Currently, pg_visibility computes its xid horizon using the
GetOldestNonRemovableTransactionId(). The problem is that this horizon can
sometimes go backward. That can lead to reporting false errors.
In order to fix that, this commit implements a new function
GetStrictOldestNonRemovableTransactionId(). This function computes the xid
horizon, which would be guaranteed to be newer or equal to any xid horizon
computed before.
We have to do the following to achieve this.
1. Ignore processes xmin's, because they consider connection to other databases
that were ignored before.
2. Ignore KnownAssignedXids, because they are not database-aware. At the same
time, the primary could compute its horizons database-aware.
3. Ignore walsender xmin, because it could go backward if some replication
connections don't use replication slots.
As a result, we're using only currently running xids to compute the horizon.
Surely these would significantly sacrifice accuracy. But we have to do so to
avoid reporting false errors.
Inspired by earlier patch by Daniel Shelepanov and the following discussion
with Robert Haas and Tom Lane.
Discussion: https://postgr.es/m/1649062270.289865713%40f403.i.mail.ru
Reviewed-by: Alexander Lakhin, Dmitry Koval
New provider for collations, like "libc" or "icu", but without any
external dependency.
Initially, the only locale supported by the builtin provider is "C",
which is identical to the libc provider's "C" locale. The libc
provider's "C" locale has always been treated as a special case that
uses an internal implementation, without using libc at all -- so the
new builtin provider uses the same implementation.
The builtin provider's locale is independent of the server environment
variables LC_COLLATE and LC_CTYPE. Using the builtin provider, the
database collation locale can be "C" while LC_COLLATE and LC_CTYPE are
set to "en_US", which is impossible with the libc provider.
By offering a new builtin provider, it clarifies that the semantics of
a collation using this provider will never depend on libc, and makes
it easier to document the behavior.
Discussion: https://postgr.es/m/ab925f69-5f9d-f85e-b87c-bd2a44798659@joeconway.com
Discussion: https://postgr.es/m/dd9261f4-7a98-4565-93ec-336c1c110d90@manitou-mail.org
Discussion: https://postgr.es/m/ff4c2f2f9c8fc7ca27c1c24ae37ecaeaeaff6b53.camel%40j-davis.com
Reviewed-by: Daniel Vérité, Peter Eisentraut, Jeremy Schneider
With the makefile rules, the output of genbki.pl was written to
src/backend/catalog/, and then the header files were linked to
src/include/catalog/.
This changes it so that the output files are written directly to
src/include/catalog/. This makes the logic simpler, and it also makes
the behavior consistent with the meson build system. Also, the list
of catalog files is now kept in parallel in
src/include/catalog/{meson.build,Makefile}, while before the makefiles
had it in src/backend/catalog/Makefile.
Reviewed-by: Andreas Karlsson <andreas@proxel.se>
Discussion: https://www.postgresql.org/message-id/flat/21b74bdc-183d-4dd5-9c27-9378d178f459@eisentraut.org
pg_stat_checkpointer contains statistics for checkpoints and restartpoints.
Before 12915a58eec9 documentation said only about checkpoints implying that
restartpoint is the variation of checkpoint. 12915a58eec9 introduced
new separate statistics fields for restartpoints. This commit explicitly
documents fields that are relevant for both checkpoints and restartpoints.
Reported-by: Magnus Hagander
Discussion: https://postgr.es/m/CABUevExav5-SR0x%2BG9kBUMV0G8XsvSUfuyyqmYBBJi6VHns6sw%40mail.gmail.com
Reviewed-by: Anton A. Melnikov
Roles with MAINTAIN on a relation may run VACUUM, ANALYZE, REINDEX,
REFRESH MATERIALIZE VIEW, CLUSTER, and LOCK TABLE on the relation.
Roles with privileges of pg_maintain may run those same commands on
all relations.
This was previously committed for v16, but it was reverted in
commit 151c22deee due to concerns about search_path tricks that
could be used to escalate privileges to the table owner. Commits
2af07e2f74, 59825d1639, and c7ea3f4229 resolved these concerns by
restricting search_path when running maintenance commands.
Bumps catversion.
Reviewed-by: Jeff Davis
Discussion: https://postgr.es/m/20240305161235.GA3478007%40nathanxps13
Before this patch, if you took a full backup on server A and then
tried to use the backup manifest to take an incremental backup on
server B, it wouldn't know that the manifest was from a different
server and so the incremental backup operation could potentially
complete without error. When you later tried to run pg_combinebackup,
you'd find out that your incremental backup was and always had been
invalid. That's poor timing, because nobody likes finding out about
backup problems only at restore time.
With this patch, you'll get an error when trying to take the (invalid)
incremental backup, which seems a lot nicer.
Amul Sul, revised by me. Review by Michael Paquier.
Discussion: http://postgr.es/m/CA+TgmoYLZzbSAMM3cAjV4Y+iCRZn-bR9H2+Mdz7NdaJFU1Zb5w@mail.gmail.com
This works just like get_controlfile(), but expects the path to the
control file rather than the path to the data directory that contains
the control file. This makes more sense in cases where the caller
has already constructed the path to the control file itself.
Amul Sul and Robert Haas, reviewed by Michael Paquier
There is a very ancient hack in check_sql_fn_retval that allows a
single SELECT targetlist entry of composite type to be taken as
supplying all the output columns of a function returning composite.
(This is grotty and fundamentally ambiguous, but it's really hard
to do nested composite-returning functions without it.)
As far as I know, that doesn't cause any problems in ordinary
functions. It's disastrous for procedures however. All procedures
that have any output parameters are labeled with prorettype RECORD,
and the CALL code expects it will get back a record with one column
per output parameter, regardless of whether any of those parameters
is composite. Doing something else leads to an assertion failure
or core dump.
This is simple enough to fix: we just need to not apply that rule
when considering procedures. However, that requires adding another
argument to check_sql_fn_retval, which at least in principle might be
getting called by external callers. Therefore, in the back branches
convert check_sql_fn_retval into an ABI-preserving wrapper around a
new function check_sql_fn_retval_ext.
Per report from Yahor Yuzefovich. This has been broken since we
implemented procedures, so back-patch to all supported branches.
Discussion: https://postgr.es/m/CABz5gWHSjj2df6uG0NRiDhZ_Uz=Y8t0FJP-_SVSsRsnrQT76Gg@mail.gmail.com
In postmaster, use a more lightweight ClientSocket struct that
encapsulates just the socket itself and the remote endpoint's address
that you get from accept() call. ClientSocket is passed to the child
process, which initializes the bigger Port struct. This makes it more
clear what information postmaster initializes, and what is left to the
child process.
Rename the StreamServerPort and StreamConnection functions to make it
more clear what they do. Remove StreamClose, replacing it with plain
closesocket() calls.
Reviewed-by: Tristan Partin, Andres Freund
Discussion: https://www.postgresql.org/message-id/7a59b073-5b5b-151e-7ed3-8b01ff7ce9ef@iki.fi
We used to smuggle it to the child process in the Port struct, but it
seems better to pass it down as a separate argument. This paves the
way for the next commit, which moves the initialization of the Port
struct to the backend process, after forking.
Reviewed-by: Tristan Partin, Andres Freund
Discussion: https://www.postgresql.org/message-id/7a59b073-5b5b-151e-7ed3-8b01ff7ce9ef@iki.fi
There is a hook called ExplainOneQuery_hook that gives modules the
possibility to plug into this code path, but, like utility.c for utility
statement execution, there is no corresponding "standard" routine in
the case of EXPLAIN executed for one Query.
This commit adds a new standard_ExplainOneQuery() in explain.c, which is
able to run explain on a non-utility Query without calling its hook.
Per the feedback received from a couple of hackers, this change gives
the possibility to cut a few hundred lines of code in some of the
popular out-of-core modules as these maintained a copy of
ExplainOneQuery(), adding custom extra information at the beginning or
the end of the EXPLAIN output.
Author: Mats Kindahl
Reviewed-by: Aleksander Alekseev, Jelte Fennema-Nio, Andrei Lepikhov
Discussion: https://postgr.es/m/CA+14427V_B4EAoC_o-iYYucRdMSOTfpuH9k-QbexffY1HYJBiA@mail.gmail.com
Rename pg_collation.colliculocale to colllocale, and
pg_database.daticulocale to datlocale. These names reflects that the
fields will be useful for the upcoming builtin provider as well, not
just for ICU.
This is purely a rename; no changes to the meaning of the fields.
Discussion: https://postgr.es/m/ff4c2f2f9c8fc7ca27c1c24ae37ecaeaeaff6b53.camel%40j-davis.com
Reviewed-by: Peter Eisentraut
... and in particular don't return them as replica identity.
The motivation for this change is letting the primary keys be seen by
code that derives NOT NULL constraints from them, when creating
inheritance children; before this change, if you had a deferrable PK,
pg_dump would not recreate the attnotnull marking properly, because the
column would not be considered as having anything to back said marking
after dropping the throwaway NOT NULL constraint.
The reason we don't want these PKs as replica identities is that
replication can corrupt data, if the uniqueness constraint is
transiently broken.
Reported-by: Amul Sul <sulamul@gmail.com>
Reviewed-by: Dean Rasheed <dean.a.rasheed@gmail.com>
Discussion: https://postgr.es/m/CAAJ_b94QonkgsbDXofakHDnORQNgafd1y3Oa5QXfpQNJyXyQ7A@mail.gmail.com
You might run out of stack space with recursion, which is not nice in
functions that might be used e.g. at cleanup after transaction
abort. MemoryContext contains pointer to parent and siblings, so we
can traverse a tree of contexts iteratively, without using
stack. Refactor the functions to do that.
MemoryContextStats() still recurses, but it now has a limit to how
deep it recurses. Once the limit is reached, it prints just a summary
of the rest of the hierarchy, similar to how it summarizes contexts
with lots of children. That seems good anyway, because a context dump
with hundreds of nested contexts isn't very readable.
Report by Egor Chindyaskin and Alexander Lakhin.
Discussion: https://postgr.es/m/1672760457.940462079%40f306.i.mail.ru
Author: Heikki Linnakangas
Reviewed-by: Robert Haas, Andres Freund, Alexander Korotkov, Tom Lane
This patch provides a way to ensure that physical standbys that are
potential failover candidates have received and flushed changes before
the primary server making them visible to subscribers. Doing so guarantees
that the promoted standby server is not lagging behind the subscribers
when a failover is necessary.
The logical walsender now guarantees that all local changes are sent and
flushed to the standby servers corresponding to the replication slots
specified in 'standby_slot_names' before sending those changes to the
subscriber.
Additionally, the SQL functions pg_logical_slot_get_changes,
pg_logical_slot_peek_changes and pg_replication_slot_advance are modified
to ensure that they process changes for failover slots only after physical
slots specified in 'standby_slot_names' have confirmed WAL receipt for those.
Author: Hou Zhijie and Shveta Malik
Reviewed-by: Masahiko Sawada, Peter Smith, Bertrand Drouvot, Ajin Cherian, Nisha Moond, Amit Kapila
Discussion: https://postgr.es/m/514f6f2f-6833-4539-39f1-96cd1e011f23@enterprisedb.com
Since b0483263dda0, this field can be used to store an access method
name for ALTER TABLE, but access methods were not mentioned in the
field's description.
Issue noticed while working on the area.
Discussion: https://postgr.es/m/ZeWKgCtk6xiAsDsc@paquier.xyz
Implements Unicode simple case mapping, in which all code points map
to exactly one other code point unconditionally.
These tables are generated from UnicodeData.txt, which is already
being used by other infrastructure in src/common/unicode. The tables
are checked into the source tree, so they only need to be regenerated
when we update the Unicode version.
In preparation for the builtin collation provider, and possibly useful
for other callers.
Discussion: https://postgr.es/m/ff4c2f2f9c8fc7ca27c1c24ae37ecaeaeaff6b53.camel%40j-davis.com
Reviewed-by: Peter Eisentraut, Daniel Verite, Jeremy Schneider
The inh field of RangeTblEntry was doubly confusingly documented.
Some parts of the code insisted that it was only valid for
RTE_RELATION entries, other parts said the field was valid for all
entries. Neither was quite correct. More correctly, the field is
valid for RTE_RELATION entries but is also used in the planner for
RTE_SUBQUERY entries. So it makes more sense to group it with other
fields that are primarily for RTE_RELATION but borrowed by
RTE_SUBQUERY. (The exact position was chosen so that it is next to
relkind for better struct packing, and next to relid, since relid and
inh are sort of the input fields and the others are filled in later.)
Also add documentation for the planner's use at the struct definition.
Discussion: https://www.postgresql.org/message-id/6c1fbccc-85c8-40d3-b08b-4f47f2093711@eisentraut.org
This implements a radix tree data structure based on the design in
"The Adaptive Radix Tree: ARTful Indexing for Main-Memory Databases"
by Viktor Leis, Alfons Kemper, and ThomasNeumann, 2013. The main
technique that makes it adaptive is using several different node types,
each with a different capacity of elements, and a different algorithm
for accessing them. The nodes start small and grow/shrink as needed.
The main advantage over hash tables is efficient sorted iteration and
better memory locality when successive keys are lexicographically
close together. The implementation currently assumes 64-bit integer
keys, and traversing the tree is in general slower than a linear
probing hash table, so this is not a general-purpose associative array.
The paper describes two other techniques not implemented here,
namely "path compression" and "lazy expansion". These can further
reduce memory usage and speed up traversal, but the former would add
significant complexity and the latter requires storing the full key
with the value. We do trivially compress the path when leading bytes
of the key are zeros, however.
For value storage, we use "combined pointer/value slots", as
recommended in the paper. Values of size equal or smaller than the the
platform's pointer type are stored in the array of child pointers in
the last level node, while larger values are each stored in a separate
allocation. This is for now fixed at compile time, but it would be
fairly trivial to allow determining at runtime how variable-length
values are stored.
One innovation in our implementation compared to the ART paper is
decoupling the notion of node "size class" from "kind". The size
classes within a given node kind have the same underlying type, but
a variable capacity for children, so we can introduce additional node
sizes with little additional code.
To enable different use cases to specialize for different value types
and for shared/local memory, we use macro-templatized code generation
in the same manner as simplehash.h and sort_template.h.
Future commits will use this infrastructure for storing TIDs.
Patch by Masahiko Sawada and John Naylor, but a substantial amount of
credit is due to Andres Freund, whose proof-of-concept was a valuable
source of coding idioms and awareness of performance pitfalls, and
who reviewed earlier versions.
Discussion: https://postgr.es/m/CAD21AoAfOZvmfR0j8VmZorZjL7RhTiQdVttNuC4W-Shdc2a-AA%40mail.gmail.com
This reverts commit eae7be600be7, following a discussion with Tom Lane,
due to concerns that this impacts the decisions made by the planner for
the number of workers spawned based on the inlining and const-folding of
index expressions and predicate for cases that would have worked until
this commit.
Discussion: https://postgr.es/m/162802.1709746091@sss.pgh.pa.us
Backpatch-through: 12
Provide functions to test for Unicode properties, such as Alphabetic
or Cased. These functions use tables derived from Unicode data files,
similar to the tables for Unicode normalization or general category,
and those tables can be updated with the 'update-unicode' build
target.
Use Unicode properties to provide functions to test for regex
character classes, like 'punct' or 'alnum'.
Infrastructure in preparation for a builtin collation provider, and
may also be useful for other callers.
Discussion: https://postgr.es/m/ff4c2f2f9c8fc7ca27c1c24ae37ecaeaeaff6b53.camel%40j-davis.com
Reviewed-by: Daniel Verite, Peter Eisentraut, Jeremy Schneider
The first argument of vshrq_n_s8 needs to be a signed vector type,
but it was passed unsigned. Clang is more lax with conversion, but
gcc needs a cast.
Fix by me, tested by Masahiko Sawada
Per buildfarm members splitfin, batta, widowbird, snakefly, parula,
massasauga
Discussion: https://postgr.es/m/20240306074106.mg6w4koohdlworbs%40alap3.anarazel.de
As coded, the planner logic that calculates the number of parallel
workers to use for a parallel index build uses expressions and
predicates from the relcache, which are flattened for the planner by
eval_const_expressions().
As reported in the bug, an immutable parallel-unsafe function flattened
in the relcache would become a Const, which would be considered as
parallel-safe, even if the predicate or the expressions including the
function are not safe in parallel workers. Depending on the expressions
or predicate used, this could cause the parallel build to fail.
Tests are included that check parallel index builds with parallel-unsafe
predicate and expressions. Two routines are added to lsyscache.h to be
able to retrieve expressions and predicate of an index from its pg_index
data.
Reported-by: Alexander Lakhin
Author: Tender Wang
Reviewed-by: Jian He, Michael Paquier
Discussion: https://postgr.es/m/CAHewXN=UaAaNn9ruHDH3Os8kxLVmtWqbssnf=dZN_s9=evHUFA@mail.gmail.com
Backpatch-through: 12
The copy_file_range() system call is available on at least Linux and
FreeBSD, and asks the kernel to use efficient ways to copy ranges of a
file. Options available to the kernel include sharing block ranges
(similar to --clone mode), and pushing down block copies to the storage
layer.
For automated testing, see PG_TEST_PG_UPGRADE_MODE. (Perhaps in a later
commit we could consider setting this mode for one of the CI targets.)
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Discussion: https://postgr.es/m/CA%2BhUKGKe7Hb0-UNih8VD5UNZy5-ojxFb3Pr3xSBBL8qj2M2%3DdQ%40mail.gmail.com
When perminfoindex was added, it was just added at the end of the
block. It would make sense to keep it closer to more related fields.
In passing, also add an inline comment, like the other fields have.
(Other field reorderings and documentation improvements in
RangeTblEntry are being discussed, but it's better not to mix them
together.)
Discussion: https://www.postgresql.org/message-id/flat/6c1fbccc-85c8-40d3-b08b-4f47f2093711%40eisentraut.org
pg_constraint.conwithoutoverlaps was recently added to support primary
keys and unique constraints with the WITHOUT OVERLAPS clause. An
upcoming patch provides the foreign-key side of this functionality,
but the syntax there is different and uses the keyword PERIOD. It
would make sense to use the same pg_constraint field for both of
these, but then we should pick a more general name that conveys "this
constraint has a temporal/period-related feature". conperiod works
for that and is nicely compact. Changing this now avoids possibly
having to introduce versioning into clients. Note there are still
some "without overlaps" variables left, which deal specifically with
the parsing of the primary key/unique constraint feature.
Author: Paul A. Jungwirth <pj@illuminatedcomputing.com>
Discussion: https://www.postgresql.org/message-id/flat/CA+renyUApHgSZF9-nd-a0+OPGharLQLO=mDHcY4_qQ0+noCUVg@mail.gmail.com
Use GUC_ACTION_SAVE rather than GUC_ACTION_SET, necessary for working
with parallel query.
Now that the call requires more arguments, wrap the call in a new
function to avoid code duplication and offer a place for a comment.
Discussion: https://postgr.es/m/E1rhJpO-0027Wf-9L@gemulon.postgresql.org
While executing maintenance operations (ANALYZE, CLUSTER, REFRESH
MATERIALIZED VIEW, REINDEX, or VACUUM), set search_path to
'pg_catalog, pg_temp' to prevent inconsistent behavior.
Functions that are used for functional indexes, in index expressions,
or in materialized views and depend on a different search path must be
declared with CREATE FUNCTION ... SET search_path='...'.
This change was previously committed as 05e1737351, then reverted in
commit 2fcc7ee7af because it was too late in the cycle.
Preparation for the MAINTAIN privilege, which was previously reverted
due to search_path manipulation hazards.
Discussion: https://postgr.es/m/d4ccaf3658cb3c281ec88c851a09733cd9482f22.camel@j-davis.com
Discussion: https://postgr.es/m/E1q7j7Y-000z1H-Hr%40gemulon.postgresql.org
Discussion: https://postgr.es/m/e44327179e5c9015c8dda67351c04da552066017.camel%40j-davis.com
Reviewed-by: Greg Stark, Nathan Bossart, Noah Misch
Presently, if an archive module's check_configured_cb callback
returns false, a generic WARNING message is emitted, which
unfortunately provides no actionable details about the reason why
the module is not configured. This commit introduces a macro that
archive module authors can use to add a DETAIL line to this WARNING
message.
Co-authored-by: Tung Nguyen
Reviewed-by: Daniel Gustafsson, Álvaro Herrera
Discussion: https://postgr.es/m/4109578306242a7cd5661171647e11b2%40oss.nttdata.com
Auto-generated array types, multirange types, and relation rowtypes
are treated as dependent objects: they can't be dropped separately
from the base object, nor can they have their own ownership or
permissions. We previously felt that, for objects that are in an
extension, only the base object needs to be listed as an extension
member in pg_depend. While that's sufficient to prevent inappropriate
drops, it results in undesirable answers if someone asks whether a
dependent type belongs to the extension. It looks like the dependent
type is just some random separately-created object that happens to
depend on the base object. Notably, this results in postgres_fdw
concluding that expressions involving an array type are not shippable
to the remote server, even when the defining extension has been
whitelisted.
To fix, cause GenerateTypeDependencies to make extension dependencies
for dependent types as well as their base objects, and adjust
ExecAlterExtensionContentsStmt so that object addition and removal
operations recurse to dependent types. The latter change means that
pg_upgrade of a type-defining extension will end with the dependent
type(s) now also listed as extension members, even if they were
not that way in the source database. Normally we want pg_upgrade
to precisely reproduce the source extension's state, but it seems
desirable to make an exception here.
This is arguably a bug fix, but we can't back-patch it since it
causes changes in the expected contents of pg_depend. (Because
it does, I've bumped catversion, even though there's no change
in the immediate post-initdb catalog contents.)
Tom Lane and David Geier
Discussion: https://postgr.es/m/4a847c55-489f-4e8d-a664-fc6b1cbe306f@gmail.com
The pid was originally used in error context of messages propagated
from parallel workers, but commit 292794f82b removed that. If the need
arises in the future, you can also get the pid with
"shm_mq_get_sender(pcxt->worker[i].error_mqh)->pid".
Remove IsBackgroundWorker, IsAutoVacuumLauncherProcess(),
IsAutoVacuumWorkerProcess(), and IsLogicalSlotSyncWorker() in favor of
new Am*Process() macros that use MyBackendType. For consistency with
the existing Am*Process() macros.
Reviewed-by: Andres Freund
Discussion: https://www.postgresql.org/message-id/f3ecd4cb-85ee-4e54-8278-5fabfb3a4ed0@iki.fi
Now that BackendId was just another index into the proc array, it was
redundant with the 0-based proc numbers used in other places. Replace
all usage of backend IDs with proc numbers.
The only place where the term "backend id" remains is in a few pgstat
functions that expose backend IDs at the SQL level. Those IDs are now
in fact 0-based ProcNumbers too, but the documentation still calls
them "backend ids". That term still seems appropriate to describe what
the numbers are, so I let it be.
One user-visible effect is that pg_temp_0 is now a valid temp schema
name, for backend with ProcNumber 0.
Reviewed-by: Andres Freund
Discussion: https://www.postgresql.org/message-id/8171f1aa-496f-46a6-afc3-c46fe7a9b407@iki.fi
Previously, backend ID was an index into the ProcState array, in the
shared cache invalidation manager (sinvaladt.c). The entry in the
ProcState array was reserved at backend startup by scanning the array
for a free entry, and that was also when the backend got its backend
ID. Things become slightly simpler if we redefine backend ID to be the
index into the PGPROC array, and directly use it also as an index to
the ProcState array. This uses a little more memory, as we reserve a
few extra slots in the ProcState array for aux processes that don't
need them, but the simplicity is worth it.
Aux processes now also have a backend ID. This simplifies the
reservation of BackendStatusArray and ProcSignal slots.
You can now convert a backend ID into an index into the PGPROC array
simply by subtracting 1. We still use 0-based "pgprocnos" in various
places, for indexes into the PGPROC array, but the only difference now
is that backend IDs start at 1 while pgprocnos start at 0. (The next
commmit will get rid of the term "backend ID" altogether and make
everything 0-based.)
There is still a 'backendId' field in PGPROC, now part of 'vxid' which
encapsulates the backend ID and local transaction ID together. It's
needed for prepared xacts. For regular backends, the backendId is
always equal to pgprocno + 1, but for prepared xact PGPROC entries,
it's the ID of the original backend that processed the transaction.
Reviewed-by: Andres Freund, Reid Thompson
Discussion: https://www.postgresql.org/message-id/8171f1aa-496f-46a6-afc3-c46fe7a9b407@iki.fi
In the past, FileRead() and FileWrite() used types based on the Unix
read() and write() functions from before C and POSIX standardization,
though not exactly (we had int for amount instead of unsigned). In
commit 2d4f1ba6 we changed to the appropriate standard C types, just
like the modern POSIX functions they wrap, but again not exactly: the
return type stayed as int. In theory, a ssize_t value could be returned
by the underlying call that is too large for an int.
That wasn't really a live bug, because we don't expect PostgreSQL code
to perform reads or writes of gigabytes, and OSes probably apply
internal caps smaller than that anyway. This change is done on the
principle that the return might as well follow the standard interfaces
consistently.
Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Discussion: https://postgr.es/m/1672202.1703441340%40sss.pgh.pa.us
This commit switches pg_enc2gettext_tbl[] in encnames.c to use a
C99-designated initializer syntax.
pg_bind_textdomain_codeset() is simplified so as it is possible to do
a direct lookup at the gettext() array with a value of the enum pg_enc
rather than doing a loop through all its elements, as long as the
encoding value provided by GetDatabaseEncoding() is in the correct range
of supported encoding values. Note that PG_MULE_INTERNAL gains a value
in the array, pointing to NULL.
Author: Jelte Fennema-Nio
Discussion: https://postgr.es/m/CAGECzQT3caUbcCcszNewCCmMbCuyP7XNAm60J3ybd6PN5kH2Dw@mail.gmail.com
Writing correct code using atomic variables is often difficult due
to the memory barrier semantics (or lack thereof) of the underlying
operations. This commit introduces atomic read/write functions
with full barrier semantics to ease this cognitive load. For
example, some spinlocks protect a single value, and these new
functions make it easy to convert the value to an atomic variable
(thus eliminating the need for the spinlock) without modifying the
barrier semantics previously provided by the spinlock. Since these
functions may be less performant than the other atomic reads and
writes, they are not suitable for every use-case. However, using a
single atomic operation with full barrier semantics may be more
performant in cases where a separate explicit barrier would
otherwise be required.
The base implementations for these new functions are atomic
exchanges (for writes) and atomic fetch/adds with 0 (for reads).
These implementations can be overwritten with better architecture-
specific versions as they are discovered.
This commit leaves converting existing code to use these new
functions as a future exercise.
Reviewed-by: Andres Freund, Yong Li, Jeff Davis
Discussion: https://postgr.es/m/20231110205128.GB1315705%40nathanxps13
This allows the target relation of MERGE to be an auto-updatable or
trigger-updatable view, and includes support for WITH CHECK OPTION,
security barrier views, and security invoker views.
A trigger-updatable view must have INSTEAD OF triggers for every type
of action (INSERT, UPDATE, and DELETE) mentioned in the MERGE command.
An auto-updatable view must not have any INSTEAD OF triggers. Mixing
auto-update and trigger-update actions (i.e., having a partial set of
INSTEAD OF triggers) is not supported.
Rule-updatable views are also not supported, since there is no
rewriter support for non-SELECT rules with MERGE operations.
Dean Rasheed, reviewed by Jian He and Alvaro Herrera.
Discussion: https://postgr.es/m/CAEZATCVcB1g0nmxuEc-A+gGB0HnfcGQNGYH7gS=7rq0u0zOBXA@mail.gmail.com
This updates the following lookup arrays to use C99-designated
initializer syntax, indexed based on the enum pg_enc:
pg_enc2icu_tbl[]
pg_enc2name_tbl[]
pg_wchar_table[]
This is more readable, and removes problems with ordering mistakes as
this removes dependencies between the arrays and their lookup index in
the enum pg_enc. So, adding new encodings becomes easier, even if this
does not happen often.
Author: Jelte Fennema-Nio
Reviewed-by: Jian He, Japin Li
Discussion: https://postgr.es/m/CAGECzQT3caUbcCcszNewCCmMbCuyP7XNAm60J3ybd6PN5kH2Dw@mail.gmail.com
More precisely, what we do here is make the SLRU cache sizes
configurable with new GUCs, so that sites with high concurrency and big
ranges of transactions in flight (resp. multixacts/subtransactions) can
benefit from bigger caches. In order for this to work with good
performance, two additional changes are made:
1. the cache is divided in "banks" (to borrow terminology from CPU
caches), and algorithms such as eviction buffer search only affect
one specific bank. This forestalls the problem that linear searching
for a specific buffer across the whole cache takes too long: we only
have to search the specific bank, whose size is small. This work is
authored by Andrey Borodin.
2. Change the locking regime for the SLRU banks, so that each bank uses
a separate LWLock. This allows for increased scalability. This work
is authored by Dilip Kumar. (A part of this was previously committed as
d172b717c6f4.)
Special care is taken so that the algorithms that can potentially
traverse more than one bank release one bank's lock before acquiring the
next. This should happen rarely, but particularly clog.c's group commit
feature needed code adjustment to cope with this. I (Álvaro) also added
lots of comments to make sure the design is sound.
The new GUCs match the names introduced by bcdfa5f2e2f2 in the
pg_stat_slru view.
The default values for these parameters are similar to the previous
sizes of each SLRU. commit_ts, clog and subtrans accept value 0, which
means to adjust by dividing shared_buffers by 512 (so 2MB for every 1GB
of shared_buffers), with a cap of 8MB. (A new slru.c function
SimpleLruAutotuneBuffers() was added to support this.) The cap was
previously 1MB for clog, so for sites with more than 512MB of shared
memory the total memory used increases, which is likely a good tradeoff.
However, other SLRUs (notably multixact ones) retain smaller sizes and
don't support a configured value of 0. These values based on
shared_buffers may need to be revisited, but that's an easy change.
There was some resistance to adding these new GUCs: it would be better
to adjust to memory pressure automatically somehow, for example by
stealing memory from shared_buffers (where the caches can grow and
shrink naturally). However, doing that seems to be a much larger
project and one which has made virtually no progress in several years,
and because this is such a pain point for so many users, here we take
the pragmatic approach.
Author: Andrey Borodin <x4mmm@yandex-team.ru>
Author: Dilip Kumar <dilipbalaut@gmail.com>
Reviewed-by: Amul Sul, Gilles Darold, Anastasia Lubennikova,
Ivan Lazarev, Robert Haas, Thomas Munro, Tomas Vondra,
Yura Sokolov, Васильев Дмитрий (Dmitry Vasiliev).
Discussion: https://postgr.es/m/2BEC2B3F-9B61-4C1D-9FB5-5FAB0F05EF86@yandex-team.ru
Discussion: https://postgr.es/m/CAFiTN-vzDvNz=ExGXz6gdyjtzGixKSqs0mKHMmaQ8sOSEFZ33A@mail.gmail.com
