Commits 041b9680 and 6377e12a changed the interface of
scan_analyze_next_block() to take a ReadStream instead of a BlockNumber
and a BufferAccessStrategy, and to return a value to indicate when the
stream has run out of blocks.
This caused integration problems for at least one known extension that
uses specially encoded BlockNumber values that map to different
underlying storage, because acquire_sample_rows() sets up the stream so
that read_stream_next_buffer() reads blocks from the main fork of the
relation's SMgrRelation.
Provide read_stream_next_block(), as a way for such an extension to
access the stream of raw BlockNumbers directly and forward them to its
own ReadBuffer() calls after decoding, as it could in earlier releases.
The new function returns the BlockNumber and BufferAccessStrategy that
were previously passed directly to scan_analyze_next_block().
Alternatively, an extension could wrap the stream of BlockNumbers in
another ReadStream with a callback that performs any decoding required
to arrive at real storage manager BlockNumber values, so that it could
benefit from the I/O combining and concurrency provided by
read_stream.c.
Another class of table access method that does nothing in
scan_analyze_next_block() because it is not block-oriented could use
this function to control the number of block sampling loops. It could
match the previous behavior with "return read_stream_next_block(stream,
&bas) != InvalidBlockNumber".
Ongoing work is expected to provide better ANALYZE support for table
access methods that don't behave like heapam with respect to storage
blocks, but that will be for future releases.
Back-patch to 17.
Reported-by: Mats Kindahl <mats@timescale.com>
Reviewed-by: Mats Kindahl <mats@timescale.com>
Discussion: https://postgr.es/m/CA%2B14425%2BCcm07ocG97Fp%2BFrD9xUXqmBKFvecp0p%2BgV2YYR258Q%40mail.gmail.com
Since we introduced unlogged sequences in v15, identity sequences
have defaulted to having the same persistence as their owning table.
However, it is possible to change that with ALTER SEQUENCE, and
pg_dump tries to preserve the logged-ness of sequences when it doesn't
match (as indeed it wouldn't for an unlogged table from before v15).
The fly in the ointment is that ALTER SEQUENCE SET [UN]LOGGED fails
in binary-upgrade mode, because it needs to assign a new relfilenode
which we cannot permit in that mode. Thus, trying to pg_upgrade a
database containing a mismatching identity sequence failed.
To fix, add syntax to ADD/ALTER COLUMN GENERATED AS IDENTITY to allow
the sequence's persistence to be set correctly at creation, and use
that instead of ALTER SEQUENCE SET [UN]LOGGED in pg_dump. (I tried to
make SET [UN]LOGGED work without any pg_dump modifications, but that
seems too fragile to be a desirable answer. This way should be
markedly faster anyhow.)
In passing, document the previously-undocumented SEQUENCE NAME option
that pg_dump also relies on for identity sequences; I see no value
in trying to pretend it doesn't exist.
Per bug #18618 from Anthony Hsu.
Back-patch to v15 where we invented this stuff.
Discussion: https://postgr.es/m/18618-d4eb26d669ed110a@postgresql.org
Commit 5bf748b8, which enhanced nbtree ScalarArrayOp execution, made
parallel index scans work with the new design for arrays via explicit
scheduling of primitive index scans. A backend that successfully
scheduled the scan's next primitive index scan saved its backend local
array keys in shared memory. Any backend could pick up the scheduled
primitive scan within _bt_first. This scheme decouples scheduling a
primitive scan from starting the scan (by performing another descent of
the index via a _bt_search call from _bt_first) to make things robust.
The scheme had a deadlock hazard, at least when the leader process
participated in the scan. _bt_parallel_seize had a code path that made
backends that were not in an immediate position to start a scheduled
primitive index scan wait for some other backend to do so instead.
Under the right circumstances, the leader process could wait here
forever: the leader would wait for any other backend to start the
primitive scan, while every worker was busy waiting on the leader to
consume tuples from the scan's tuple queue.
To fix, don't wait for a scheduled primitive index scan to be started by
some other eligible backend from within _bt_parallel_seize (when the
calling backend isn't in a position to do so itself). Return false
instead, while recording that the scan has a scheduled primitive index
scan in backend local state. This leaves the backend in the same state
as the existing case where a backend schedules (or tries to schedule)
another primitive index scan from within _bt_advance_array_keys, before
calling _bt_parallel_seize. _bt_parallel_seize already handles that
case by returning false without waiting, and without unsetting the
backend local state. Leaving the backend in this state enables it to
start a previously scheduled primitive index scan once it gets back to
_bt_first.
Oversight in commit 5bf748b8, which enhanced nbtree ScalarArrayOp
execution.
Matthias van de Meent, with tweaks by me.
Author: Matthias van de Meent <boekewurm+postgres@gmail.com>
Reported-By: Tomas Vondra <tomas@vondra.me>
Reviewed-By: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAH2-WzmMGaPa32u9x_FvEbPTUkP5e95i=QxR8054nvCRydP-sw@mail.gmail.com
Backpatch: 17-, where nbtree SAOP execution was enhanced.
In existing releases of libxml2, xmlXPathCompile can be driven
to stack overflow because it fails to protect itself against
too-deeply-nested input. While there is an upstream fix as of
yesterday, it will take years for that to propagate into all
shipping versions. In the meantime, we can protect our own
usages basically for free by calling xmlXPathCtxtCompile instead.
(The actual bug is that libxml2 keeps its nesting counter in the
xmlXPathContext, and its parsing code was willing to just skip
counting nesting levels if it didn't have a context. So if we supply
a context, all is well. It seems odd actually that it works at all
to not supply a context, because this means that XPath parsing does
not have access to XML namespace info. Apparently libxml2 never
checks namespaces until runtime? Anyway, this seems like good
future-proofing even if its only immediate effect is to dodge a bug.)
Sadly, this hack only offers protection with libxml2 2.9.11 and newer.
Before that there are multiple similar problems, so if you are
processing untrusted XML it behooves you to get a newer version.
But we have some pretty old libxml2 in the buildfarm, so it seems
impractical to add a regression test to verify this fix.
Per bug #18617 from Jingzhou Fu. Back-patch to all supported
versions.
Discussion: https://postgr.es/m/18617-1cee4d2ed1f4e7ae@postgresql.org
Discussion: https://gitlab.gnome.org/GNOME/libxml2/-/issues/799
When we are building a hash index that is large enough to need
pre-sorting (larger than either maintenance_work_mem or NBuffers),
the initial sorting phase is interruptible, but the insertion
phase wasn't. Add the missing CHECK_FOR_INTERRUPTS().
Per bug #18616 from Alexander Lakhin. Back-patch to all
supported branches.
Pavel Borisov
Discussion: https://postgr.es/m/18616-acbb9e5caf41e964@postgresql.org
Discussion of commit ed055d249 revealed that we don't actually
want jsonpath's .string() method to depend on DateStyle, nor
TimeZone either, because the non-"_tz" jsonpath functions are
supposed to be immutable. Potentially we could allow a TimeZone
dependency in the "_tz" variants, but it seems better to just
uniformly define this method as returning the same string that
jsonb text output would do. That's easier to implement too,
saving a couple dozen lines.
Patch by me, per complaint from Peter Eisentraut. Back-patch
to v17 where this feature came in (in 66ea94e8e). Also
back-patch ed055d249 to provide test cases.
Discussion: https://postgr.es/m/5e8879d0-a3c8-4be2-950f-d83aa2af953a@eisentraut.org
check_agglevels_and_constraints() asserted that if we find an
aggregate function in an EXPR_KIND_FROM_SUBSELECT expression, the
expression must be in a LATERAL subquery. Alexander Lakhin found a
case where that's not so: because of the odd scoping rules for NEW/OLD
within a rule, a reference to NEW/OLD could cause an aggregate to be
considered top-level even though it's in an unmarked sub-select.
The error message that would be thrown seems sufficiently on-point,
so just remove the Assert. (Hence, this is not a bug for production
builds.)
This Assert was added by me in commit eaccfded9 (9.3 era). It looks
like I put it in to cross-check that the new logic for detecting
misplaced aggregates (using agglevelsup) caught the same cases that a
previous check on p_lateral_active did. So there might have been some
related misbehavior before eaccfded9 ... but that's very ancient
history by now, so I didn't dig any deeper.
Per bug #18608 from Alexander Lakhin. Back-patch to all supported
branches.
Discussion: https://postgr.es/m/18608-48de0717508ee429@postgresql.org
When building a JSON object, the code builds a hash table of keys, to
allow checking if the keys are unique. The uniqueness check and adding
the new key happens in json_unique_check_key(), but this assumes the
pointer to the key remains valid.
Unfortunately, two places passed pointers to keys in a buffer, while
also appending more data (additional key/value pairs) to the buffer.
With enough data the buffer is resized by enlargeStringInfo(), which
calls repalloc(), invalidating the earlier key pointers.
Due to this the uniqueness check may fail with both false negatives and
false positives, producing JSON objects with duplicate keys or failing
to produce a perfectly valid JSON object.
This affects multiple functions that enforce uniqueness of keys, all
introduced in PG16 with the new SQL/JSON:
- json_object_agg_unique / jsonb_object_agg_unique
- json_object / jsonb_objectagg
Existing regression tests did not detect the issue, simply because the
initial buffer size is 1024 and the objects were small enough not to
require the repalloc.
With a sufficiently large object, AddressSanitizer reported the access
to invalid memory immediately. So would valgrind, of course.
Fixed by copying the key into the hash table memory context, and adding
regression tests with enough data to repalloc the buffer. Backpatch to
16, where the functions were introduced.
Reported by Alexander Lakhin. Investigation and initial fix by Junwang
Zhao, with various improvements and tests by me.
Reported-by: Alexander Lakhin
Author: Junwang Zhao, Tomas Vondra
Backpatch-through: 16
Discussion: https://postgr.es/m/18598-3279ed972a2347c7@postgresql.org
Discussion: https://postgr.es/m/CAEG8a3JjH0ReJF2_O7-8LuEbO69BxPhYeXs95_x7+H9AMWF1gw@mail.gmail.com
We must drop whitespace while parsing the input, else libxml2
will include "blank" nodes that interfere with the desired
indentation behavior. The end result is that we didn't indent
nodes separated by whitespace.
Also, it seems that libxml2 may add a trailing newline when working
in DOCUMENT mode. This is semantically insignificant, so strip it.
This is in the gray area between being a bug fix and a definition
change. However, the INDENT option is still pretty new (since v16),
so I think we can get away with changing this in stable branches.
Hence, back-patch to v16.
Jim Jones
Discussion: https://postgr.es/m/872865a8-548b-48e1-bfcd-4e38e672c1e4@uni-muenster.de
When the ON ERROR / ON EMPTY behavior is to return NULL, returning
NULL directly from ExecEvalJsonExprPath() suffices. Therefore, there's
no need to create separate steps to check the error/empty flag or
those to evaluate the the constant NULL expression. This speeds up
common cases because the default ON ERROR / ON EMPTY behavior for
JSON_QUERY() and JSON_VALUE() is to return NULL. However, these steps
are necessary if the RETURNING type is a domain, as constraints on the
domain may need to be checked.
Reported-by: Jian He <jian.universality@gmail.com>
Author: Jian He <jian.universality@gmail.com>
Author: Amit Langote <amitlangote09@gmail.com>
Discussion: https://postgr.es/m/CACJufxEo4sUjKCYtda0_qt9tazqqKPmF1cqhW9KBOUeJFqQd2g@mail.gmail.com
Backpatch-through: 17
As introduced by f9900df5f9, a REINDEX CONCURRENTLY job done for an
index with predicates or expressions would set PROC_IN_SAFE_IC in its
MyProc->statusFlags, causing it to be ignored by other concurrent
operations.
Such concurrent index rebuilds should never be ignored, as a predicate
or an expression could call a user-defined function that accesses a
different table than the table where the index is rebuilt.
A test that uses injection points is added, backpatched down to 17.
Michail has proposed a different test, but I have added something
simpler with more coverage.
Oversight in f9900df5f9.
Author: Michail Nikolaev
Discussion: https://postgr.es/m/CANtu0oj9A3kZVduFTG0vrmGnKB+DCHgEpzOp0qAyOgmks84j0w@mail.gmail.com
Backpatch-through: 14
pg_stat_get_io() applied TimestampTzGetDatum twice to the
stat_reset_timestamp value. On 64-bit builds that's harmless because
TimestampTzGetDatum is a no-op, but on 32-bit builds it results in
displaying garbage in the stats_reset column of the pg_stat_io view.
Bug dates to commit a9c70b46d which introduced pg_stat_io, so
back-patch to v16 where that came in.
Bertrand Drouvot
Discussion: https://postgr.es/m/Ztrd+XcPTz1zorkg@ip-10-97-1-34.eu-west-3.compute.internal
The deparsing code in get_json_expr_options() unnecessarily emitted
the default column-specific ON ERROR / EMPTY behavior when the
top-level ON ERROR behavior in JSON_TABLE was set to ERROR. Fix that
by not overriding the column-specific default, determined based on
the column's JsonExprOp in get_json_table_columns(), with
JSON_BEHAVIOR_ERROR when that is the top-level ON ERROR behavior.
Note that this only removes redundancy; the current deparsing output
is not incorrect, just redundant.
Reviewed-by: Jian He <jian.universality@gmail.com>
Discussion: https://postgr.es/m/CACJufxEo4sUjKCYtda0_qt9tazqqKPmF1cqhW9KBOUeJFqQd2g@mail.gmail.com
Backpatch-through: 17
When the ON ERROR / ON EMPTY behavior is to return NULL, returning
NULL directly from ExecEvalJsonExprPath() suffices. Therefore, there's
no need to create separate steps to check the error/empty flag or
those to evaluate the the constant NULL expression. This speeds up
common cases because the default ON ERROR / ON EMPTY behavior for
JSON_QUERY() and JSON_VALUE() is to return NULL. However, these steps
are necessary if the RETURNING type is a domain, as constraints on the
domain may need to be checked.
Reported-by: Jian He <jian.universality@gmail.com>
Author: Jian He <jian.universality@gmail.com>
Author: Amit Langote <amitlangote09@gmail.com>
Discussion: https://postgr.es/m/CACJufxEo4sUjKCYtda0_qt9tazqqKPmF1cqhW9KBOUeJFqQd2g@mail.gmail.com
Backpatch-through: 17
The deparsing code in get_json_expr_options() unnecessarily emitted
the default column-specific ON ERROR / EMPTY behavior when the
top-level ON ERROR behavior in JSON_TABLE was set to ERROR. Fix that
by not overriding the column-specific default, determined based on
the column's JsonExprOp in get_json_table_columns(), with
JSON_BEHAVIOR_ERROR when that is the top-level ON ERROR behavior.
Note that this only removes redundancy; the current deparsing output
is not incorrect, just redundant.
Reviewed-by: Jian He <jian.universality@gmail.com>
Discussion: https://postgr.es/m/CACJufxEo4sUjKCYtda0_qt9tazqqKPmF1cqhW9KBOUeJFqQd2g@mail.gmail.com
Backpatch-through: 17
Since commit 2549f0661, we reject an identifier immediately following
a numeric literal (without separating whitespace), because that risks
ambiguity with hex/octal/binary integers. However, that patch used
token patterns like "{integer}{ident_start}", which is problematic
because {ident_start} matches only a single byte. If the first
character after the integer is a multibyte character, this ends up
with flex reporting an error message that includes a partial multibyte
character. That can cause assorted bad-encoding problems downstream,
both in the report to the client and in the postmaster log file.
To fix, use {identifier} not {ident_start} in the "junk" token
patterns, so that they will match complete multibyte characters.
This seems generally better user experience quite aside from the
encoding problem: for "123abc" the error message will now say that
the error appeared at or near "123abc" instead of "123a".
While at it, add some commentary about why these patterns exist
and how they work.
Report and patch by Karina Litskevich; review by Pavel Borisov.
Back-patch to v15 where the problem came in.
Discussion: https://postgr.es/m/CACiT8iZ_diop=0zJ7zuY3BXegJpkKK1Av-PU7xh0EDYHsa5+=g@mail.gmail.com
This term was using an inconsistent casing between the code and the
documentation, using "CommitTsSLRU" in wait_event_names.txt and
"CommitTSSLRU" in the code.
Let's update the term in the code to reflect what's in the
documentation, "CommitTs" being more commonly used, so as
pg_stat_activity shows the same term as the documentation.
Oversight in 53c2a97a92.
Author: Alexander Lakhin
Discussion: https://postgr.es/m/f7e514cf-2446-21f1-a5d2-8c089a6e2168@gmail.com
Backpatch-through: 17
Commit b5a9b18c introduced block streaming infrastructure with a special
fast path for all-cached scans, and commit b7b0f3f2 connected the
infrastructure up to sequential scans. One of the fast path
micro-optimizations had an unintended consequence: it interfered with
parallel sequential scan's block range allocator (from commit 56788d21),
which has its own ramp-up and ramp-down algorithm when handing out
groups of pages to workers. A scan of an all-cached table could give
extra blocks to one worker, when others had finished. In some plans
(probably already very bad plans, such as the one reported by
Alexander), the unfairness could be magnified.
An internal buffer of 16 block numbers is removed, keeping just a single
block buffer for technical reasons.
Back-patch to 17.
Reported-by: Alexander Lakhin <exclusion@gmail.com>
Discussion: https://postgr.es/m/63a63690-dd92-c809-0b47-af05459e95d1%40gmail.com
This change improves the description of the
restrict_nonsystem_relation_kind parameter in guc_table.c and the
documentation for better clarity.
Backpatch to 12, where this GUC parameter was introduced.
Reviewed-by: Peter Eisentraut
Discussion: https://postgr.es/m/6a96f1af-22b4-4a80-8161-1f26606b9ee2%40eisentraut.org
Backpatch-through: 12
Commit 2489d76c4 removed some logic from pullup_replace_vars()
that avoided wrapping a PlaceHolderVar around a pulled-up
subquery output expression if the expression could be proven
to go to NULL anyway (because it contained Vars or PHVs of the
pulled-up relation and did not contain non-strict constructs).
But removing that logic turns out to cause performance regressions
in some cases, because the extra PHV blocks subexpression folding,
and will do so even if outer-join reduction later turns it into a
no-op with no phnullingrels bits. This can for example prevent
an expression from being matched to an index.
The reason for always adding a PHV was to ensure we had someplace
to put the varnullingrels marker bits of the Var being replaced.
However, it turns out we can optimize in exactly the same cases that
the previous code did, because we can instead attach the needed
varnullingrels bits to the contained Var(s)/PHV(s).
This is not a complete solution --- it would be even better if we
could remove PHVs after reducing them to no-ops. It doesn't look
practical to back-patch such an improvement, but this change seems
safe and at least gets rid of the performance-regression cases.
Per complaint from Nikhil Raj. Back-patch to v16 where the
problem appeared.
Discussion: https://postgr.es/m/CAG1ps1xvnTZceKK24OUfMKLPvDP2vjT-d+F2AOCWbw_v3KeEgg@mail.gmail.com
If an ORDER BY item in SELECT is a bare identifier, the parser
first seeks it as an output column name of the SELECT (for SQL92
compatibility). However, ruleutils.c is expecting the SQL99
interpretation where such a name is an input column name. So it's
possible to produce an incorrect display of a view in the (admittedly
pretty ill-advised) case where some other column is renamed in the
SELECT output list to match an ORDER BY column.
This can be fixed by table-qualifying such names in the dumped
view text. To avoid cluttering less-ill-advised queries, we'd
like to do so only when there's an actual name conflict.
That requires passing the current get_query_def call's resultDesc
parameter down to get_variable, so that it can determine what
the output column names are. In hopes of reducing rather than
increasing notational clutter in ruleutils.c, I moved that value
into the deparse_context struct and removed it from the parameter
lists of get_query_def's other subroutines.
I made a few other cosmetic changes while at it:
* Likewise move the colNamesVisible parameter into deparse_context.
* Rename deparse_context's windowTList field to targetList,
since it's no longer used only in connection with WINDOW clauses.
* Replace the special_exprkind field with a bool inGroupBy,
since that was all it was being used for, and the apparent
flexibility of storing a ParseExprKind proved to be illusory.
(We need a separate varInOrderBy field to make this patch work.)
* Remove useless save/restore logic in get_select_query_def.
In principle, this bug is quite old. However, it seems unreachable
before 1b4d280ea, because before that the presence of "new" and "old"
entries in a view's rangetable caused us to always table-qualify every
Var reference in dumped views. Hence, back-patch to v16 where that
came in.
Per bug #18589 from Quynh Tran.
Discussion: https://postgr.es/m/18589-70091cb81db1a3f1@postgresql.org
Commit 5bec1d6bc5 changed the memory usage updates of the
ReorderBufferTXN to zero all at once by subtracting txn->size, rather
than updating it for each change. However, if TOAST reconstruction
data remained in the transaction when freeing it, there were cases
where it further subtracted the memory counter from zero, resulting in
an assertion failure.
This change calculates the memory size for each change and updates the
memory usage to precisely the amount that has been freed.
Backpatch to v17, where this was introducd.
Reviewed-by: Amit Kapila, Shlok Kyal
Discussion: https://postgr.es/m/CAD21AoAqkNUvicgKPT_dXzNoOwpPkVTg0QPPxEcWmzT0moCJ1g%40mail.gmail.com
Backpatch-through: 17
Add bounds checking to nbtree's lookahead/skip-within-a-page mechanism.
Otherwise it's possible for cases with lots of before-array-keys tuples
to overflow an int16 variable, causing the mechanism to generate an out
of bounds page offset number.
Oversight in commit 5bf748b8, which enhanced nbtree ScalarArrayOp
execution.
Reported-By: Alexander Lakhin <exclusion@gmail.com>
Discussion: https://postgr.es/m/6c68ac42-bbb5-8b24-103e-af0e279c536f@gmail.com
Backpatch: 17-, where nbtree SAOP execution was enhanced.
It's normal for the name in a free slot to match the new name. The
max_inuse mechanism kept simple cases from reaching the problem. The
problem could appear when index 0 was the previously-detached entry and
index 1 is in use. Back-patch to v17, where this code first appeared.
Currently, createPartitionTable() opens newly created table using its name.
This approach is prone to privilege escalation attack, because we might end
up opening another table than we just created.
This commit address the issue above by opening newly created table by its
OID. It appears to be tricky to get a relation OID out of ProcessUtility().
We have to extend TableLikeClause with new newRelationOid field, which is
filled within ProcessUtility() to be further accessed by caller.
Security: CVE-2014-0062
Reported-by: Noah Misch
Discussion: https://postgr.es/m/20240808171351.a9.nmisch%40google.com
Reviewed-by: Pavel Borisov, Dmitry Koval
For a long time we have forbidden binary-coercible casts to or from
composite and array types, because such a cast cannot work correctly:
the type OID embedded in the value would need to change, but it won't
in a binary coercion. That reasoning applies equally to range types,
but we overlooked installing a similar restriction here when we
invented range types. Do so now.
Given the lack of field complaints, we won't change this in stable
branches, but it seems not too late for v17.
Per discussion of a problem noted by Peter Eisentraut.
Discussion: https://postgr.es/m/076968e1-0852-40a9-bc0b-117cd3f0e43c@eisentraut.org
We advance origin progress during abort on successful streaming and
application of ROLLBACK in parallel streaming mode. But the origin
shouldn't be advanced during an error or unsuccessful apply due to
shutdown. Otherwise, it will result in a transaction loss as such a
transaction won't be sent again by the server.
Reported-by: Hou Zhijie
Author: Hayato Kuroda and Shveta Malik
Reviewed-by: Amit Kapila
Backpatch-through: 16
Discussion: https://postgr.es/m/TYAPR01MB5692FAC23BE40C69DA8ED4AFF5B92@TYAPR01MB5692.jpnprd01.prod.outlook.com
The descriptions for ProcArrayGroupUpdate and XactGroupUpdate claim
that these events mean we are waiting for the group leader "at end
of a parallel operation," but neither pertains to parallel
operations. This commit reverts these descriptions to their
wording before commit 3048898e73, i.e., "end of a parallel
operation" is changed to "transaction end."
Author: Sameer Kumar
Reviewed-by: Amit Kapila
Discussion: https://postgr.es/m/CAGPeHmh6UMrKQHKCmX%2B5vV5TH9P%3DKw9en3k68qEem6J%3DyrZPUA%40mail.gmail.com
Backpatch-through: 13
When a partition is detached and immediately dropped, a prepared
statement could try to compute a new partition descriptor that includes
it. This leads to this kind of error:
ERROR: could not open relation with OID 457639
Avoid this by skipping the partition in expand_partitioned_rtentry if it
doesn't exist.
Noted by me while investigating bug #18559. Kuntal Gosh helped to
identify the exact failure.
Backpatch to 14, where DETACH CONCURRENTLY was introduced.
Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Kuntal Ghosh <kuntalghosh.2007@gmail.com>
Reviewed-by: Junwang Zhao <zhjwpku@gmail.com>
Discussion: https://postgr.es/m/202408122233.bo4adt3vh5bi@alvherre.pgsql
Add a comment explaining dropdb() can't rely on syscache. The issue with
flattened rows was fixed by commit 0f92b230f8, but better to have
a clear explanation why the systable scan is necessary. The other places
doing in-place updates on pg_database have the same comment.
Suggestion and patch by Yugo Nagata. Backpatch to 12, same as the fix.
Author: Yugo Nagata
Backpatch-through: 12
Discussion: https://postgr.es/m/CAJTYsWWNkCt+-UnMhg=BiCD3Mh8c2JdHLofPxsW3m2dkDFw8RA@mail.gmail.com
Commit ca051d8b10 called newlocale(LC_COLLATE, ...) instead of
newlocale(LC_COLLATE_MASK, ...), in code reached only on FreeBSD. They
have the same value on that OS, explaining why it worked. Fix.
Back-patch to 14, where ca051d8b10 landed.
Commit c66a7d75e6 modified DROP DATABASE so that if interrupted, the
database is known to be in an invalid state and can only be dropped.
This is done by setting a flag using an in-place update, so that it's
not lost in case of rollback.
For databases with many ACLs, this may however fail like this:
ERROR: wrong tuple length
This happens because with many ACLs, the pg_database.datacl attribute
gets TOASTed. The dropdb() code reads the tuple from the syscache, which
means it's detoasted. But the in-place update expects the tuple length
to match the on-disk tuple.
Fixed by reading the tuple from the catalog directly, not from syscache.
Report and fix by Ayush Tiwari. Backpatch to 12. The DROP DATABASE fix
was backpatched to 11, but 11 is EOL at this point.
Reported-by: Ayush Tiwari
Author: Ayush Tiwari
Reviewed-by: Tomas Vondra
Backpatch-through: 12
Discussion: https://postgr.es/m/CAJTYsWWNkCt+-UnMhg=BiCD3Mh8c2JdHLofPxsW3m2dkDFw8RA@mail.gmail.com
If a partition undergoes DETACH CONCURRENTLY immediately followed by
DROP, this could cause a problem for a concurrent transaction
recomputing the partition descriptor when running a prepared statement,
because it tries to dereference a pointer to a tuple that's not found in
a catalog scan.
The existing retry logic added in commit dbca3469eb is sufficient to
cope with the overall problem, provided we don't try to dereference a
non-existant heap tuple.
Arguably, the code in RelationBuildPartitionDesc() has been wrong all
along, since no check was added in commit 898e5e3290 against receiving
a NULL tuple from the catalog scan; that bug has only become
user-visible with DETACH CONCURRENTLY which was added in branch 14.
Therefore, even though there's no known mechanism to cause a crash
because of this, backpatch the addition of such a check to all supported
branches. In branches prior to 14, this would cause the code to fail
with a "missing relpartbound for relation XYZ" error instead of
crashing; that's okay, because there are no reports of such behavior
anyway.
Author: Kuntal Ghosh <kuntalghosh.2007@gmail.com>
Reviewed-by: Junwang Zhao <zhjwpku@gmail.com>
Reviewed-by: Tender Wang <tndrwang@gmail.com>
Discussion: https://postgr.es/m/18559-b48286d2eacd9a4e@postgresql.org
Coverity thinks dpns->plan could be null at these points. That
shouldn't really be possible, but it's easy enough to modify the
Asserts so they'd not core-dump if it were true.
These are new in b919a97a6. Back-patch to v13; the v12 version
of the patch didn't have these Asserts.
The code intends to allow GUCs to be set within parallel workers
via function SET clauses, but not otherwise. However, doing so fails
for "session_authorization" and "role", because the assign hooks for
those attempt to set the subsidiary "is_superuser" GUC, and that call
falls foul of the "not otherwise" prohibition. We can't switch to
using GUC_ACTION_SAVE for this, so instead add a new GUC variable
flag GUC_ALLOW_IN_PARALLEL to mark is_superuser as being safe to set
anyway. (This is okay because is_superuser has context PGC_INTERNAL
and thus only hard-wired calls can change it. We'd need more thought
before applying the flag to other GUCs; but maybe there are other
use-cases.) This isn't the prettiest fix perhaps, but other
alternatives we thought of would be much more invasive.
While here, correct a thinko in commit 059de3ca4: when rejecting
a GUC setting within a parallel worker, we should return 0 not -1
if the ereport doesn't longjmp. (This seems to have no consequences
right now because no caller cares, but it's inconsistent.) Improve
the comments to try to forestall future confusion of the same kind.
Despite the lack of field complaints, this seems worth back-patching.
Thanks to Nathan Bossart for the idea to invent a new flag,
and for review.
Discussion: https://postgr.es/m/2833457.1723229039@sss.pgh.pa.us
