slru.h described incorrectly how SLRU segment names are formatted
depending on the segment number and if long or short segment names are
used. This commit closes the gap with a better description, fitting
with the reality.
Reported-by: Noah Misch
Author: Aleksander Alekseev
Discussion: https://postgr.es/m/20240626002747.dc.nmisch@google.com
Backpatch-through: 17
In the case of a parallel plan, when computing the number of tuples
processed per worker, we divide the total number of tuples by the
parallel_divisor obtained from get_parallel_divisor(), which accounts
for the leader's contribution in addition to the number of workers.
Accordingly, when estimating the number of tuples for gather (merge)
nodes, we should multiply the number of tuples per worker by the same
parallel_divisor to reverse the division. However, currently we use
parallel_workers rather than parallel_divisor for the multiplication.
This could result in an underestimation of the number of tuples for
gather (merge) nodes, especially when there are fewer than four
workers.
This patch fixes this issue by using the same parallel_divisor for the
multiplication. There is one ensuing plan change in the regression
tests, but it looks reasonable and does not compromise its original
purpose of testing parallel-aware hash join.
In passing, this patch removes an unnecessary assignment for path.rows
in create_gather_merge_path, and fixes an uninitialized-variable issue
in generate_useful_gather_paths.
No backpatch as this could result in plan changes.
Author: Anthonin Bonnefoy
Reviewed-by: Rafia Sabih, Richard Guo
Discussion: https://postgr.es/m/CAO6_Xqr9+51NxgO=XospEkUeAg-p=EjAWmtpdcZwjRgGKJ53iA@mail.gmail.com
Previously, the code charged disable_cost for CurrentOfExpr, and then
subtracted disable_cost from the cost of a TID path that used
CurrentOfExpr as the TID qual, effectively disabling all paths except
that one. Now, we instead suppress generation of the disabled paths
entirely, and generate only the one that the executor will actually
understand.
With this approach, we do not need to rely on disable_cost being
large enough to prevent the wrong path from being chosen, and we
save some CPU cycle by avoiding generating paths that we can't
actually use. In my opinion, the code is also easier to understand
like this.
Patch by me. Review by Heikki Linnakangas.
Discussion: http://postgr.es/m/591b3596-2ea0-4b8e-99c6-fad0ef2801f5@iki.fi
Reaching that code would have required multiple processes performing
relation extension during recovery, which does not happen. That caller
has the persistence available, so pass it. This was dead code as soon
as commit 210622c60e1a9db2e2730140b8106ab57d259d15 added it.
Discussion: https://postgr.es/m/CAN55FZ0JKL6vk1xQp6rfOXiNFV1u1H0tJDPPGHWoiO3ea2Wc=A@mail.gmail.com
To do this, we must include the wal_level in the first WAL record
covered by each summary file; so add wal_level to struct Checkpoint
and the payload of XLOG_CHECKPOINT_REDO and XLOG_END_OF_RECOVERY.
This, in turn, requires bumping XLOG_PAGE_MAGIC and, since the
Checkpoint is also stored in the control file, also
PG_CONTROL_VERSION. It's not great to do that so late in the release
cycle, but the alternative seems to ship v17 without robust
protections against this scenario, which could result in corrupted
incremental backups.
A side effect of this patch is that, when a server with
wal_level=replica is started with summarize_wal=on for the first time,
summarization will no longer begin with the oldest WAL that still
exists in pg_wal, but rather from the first checkpoint after that.
This change should be harmless, because a WAL summary for a partial
checkpoint cycle can never make an incremental backup possible when
it would otherwise not have been.
Report by Fujii Masao. Patch by me. Review and/or testing by Jakub
Wartak and Fujii Masao.
Discussion: http://postgr.es/m/6e30082e-041b-4e31-9633-95a66de76f5d@oss.nttdata.com
This new macro is able to perform a direct lookup from the local cache
of injection points (refreshed each time a point is loaded or run),
without touching the shared memory state of injection points at all.
This works in combination with INJECTION_POINT_LOAD(), and it is better
than INJECTION_POINT() in a critical section due to the fact that it
would avoid all memory allocations should a concurrent detach happen
since a LOAD(), as it retrieves a callback from the backend-private
memory.
The documentation is updated to describe in more details how to use this
new macro with a load. Some tests are added to the module
injection_points based on a new SQL function that acts as a wrapper of
INJECTION_POINT_CACHED().
Based on a suggestion from Heikki Linnakangas.
Author: Heikki Linnakangas, Michael Paquier
Discussion: https://postgr.es/m/58d588d0-e63f-432f-9181-bed29313dece@iki.fi
Commit f4b54e1ed9, which introduced macros for protocol characters,
missed updating a few places. It also did not introduce macros for
messages sent from parallel workers to their leader processes.
This commit adds a new section in protocol.h for those.
Author: Aleksander Alekseev
Discussion: https://postgr.es/m/CAJ7c6TNTd09AZq8tGaHS3LDyH_CCnpv0oOz2wN1dGe8zekxrdQ%40mail.gmail.com
Backpatch-through: 17
Previously, CREATE MATERIALIZED VIEW ... WITH DATA populated the MV
the same way as CREATE TABLE ... AS.
Instead, reuse the REFRESH logic, which locks down security-restricted
operations and restricts the search_path. This reduces the chance that
a subsequent refresh will fail.
Reported-by: Noah Misch
Backpatch-through: 17
Discussion: https://postgr.es/m/20240630222344.db.nmisch@google.com
When creating and initializing a logical slot, the restart_lsn is set
to the latest WAL insertion point (or the latest replay point on
standbys). Subsequently, WAL records are decoded from that point to
find the start point for extracting changes in the
DecodingContextFindStartpoint() function. Since the initial
restart_lsn could be in the middle of a transaction, the start point
must be a consistent point where we won't see the data for partial
transactions.
Previously, when not building a full snapshot, serialized snapshots
were restored, and the SnapBuild jumps to the consistent state even
while finding the start point. Consequently, the slot's restart_lsn
and confirmed_flush could be set to the middle of a transaction. This
could lead to various unexpected consequences. Specifically, there
were reports of logical decoding decoding partial transactions, and
assertion failures occurred because only subtransactions were decoded
without decoding their top-level transaction until decoding the commit
record.
To resolve this issue, the changes prevent restoring the serialized
snapshot and jumping to the consistent state while finding the start
point.
On v17 and HEAD, a flag indicating whether snapshot restores should be
skipped has been added to the SnapBuild struct, and SNAPBUILD_VERSION
has been bumpded.
On backbranches, the flag is stored in the LogicalDecodingContext
instead, preserving on-disk compatibility.
Backpatch to all supported versions.
Reported-by: Drew Callahan
Reviewed-by: Amit Kapila, Hayato Kuroda
Discussion: https://postgr.es/m/2444AA15-D21B-4CCE-8052-52C7C2DAFE5C%40amazon.com
Backpatch-through: 12
This new entry type is used for all the fixed-numbered statistics,
making possible support for custom pluggable stats. In short, we need
to be able to detect more easily if a stats kind exists or not when
reading back its data from the pgstats file without a dependency on the
order of the entries read. The kind ID of the stats is added to the
data written.
The data is written in the same fashion as previously, with the
fixed-numbered stats first and the dshash entries next. The read part
becomes more flexible, loading fixed-numbered stats into shared memory
based on the new entry type found.
Bump PGSTAT_FILE_FORMAT_ID.
Reviewed-by: Bertrand Drouvot
Discussion: https://postgr.es/m/Zot5bxoPYdS7yaoy@paquier.xyz
This new callback gives fixed-numbered stats the possibility to take
actions based on the area of shared memory allocated for them.
This removes from pgstat_shmem.c any knowledge specific to the types
of fixed-numbered stats, and the initializations happen in their own
files. Like b68b29bc8fec, this change is useful to make this area of
the code more pluggable, so as custom fixed-numbered stats can take
actions after their shared memory area is initialized.
Reviewed-by: Bertrand Drouvot
Discussion: https://postgr.es/m/Zot5bxoPYdS7yaoy@paquier.xyz
This patch modifies the pg_get_acl() function to accept a third argument
called "objsubid", bringing it on par with similar functions in this
area like pg_describe_object(). This enables the retrieval of ACLs for
relation attributes when scanning dependencies.
Bump catalog version.
Author: Joel Jacobson
Discussion: https://postgr.es/m/f2539bff-64be-47f0-9f0b-df85d3cc0432@app.fastmail.com
Since commit 3a9b18b309, roles with privileges of pg_signal_backend
cannot signal autovacuum workers. Many users treated the ability
to signal autovacuum workers as a feature instead of a bug, so we
are reintroducing it via a new predefined role. Having privileges
of this new role, named pg_signal_autovacuum_worker, only permits
signaling autovacuum workers. It does not permit signaling other
types of superuser backends.
Bumps catversion.
Author: Kirill Reshke
Reviewed-by: Anthony Leung, Michael Paquier, Andrey Borodin
Discussion: https://postgr.es/m/CALdSSPhC4GGmbnugHfB9G0%3DfAxjCSug_-rmL9oUh0LTxsyBfsg%40mail.gmail.com
This is similar to 9004abf6206e, but this time for the write part of the
stats file. The code is changed so as, rather than referring to
individual members of PgStat_Snapshot in an order based on their
PgStat_Kind value, a loop based on pgstat_kind_infos is used to retrieve
the contents to write from the snapshot structure, for a size of
PgStat_KindInfo's shared_data_len.
This requires the addition to PgStat_KindInfo of an offset to track the
location of each fixed-numbered stats in PgStat_Snapshot. This change
is useful to make this area of the code more easily pluggable, and
reduces the knowledge of specific fixed-numbered kinds in pgstat.c.
Reviewed-by: Bertrand Drouvot
Discussion: https://postgr.es/m/Zot5bxoPYdS7yaoy@paquier.xyz
a6417078c414 has introduced as project policy that new features
committed during the development cycle should use new OIDs in the
[8000,9999] range.
4564f1cebd43 did not respect that rule, so let's renumber pg_get_acl()
to use an OID in the correct range.
Bump catalog version.
Both of these counters were using the "long" data type. On MSVC that's
a 32-bit type. On modern hardware, I was able to demonstrate that we can
wrap those counters with a query that only takes 15 minutes to run.
This issue may manifest itself either by not showing the values of the
counters because they've wrapped and are less than zero, resulting in
them being filtered by the > 0 checks in show_tidbitmap_info(), or bogus
numbers being displayed which are modulus 2^32 of the actual number.
Widen these counters to uint64.
Discussion: https://postgr.es/m/CAApHDvpS_97TU+jWPc=T83WPp7vJa1dTw3mojEtAVEZOWh9bjQ@mail.gmail.com
macOS 15's SDK pulls in headers related to <regex.h> when we include
<xlocale.h>. This causes our own regex_t implementation to clash with
the OS's regex_t implementation. Luckily our function names already had
pg_ prefixes, but the macros and typenames did not.
Include <regex.h> explicitly on all POSIX systems, and fix everything
that breaks. Then we can prove that we are capable of fully hiding and
replacing the system regex API with our own.
1. Deal with standard-clobbering macros by undefining them all first.
POSIX says they are "symbolic constants". If they are macros, this
allows us to redefine them. If they are enums or variables, our macros
will hide them.
2. Deal with standard-clobbering types by giving our types pg_
prefixes, and then using macros to redirect xxx_t -> pg_xxx_t.
After including our "regex/regex.h", the system <regex.h> is hidden,
because we've replaced all the standard names. The PostgreSQL source
tree and extensions can continue to use standard prefix-less type and
macro names, but reach our implementation, if they included our
"regex/regex.h" header.
Back-patch to all supported branches, so that macOS 15's tool chain can
build them.
Reported-by: Stan Hu <stanhu@gmail.com>
Suggested-by: Tom Lane <tgl@sss.pgh.pa.us>
Tested-by: Aleksander Alekseev <aleksander@timescale.com>
Discussion: https://postgr.es/m/CAMBWrQnEwEJtgOv7EUNsXmFw2Ub4p5P%2B5QTBEgYwiyjy7rAsEQ%40mail.gmail.com
Each of max_connections, max_worker_processes,
autovacuum_max_workers, and max_wal_senders has a GUC check hook
that verifies the sum of those GUCs does not exceed a hard-coded
limit (see the comment for MAX_BACKENDS in postmaster.h). In
general, the hooks effectively guard against egregious
misconfigurations.
However, this approach has some problems. Since these check hooks
are called as each GUC is assigned its user-specified value, only
one of the hooks will be called with all the relevant GUCs set. If
one or more of the user-specified values are less than the initial
values of the GUCs' underlying variables, false positives can
occur.
Furthermore, the error message emitted when one of the check hooks
fails is not tremendously helpful. For example, the command
$ pg_ctl -D . start -o "-c max_connections=262100 -c max_wal_senders=10000"
fails with the following error:
FATAL: invalid value for parameter "max_wal_senders": 10000
Fortunately, there is an extra copy of this check in
InitializeMaxBackends() that we can rely on, so this commit removes
the aforementioned GUC check hooks in favor of that one. It also
enhances the error message to clearly show the values of the
relevant GUCs and the hard-coded limit their sum may not exceed.
The downside of this change is that server startup progresses
further before failing due to such misconfigurations (thus taking
longer), but these failures are expected to be rare, so we don't
anticipate any real harm in practice.
Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/ZnMr2k-Nk5vj7T7H%40nathan
This can be used to load an injection point and prewarm the
backend-level cache before running it, to avoid issues if the point
cannot be loaded due to restrictions in the code path where it would be
run, like a critical section where no memory allocation can happen
(load_external_function() can do allocations when expanding a library
name).
Tests can use a macro called INJECTION_POINT_LOAD() to load an injection
point. The test module injection_points gains some tests, and a SQL
function able to load an injection point.
Based on a request from Andrey Borodin, who has implemented a test for
multixacts requiring this facility.
Reviewed-by: Andrey Borodin
Discussion: https://postgr.es/m/ZkrBE1e2q2wGvsoN@paquier.xyz
Since commit 5764f611e1, we've been using the ilist.h functions for
handling the linked list. There's no need for 'links' to be the first
element of the struct anymore, except for one call in InitProcess
where we used a straight cast from the 'dlist_node *' to PGPROC *,
without the dlist_container() macro. That was just an oversight in
commit 5764f611e1, fix it.
There no imminent need to move 'links' from being the first field, but
let's be tidy.
Reviewed-by: Aleksander Alekseev, Andres Freund
Discussion: https://www.postgresql.org/message-id/22aa749e-cc1a-424a-b455-21325473a794@iki.fi
Up until now, there was no ability to easily determine if a Material
node caused the underlying tuplestore to spill to disk or even see how
much memory the tuplestore used if it didn't.
Here we add some new functions to tuplestore.c to query this information
and add some additional output in EXPLAIN ANALYZE to display this
information for the Material node.
There are a few other executor node types that use tuplestores, so we
could also consider adding these details to the EXPLAIN ANALYZE for
those nodes too. Let's consider those independently from this. Having
the tuplestore.c infrastructure in to allow that is step 1.
Author: David Rowley
Reviewed-by: Matthias van de Meent, Dmitry Dolgov
Discussion: https://postgr.es/m/CAApHDvp5Py9g4Rjq7_inL3-MCK1Co2CRt_YWFwTU2zfQix0p4A@mail.gmail.com
Hash joins can support semijoin with the LHS input on the right, using
the existing logic for inner join, combined with the assurance that only
the first match for each inner tuple is considered, which can be
achieved by leveraging the HEAP_TUPLE_HAS_MATCH flag. This can be very
useful in some cases since we may now have the option to hash the
smaller table instead of the larger.
Merge join could likely support "Right Semi Join" too. However, the
benefit of swapping inputs tends to be small here, so we do not address
that in this patch.
Note that this patch also modifies a test query in join.sql to ensure it
continues testing as intended. With this patch the original query would
result in a right-semi-join rather than semi-join, compromising its
original purpose of testing the fix for neqjoinsel's behavior for
semi-joins.
Author: Richard Guo
Reviewed-by: wenhui qiu, Alena Rybakina, Japin Li
Discussion: https://postgr.es/m/CAMbWs4_X1mN=ic+SxcyymUqFx9bB8pqSLTGJ-F=MHy4PW3eRXw@mail.gmail.com
This code wanted to ensure that the 'exchange' variable passed to
pg_atomic_compare_exchange_u64 has correct alignment, but apparently
platforms don't actually require anything that doesn't come naturally.
While messing with pg_atomic_monotonic_advance_u64: instead of using
Max() to determine the value to return, just use
pg_atomic_compare_exchange_u64()'s return value to decide; also, use
pg_atomic_compare_exchange_u64 instead of the _impl version; also remove
the unnecessary underscore at the end of variable name "target".
Backpatch to 17, where this code was introduced by commit bf3ff7bf83bc.
Reported-by: Alexander Lakhin <exclusion@gmail.com>
Discussion: https://postgr.es/m/36796438-a718-cf9b-2071-b2c1b947c1b5@gmail.com
This function returns the ACL for a database object, specified by
catalog OID and object OID. This is useful to be able to
retrieve the ACL associated to an object specified with a
(class_id,objid) couple, similarly to the other functions for object
identification, when joined with pg_depend or pg_shdepend.
Original idea by Álvaro Herrera.
Bump catalog version.
Author: Joel Jacobson
Reviewed-by: Isaac Morland, Michael Paquier, Ranier Vilela
Discussion: https://postgr.es/m/80b16434-b9b1-4c3d-8f28-569f21c2c102@app.fastmail.com
We have in launch_backend.c:
/*
* The following need to be available to the save/restore_backend_variables
* functions. They are marked NON_EXEC_STATIC in their home modules.
*/
extern slock_t *ShmemLock;
extern slock_t *ProcStructLock;
extern PGPROC *AuxiliaryProcs;
extern PMSignalData *PMSignalState;
extern pg_time_t first_syslogger_file_time;
extern struct bkend *ShmemBackendArray;
extern bool redirection_done;
That comment is not completely true: ShmemLock, ShmemBackendArray, and
redirection_done are not in fact NON_EXEC_STATIC. ShmemLock once was,
but was then needed elsewhere. ShmemBackendArray was static inside
postmaster.c before launch_backend.c was created. redirection_done
was never static.
This patch moves the declaration of ShmemLock and redirection_done to
a header file.
ShmemBackendArray gets a NON_EXEC_STATIC. This doesn't make a
difference, since it only exists if EXEC_BACKEND anyway, but it makes
it consistent.
After that, the comment is now correct.
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://www.postgresql.org/message-id/flat/e0a62134-83da-4ba4-8cdb-ceb0111c95ce@eisentraut.org
This old CPU architecture hasn't been produced in decades, and
whatever instances might still survive are surely too underpowered
for anyone to consider running Postgres on in production. We'd
nonetheless continued to carry code support for it (largely at my
insistence), because its unique implementation of spinlocks seemed
like a good edge case for our spinlock infrastructure. However,
our last buildfarm animal of this type was retired last year, and
it seems quite unlikely that another will emerge. Without the ability
to run tests, the argument that this is useful test code fails to
hold water. Furthermore, carrying code support for an untestable
architecture has costs not to be ignored. So, remove HPPA-specific
code, in the same vein as commits 718aa43a4 and 92d70b77e.
Discussion: https://postgr.es/m/3351991.1697728588@sss.pgh.pa.us
This commit adjusts pg_sequence_last_value() to return NULL instead
of ERROR-ing for sequences for which the current user lacks
privileges. This allows us to remove the call to
has_sequence_privilege() in the definition of the pg_sequences
system view.
Bumps catversion.
Suggested-by: Michael Paquier
Reviewed-by: Michael Paquier, Tom Lane
Discussion: https://postgr.es/m/20240501005730.GA594666%40nathanxps13
The standby_slot_names GUC allows the specification of physical standby
slots that must be synchronized before the logical walsenders associated
with logical failover slots. However, for this purpose, the GUC name is
too generic.
Author: Hou Zhijie
Reviewed-by: Bertrand Drouvot, Masahiko Sawada
Backpatch-through: 17
Discussion: https://postgr.es/m/ZnWeUgdHong93fQN@momjian.us
Shared statistics with a fixed number of objects are read from the stats
file in pgstat_read_statsfile() using members of PgStat_ShmemControl and
following an order based on their PgStat_Kind value.
Instead of being explicit, this commit changes the stats read to iterate
over the pgstat_kind_infos array to find the memory locations to read
into, based on a new shared_ctl_off in PgStat_KindInfo that can be used
to define the position of this stats kind in shared memory. This makes
the read logic simpler, and eases the introduction of future
improvements aimed at making this area more pluggable for external
modules.
Original idea suggested by Andres Freund.
Author: Tristan Partin
Reviewed-by: Andres Freund, Michael Paquier
Discussion: https://postgr.es/m/D12SQ7OYCD85.20BUVF3DWU5K7@neon.tech
This field is used to track if a stats kind can use a custom format
representation on disk when reading or writing its stats case. On HEAD,
this exists for replication slots stats, that need a mapping between an
internal index ID and the slot names.
named_on_disk is currently used nowhere and the callbacks
to_serialized_name and from_serialized_name are in charge of checking if
the serialization of the stats data should apply, so let's remove it.
Reviewed-by: Andres Freund
Discussion: https://postgr.es/m/ZmKVlSX_T5YvIOsd@paquier.xyz
Instead of looking up casts at parse time for converting the result
of JsonPath* query functions to the specified or the default
RETURNING type, always perform the conversion at runtime using either
the target type's input function or the function
json_populate_type().
There are two motivations for this change:
1. json_populate_type() coerces to types with typmod such that any
string values that exceed length limit cause an error instead of
silent truncation, which is necessary to be standard-conforming.
2. It was possible to end up with a cast expression that doesn't
support soft handling of errors causing bugs in the of handling
ON ERROR clause.
JsonExpr.coercion_expr which would store the cast expression is no
longer necessary, so remove.
Bump catversion because stored rules change because of the above
removal.
Reported-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Jian He <jian.universality@gmail.com>
Discussion: Discussion: https://postgr.es/m/202405271326.5a5rprki64aw%40alvherre.pgsql
Before this commit, when the WAL summarizer started up or recovered
from an error, it would resume summarization from wherever it left
off. That was OK normally, but wrong if summarize_wal=off had been
turned off temporary, allowing some WAL to be removed, and then turned
back on again. In such cases, the WAL summarizer would simply hang
forever. This commit changes the reinitialization sequence for WAL
summarizer to rederive the starting position in the way we were
already doing at initial startup, fixing the problem.
Per report from Israel Barth Rubio. Reviewed by Tom Lane.
Discussion: http://postgr.es/m/CA+TgmoYN6x=YS+FoFOS6=nr6=qkXZFWhdiL7k0oatGwug2hcuA@mail.gmail.com
Commit 2c03216d831160bedd72d45f712601b6f7d03f1c moved the tuple data
from there to the buffer-0 data. Back-patch to v12 (all supported
versions), the plan for the next change to this struct.
Discussion: https://postgr.es/m/20240523000548.58.nmisch@google.com
This extends ad98fb14226ae6456fbaed7990ee7591cbe5efd2 to invals of
inplace updates. Trouble requires an inplace update of a catalog having
a TOAST table, so only pg_database was at risk. (The other catalog on
which core code performs inplace updates, pg_class, has no TOAST table.)
Trouble would require something like the inplace-inval.spec test.
Consider GRANT ... ON DATABASE fetching a stale row from cache and
discarding a datfrozenxid update that vac_truncate_clog() has already
relied upon. Back-patch to v12 (all supported versions).
Reviewed (in an earlier version) by Robert Haas.
Discussion: https://postgr.es/m/20240114201411.d0@rfd.leadboat.com
Discussion: https://postgr.es/m/20240512232923.aa.nmisch@google.com
Commit 5b562644fec696977df4a82790064e8287927891 added a comment that
SetRelationHasSubclass() callers must hold this lock. When commit
17f206fbc824d2b4b14480199ca9ff7dea417eda extended use of this column to
partitioned indexes, it didn't take the lock. As the latter commit
message mentioned, we currently never reset a partitioned index to
relhassubclass=f. That largely avoids harm from the lock omission. The
cause for fixing this now is to unblock introducing a rule about locks
required to heap_update() a pg_class row. This might cause more
deadlocks. It gives minor user-visible benefits:
- If an ALTER INDEX SET TABLESPACE runs concurrently with ALTER TABLE
ATTACH PARTITION or CREATE PARTITION OF, one transaction blocks
instead of failing with "tuple concurrently updated". (Many cases of
DDL concurrency still fail that way.)
- Match ALTER INDEX ATTACH PARTITION in choosing to lock the index.
While not user-visible today, we'll need this if we ever make something
set the flag to false for a partitioned index, like ANALYZE does today
for tables. Back-patch to v12 (all supported versions), the plan for
the commit relying on the new rule. In back branches, add
LockOrStrongerHeldByMe() instead of adding a LockHeldByMe() parameter.
Reviewed (in an earlier version) by Robert Haas.
Discussion: https://postgr.es/m/20240611024525.9f.nmisch@google.com
We did not recover the subtransaction IDs of prepared transactions
when starting a hot standby from a shutdown checkpoint. As a result,
such subtransactions were considered as aborted, rather than
in-progress. That would lead to hint bits being set incorrectly, and
the subtransactions suddenly becoming visible to old snapshots when
the prepared transaction was committed.
To fix, update pg_subtrans with prepared transactions's subxids when
starting hot standby from a shutdown checkpoint. The snapshots taken
from that state need to be marked as "suboverflowed", so that we also
check the pg_subtrans.
Backport to all supported versions.
Discussion: https://www.postgresql.org/message-id/6b852e98-2d49-4ca1-9e95-db419a2696e0@iki.fi
RT_NODE_16_SEARCH_EQ() performs comparisions using vector registers
on x64-64 and aarch64. We apply a mask to the resulting bitfield
to eliminate irrelevant bits that may be set. This ensures correct
behavior, but Valgrind complains of the partially-uninitialised
values. So far the warnings have only occurred on aarch64, which
explains why this hasn't been seen earlier.
To fix this warning, initialize the whole fixed-sized part of the nodes
upon allocation, rather than just do the minimum initialization to
function correctly. The initialization for node48 is a bit different
in that the 256-byte slot index array must be populated with "invalid
index" rather than zero. Experimentation has shown that compilers
tend to emit code that uselessly memsets that array twice. To avoid
pessimizing this path, swap the order of the slot_idxs[] and isset[]
arrays so we can initialize with two non-overlapping memset calls.
Reported by Tomas Vondra
Analysis and patch by Tom Lane, reviewed by Masahiko Sawada. I
investigated the behavior of memset calls to overlapping regions,
leading to the above tweaks to node48 as discussed in the thread.
Discussion: https://postgr.es/m/120c63ad-3d12-415f-a7bf-3da451c31bf6%40enterprisedb.com
