There were two issues in how the extended statistics handled NULL values
in opclauses. Firstly, the code was oblivious to the possibility that
Const may be NULL (constisnull=true) in which case the constvalue is
undefined. We need to treat this as a mismatch, and not call the proc.
Secondly, the MCV item itself may contain NULL values too - the code
already did check that, and updated the match bitmap accordingly, but
failed to ensure we won't call the operator procedure anyway. It did
work for AND-clauses, because in that case false in the bitmap stops
evaluation of further clauses. But for OR-clauses ir was not easy to
get incorrect estimates or even trigger a crash.
This fixes both issues by extending the existing check so that it looks
at constisnull too, and making sure it skips calling the procedure.
Discussion: https://postgr.es/m/8736jdhbhc.fsf%40ansel.ydns.eu
Formerly, lcons was about the same speed as lappend, but with the new
List implementation, that's not so; with a long List, data movement
imposes an O(N) cost on lcons and list_delete_first, but not lappend.
Hence, invent list_delete_last with semantics parallel to
list_delete_first (but O(1) cost), and change various places to use
lappend and list_delete_last where this can be done without much
violence to the code logic.
There are quite a few places that construct result lists using lcons not
lappend. Some have semantic rationales for that; I added comments about
it to a couple that didn't have them already. In many such places though,
I think the coding is that way only because back in the dark ages lcons
was faster than lappend. Hence, switch to lappend where this can be done
without causing semantic changes.
In ExecInitExprRec(), this results in aggregates and window functions that
are in the same plan node being executed in a different order than before.
Generally, the executions of such functions ought to be independent of
each other, so this shouldn't result in visibly different query results.
But if you push it, as one regression test case does, you can show that
the order is different. The new order seems saner; it's closer to
the order of the functions in the query text. And we never documented
or promised anything about this, anyway.
Also, in gistfinishsplit(), don't bother building a reverse-order list;
it's easy now to iterate backwards through the original list.
It'd be possible to go further towards removing uses of lcons and
list_delete_first, but it'd require more extensive logic changes,
and I'm not convinced it's worth it. Most of the remaining uses
deal with queues that probably never get long enough to be worth
sweating over. (Actually, I doubt that any of the changes in this
patch will have measurable performance effects either. But better
to have good examples than bad ones in the code base.)
Patch by me, thanks to David Rowley and Daniel Gustafsson for review.
Discussion: https://postgr.es/m/21272.1563318411@sss.pgh.pa.us
This is numbered take 7, and addresses a set of issues around:
- Fixes for typos and incorrect reference names.
- Removal of unneeded comments.
- Removal of unreferenced functions and structures.
- Fixes regarding variable name consistency.
Author: Alexander Lakhin
Discussion: https://postgr.es/m/10bfd4ac-3e7c-40ab-2b2e-355ed15495e8@gmail.com
This adds a built-in function to generate UUIDs.
PostgreSQL hasn't had a built-in function to generate a UUID yet,
relying on external modules such as uuid-ossp and pgcrypto to provide
one. Now that we have a strong random number generator built-in, we
can easily provide a version 4 (random) UUID generation function.
This patch takes the existing function gen_random_uuid() from pgcrypto
and makes it a built-in function. The pgcrypto implementation now
internally redirects to the built-in one.
Reviewed-by: Fabien COELHO <coelho@cri.ensmp.fr>
Discussion: https://www.postgresql.org/message-id/6a65610c-46fc-2323-6b78-e8086340a325@2ndquadrant.com
Index-based calculation of this operator is exact. So, signature of
gist_bbox_distance() function is changes so that caller is responsible for
setting *recheck flag.
Discussion: https://postgr.es/m/f71ba19d-d989-63b6-f04a-abf02ad9345d%40postgrespro.ru
Author: Nikita Glukhov
Reviewed-by: Tom Lane, Alexander Korotkov
Some of <-> operators between geometric types have their commutators missed.
This commit adds them. The motivation is upcoming kNN support for some of those
operators.
Discussion: https://postgr.es/m/f71ba19d-d989-63b6-f04a-abf02ad9345d%40postgrespro.ru
Author: Nikita Glukhov
Reviewed-by: Tom Lane, Alexander Korotkov
match_clause_to_partition_key incorrectly would return
PARTCLAUSE_UNSUPPORTED if a bool qual could not be matched to the current
partition key. This was a problem, as it causes the calling function to
discard the qual and not try to match it to any other partition key. If
there was another partition key which did match this qual, then the qual
would not be checked again and we could fail to prune some partitions.
The worst this could do was to cause partitions not to be pruned when they
could have been, so there was no danger of incorrect query results here.
Fix this by changing match_boolean_partition_clause to have it return a
PartClauseMatchStatus rather than a boolean value. This allows it to
communicate if the qual is unsupported or if it just does not match this
particular partition key, previously these two cases were treated the
same. Now, if match_clause_to_partition_key is unable to match the qual
to any other qual type then we can simply return the value from the
match_boolean_partition_clause call so that the calling function properly
treats the qual as either unmatched or unsupported.
Reported-by: Rares Salcudean
Reviewed-by: Amit Langote
Backpatch-through: 11 where partition pruning was introduced
Discussion: https://postgr.es/m/CAHp_FN2xwEznH6oyS0hNTuUUZKp5PvegcVv=Co6nBXJ+mC7Y5w@mail.gmail.com
Otherwise the regressplans.sh tests generate extremely slow nested
loop joins. Back-patch to 11 where the hash join tests came in.
Reported-by: Michael Paquier
Discussion: https://postgr.es/m/20190708055256.GB2709%40paquier.xyz
This addresses a couple of issues in the code:
- Typos and inconsistencies in comments and function declarations.
- Removal of unreferenced function declarations.
- Removal of unnecessary compile flags.
- A cleanup error in regressplans.sh.
Author: Alexander Lakhin
Discussion: https://postgr.es/m/0c991fdf-2670-1997-c027-772a420c4604@gmail.com
I chanced to notice while thumbing through lcov reports that we had
exactly no coverage of BETWEEN SYMMETRIC, nor of current_time(N) and
localtime(N). Improve that.
parse_expr.c still has a pretty awful coverage number, but a large part
of that is due to lack of coverage of the operator_precedence_warning
logic. I have zero desire to write tests for that; I think ripping it
out would be more sensible at this point.
The code for conversions SQL_ASCII <-> MULE_INTERNAL and
SQL_ASCII <-> UTF8 was unreachable, because we long ago changed
the wrapper functions pg_do_encoding_conversion() et al so that
they have hard-wired behaviors for conversions involving SQL_ASCII.
(At least some of those fast paths date back to 2002, though it
looks like we may not have been totally consistent about this until
later.) Given the lack of complaints, nobody is dissatisfied with
this state of affairs. Hence, let's just remove the unreachable code.
Also, change CREATE CONVERSION so that it rejects attempts to
define such conversions. Since we consider that SQL_ASCII represents
lack of knowledge about the encoding in use, such a conversion would
be semantically dubious even if it were reachable.
Adjust a couple of regression test cases that had randomly decided
to rely on these conversion functions rather than any other ones.
Discussion: https://postgr.es/m/41163.1559156593@sss.pgh.pa.us
This is like \echo except that the text is sent to stderr not stdout.
In passing, fix a pre-existing bug in \echo and \qecho: per documentation
the -n switch should only be recognized when it is the first argument,
but actually any argument matching "-n" was treated as a switch.
(Should we back-patch that?)
David Fetter (bug fix by me), reviewed by Fabien Coelho
Discussion: https://postgr.es/m/20190421183115.GA4311@fetter.org
The function pg_mcv_list_items() returns values stored in MCV items. The
items may contain columns with different data types, so the function was
generating text array-like representation, but in an ad-hoc way without
properly escaping various characters etc.
Fixed by simply building a text[] array, which also makes it easier to
use from queries etc.
Requires changes to pg_proc entry, so bump catversion.
Backpatch to 12, where multi-column MCV lists were introduced.
Author: Tomas Vondra
Reviewed-by: Dean Rasheed
Discussion: https://postgr.es/m/20190618205920.qtlzcu73whfpfqne@development
d4c3a156c added code to remove columns that were not part of a table's
PRIMARY KEY constraint from the GROUP BY clause when all the primary key
columns were present in the group by. This is fine to do since we know
that there will only be one row per group coming from this relation.
However, the logic failed to consider inheritance parent relations. These
can have child relations without a primary key, but even if they did, they
could duplicate one of the parent's rows or one from another child
relation. In this case, those additional GROUP BY columns are required.
Fix this by disabling the optimization for inheritance parent tables.
In v11 and beyond, partitioned tables are fine since partitions cannot
overlap and before v11 partitioned tables could not have a primary key.
Reported-by: Manuel Rigger
Discussion: http://postgr.es/m/CA+u7OA7VLKf_vEr6kLF3MnWSA9LToJYncgpNX2tQ-oWzYCBQAw@mail.gmail.com
Backpatch-through: 9.6
The previous rule was "primary key (if any) first, then other unique
indexes in name order, then all other indexes in name order".
But the preference for unique indexes seems a bit obsolete since the
introduction of exclusion constraints. It's no longer the case
that unique indexes are the only ones that constrain what data can
be in the table, and it's hard to see what other rationale there is
for separating out unique indexes. Other new features like the
possibility for some indexes to be INVALID (hence, not constraining
anything) make this even shakier.
Hence, simplify the sort order to be "primary key (if any) first,
then all other indexes in name order".
No documentation change, since this was never documented anyway.
A couple of existing regression test cases change output, though.
Discussion: https://postgr.es/m/14422.1561474929@sss.pgh.pa.us
The logic in reorder_grouping_sets to order grouping set elements to
match a pre-specified sort ordering was defective, resulting in
unnecessary sort nodes (though the query output would still be
correct). Repair, simplifying the code a little, and add a test.
Per report from Richard Guo, though I didn't use their patch. Original
bug seems to have been my fault.
Backpatch back to 9.5 where grouping sets were introduced.
Discussion: https://postgr.es/m/CAN_9JTzyjGcUjiBHxLsgqfk7PkdLGXiM=pwM+=ph2LsWw0WO1A@mail.gmail.com
Up to now, pg_regress --config-auth had a hard-wired assumption
that the target cluster uses the default bootstrap superuser name.
pg_dump's 010_dump_connstr.pl TAP test uses non-default superuser
names, and was klugily getting around the restriction by listing
the desired superuser name as a role to "create". This is pretty
confusing (or at least, it confused me). Let's make it clearer by
allowing --config-auth mode to be told the bootstrap superuser name.
Repurpose the existing --user switch for that, since it has no
other function in --config-auth mode.
Per buildfarm. I don't have an environment at hand in which I can
test this fix, but the buildfarm should soon show if it works.
Discussion: https://postgr.es/m/3142.1561840611@sss.pgh.pa.us
This test script is unsafe to run in "make installcheck" mode for
(at least) two reasons: it creates and destroys some role names
that don't follow the "regress_xxx" naming convention, and it
sets and then resets the application_name GUC attached to every
existing role. While we've not had complaints, these surely are
not good things to do within a production installation, and
regress.sgml pretty clearly implies that we won't do them.
Rather than lose test coverage altogether, let's just move this
script somewhere where it will get run by "make check" but not
"make installcheck". src/test/modules/ already has that property.
Since it seems likely that we'll want other regression tests in
future that also exceed the constraints of "make installcheck",
create a generically-named src/test/modules/unsafe_tests/
directory to hold them.
Discussion: https://postgr.es/m/16638.1468620817@sss.pgh.pa.us
The date/time values 'current', 'invalid', and 'undefined' were
removed a long time ago, but the code still contains explicit error
handling for the transition. To simplify the code and avoid having to
handle these values everywhere, just remove the recognition of these
tokens altogether now.
Reviewed-by: Michael Paquier <michael@paquier.xyz>
In commit 18555b132 we tentatively established a rule that regression
tests should use names containing "regression" for databases, and names
starting with "regress_" for all other globally-visible object names, so
as to circumscribe the side-effects that "make installcheck" could have
on an existing installation.
This commit adds a simple enforcement mechanism for that rule: if the code
is compiled with ENFORCE_REGRESSION_TEST_NAME_RESTRICTIONS defined, it
will emit a warning (not an error) whenever a database, role, tablespace,
subscription, or replication origin name is created that doesn't obey the
rule. Running one or more buildfarm members with that symbol defined
should be enough to catch new violations, at least in the regular
regression tests. Most TAP tests wouldn't notice such warnings, but
that's actually fine because TAP tests don't execute against an existing
server anyway.
Since it's already the case that running src/test/modules/ tests in
installcheck mode is deprecated, we can use that as a home for tests
that seem unsafe to run against an existing server, such as tests that
might have side-effects on existing roles. Document that (though this
commit doesn't in itself make it any less safe than before).
Update regress.sgml to define these restrictions more clearly, and
to clean up assorted lack-of-up-to-date-ness in its descriptions of
the available regression tests.
Discussion: https://postgr.es/m/16638.1468620817@sss.pgh.pa.us
In commit 18555b132 we tentatively established a rule that regression
tests should use names containing "regression" for databases, and names
starting with "regress_" for all other globally-visible object names, so
as to circumscribe the side-effects that "make installcheck" could have on
an existing installation. However, no enforcement mechanism was created,
so it's unsurprising that some new violations have crept in since then.
In fact, a whole new *category* of violations has crept in, to wit we now
also have globally-visible subscription and replication origin names, and
"make installcheck" could very easily clobber user-created objects of
those types. So it's past time to do something about this.
This commit sanitizes the tests enough that they will pass (i.e. not
generate any visible warnings) with the enforcement mechanism I'll add
in the next commit. There are some TAP tests that still trigger the
warnings, but the warnings do not cause test failure. Since these tests
do not actually run against a pre-existing installation, there's no need
to worry whether they could conflict with user-created objects.
The problem with rolenames.sql testing special role names like "user"
is still there, and is dealt with only very cosmetically in this patch
(by hiding the warnings :-(). What we actually need to do to be safe is
to take that test script out of "make installcheck" altogether, but that
seems like material for a separate patch.
Discussion: https://postgr.es/m/16638.1468620817@sss.pgh.pa.us
We forgot to map column numbers to/from the default partition for
various operations, leading to valid cases failing with spurious
errors, such as
ERROR: attribute N of type some_partition has been dropped
It was also possible that the search for conflicting rows in the default
partition when attaching another partition would fail to detect some.
Secondarily, it was also possible that such a search should be skipped
(because the constraint was implied) but wasn't.
Fix all this by mapping column numbers when necessary.
Reported by: Daniel Wilches
Author: Amit Langote
Discussion: https://postgr.es/m/15873-8c61945d6b3ef87c@postgresql.org
When a partitioned tables contains foreign tables as partitions, it is
not possible to implement unique or primary key indexes -- but when
regular indexes are created, there is no reason to do anything other
than ignoring such partitions. We were raising errors upon encountering
the foreign partitions, which is unfriendly and doesn't protect against
any actual problems.
Relax this restriction so that index creation is allowed on partitioned
tables containing foreign partitions, becoming a no-op on them. (We may
later want to redefine this so that the FDW is told to create the
indexes on the foreign side.) This applies to CREATE INDEX, as well as
ALTER TABLE / ATTACH PARTITION and CREATE TABLE / PARTITION OF.
Backpatch to 11, where indexes on partitioned tables were introduced.
Discussion: https://postgr.es/m/15724-d5a58fa9472eef4f@postgresql.org
Author: Álvaro Herrera
Reviewed-by: Amit Langote
a96c41f has introduced the option for heap, but it still lacked the
variant to control the behavior for toast relations.
While on it, refactor the tests so as they stress more scenarios with
the various values that vacuum_index_cleanup can use. It would be
useful to couple those tests with pageinspect to check that pages are
actually cleaned up, but this is left for later.
Author: Masahiko Sawada, Michael Paquier
Reviewed-by: Peter Geoghegan
Discussion: https://postgr.es/m/CAD21AoCqs8iN04RX=i1KtLSaX5RrTEM04b7NHYps4+rqtpWNEg@mail.gmail.com
This patch reverts all the code changes of commit e76de8861, which turns
out to have been seriously misguided. We can't wait till later to compute
the definition string for an index; we must capture that before applying
the data type change for any column it depends on, else ruleutils.c will
deliverr wrong/misleading results. (This fine point was documented
nowhere, of course.)
I'd also managed to forget that ATExecAlterColumnType executes once per
ALTER COLUMN TYPE clause, not once per statement; which resulted in the
code being basically completely broken for any case in which multiple ALTER
COLUMN TYPE clauses are applied to a table having non-constraint indexes
that must be rebuilt. Through very bad luck, none of the existing test
cases nor the ones added by e76de8861 caught that, but of course it was
soon found in the field.
The previous patch also had an implicit assumption that if a constraint's
index had a dependency on a table column, so would the constraint --- but
that isn't actually true, so it didn't fix such cases.
Instead of trying to delete unneeded index dependencies later, do the
is-there-a-constraint lookup immediately on seeing an index dependency,
and switch to remembering the constraint if so. In the unusual case of
multiple column dependencies for a constraint index, this will result in
duplicate constraint lookups, but that's not that horrible compared to all
the other work that happens here. Besides, such cases did not work at all
before, so it's hard to argue that they're performance-critical for anyone.
Per bug #15865 from Keith Fiske. As before, back-patch to all supported
branches.
Discussion: https://postgr.es/m/15865-17940eacc8f8b081@postgresql.org
Commit d7f8d26d9 added a test case that created a user, but forgot
to drop it again. This is no good; for one thing, it causes repeated
"make installcheck" runs to fail.
The multivariate MCV estimation code may run user-defined operators on
the values in the MCV list, which means that those operators may
potentially leak the values from the MCV list. Guard against leaking
data to unprivileged users by checking that the user has SELECT
privileges on the table or all of the columns referred to by the
statistics.
Additionally, if there are any securityQuals on the RTE (either due to
RLS policies on the table, or accessing the table via a security
barrier view), not all rows may be visible to the current user, even
if they have table or column privileges. Thus we further insist that
the operator be leakproof in this case.
Dean Rasheed, reviewed by Tomas Vondra.
Discussion: https://postgr.es/m/CAEZATCUhT9rt7Ui=Vdx4N==VV5XOK5dsXfnGgVOz_JhAicB=ZA@mail.gmail.com
This fixes some TAP suites when using msys Perl and a builddir located
in an msys mount point other than "/". For example, builddir=/c/pg
exhibited the problem, since /c/pg falls in mount point "/c".
Back-patch to 9.6, where tests first started to perform such
translations. In back branches, offer both new and old APIs.
Reviewed by Andrew Dunstan.
Discussion: https://postgr.es/m/20190610045838.GA238501@rfd.leadboat.com
This makes the whole user experience more consistent when bumping into
failures, and more in line with the rewording done via 508300e.
Author: Michael Paquier
Reviewed-by: Álvaro Herrera
Discussion: https://postgr.es/m/20190514153252.GA22168@alvherre.pgsql
This fixes an embarrassing oversight I (Andres) made in 737a292b,
namely missing two place where liverows/deadrows were used when
converting those variables to pointers, leading to incrementing the
pointer, rather than the value.
It's not that actually that easy to trigger a crash: One needs tuples
deleted by the current transaction, followed by a tuple deleted in
another session, all in one page. Which is presumably why this hasn't
been noticed before.
Reported-By: Steve Singer
Author: Steve Singer
Discussion: https://postgr.es/m/c7988239-d42c-ddc4-41db-171b23b35e4f@ssinger.info
This puts back reverted commit de87a084c0, with some bug fixes.
When two (or more) transactions are waiting for transaction T1 to release a
tuple-level lock, and transaction T1 upgrades its lock to a higher level, a
spurious deadlock can be reported among the waiting transactions when T1
finishes. The simplest example case seems to be:
T1: select id from job where name = 'a' for key share;
Y: select id from job where name = 'a' for update; -- starts waiting for T1
Z: select id from job where name = 'a' for key share;
T1: update job set name = 'b' where id = 1;
Z: update job set name = 'c' where id = 1; -- starts waiting for T1
T1: rollback;
At this point, transaction Y is rolled back on account of a deadlock: Y
holds the heavyweight tuple lock and is waiting for the Xmax to be released,
while Z holds part of the multixact and tries to acquire the heavyweight
lock (per protocol) and goes to sleep; once T1 releases its part of the
multixact, Z is awakened only to be put back to sleep on the heavyweight
lock that Y is holding while sleeping. Kaboom.
This can be avoided by having Z skip the heavyweight lock acquisition. As
far as I can see, the biggest downside is that if there are multiple Z
transactions, the order in which they resume after T1 finishes is not
guaranteed.
Backpatch to 9.6. The patch applies cleanly on 9.5, but the new tests don't
work there (because isolationtester is not smart enough), so I'm not going
to risk it.
Author: Oleksii Kliukin
Discussion: https://postgr.es/m/B9C9D7CD-EB94-4635-91B6-E558ACEC0EC3@hintbits.com
Discussion: https://postgr.es/m/2815.1560521451@sss.pgh.pa.us
Any authenticated user can overflow a stack-based buffer by changing the
user's own password to a purpose-crafted value. This often suffices to
execute arbitrary code as the PostgreSQL operating system account.
This fix is contributed by multiple folks, based on an initial analysis
from Tom Lane. This issue has been introduced by 68e61ee, so it was
possible to make use of it at authentication time. It became more
easily to trigger after ccae190 which has made the SCRAM parsing more
strict when changing a password, in the case where the client passes
down a verifier already hashed using SCRAM. Back-patch to v10 where
SCRAM has been introduced.
Reported-by: Alexander Lakhin
Author: Jonathan Katz, Heikki Linnakangas, Michael Paquier
Security: CVE-2019-10164
Backpatch-through: 10
This reverts commits 3da73d6839 and de87a084c0.
This code has some tricky corner cases that I'm not sure are correct and
not properly tested anyway, so I'm reverting the whole thing for next
week's releases (reintroducing the deadlock bug that we set to fix).
I'll try again afterwards.
Discussion: https://postgr.es/m/E1hbXKQ-0003g1-0C@gemulon.postgresql.org
Regular per-column statistics are stored in pg_statistics catalog, which
is however rather difficult to read, so we also have pg_stats view with
a human-reablable version of the data.
For extended statistic the catalog was fairly easy to read, so we did
not have such human-readable view so far. Commit 9b6babfa2d however did
split the catalog into two, which makes querying harder. Furthermore,
we want to show the multi-column MCV list in a way similar to per-column
stats (and not as a bytea value).
This commit introduces pg_stats_ext view, joining the two catalogs and
massaging the data to produce human-readable output similar to pg_stats.
It also considers RLS and access privileges - the data is shown only when
the user has access to all columns the extended statistic is defined on.
Bumped CATVERSION due to adding new system view.
Author: Dean Rasheed, with improvements by me
Reviewed-by: Dean Rasheed, John Naylor
Discussion: https://postgr.es/m/CAEZATCUhT9rt7Ui%3DVdx4N%3D%3DVV5XOK5dsXfnGgVOz_JhAicB%3DZA%40mail.gmail.com
Since extended statistic got introduced in PostgreSQL 10, there was a
single catalog pg_statistic_ext storing both the definitions and built
statistic. That's however problematic when a user is supposed to have
access only to the definitions, but not to user data.
Consider for example pg_dump on a database with RLS enabled - if the
pg_statistic_ext catalog respects RLS (which it should, if it contains
user data), pg_dump would not see any records and the result would not
define any extended statistics. That would be a surprising behavior.
Until now this was not a pressing issue, because the existing types of
extended statistic (functional dependencies and ndistinct coefficients)
do not include any user data directly. This changed with introduction
of MCV lists, which do include most common combinations of values.
The easiest way to fix this is to split the pg_statistic_ext catalog
into two - one for definitions, one for the built statistic values.
The new catalog is called pg_statistic_ext_data, and we're maintaining
a 1:1 relationship with the old catalog - either there are matching
records in both catalogs, or neither of them.
Bumped CATVERSION due to changing system catalog definitions.
Author: Dean Rasheed, with improvements by me
Reviewed-by: Dean Rasheed, John Naylor
Discussion: https://postgr.es/m/CAEZATCUhT9rt7Ui%3DVdx4N%3D%3DVV5XOK5dsXfnGgVOz_JhAicB%3DZA%40mail.gmail.com
When two (or more) transactions are waiting for transaction T1 to release a
tuple-level lock, and transaction T1 upgrades its lock to a higher level, a
spurious deadlock can be reported among the waiting transactions when T1
finishes. The simplest example case seems to be:
T1: select id from job where name = 'a' for key share;
Y: select id from job where name = 'a' for update; -- starts waiting for X
Z: select id from job where name = 'a' for key share;
T1: update job set name = 'b' where id = 1;
Z: update job set name = 'c' where id = 1; -- starts waiting for X
T1: rollback;
At this point, transaction Y is rolled back on account of a deadlock: Y
holds the heavyweight tuple lock and is waiting for the Xmax to be released,
while Z holds part of the multixact and tries to acquire the heavyweight
lock (per protocol) and goes to sleep; once X releases its part of the
multixact, Z is awakened only to be put back to sleep on the heavyweight
lock that Y is holding while sleeping. Kaboom.
This can be avoided by having Z skip the heavyweight lock acquisition. As
far as I can see, the biggest downside is that if there are multiple Z
transactions, the order in which they resume after X finishes is not
guaranteed.
Backpatch to 9.6. The patch applies cleanly on 9.5, but the new tests don't
work there (because isolationtester is not smart enough), so I'm not going
to risk it.
Author: Oleksii Kliukin
Discussion: https://postgr.es/m/B9C9D7CD-EB94-4635-91B6-E558ACEC0EC3@hintbits.com
Given a query in which multiple JOIN nodes used the same alias
(which'd necessarily be in different sub-SELECTs), ruleutils.c
would assign the JOIN nodes distinct aliases for clarity ...
but then it forgot to print the modified aliases when dumping
the JOIN nodes themselves. This results in a dump/reload hazard
for views, because the emitted query is flat-out incorrect:
Vars will be printed with table names that have no referent.
This has been wrong for a long time, so back-patch to all supported
branches.
Philip Dubé
Discussion: https://postgr.es/m/CY4PR2101MB080246F2955FF58A6ED1FEAC98140@CY4PR2101MB0802.namprd21.prod.outlook.com
ATExecAlterColumnType failed to consider the possibility that an index
that needs to be rebuilt might be a child of a constraint that needs to be
rebuilt. We missed this so far because usually a constraint index doesn't
have a direct dependency on its table, just on the constraint object.
But if there's a WHERE clause, then dependency analysis of the WHERE
clause results in direct dependencies on the column(s) mentioned in WHERE.
This led to trying to drop and rebuild both the constraint and its
underlying index.
In v11/HEAD, we successfully drop both the index and the constraint,
and then try to rebuild both, and of course the second rebuild hits a
duplicate-index-name problem. Before v11, it fails with obscure messages
about a missing relation OID, due to trying to drop the index twice.
This is essentially the same kind of problem noted in commit
20bef2c31: the possible dependency linkages are broader than what
ATExecAlterColumnType was designed for. It was probably OK when
written, but it's certainly been broken since the introduction of
partial exclusion constraints. Fix by adding an explicit check
for whether any of the indexes-to-be-rebuilt belong to any of the
constraints-to-be-rebuilt, and ignoring any that do.
In passing, fix a latent bug introduced by commit 8b08f7d48: in
get_constraint_index() we must "continue" not "break" when rejecting
a relation of a wrong relkind. This is harmless today because we don't
expect that code path to be taken anyway; but if there ever were any
relations to be ignored, the existing coding would have an extremely
undesirable dependency on the order of pg_depend entries.
Also adjust a couple of obsolete comments.
Per bug #15835 from Yaroslav Schekin. Back-patch to all supported
branches.
Discussion: https://postgr.es/m/15835-32d9b7a76c06a7a9@postgresql.org
For a non-superuser, changing a comment on a domain constraint was
leading to a cache lookup failure as the code tried to perform the
ownership lookup on the constraint OID itself, thinking that it was a
type, but this check needs to happen on the type the domain constraint
relies on. As the type a domain constraint relies on can be guessed
directly based on the constraint OID, first fetch its type OID and
perform the ownership on it.
This is broken since 7eca575, which has split the handling of comments
for table constraints and domain constraints, so back-patch down to
9.5.
Reported-by: Clemens Ladisch
Author: Daniel Gustafsson, Michael Paquier
Reviewed-by: Álvaro Herrera
Discussion: https://postgr.es/m/15833-808e11904835d26f@postgresql.org
Backpatch-through: 9.5
json_to_record(), when an output column is declared as type json or jsonb,
should emit the corresponding field of the input JSON object. But it got
this slightly wrong when the field is just a string literal: it failed to
escape the contents of the string. That typically resulted in syntax
errors if the string contained any double quotes or backslashes.
jsonb_to_record() handles such cases correctly, but I added corresponding
test cases for it too, to prevent future backsliding.
Improve the documentation, as it provided only a very hand-wavy
description of the conversion rules used by these functions.
Per bug report from Robert Vollmert. Back-patch to v10 where the
error was introduced (by commit cf35346e8).
Note that PG 9.4 - 9.6 also get this case wrong, but differently so:
they feed the de-escaped contents of the string literal to json[b]_in.
That behavior is less obviously wrong, so possibly it's being depended on
in the field, so I won't risk trying to make the older branches behave
like the newer ones.
Discussion: https://postgr.es/m/D6921B37-BD8E-4664-8D5F-DB3525765DCD@vllmrt.net
Tomas Vondra