To interlock against concurrent drops, we use to hold ExclusiveLock on
pg_replication_origin till xact commit. This blocks even concurrent drops
of different origins by tablesync workers. So, instead, lock the specific
origin to interlock against concurrent drops.
This reduces the test time variability in src/test/subscription where
multiple tables are being synced.
Author: Vignesh C
Reviewed-by: Hou Zhijie, Amit Kapila
Discussion: https://postgr.es/m/1412708.1674417574@sss.pgh.pa.us
Backward and forward scans share much of the same page acquisition code.
Here we consolidate that code to reduce some duplication.
Additionally, add a new rs_coffset field to HeapScanDescData to track the
offset of the current tuple. The new field fits nicely into the padding
between a bool and BlockNumber field and saves having to look at the last
returned tuple to figure out which offset we should be looking at for the
current tuple.
Author: Melanie Plageman
Reviewed-by: David Rowley
Discussion: https://postgr.es/m/CAAKRu_bvkhka0CZQun28KTqhuUh5ZqY=_T8QEqZqOL02rpi2bw@mail.gmail.com
In the 90s we needed to deal with computers that still had the
pre-standard signal masking APIs. That hasn't been relevant for a very
long time on Unix systems, and c94ae9d8 got rid of a remaining
dependency in our Windows porting code. PG_SETMASK didn't expose
save/restore functionality, so we'd already started using sigprocmask()
directly in places, creating the visual distraction of having two ways
to spell it. It's not part of the API that extensions are expected to
be using (but if they are, the change will be trivial). It seems like a
good time to drop the old macro and just call the standard POSIX
function.
Reviewed-by: Nathan Bossart <nathandbossart@gmail.com>
Discussion: https://postgr.es/m/CA%2BhUKG%2BKfQgrhHP2DLTohX1WwubaCBHmTzGnAEDPZ-Gug-Xskg%40mail.gmail.com
Installing with plain cpan failed for me recently, as the archive it
searched has been purged of old releases. However, you can give cpanm a
complete URL to the exact version you want to install, so document using
that.
Improve the comment explaining the choice of rscale in numeric_sqrt(),
and ensure that the code works consistently when other values of
NBASE/DEC_DIGITS are used.
Note that, in practice, we always expect DEC_DIGITS == 4, and this
does not change the computation in that case.
Joel Jacobson and Dean Rasheed
Discussion: https://postgr.es/m/06712c29-98e9-43b3-98da-f234d81c6e49%40app.fastmail.com
An early release of AF_UNIX in Windows apparently supported Linux-style
"abstract" Unix sockets, but they do not seem to work in current Windows
versions and there is no mention of any of this in the Winsock
documentation. Remove the mention of Windows from the documentation.
Back-patch to 14, where commit c9f0624b landed.
Discussion: https://postgr.es/m/CA%2BhUKGKrYbSZhrk4NGfoQGT_3LQS5pC5KNE1g0tvE_pPBZ7uew%40mail.gmail.com
Extend the existing developer option 'logical_replication_mode' to help
test the parallel apply of large transactions on the subscriber.
When set to 'buffered', the leader sends changes to parallel apply workers
via a shared memory queue. When set to 'immediate', the leader serializes
all changes to files and notifies the parallel apply workers to read and
apply them at the end of the transaction.
This helps in adding tests to cover the serialization code path in
parallel streaming mode.
Author: Hou Zhijie
Reviewed-by: Peter Smith, Kuroda Hayato, Sawada Masahiko, Amit Kapila
Discussion: https://postgr.es/m/CAA4eK1+wyN6zpaHUkCLorEWNx75MG0xhMwcFhvjqm2KURZEAGw@mail.gmail.com
As coded, the timeout given to WaitLatch() was always equal to
PGARCH_AUTOWAKE_INTERVAL, as time() was called two times repeatedly.
This simplification could have been done in d75288f.
While on it, this adjusts a comment in pgarch.c to describe the archiver
in a more neutral way.
Author: Sravan Kumar, Nathan Bossart
Reviewed-by: Kyotaro Horiguchi
Discussion: https://postgr.es/m/CA+=NbjjqYE9-Lnw7H7DAiS5jebmoMikwZQb_sBP7kgBCn9q6Hg@mail.gmail.com
Thanks to Robins to find the issue and Nathan for promptly writing a test case
to prevent future problems like this.
Reported-by: Nathan Bossart <nathandbossart@gmail.com>
Reported-by: Robins Tharakan <tharakan@gmail.com>
Author: Nathan Bossart <nathandbossart@gmail.com>
Discussion: https://postgr.es/m/20230130193008.GA2740781@nathanxps13
DST law changes in Greenland and Mexico. Notably, a new timezone
America/Ciudad_Juarez has been split off from America/Ojinaga.
Historical corrections for northern Canada, Colombia, and Singapore.
Here remove some dead code from heapgettup() and heapgettup_pagemode()
which was trying to support NoMovementScanDirection scans. This code can
never be reached as standard_ExecutorRun() never calls ExecutePlan with
NoMovementScanDirection.
Additionally, plans which were scanning an unordered index would use
NoMovementScanDirection rather than ForwardScanDirection. There was no
real need for this, so here we adjust this so we use ForwardScanDirection
for unordered index scans. A comment in pathnodes.h claimed that
NoMovementScanDirection was used for PathKey reasons, but if that was
true, it no longer is, per code in build_index_paths().
This does change the non-text format of the EXPLAIN output so that
unordered index scans now have a "Forward" scan direction rather than
"NoMovement". The text format of EXPLAIN has not changed.
Author: Melanie Plageman
Reviewed-by: Tom Lane, David Rowley
Discussion: https://postgr.es/m/CAAKRu_bvkhka0CZQun28KTqhuUh5ZqY=_T8QEqZqOL02rpi2bw@mail.gmail.com
This was only mentioned in the description of the text/label, which
are marked as being in quotes in the synopsis, which can cause
confusion (as witnessed on IRC).
Also separate the literal and NULL cases in the parameter list, per
suggestion from Tom Lane.
Also add an example of dropping a security label.
Dagfinn Ilmari Mannsåker, with some tweaks by me
Discussion: https://postgr.es/m/87sffqk4zp.fsf@wibble.ilmari.org
In commit 2489d76c4, I'd thought it'd be safe to assert that a
PlaceHolderVar appearing in a scan-level expression has empty
nullingrels. However this is not so, as when we determine that a
join relation is certainly empty we'll put its targetlist into a
Result-with-constant-false-qual node, and nothing is done to adjust
the nullingrels of the Vars or PHVs therein. (Arguably, a Result
used in this way isn't really a scan-level node, but it certainly
isn't an upper node either ...)
It's not clear this is worth any close analysis, so let's just
take out the faulty Assert.
Per report from Robins Tharakan. I added a test case based on
his example, just in case somebody tries to tighten this up.
Discussion: https://postgr.es/m/CAEP4nAz7Enq3+DEthGG7j27DpuwSRZnW0Nh6jtNh75yErQ_nbA@mail.gmail.com
This commit changes the query jumbling code in queryjumblefuncs.c to be
generated automatically based on the information of the nodes in the
headers of src/include/nodes/ by using gen_node_support.pl. This
approach offers many advantages:
- Support for query jumbling for all the utility statements, based on the
state of their parsed Nodes and not only their query string. This will
greatly ease the switch to normalize the information of some DDLs, like
SET or CALL for example (this is left unchanged and should be part of a
separate discussion). With this feature, the number of entries stored
for utilities in pg_stat_statements is reduced (for example now
"CHECKPOINT" and "checkpoint" mean the same thing with the same query
ID).
- Documentation of query jumbling directly in the structure definition
of the nodes. Since this code has been introduced in pg_stat_statements
and then moved to code, the reasons behind the choices of what should be
included in the jumble are rather sparse. Note that some explanation is
added for the most relevant parts, as a start.
- Overall code reduction and more consistency with the other parts
generating read, write and copy depending on the nodes.
The query jumbling is controlled by a couple of new node attributes,
documented in nodes/nodes.h:
- custom_query_jumble, to mark a Node as having a custom
implementation.
- no_query_jumble, to ignore entirely a Node.
- query_jumble_ignore, to ignore a field in a Node.
- query_jumble_location, to mark a location in a Node, for
normalization. This can apply only to int fields, with "location" in
their name (only Const as of this commit).
There should be no compatibility impact on pg_stat_statements, as the
new code applies the jumbling to the same fields for each node (its
regression tests have no modification, for one).
Some benchmark of the query jumbling between HEAD and this commit for
SELECT and DMLs has proved that this new code does not cause a
performance regression, with computation times close for both methods.
For utility queries, the new method is slower than the previous method
of calculating a hash of the query string, though we are talking about
extra ns-level changes based on what I measured, which is unnoticeable
even for OLTP workloads as a query ID is calculated once per query
post-parse analysis.
Author: Michael Paquier
Reviewed-by: Peter Eisentraut
Discussion: https://postgr.es/m/Y5BHOUhX3zTH/ig6@paquier.xyz
This test has been added as of 857ee8e that has introduced the SQL
function txid_status(), with the purpose of checking that a transaction
ID still in-progress during a crash is correctly marked as aborted after
recovery finishes.
This test is unstable, and some configuration scenarios may that easier
to reproduce (wal_level=minimal, wal_compression=on) because the WAL
holding the information about the in-progress transaction ID may not
have made it to disk yet, hence a post-crash recovery may cause the same
XID to be reused, triggering a test failure.
We have discussed a few approaches, like making this function force a
WAL flush to make it reliable across crashes, but we don't want to pay a
performance penalty in some scenarios, as well. The test could have
been tweaked to enforce a checkpoint but that actually breaks the
promise of the test to rely on a stable result of txid_status() after
a crash.
This issue has been reported a few times across the past years, with an
original report from Kyotaro Horiguchi. The buildfarm machines tanager,
hachi and gokiburi enable wal_compression, and fail on this test
periodically.
Discussion: https://postgr.es/m/3163112.1674762209@sss.pgh.pa.us
Discussion: https://postgr.es/m/20210305.115011.558061052471425531.horikyota.ntt@gmail.com
Backpatch-through: 11
Switch to get_dirent_type() instead of lstat() while traversing a
directory tree, to see if that fixes the intermittent ENOTEMPTY failures
seen in recent pg_upgrade tests, on Windows CI. While refactoring, also
use AllocateDir() instead of opendir() in the backend, which knows how
to handle descriptor pressure.
Our CI system currently uses Windows Server 2019, a version known not to
have POSIX unlink semantics enabled by default yet, unlike typical
Windows 10 and 11 systems. That might explain why we see this flapping
on CI but (apparently) not in the build farm, though the frequency is
quite low.
The theory is that some directory entry must be in state
STATUS_DELETE_PENDING, which lstat() would report as ENOENT, though
unfortunately we don't know exactly why yet. With this change, rmtree()
will not skip them, and try to unlink (again). Our unlink() wrapper
should either wait a short time for them to go away when some other
process closes the handle, or log a message to tell us the path of the
problem file if not, so we can dig further.
Discussion: https://postgr.es/m/20220919213217.ptqfdlcc5idk5xup%40awork3.anarazel.de
EquivalenceClasses are now understood as applying within a "join
domain", which is a set of inner-joined relations (possibly underneath
an outer join). We no longer need to treat an EC from below an outer
join as a second-class citizen.
I have hopes of eventually being able to treat outer-join clauses via
EquivalenceClasses, by means of only applying deductions within the
EC's join domain. There are still problems in the way of that, though,
so for now the reconsider_outer_join_clause logic is still here.
I haven't been able to get rid of RestrictInfo.is_pushed_down either,
but I wonder if that could be recast using JoinDomains.
I had to hack one test case in postgres_fdw.sql to make it still test
what it was meant to, because postgres_fdw is inconsistent about
how it deals with quals containing non-shippable expressions; see
https://postgr.es/m/1691374.1671659838@sss.pgh.pa.us. That should
be improved, but I don't think it's within the scope of this patch
series.
Patch by me; thanks to Richard Guo for review.
Discussion: https://postgr.es/m/830269.1656693747@sss.pgh.pa.us
Remove RestrictInfo.nullable_relids, along with a good deal of
infrastructure that calculated it. One use-case for it was in
join_clause_is_movable_to, but we can now replace that usage with
a check to see if the clause's relids include any outer join
that can null the target relation. The other use-case was in
join_clause_is_movable_into, but that test can just be dropped
entirely now that the clause's relids include outer joins.
Furthermore, join_clause_is_movable_into should now be
accurate enough that it will accept anything returned by
generate_join_implied_equalities, so we can restore the Assert
that was diked out in commit 95f4e59c3.
Remove the outerjoin_delayed mechanism. We needed this before to
prevent quals from getting evaluated below outer joins that should
null some of their vars. Now that we consider varnullingrels while
placing quals, that's taken care of automatically, so throw the
whole thing away.
Teach remove_useless_result_rtes to also remove useless FromExprs.
Having done that, the delay_upper_joins flag serves no purpose any
more and we can remove it, largely reverting 11086f2f2.
Use constant TRUE for "dummy" clauses when throwing back outer joins.
This improves on a hack I introduced in commit 6a6522529. If we
have a left-join clause l.x = r.y, and a WHERE clause l.x = constant,
we generate r.y = constant and then don't really have a need for the
join clause. But we must throw the join clause back anyway after
marking it redundant, so that the join search heuristics won't think
this is a clauseless join and avoid it. That was a kluge introduced
under time pressure, and after looking at it I thought of a better
way: let's just introduce constant-TRUE "join clauses" instead,
and get rid of them at the end. This improves the generated plans for
such cases by not having to test a redundant join clause. We can also
get rid of the ugly hack used to mark such clauses as redundant for
selectivity estimation.
Patch by me; thanks to Richard Guo for review.
Discussion: https://postgr.es/m/830269.1656693747@sss.pgh.pa.us
Traditionally we used the same Var struct to represent the value
of a table column everywhere in parse and plan trees. This choice
predates our support for SQL outer joins, and it's really a pretty
bad idea with outer joins, because the Var's value can depend on
where it is in the tree: it might go to NULL above an outer join.
So expression nodes that are equal() per equalfuncs.c might not
represent the same value, which is a huge correctness hazard for
the planner.
To improve this, decorate Var nodes with a bitmapset showing
which outer joins (identified by RTE indexes) may have nulled
them at the point in the parse tree where the Var appears.
This allows us to trust that equal() Vars represent the same value.
A certain amount of klugery is still needed to cope with cases
where we re-order two outer joins, but it's possible to make it
work without sacrificing that core principle. PlaceHolderVars
receive similar decoration for the same reason.
In the planner, we include these outer join bitmapsets into the relids
that an expression is considered to depend on, and in consequence also
add outer-join relids to the relids of join RelOptInfos. This allows
us to correctly perceive whether an expression can be calculated above
or below a particular outer join.
This change affects FDWs that want to plan foreign joins. They *must*
follow suit when labeling foreign joins in order to match with the
core planner, but for many purposes (if postgres_fdw is any guide)
they'd prefer to consider only base relations within the join.
To support both requirements, redefine ForeignScan.fs_relids as
base+OJ relids, and add a new field fs_base_relids that's set up by
the core planner.
Large though it is, this commit just does the minimum necessary to
install the new mechanisms and get check-world passing again.
Follow-up patches will perform some cleanup. (The README additions
and comments mention some stuff that will appear in the follow-up.)
Patch by me; thanks to Richard Guo for review.
Discussion: https://postgr.es/m/830269.1656693747@sss.pgh.pa.us
defGetBoolean() allows the "value" part of "option = value"
syntax to be omitted, in which case it's taken as "true".
This is acknowledged in our syntax summaries for relevant commands,
but we don't seem to have documented the actual behavior anywhere.
Do so for CREATE/ALTER PUBLICATION/SUBSCRIPTION. Use generic
boilerplate text for this, with the idea that we can copy-and-paste
it into other relevant reference pages, whenever someone gets
around to that.
Peter Smith, edited a bit by me
Discussion: https://postgr.es/m/CAHut+PvwjZfdGt2R8HTXgSZft=jZKymrS8KUg31pS7zqaaWKKw@mail.gmail.com
This fixes a bug that, under some circumstances, would cause MERGE to
fail to properly recompute expressions for GENERATED STORED columns.
Formerly, ExecInitModifyTable() did not call ExecInitStoredGenerated()
for a MERGE command, which meant that the generated expressions
information was not computed until later, when the first merge action
was executed. However, if the first merge action to execute was an
UPDATE, then ExecInitStoredGenerated() could decide to skip some some
generated columns, if the columns on which they depended were not
updated, which was a problem if the MERGE also contained an INSERT
action, for which no generated columns should be skipped.
So fix by having ExecInitModifyTable() call ExecInitStoredGenerated()
for MERGE, and assume that it isn't safe to skip any generated columns
in a MERGE. Possibly that could be relaxed, by allowing some generated
columns to be skipped for a MERGE without an INSERT action, but it's
not clear that it's worth the effort.
Noticed while investigating bug #17759. Back-patch to v15, where MERGE
was added.
Dean Rasheed, reviewed by Tom Lane.
Discussion:
https://postgr.es/m/17759-e76d9bece1b5421c%40postgresql.orghttps://postgr.es/m/CAEZATCXb_ezoMCcL0tzKwRGA1x0oeE%3DawTaysRfTPq%2B3wNJn8g%40mail.gmail.com
Rename the developer option 'logical_decoding_mode' to the more flexible
name 'logical_replication_mode' because doing so will make it easier to
extend this option in the future to help test other areas of logical
replication.
Currently, it is used on the publisher side to allow streaming or
serializing each change in logical decoding. In the upcoming patch, we are
planning to use it on the subscriber. On the subscriber, it will allow
serializing the changes to file and notifies the parallel apply workers to
read and apply them at the end of the transaction.
We discussed exposing this parameter as a subscription option but
it did not seem advisable since it is primarily used for testing/debugging
and there is no other such parameter. We also discussed having separate
GUCs for publisher and subscriber but for current testing/debugging
requirements, one GUC is sufficient.
Author: Hou Zhijie
Reviewed-by: Peter Smith, Kuroda Hayato, Sawada Masahiko, Amit Kapila
Discussion: https://postgr.es/m/CAD21AoAy2c=Mx=FTCs+EwUsf2kQL5MmU3N18X84k0EmCXntK4g@mail.gmail.com
Discussion: https://postgr.es/m/CAA4eK1+wyN6zpaHUkCLorEWNx75MG0xhMwcFhvjqm2KURZEAGw@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
This includes a unification of the logic used to find the excludes file
and the typedefs file.
Also, remove the dangerous and deprecated feature where the first
non-option argument was taken as a typdefs file if it wasn't a .c or .h
file, remove some extraneous blank lines, and improve the documentation
somewhat.
We have the long-standing logic to append "postgresql" to some
installation paths if it does not already contain "pgsql" or
"postgres". The existing meson implementation of that only considered
the subdirectory under the prefix, not the prefix itself. Fix that,
so that it now works the same way as the implementation in
Makefile.global.
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://www.postgresql.org/message-id/a6a6de12-f705-2b33-2fd9-9743277deb08@enterprisedb.com
9d9c02ccd introduced runConditions for window functions to allow
monotonic window function evaluation to be made more efficient when the
window function value went beyond some value that it would never go back
from due to its monotonic nature. That commit added prosupport functions
to inform the planner that row_number(), rank(), dense_rank() and some
forms of count(*) were monotonic. Here we add support for ntile(),
cume_dist() and percent_rank().
Reviewed-by: Melanie Plageman
Discussion: https://postgr.es/m/CAApHDvqR+VqB8s+xR-24bzJbU8xyFrBszJ17qKgECf7cWxLCaA@mail.gmail.com
pg_restore -l has always been able to read the TOC data of a dump even
if its binary has no support for compression, for both compressed and
uncompressed dumps. 5e73a60 has introduced a backward-incompatible
behavior by switching a warning to a hard error in the code path reading
the header data of a dump, preventing the TOC items to be listed even if
pg_restore -l, with no support for compression, is used on a compressed
dump. Most modern systems should have support for zlib, but it can be
also possible that somebody relies on the past behavior when copying
over a dump where binaries are not built with zlib support (most likely
some WIN32 flavors these days, though most environments should provide
that).
There is no easy way to have a regression test for this pattern, as it
requires a mix of dump/restore commands with different compilation
options, with and without compression. One possibility I see here would
be to have a command-line option that enforces a non-compression check
for a build that supports compression, but that does not seem worth the
cost, either.
Reported-by: Justin Pryzby
Author: Georgios Kokolatos
Discussion: https://postgr.es/m/20230125180020.GF22427@telsasoft.com
We'd like to use TimestampDifferenceMilliseconds with the stop_time
possibly being TIMESTAMP_INFINITY, but up to now it's disclaimed
responsibility for overflow cases. Define it to clamp its output to
the range [0, INT_MAX], handling overflow correctly. (INT_MAX rather
than LONG_MAX seems appropriate, because the function is already
described as being intended for calculating wait times for WaitLatch
et al, and that infrastructure only handles waits up to INT_MAX.
Also, this choice gets rid of cross-platform behavioral differences.)
Having done that, we can replace some ad-hoc code in walreceiver.c
with a simple call to TimestampDifferenceMilliseconds.
While at it, fix some buglets in existing callers of
TimestampDifferenceMilliseconds: basebackup_copy.c had not read the
memo about TimestampDifferenceMilliseconds never returning a negative
value, and postmaster.c had not read the memo about Min() and Max()
being macros with multiple-evaluation hazards. Neither of these
quite seem worth back-patching.
Patch by me; thanks to Nathan Bossart for review.
Discussion: https://postgr.es/m/3126727.1674759248@sss.pgh.pa.us
Avoid having walreceiver code know explicitly about the precision
and underlying datatype of TimestampTz. (There is still one
calculation that knows that, which should be replaced with use of
TimestampDifferenceMilliseconds; but we need to figure out what to do
about overflow cases first.)
In support of this, provide a TimestampTzPlusSeconds macro, as well
as TIMESTAMP_INFINITY and TIMESTAMP_MINUS_INFINITY macros. (We could
have used the existing DT_NOEND and DT_NOBEGIN symbols, but I judged
those too opaque and confusing.)
Move GetCurrentTimestamp calls so that it's more obvious that we
are not using stale values of "now" anyplace. This doesn't result
in net more calls, and might indeed make for net fewer.
Avoid having a dummy value in the WalRcvWakeupReason enum, so that
we can hope for the compiler to catch overlooked switch cases.
Nathan Bossart and Tom Lane
Discussion: https://postgr.es/m/20230125235004.GA1327755@nathanxps13
When auto_explain.log_verbose is on, auto_explain should print in the
logs plans equivalent to the EXPLAIN (VERBOSE). However, when
compute_query_id is on, query identifiers were not showing up, being
only handled by EXPLAIN (VERBOSE). This brings auto_explain on par with
EXPLAIN regarding that. Note that like EXPLAIN, auto_explain does not
show the query identifier when compute_query_id=regress.
The change is done so as the choice of printing the query identifier is
done in ExplainPrintPlan() rather than in ExplainOnePlan(), to avoid a
duplication of the logic dealing with the query ID. auto_explain is the
only in-core caller of ExplainPrintPlan().
While looking at the area, I have noticed that more consolidation
between EXPLAIN and auto_explain would be in order for the logging of
the plan duration and the buffer usage. This refactoring is left as a
future change.
Author: Atsushi Torikoshi
Reviewed-by: Justin Pryzby, Julien Rouhaud
Discussion: https://postgr.es/m/1ea21936981f161bccfce05765c03bee@oss.nttdata.com
If the final chunk of an oversized tuple being written out to disk was
exactly 32760 bytes, it would be corrupted due to a fencepost bug.
Bug #17619. Back-patch to 11 where the code arrived.
While testing that (see test module in archives), I (tmunro) noticed
that the per-participant page counter was not initialized to zero as it
should have been; that wasn't a live bug when it was written since DSM
memory was originally always zeroed, but since 14
min_dynamic_shared_memory might be configured and it supplies non-zeroed
memory, so that is also fixed here.
Author: Dmitry Astapov <dastapov@gmail.com>
Discussion: https://postgr.es/m/17619-0de62ceda812b8b5%40postgresql.org
VACUUM VERBOSE/autovacuuming logging have reported on the number of
pages frozen by VACUUM since commit d977ffd9 added that capability.
This information is directly related to relfrozenxid advancement, so
update an older tip from the documentation about how relfrozenxid is
reported on by the same instrumentation code. Now the tip directly
mentions newly frozen pages, too.
Eager freezing strategy avoids large build-ups of all-visible pages. It
makes VACUUM trigger page-level freezing whenever doing so will enable
the page to become all-frozen in the visibility map. This is useful for
tables that experience continual growth, particularly strict append-only
tables such as pgbench's history table. Eager freezing significantly
improves performance stability by spreading out the cost of freezing
over time, rather than doing most freezing during aggressive VACUUMs.
It complements the insert autovacuum mechanism added by commit b07642db.
VACUUM determines its freezing strategy based on the value of the new
vacuum_freeze_strategy_threshold GUC (or reloption) with logged tables.
Tables that exceed the size threshold use the eager freezing strategy.
Unlogged tables and temp tables always use eager freezing strategy,
since the added cost is negligible there. Non-permanent relations won't
incur any extra overhead in WAL written (for the obvious reason), nor in
pages dirtied (since any extra freezing will only take place on pages
whose PD_ALL_VISIBLE bit needed to be set either way).
VACUUM uses lazy freezing strategy for logged tables that fall under the
GUC size threshold. Page-level freezing triggers based on the criteria
established in commit 1de58df4, which added basic page-level freezing.
Eager freezing is strictly more aggressive than lazy freezing. Settings
like vacuum_freeze_min_age still get applied in just the same way in
every VACUUM, independent of the strategy in use. The only mechanical
difference between eager and lazy freezing strategies is that only the
former applies its own additional criteria to trigger freezing pages.
Note that even lazy freezing strategy will trigger freezing whenever a
page happens to have required that an FPI be written during pruning,
provided that the page will thereby become all-frozen in the visibility
map afterwards (due to the FPI optimization from commit 1de58df4).
The vacuum_freeze_strategy_threshold default setting is 4GB. This is a
relatively low setting that prioritizes performance stability. It will
be reviewed at the end of the Postgres 16 beta period.
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Jeff Davis <pgsql@j-davis.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Matthias van de Meent <boekewurm+postgres@gmail.com>
Discussion: https://postgr.es/m/CAH2-WzkFok_6EAHuK39GaW4FjEFQsY=3J0AAd6FXk93u-Xq3Fg@mail.gmail.com
We undefined them to avoid warnings about macro redefinitions. But we haven't
fully followed the necessary include order, since at least 147c248254, in
2011. Recently the combination of the include order rules not being followed
and undefining _POSIX_C_SOURCE started to cause a compile failure, starting
with 03023a2664. Undefining _POSIX_C_SOURCE hides clock_gettime(), which is
referenced in an inline function as of 03023a2664, whereas it was a macro
before.
After seeing some evidence that undefining _POSIX_C_SOURCE et al isn't
required, I tried to build postgres with plpython on most of our supported
platforms (except DragonFlyBSD and Illumos, but similar systems were tested),
with/without the #undefines. No compiler warning / behavioral difference.
The oldest supported python version, 3.2, defines _POSIX_C_SOURCE to 200112L
ad _XOPEN_SOURCE to 600, whereas newer versions of python use 200809L/700
respectively. As _POSIX_C_SOURCE/_XOPEN_SOURCE will default to the newer
operating system on most platforms, it's possible that when using python 3.2
new warnings would be emitted - but that seems acceptable.
It's possible that this approach won't work on some older platforms. But
getting rid of most of the include-order complexity seems promising, and it's
an easily revertible patch if we end up having to go another way.
Discussion: https://postgr.es/m/20230124165814.2njc7gnvubn2amh6@awork3.anarazel.de
David Rowley