Run pgindent, pgperltidy, and reformat-dat-files.
This set of diffs is a bit larger than typical. We've updated to
pg_bsd_indent 2.1.2, which properly indents variable declarations that
have multi-line initialization expressions (the continuation lines are
now indented one tab stop). We've also updated to perltidy version
20230309 and changed some of its settings, which reduces its desire to
add whitespace to lines to make assignments etc. line up. Going
forward, that should make for fewer random-seeming changes to existing
code.
Discussion: https://postgr.es/m/20230428092545.qfb3y5wcu4cm75ur@alvherre.pgsql
This fixes many spelling mistakes in comments, but a few references to
invalid parameter names, function names and option names too in comments
and also some in string constants
Also, fix an #undef that was undefining the incorrect definition
Author: Alexander Lakhin
Reviewed-by: Justin Pryzby
Discussion: https://postgr.es/m/d5f68d19-c0fc-91a9-118d-7c6a5a3f5fad@gmail.com
This GUC was renamed to debug_parallel_query in 5352ca22e. That commit
added an entry into map_old_guc_names[] to allow the old name still to
work. That was done to allow a transition time where the buildfarm
configs could be swapped over to use debug_parallel_query instead. That
work is now complete.
Here we remove the old name with the intention of breaking any user code
which is using force_parallel_query. As mentioned in the commit message
for 5352ca22e, it appeared many users were misled into thinking that
setting this GUC was doing something useful for them to make queries run
more quickly.
Discussion: https://postgr.es/m/CAApHDvoR7EOz7Tvyzrd18FO-Dw2Cp4Uyq25TEWguK+XyCJtzOw@mail.gmail.com
Mainly move some detail from errmsg to errdetail, remove explicit
mention of superuser where appropriate, since that is implied in most
permission checks, and make messages more uniform.
Author: Nathan Bossart <nathandbossart@gmail.com>
Discussion: https://www.postgresql.org/message-id/20230316234701.GA903298@nathanxps13
force_parallel_mode is meant to be used to allow us to exercise the
parallel query infrastructure to ensure that it's working as we expect.
It seems some users think this GUC is for forcing the query planner into
picking a parallel plan regardless of the costs. A quick look at the
documentation would have made them realize that they were wrong, but the
GUC is likely too conveniently named which, evidently, seems to often
result in users expecting that it forces the planner into usefully
parallelizing queries.
Here we rename the GUC to something which casual users are less likely to
mistakenly think is what they need to make their query run more quickly.
For now, the old name can still be used. We'll revisit if the old name
mapping can be removed once the buildfarm configs are all updated.
Reviewed-by: John Naylor
Discussion: https://postgr.es/m/CAApHDvrsOi92_uA7PEaHZMH-S4Xv+MGhQWA+GrP8b1kjpS1HjQ@mail.gmail.com
This extends the work begun by a73952b, with the addition of a GUC check
for flag combinations in check_GUC_init(), making sure that anything
defined with GUC_NO_SHOW_ALL also includes GUC_NOT_IN_SAMPLE, as first
step. There has never been any GUCs of this kind in the core code, and
this combination makes little sense as a parameter marked as not fit for
SHOW ALL should not be hidden in postgresql.conf.sample.
Note that GUCs marked with GUC_NO_SHOW_ALL are not listed under
pg_settings or SHOW ALL (still they can be queried individually), making
them unfit for checks via SQL queries in the regression tests that do a
full scan of the parameters available. The SQL tests are still a bit
incorrect about that, and will be cleaned up in a separate commit. We
have also discussed the possibility to extend the SQL functions for GUCs
so as they could show more information about parameters defined with
GUC_NO_SHOW_ALL, though it has been concluded that this is not worth the
extra complication in the long run, an enforced policy at initialization
time being enough to do the same job.
Per discussion with Nitin Jadhav and Tom Lane.
Discussion: https://postgr.es/m/CAMm1aWaYe0muu3ABo7iSAgK+OWDS9yNe8GGRYnCyeEpScYKa+g@mail.gmail.com
Split out "ConfigOptionIsVisible" to perform the privilege
check for GUC_SUPERUSER_ONLY GUCs (which these days can also
be read by pg_read_all_settings role members), and move the
should-we-show-it checks from GetConfigOptionValues to its
sole caller.
This commit also removes get_explain_guc_options's check of
GUC_NO_SHOW_ALL, which seems to have got cargo-culted in there.
While there's no obvious use-case for marking a GUC both
GUC_EXPLAIN and GUC_NO_SHOW_ALL, if it were set up that way
one would expect EXPLAIN to show it --- if that's not what
you want, then don't set GUC_EXPLAIN.
In passing, simplify the loop logic in show_all_settings.
Nitin Jadhav, Bharath Rupireddy, Tom Lane
Discussion: https://postgr.es/m/CAMm1aWYgfekpRK-Jz5=pM_bV+Om=ktGq1vxTZ_dr1Z6MV-qokA@mail.gmail.com
The USER SET flag specifies that the variable should be set on behalf of an
ordinary role. That lets ordinary roles set placeholder variables, which
permission requirements are not known yet. Such a value wouldn't be used if
the variable finally appear to require superuser privileges.
The new flags are stored in the pg_db_role_setting.setuser array. Catversion
is bumped.
This commit is inspired by the previous work by Steve Chavez.
Discussion: https://postgr.es/m/CAPpHfdsLd6E--epnGqXENqLP6dLwuNZrPMcNYb3wJ87WR7UBOQ%40mail.gmail.com
Author: Alexander Korotkov, Steve Chavez
Reviewed-by: Pavel Borisov, Steve Chavez
The code has been assuming already in a few places that the initial
recursion nesting depth is 0, and the recent changes in hba.c (mainly
783e8c6) have relies on this assumption in more places. The maximum
recursion nesting level is assumed to be 10 for hba.c and GUCs.
Author: Julien Rouhaud
Discussion: https://postgr.es/m/20221124090724.n7amf5kpdhx6vb76@jrouhaud
This commit adds a function to perform a cross-check between the initial
value of the C declaration associated to a GUC and its actual boot
value in assert-enabled builds. The purpose of this is to prevent
anybody reading these C declarations from being fooled by mismatched
values before they are loaded at program startup.
The following rules apply depending on the GUC type:
* bool - can be false, or same as boot_val.
* int - can be 0, or same as the boot_val.
* real - can be 0.0, or same as the boot_val.
* string - can be NULL, or strcmp'd equal to the boot_val.
* enum - equal to the boot_val.
This is done for the system as well custom GUCs loaded by external
modules, which may require extension developers to adapt the C
declaration of the variables used by these GUCs (testing this change
with some of my own modules has allowed me to catch some stupid typos,
FWIW). This may finish by being a bad experiment depending on the
feedbcak received, but let's see how it goes.
Author: Peter Smith
Reviewed-by: Nathan Bossart, Tom Lane, Michael Paquier, Justin Pryzby
Discussion: https://postgr.es/m/CAHut+PtHE0XSfjjRQ6D4v7+dqzCw=d+1a64ujra4EX8aoc_Z+w@mail.gmail.com
The previous patch made addition of new GUCs cheap, but other GUC
operations aren't improved and indeed get a bit slower, because
hash_seq_search() is slower than just scanning a pointer array.
However, most performance-critical GUC operations only need
to touch a relatively small fraction of the GUCs; especially
so for AtEOXact_GUC(). We can improve matters at the cost
of a bit more space by adding dlist or slist links to the
GUC data structures. This patch invents lists that track
(1) all GUCs with non-default "source";
(2) all GUCs with nonempty state stack (implying they've
been changed in the current transaction);
(3) all GUCs due for reporting to the client.
All of guc.c's performance-critical cases can make use of one or
another of these lists to avoid searching the whole hash table.
In particular, the stack list means that transaction end
doesn't take time proportional to the number of GUCs, but
only to the number changed in the current transaction.
Discussion: https://postgr.es/m/2982579.1662416866@sss.pgh.pa.us
This gets rid of bsearch() in favor of hashed lookup. The main
advantage is that it becomes far cheaper to add new GUCs, since
we needn't re-sort the pointer array. Adding N new GUCs had
been O(N^2 log N), but now it's closer to O(N). We need to
sort only in SHOW ALL and equivalent functions, which are
hopefully not performance-critical to anybody.
Also, merge GetNumConfigOptions() into get_guc_variables(),
because in a world where the set of GUCs isn't fairly static
you really want to consider those two results as tied together
not independent.
Discussion: https://postgr.es/m/2982579.1662416866@sss.pgh.pa.us
The only real argument for using malloc directly was that we needed
the ability to not throw error on OOM; but mcxt.c grew that feature
awhile ago.
Keeping the data in a memory context improves accountability and
debuggability --- for example, without this it's almost impossible
to detect memory leaks in the GUC code with anything less costly
than valgrind. Moreover, the next patch in this series will add a
hash table for GUC lookup, and it'd be pretty silly to be using
palloc-dependent hash facilities alongside malloc'd storage of the
underlying data.
This is a bit invasive though, in particular causing an API break
for GUC check hooks that want to modify the GUC's value or use an
"extra" data structure. They must now use guc_malloc() and
guc_free() instead of malloc() and free(). Failure to change
affected code will result in assertion failures or worse; but
thanks to recent effort in the mcxt infrastructure, it shouldn't
be too hard to diagnose such oversights (at least in assert-enabled
builds).
One note is that this changes ParseLongOption() to return short-lived
palloc'd not malloc'd data. There wasn't any caller for which the
previous definition was better.
Discussion: https://postgr.es/m/2982579.1662416866@sss.pgh.pa.us
This cleans up a couple of areas:
- Remove XLogSegNo calculation for the last WAL segment in backup in
xlog.c (7d70809 has moved this logic entirely to xlogbackup.c when
building the contents of the backup history file).
- Remove check on log_min_duration in analyze.c, as it is already true
where this code path is reached.
- Simplify call to find_option() in guc.c.
Author: Ranier Vilela
Reviewed-by: Masahiko Sawada
Discussion: https://postgr.es/m/CAEudQArCDQQiPiFR16=yu9k5s2tp4tgEe1U1ZbkW4ofx81AWWQ@mail.gmail.com
Previously, the transaction-property GUCs such as transaction_isolation
could be reset after starting a transaction, because we marked them
as GUC_NO_RESET_ALL but still allowed a targeted RESET. That leads to
assertion failures or worse, because those properties aren't supposed
to change after we've acquired a transaction snapshot.
There are some NO_RESET_ALL variables for which RESET is okay, so
we can't just redefine the semantics of that flag. Instead introduce
a separate GUC_NO_RESET flag. Mark "seed", as well as the transaction
property GUCs, as GUC_NO_RESET.
We have to disallow GUC_ACTION_SAVE as well as straight RESET, because
otherwise a function having a "SET transaction_isolation" clause can
still break things: the end-of-function restore action is equivalent
to a RESET.
No back-patch, as it's conceivable that someone is doing something
this patch will forbid (like resetting one of these GUCs at transaction
start, or "CREATE FUNCTION ... SET transaction_read_only = 1") and not
running into problems with it today. Given how long we've had this
issue and not noticed, the side effects in non-assert builds can't be
too serious.
Per bug #17385 from Andrew Bille.
Masahiko Sawada
Discussion: https://postgr.es/m/17385-9ee529fb091f0ce5@postgresql.org
Make sure that function declarations use names that exactly match the
corresponding names from function definitions in optimizer, parser,
utility, libpq, and "commands" code, as well as in remaining library
code. Do the same for all code related to frontend programs (with the
exception of pg_dump/pg_dumpall related code).
Like other recent commits that cleaned up function parameter names, this
commit was written with help from clang-tidy. Later commits will handle
ecpg and pg_dump/pg_dumpall.
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: David Rowley <dgrowleyml@gmail.com>
Discussion: https://postgr.es/m/CAH2-WznJt9CMM9KJTMjJh_zbL5hD9oX44qdJ4aqZtjFi-zA3Tg@mail.gmail.com
guc.c has grown to be one of our largest .c files, making it
a bottleneck for compilation. It's also acquired a bunch of
knowledge that'd be better kept elsewhere, because of our not
very good habit of putting variable-specific check hooks here.
Hence, split it up along these lines:
* guc.c itself retains just the core GUC housekeeping mechanisms.
* New file guc_funcs.c contains the SET/SHOW interfaces and some
SQL-accessible functions for GUC manipulation.
* New file guc_tables.c contains the data arrays that define the
built-in GUC variables, along with some already-exported constant
tables.
* GUC check/assign/show hook functions are moved to the variable's
home module, whenever that's clearly identifiable. A few hard-
to-classify hooks ended up in commands/variable.c, which was
already a home for miscellaneous GUC hook functions.
To avoid cluttering a lot more header files with #include "guc.h",
I also invented a new header file utils/guc_hooks.h and put all
the GUC hook functions' declarations there, regardless of their
originating module. That allowed removal of #include "guc.h"
from some existing headers. The fallout from that (hopefully
all caught here) demonstrates clearly why such inclusions are
best minimized: there are a lot of files that, for example,
were getting array.h at two or more levels of remove, despite
not having any connection at all to GUCs in themselves.
There is some very minor code beautification here, such as
renaming a couple of inconsistently-named hook functions
and improving some comments. But mostly this just moves
code from point A to point B and deals with the ensuing
needs for #include adjustments and exporting a few functions
that previously weren't exported.
Patch by me, per a suggestion from Andres Freund; thanks also
to Michael Paquier for the idea to invent guc_funcs.c.
Discussion: https://postgr.es/m/587607.1662836699@sss.pgh.pa.us
Since HAVE_UNIX_SOCKETS is now defined unconditionally, remove the macro
and drop a small amount of dead code.
The last known systems not to have them (as far as I know at least) were
QNX, which we de-supported years ago, and Windows, which now has them.
If a new OS ever shows up with the POSIX sockets API but without working
AF_UNIX, it'll presumably still be able to compile the code, and fail at
runtime with an unsupported address family error. We might want to
consider adding a HINT that you should turn off the option to use it if
your network stack doesn't support it at that point, but it doesn't seem
worth making the relevant code conditional at compile time.
Also adjust a couple of places in the docs and comments that referred to
builds without Unix-domain sockets, since there aren't any. Windows
still gets a special mention in those places, though, because we don't
try to use them by default there yet.
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Discussion: https://postgr.es/m/CA%2BhUKG%2BL_3brvh%3D8e0BW_VfX9h7MtwgN%3DnFHP5o7X2oZucY9dg%40mail.gmail.com
This commit addresses a few things around GUCs:
- The TCP-related parameters (the four tcp_keepalives_* and
client_connection_check_interval are listed in postgresql.conf.sample in
a subsection called "TCP settings" of "CONNECTIONS AND AUTHENTICATION",
but they did not have their own group name in guc.c.
- enable_group_by_reordering, stats_fetch_consistency and
recovery_prefetch had an inconsistent description, missing a dot at the
end.
- In postgresql.conf.sample, "Process title" should not have a section
of its own, but it should be a subsection of "REPORTING AND LOGGING".
This impacts the contents of pg_settings, which could be seen as a
compatibility break, so no backpatch is done. This is similar to the
cleanup done in a55a984.
Author: Shinya Kato
Discussion: https://postgr.es/m/5e0c9c608624eafbba910c344282cb14@oss.nttdata.com
Detail and hint messages should be full sentences and should end with a
period, but some of the messages newly-introduced in v15 did not follow
that.
Author: Justin Pryzby
Reviewed-by: Álvaro Herrera
Discussion: https://postgr.es/m/20220719120948.GF12702@telsasoft.com
Backpatch-through: 15
We allow users to set the values of not-yet-loaded extension GUCs,
remembering those values in "placeholder" GUC entries. When/if
the extension is loaded later in the session, we need to verify that
the user had permissions to set the GUC. That was done correctly
before commit a0ffa885e, but as of that commit, we'd check the
permissions of the active role when the LOAD happens, not the role
that had set the value. (This'd be a security bug if it had made it
into a released version.)
In principle this is simple enough to fix: we just need to remember
the exact role OID that set each GUC value, and use that not
GetUserID() when verifying permissions. Maintaining that data in
the guc.c data structures is slightly tedious, but fortunately it's
all basically just copy-n-paste of the logic for tracking the
GucSource of each setting, as we were already doing.
Another oversight is that validate_option_array_item() hadn't
been taught to check for granted GUC privileges. This appears
to manifest only in that ALTER ROLE/DATABASE RESET ALL will
fail to reset settings that the user should be allowed to reset.
Patch by myself and Nathan Bossart, per report from Nathan Bossart.
Back-patch to v15 where the faulty code came in.
Discussion: https://postgr.es/m/20220706224727.GA2158260@nathanxps13
There were many calls to construct_array() and deconstruct_array() for
built-in types, for example, when dealing with system catalog columns.
These all hardcoded the type attributes necessary to pass to these
functions.
To simplify this a bit, add construct_array_builtin(),
deconstruct_array_builtin() as wrappers that centralize this hardcoded
knowledge. This simplifies many call sites and reduces the amount of
hardcoded stuff that is spread around.
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/2914356f-9e5f-8c59-2995-5997fc48bcba%40enterprisedb.com
The original advice for hard-wired SetConfigOption calls was to use
PGC_S_OVERRIDE, particularly for PGC_INTERNAL GUCs. However,
that's really overkill for PGC_INTERNAL GUCs, since there is no
possibility that we need to override a user-provided setting.
Instead use PGC_S_DYNAMIC_DEFAULT in most places, so that the
value will appear with source = 'default' in pg_settings and thereby
not be shown by psql's new \dconfig command. The one exception is
that when changing in_hot_standby in a hot-standby session, we still
use PGC_S_OVERRIDE, because people felt that seeing that in \dconfig
would be a good thing.
Similarly use PGC_S_DYNAMIC_DEFAULT for the auto-tune value of
wal_buffers (if possible, that is if wal_buffers wasn't explicitly
set to -1), and for the typical 2MB value of max_stack_depth.
In combination these changes remove four not-very-interesting
entries from the typical output of \dconfig, all of which people
fingered as "why is that showing up?" in the discussion thread.
Discussion: https://postgr.es/m/3118455.1649267333@sss.pgh.pa.us
If a short description is specified as NULL in one of the various
DefineCustomXXXVariable() functions available to external modules to
define a custom parameter, SHOW ALL would crash. This change teaches
SHOW ALL to properly handle NULL short descriptions, as well as any code
paths that manipulate it, to gain in flexibility. Note that
help_config.c was already able to do that, when describing a set of GUCs
for postgres --describe-config.
Author: Steve Chavez
Reviewed by: Nathan Bossart, Andres Freund, Michael Paquier, Tom Lane
Discussion: https://postgr.es/m/CAGRrpzY6hO-Kmykna_XvsTv8P2DshGiU6G3j8yGao4mk0CqjHA%40mail.gmail.com
Backpatch-through: 10
Introduce a new GUC recovery_prefetch. When enabled, look ahead in the
WAL and try to initiate asynchronous reading of referenced data blocks
that are not yet cached in our buffer pool. For now, this is done with
posix_fadvise(), which has several caveats. Since not all OSes have
that system call, "try" is provided so that it can be enabled where
available. Better mechanisms for asynchronous I/O are possible in later
work.
Set to "try" for now for test coverage. Default setting to be finalized
before release.
The GUC wal_decode_buffer_size limits the distance we can look ahead in
bytes of decoded data.
The existing GUC maintenance_io_concurrency is used to limit the number
of concurrent I/Os allowed, based on pessimistic heuristics used to
infer that I/Os have begun and completed. We'll also not look more than
maintenance_io_concurrency * 4 block references ahead.
Reviewed-by: Julien Rouhaud <rjuju123@gmail.com>
Reviewed-by: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Reviewed-by: Alvaro Herrera <alvherre@2ndquadrant.com> (earlier version)
Reviewed-by: Andres Freund <andres@anarazel.de> (earlier version)
Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> (earlier version)
Tested-by: Tomas Vondra <tomas.vondra@2ndquadrant.com> (earlier version)
Tested-by: Jakub Wartak <Jakub.Wartak@tomtom.com> (earlier version)
Tested-by: Dmitry Dolgov <9erthalion6@gmail.com> (earlier version)
Tested-by: Sait Talha Nisanci <Sait.Nisanci@microsoft.com> (earlier version)
Discussion: https://postgr.es/m/CA%2BhUKGJ4VJN8ttxScUFM8dOKX0BrBiboo5uz1cq%3DAovOddfHpA%40mail.gmail.com
Allow extensions to specify a new custom resource manager (rmgr),
which allows specialized WAL. This is meant to be used by a Table
Access Method or Index Access Method.
Prior to this commit, only Generic WAL was available, which offers
support for recovery and physical replication but not logical
replication.
Reviewed-by: Julien Rouhaud, Bharath Rupireddy, Andres Freund
Discussion: https://postgr.es/m/ed1fb2e22d15d3563ae0eb610f7b61bb15999c0a.camel%40j-davis.com
With stats now being stored in shared memory, the GUC isn't needed
anymore. However, the pg_stat_tmp directory and PG_STAT_TMP_DIR define are
kept, as pg_stat_statements (and some out-of-core extensions) store data in
it.
Docs will be updated in a subsequent commit, together with the other pending
docs updates due to shared memory stats.
Author: Andres Freund <andres@anarazel.de>
Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reviewed-By: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Discussion: https://postgr.es/m/20220330233550.eiwsbearu6xhuqwe@alap3.anarazel.de
Discussion: https://postgr.es/m/20220303021600.hs34ghqcw6zcokdh@alap3.anarazel.de
Previously the statistics collector received statistics updates via UDP and
shared statistics data by writing them out to temporary files regularly. These
files can reach tens of megabytes and are written out up to twice a
second. This has repeatedly prevented us from adding additional useful
statistics.
Now statistics are stored in shared memory. Statistics for variable-numbered
objects are stored in a dshash hashtable (backed by dynamic shared
memory). Fixed-numbered stats are stored in plain shared memory.
The header for pgstat.c contains an overview of the architecture.
The stats collector is not needed anymore, remove it.
By utilizing the transactional statistics drop infrastructure introduced in a
prior commit statistics entries cannot "leak" anymore. Previously leaked
statistics were dropped by pgstat_vacuum_stat(), called from [auto-]vacuum. On
systems with many small relations pgstat_vacuum_stat() could be quite
expensive.
Now that replicas drop statistics entries for dropped objects, it is not
necessary anymore to reset stats when starting from a cleanly shut down
replica.
Subsequent commits will perform some further code cleanup, adapt docs and add
tests.
Bumps PGSTAT_FILE_FORMAT_ID.
Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Author: Andres Freund <andres@anarazel.de>
Author: Melanie Plageman <melanieplageman@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Thomas Munro <thomas.munro@gmail.com>
Reviewed-By: Justin Pryzby <pryzby@telsasoft.com>
Reviewed-By: "David G. Johnston" <david.g.johnston@gmail.com>
Reviewed-By: Tomas Vondra <tomas.vondra@2ndquadrant.com> (in a much earlier version)
Reviewed-By: Arthur Zakirov <a.zakirov@postgrespro.ru> (in a much earlier version)
Reviewed-By: Antonin Houska <ah@cybertec.at> (in a much earlier version)
Discussion: https://postgr.es/m/20220303021600.hs34ghqcw6zcokdh@alap3.anarazel.de
Discussion: https://postgr.es/m/20220308205351.2xcn6k4x5yivcxyd@alap3.anarazel.de
Discussion: https://postgr.es/m/20210319235115.y3wz7hpnnrshdyv6@alap3.anarazel.de
This patch allows "PGC_SUSET" parameters to be set by non-superusers
if they have been explicitly granted the privilege to do so.
The privilege to perform ALTER SYSTEM SET/RESET on a specific parameter
can also be granted.
Such privileges are cluster-wide, not per database. They are tracked
in a new shared catalog, pg_parameter_acl.
Granting and revoking these new privileges works as one would expect.
One caveat is that PGC_USERSET GUCs are unaffected by the SET privilege
--- one could wish that those were handled by a revocable grant to
PUBLIC, but they are not, because we couldn't make it robust enough
for GUCs defined by extensions.
Mark Dilger, reviewed at various times by Andrew Dunstan, Robert Haas,
Joshua Brindle, and myself
Discussion: https://postgr.es/m/3D691E20-C1D5-4B80-8BA5-6BEB63AF3029@enterprisedb.com
When evaluating a query with a multi-column GROUP BY clause using sort,
the cost may be heavily dependent on the order in which the keys are
compared when building the groups. Grouping does not imply any ordering,
so we're allowed to compare the keys in arbitrary order, and a Hash Agg
leverages this. But for Group Agg, we simply compared keys in the order
as specified in the query. This commit explores alternative ordering of
the keys, trying to find a cheaper one.
In principle, we might generate grouping paths for all permutations of
the keys, and leave the rest to the optimizer. But that might get very
expensive, so we try to pick only a couple interesting orderings based
on both local and global information.
When planning the grouping path, we explore statistics (number of
distinct values, cost of the comparison function) for the keys and
reorder them to minimize comparison costs. Intuitively, it may be better
to perform more expensive comparisons (for complex data types etc.)
last, because maybe the cheaper comparisons will be enough. Similarly,
the higher the cardinality of a key, the lower the probability we’ll
need to compare more keys. The patch generates and costs various
orderings, picking the cheapest ones.
The ordering of group keys may interact with other parts of the query,
some of which may not be known while planning the grouping. E.g. there
may be an explicit ORDER BY clause, or some other ordering-dependent
operation, higher up in the query, and using the same ordering may allow
using either incremental sort or even eliminate the sort entirely.
The patch generates orderings and picks those minimizing the comparison
cost (for various pathkeys), and then adds orderings that might be
useful for operations higher up in the plan (ORDER BY, etc.). Finally,
it always keeps the ordering specified in the query, on the assumption
the user might have additional insights.
This introduces a new GUC enable_group_by_reordering, so that the
optimization may be disabled if needed.
The original patch was proposed by Teodor Sigaev, and later improved and
reworked by Dmitry Dolgov. Reviews by a number of people, including me,
Andrey Lepikhov, Claudio Freire, Ibrar Ahmed and Zhihong Yu.
Author: Dmitry Dolgov, Teodor Sigaev, Tomas Vondra
Reviewed-by: Tomas Vondra, Andrey Lepikhov, Claudio Freire, Ibrar Ahmed, Zhihong Yu
Discussion: https://postgr.es/m/7c79e6a5-8597-74e8-0671-1c39d124c9d6%40sigaev.ru
Discussion: https://postgr.es/m/CA%2Bq6zcW_4o2NC0zutLkOJPsFt80megSpX_dVRo6GK9PC-Jx_Ag%40mail.gmail.com
Generally if a role is granted membership to another role with NOINHERIT
they must use SET ROLE to access the privileges of that role, however
with predefined roles the membership and privilege is conflated. Fix that
by replacing is_member_of_role with has_privs_for_role for predefined
roles. Patch does not remove is_member_of_role from acl.h, but it does
add a warning not to use that function for privilege checking. Not
backpatched based on hackers list discussion.
Author: Joshua Brindle
Reviewed-by: Stephen Frost, Nathan Bossart, Joe Conway
Discussion: https://postgr.es/m/flat/CAGB+Vh4Zv_TvKt2tv3QNS6tUM_F_9icmuj0zjywwcgVi4PAhFA@mail.gmail.com
Up to now, the planner estimated the size of a recursive query's
worktable as 10 times the size of the non-recursive term. It's hard
to see how to do significantly better than that automatically, but
we can give users control over the multiplier to allow tuning for
specific use-cases. The default behavior remains the same.
Simon Riggs
Discussion: https://postgr.es/m/CANbhV-EuaLm4H3g0+BSTYHEGxJj3Kht0R+rJ8vT57Dejnh=_nA@mail.gmail.com
wal_compression gains a new value, "zstd", to allow the compression of
full-page images using the compression method of the same name.
Compression is done using the default level recommended by the library,
as of ZSTD_CLEVEL_DEFAULT = 3. Some benchmarking has shown that it
could make sense to use a level lower for the FPI compression, like 1 or
2, as the compression rate did not change much with a bit less CPU
consumed, but any tests done would only cover few scenarios so it is
hard to come to a clear conclusion. Anyway, there is no reason to not
use the default level instead, which is the level recommended by the
library so it should be fine for most cases.
zstd outclasses easily pglz, and is better than LZ4 where one wants to
have more compression at the cost of extra CPU but both are good enough
in their own scenarios, so the choice between one or the other of these
comes to a study of the workload patterns and the schema involved,
mainly.
This commit relies heavily on 4035cd5, that reshaped the code creating
and restoring full-page writes to be aware of the compression type,
making this integration straight-forward.
This patch borrows some early work from Andrey Borodin, though the patch
got a complete rewrite.
Author: Justin Pryzby
Discussion: https://postgr.es/m/20220222231948.GJ9008@telsasoft.com
Tom Lane
Alexander Korotkov
David Rowley
Peter Eisentraut
Michael Paquier
Bruce Momjian
Peter Geoghegan
Alvaro Herrera
John Naylor
Thomas Munro
Jeff Davis
Andres Freund
Tomas Vondra
Joe Conway
Andrew Dunstan