Paquier did the back-porting work; original patches were by
him and assorted other people.
Since commit 11e131854f, 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.
Back-patch to 9.3 where this code was introduced.
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".)
Back-patch to all supported branches.
The error message wording for AttributeError has changed in Python 3.5.
For the plpython_error test, add a new expected file. In the
plpython_subtransaction test, we didn't really care what the exception
is, only that it is something coming from Python. So use a generic
exception instead, which has a message that doesn't vary across
versions.
In commit 210eb9b743 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
c3e7c24a1d, 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 c3e7c24a1d.
Commit 8457d0beca 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.
In commit a5ec86a7c7 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.
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.
Reported (bug #13611) and designed by Kondo Yuta.
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.
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.
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.
