This patch builds on the work done in commit 745217a051 by enabling the
replication of generated columns alongside regular column changes through
a new publication parameter: publish_generated_columns.
Example usage:
CREATE PUBLICATION pub1 FOR TABLE tab_gencol WITH (publish_generated_columns = true);
The column list takes precedence. If the generated columns are specified
in the column list, they will be replicated even if
'publish_generated_columns' is set to false. Conversely, if generated
columns are not included in the column list (assuming the user specifies a
column list), they will not be replicated even if
'publish_generated_columns' is true.
Author: Vignesh C, Shubham Khanna
Reviewed-by: Peter Smith, Amit Kapila, Hayato Kuroda, Shlok Kyal, Ajin Cherian, Hou Zhijie, Masahiko Sawada
Discussion: https://postgr.es/m/B80D17B2-2C8E-4C7D-87F2-E5B4BE3C069E@gmail.com
A newline is not added at the end of an empty query result, causing the
banner of the hardcoded \echo to not be discarded. This would reflect
on scripts that expect an empty result by showing the "QUERY_SEPARATOR"
in the output returned back to the caller, which was confusing.
This commit changes BackgroundPsql::query() so as empty results are able
to work correctly, making the first newline before the banner optional,
bringing more flexibility.
Note that this change affects 037_invalid_database.pl, where three
queries generated an empty result, with the script relying on the data
from the hardcoded banner to exist in the expected output. These
queries are changed to use query_safe(), leading to a simpler script.
The author has also proposed a test in a different patch where empty
results would exist when using BackgroundPsql.
Author: Jacob Champion
Reviewed-by: Andrew Dunstan, Michael Paquier
Discussion: https://postgr.es/m/CAOYmi+=60deN20WDyCoHCiecgivJxr=98s7s7-C8SkXwrCfHXg@mail.gmail.com
The low variable has not been used since it was added in d168b66682
and can be safely removed. The variable is present in the Sedgewick
paper "Analysis of Shellsort and Related Algorithms" as a parameter
to the shellsort function, but our implementation does not use it.
Remove to improve readability of the code.
Author: Koki Nakamura <btnakamurakoukil@oss.nttdata.com>
Discussion: https://postgr.es/m/8aeb7b3eda53ca4c65fbacf8f43628fb@oss.nttdata.com
This is difficult to maintain accurately, and it was probably already
somewhat incorrect, especially in the sql_drop and table_rewrite
categories.
The prior section already documented which DDL commands are *not*
supported (which was also slightly outdated), so let's expand that a
bit and just rely on that instead of listing out each command in full
detail.
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Jian He <jian.universality@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CACJufxE_UAuxcM08BW5oVsg34v0cFWoEt8yBa5xSAoKLmL6LTQ%40mail.gmail.com
Supply a new memory manager for RuntimeDyld, to avoid crashes in
generated code caused by memory placement that can overflow a 32 bit
data type. This is a drop-in replacement for the
llvm::SectionMemoryManager class in the LLVM library, with Michael
Smith's proposed fix from
https://www.github.com/llvm/llvm-project/pull/71968.
We hereby slurp it into our own source tree, after moving into a new
namespace llvm::backport and making some minor adjustments so that it
can be compiled with older LLVM versions as far back as 12. It's harder
to make it work on even older LLVM versions, but it doesn't seem likely
that people are really using them so that is not investigated for now.
The problem could also be addressed by switching to JITLink instead of
RuntimeDyld, and that is the LLVM project's recommended solution as
the latter is about to be deprecated. We'll have to do that soon enough
anyway, and then when the LLVM version support window advances far
enough in a few years we'll be able to delete this code. Unfortunately
that wouldn't be enough for PostgreSQL today: in most relevant versions
of LLVM, JITLink is missing or incomplete.
Several other projects have already back-ported this fix into their fork
of LLVM, which is a vote of confidence despite the lack of commit into
LLVM as of today. We don't have our own copy of LLVM so we can't do
exactly what they've done; instead we have a copy of the whole patched
class so we can pass an instance of it to RuntimeDyld.
The LLVM project hasn't chosen to commit the fix yet, and even if it
did, it wouldn't be back-ported into the releases of LLVM that most of
our users care about, so there is not much point in waiting any longer
for that. If they make further changes and commit it to LLVM 19 or 20,
we'll still need this for older versions, but we may want to
resynchronize our copy and update some comments.
The changes that we've had to make to our copy can be seen by diffing
our SectionMemoryManager.{h,cpp} files against the ones in the tree of
the pull request. Per the LLVM project's license requirements, a copy
is in SectionMemoryManager.LICENSE.
This should fix the spate of crash reports we've been receiving lately
from users on large memory ARM systems.
Back-patch to all supported releases.
Co-authored-by: Thomas Munro <thomas.munro@gmail.com>
Co-authored-by: Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com>
Reviewed-by: Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se> (license aspects)
Reported-by: Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com>
Discussion: https://postgr.es/m/CAO6_Xqr63qj%3DSx7HY6ZiiQ6R_JbX%2B-p6sTPwDYwTWZjUmjsYBg%40mail.gmail.com
This commit extends the constructor routine of BackgroundPsql.pm with a
new "wait" parameter. If set to 0, the routine returns without waiting
for psql to start, ready to consume input.
background_psql() in Cluster.pm gains the same "wait" parameter. The
default behavior is still to wait for psql to start. It becomes now
possible to not wait, giving to TAP scripts the possibility to perform
actions between a BackgroundPsql startup and its wait_connect() call.
Author: Jacob Champion
Discussion: https://postgr.es/m/CAOYmi+=60deN20WDyCoHCiecgivJxr=98s7s7-C8SkXwrCfHXg@mail.gmail.com
adf97c156 gave ExprStates the ability to hash expressions and return a
single hash value. That commit supports seeding the hash value with an
initial value to have that blended into the final hash value.
Here we fix a hypothetical bug where if there are zero expressions to
hash, the initial value is stored in the wrong location. The existing
code stored the initial value in an intermediate location expecting that
when the expressions were hashed that those steps would store the final
hash value in the ExprState.resvalue field. However, that wouldn't happen
when there are zero expressions to hash. The correct thing to do instead
is to have a special case for zero expressions and when we hit that case,
store the initial value directly in the ExprState.resvalue. The reason
that this is a hypothetical bug is that no code currently calls
ExecBuildHash32Expr passing a non-zero initial value.
Discussion: https://postgr.es/m/CAApHDvpMAL_zxbMRr1LOex3O7Y7R7ZN2i8iUFLQhqQiJMAg3qw@mail.gmail.com
Commit 99b937a44f introduced this warning when you run "meson setup":
Configuring Makefile.global using configuration
../src/meson.build:31: WARNING: The variable(s) 'PG_TEST_EXTRA' in the input file 'src/Makefile.global.in' are not present in the given configuration data.
To fix, add PG_TEST_EXTRA to the list of variables that are not needed
in the makefiles generated by meson. In meson builds, the makefiles
are only used for PGXS, not for building or testing the server itself.
Reported-by: Peter Eisentraut
Discussion: https://www.postgresql.org/message-id/5c380997-e270-425a-9542-e4ef36a285de@eisentraut.org
PgStat_HashKey is currently initialized in a way that could result in
random data if the structure has any padding bytes. The structure
has no padding bytes currently, fortunately, but it could become a
problem should the structure change at some point in the future.
The code is changed to use some memset(0) so as any padding would be
handled properly, as it would be surprising to see random failures in
the pgstats entry lookups. PgStat_HashKey is a structure internal to
pgstats, and an ABI change could be possible in the scope of a bug fix,
so backpatch down to 15 where this has been introduced.
Author: Bertrand Drouvot
Reviewed-by: Jelte Fennema-Nio, Michael Paquier
Discussion: https://postgr.es/m/Zyb7RW1y9dVfO0UH@ip-10-97-1-34.eu-west-3.compute.internal
Backpatch-through: 15
We had been using "diff -upd", which evidently works for most people,
but Solaris's diff doesn't like it. (We'd not noticed because the
Solaris buildfarm animals weren't running this test until they were
upgraded to the latest buildfarm client script.) Change to "diff -U3"
which is what pg_regress has used for ages.
Per buildfarm (and off-list discussion with Noah Misch).
Back-patch to v16 where this test was added. In v16,
also back-patch the relevant part of 628c1d1f2 so that
the test script looks about the same in all branches.
Sloppy refactoring in commit cca97ce6a caused these programs
to pass dbname = NULL to libpq if there was no "--dbname" switch
on the command line, where before "replication" would be passed.
This didn't break things completely, because the source server doesn't
care about the dbname specified for a physical replication connection.
However, it did cause libpq to fail to match a ~/.pgpass entry that
has "replication" in the dbname field. Restore the previous behavior
of passing "replication".
Also, closer inspection shows that if you do specify a dbname
in the connection string, that is what will be matched to ~/.pgpass,
not "replication". This was the pre-existing behavior so we should
not change it, but the SGML docs were pretty misleading about it.
Improve that.
Per bug #18685 from Toshi Harada. Back-patch to v17 where the
error crept in.
Discussion: https://postgr.es/m/18685-fee2dd142b9688f1@postgresql.org
Discussion: https://postgr.es/m/2702546.1730740456@sss.pgh.pa.us
Previously, we sorted rules by schema name and then rule name;
if that wasn't unique, we sorted by rule OID. This can be
problematic for comparing dumps from databases with different
histories, especially since certain rule names like "_RETURN"
are very common. Let's make the sort key schema name, rule name,
table name, which should be unique. (This is the same behavior
we've long used for triggers and RLS policies.)
Andreas Karlsson
Discussion: https://postgr.es/m/b4e468d8-0cd6-42e6-ac8a-1d6afa6e0cf1@proxel.se
_bt_first doesn't necessarily hold onto a buffer pin on success exit.
Fix header comments that claimed that we'll always hold onto a pin.
Oversight in commit 2ed5b87f96.
Remove a local variable that was used to avoid overwriting strat_total
with the = operator strategy when a >= operator strategy key was already
included in the initial positioning/insertion scan keys by _bt_first
(for backwards scans it would have to be a <= key that was included).
_bt_first's strat_total local variable now simply tracks the operator
strategy of the final scan key that was included in the scan's insertion
scan key (barring the case where the !used_all_subkeys row compare path
adjusts strat_total in its own way).
_bt_first already treated >= keys (or <= keys) as = keys for initial
positioning purposes. There is no good reason to remember that that was
what happened; no later _bt_first step cares about the distinction.
Note, in particular, that the insertion scan key's 'nextkey' and
'backward' fields will be initialized the same way regardless.
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Tomas Vondra <tomas@vondra.me>
Discussion: https://postgr.es/m/CAH2-Wz=PKR6rB7qbx+Vnd7eqeB5VTcrW=iJvAsTsKbdG+kW_UA@mail.gmail.com
Split ProcSleep into two functions: JoinWaitQueue and ProcSleep.
JoinWaitQueue is called while holding the partition lock, and inserts
the current process to the wait queue, while ProcSleep() does the
actual sleeping. ProcSleep() is now called without holding the
partition lock, and it no longer re-acquires the partition lock before
returning. That makes the wakeup a little cheaper. Once upon a time,
re-acquiring the partition lock was needed to prevent a signal handler
from longjmping out at a bad time, but these days our signal handlers
just set flags, and longjmping can only happen at points where we
explicitly run CHECK_FOR_INTERRUPTS().
If JoinWaitQueue detects an "early deadlock" before even joining the
wait queue, it returns without changing the shared lock entry, leaving
the cleanup of the shared lock entry to the caller. This makes the
handling of an early deadlock the same as the dontWait=true case.
One small user-visible side-effect of this refactoring is that we now
only set the 'ps' title to say "waiting" when we actually enter the
sleep, not when the lock is skipped because dontWait=true, or when a
deadlock is detected early before entering the sleep.
This eliminates the 'lockAwaited' global variable in proc.c, which was
largely redundant with 'awaitedLock' in lock.c
Note: Updating the local lock table is now the caller's responsibility.
JoinWaitQueue and ProcSleep are now only responsible for modifying the
shared state. Seems a little nicer that way.
Based on Thomas Munro's earlier patch and observation that ProcSleep
doesn't really need to re-acquire the partition lock.
Reviewed-by: Maxim Orlov
Discussion: https://www.postgresql.org/message-id/7c2090cd-a72a-4e34-afaa-6dd2ef31440e@iki.fi
Suppose that you run a command like "pg_combinebackup b1 b2 -o output",
but both b1 and b2 contain an INCREMENTAL.$something file in a directory
that is expected to contain relation files. This is an error, but the
previous code would not detect the problem and instead write a garbage
full file named $something to the output directory. This commit adds
code to detect the error and a test case to verify the behavior.
It's difficult to imagine that this will ever happen unless someone
is intentionally trying to break incremental backup, but per discussion,
let's consider that the lack of adequate sanity checking in this area is
a bug and back-patch to v17, where incremental backup was introduced.
Patch by me, reviewed by Bertrand Drouvot and Amul Sul.
Discussion: http://postgr.es/m/CA+TgmoaD7dBYPqe7kMtO0dyto7rd0rUh7joh=JPUSaFszKY6Pg@mail.gmail.com
This function is always called with a relative_path that ends in a
slash, so there's no need to insert a second one. So, don't. Instead,
add an assertion to verify that nothing gets broken in the future, and
adjust the comments.
While this is not a critical bug, the duplicate slash is visible in
error messages, which could create confusion, so back-patch to v17.
This is also better in that it keeps the code consistent across
branches.
Patch by me, reviewed by Bertrand Drouvot and Amul Sul.
Discussion: http://postgr.es/m/CA+TgmoaD7dBYPqe7kMtO0dyto7rd0rUh7joh=JPUSaFszKY6Pg@mail.gmail.com
Previously, ProcSleep()'s caller was responsible for setting
MyProc->heldLocks, and we had comments to remind about that. But it
seems simpler to make ProcSleep() itself responsible for it.
ProcSleep() already set the other info about the lock its waiting for
(waitLock, waitProcLock and waitLockMode), so it is natural for it to
set heldLocks too.
Reviewed-by: Maxim Orlov
Discussion: https://www.postgresql.org/message-id/7c2090cd-a72a-4e34-afaa-6dd2ef31440e@iki.fi
_bt_endpoint is a helper function for _bt_first that's called whenever
no useful insertion scan key can be used, and we need to lock and read
either the leftmost or rightmost leaf page in the index. Simplify and
document its preconditions, relieving its _bt_first caller from having
to end the parallel scan when it returns false.
Also stop unnecessarily invalidating the current scan position in nearby
code in both _bt_first and _bt_endpoint. This seems to have been
copy-pasted from _bt_readnextpage, where invalidating the scan's current
position really is necessary.
Follow-up to the refactoring work in commit 1bd4bc85.
The Meson builds have PG_TEST_EXTRA as a configure-time variable,
which was not available in the Make builds. To ensure both build
systems are in sync, PG_TEST_EXTRA is now added as a configure-time
variable. It can be set like this:
./configure PG_TEST_EXTRA="kerberos, ssl, ..."
Note that to preserve the old behavior, this configure-time variable
is overridden by the PG_TEST_EXTRA environment variable when you run
the tests.
Author: Jacob Champion
Reviewed by: Ashutosh Bapat, Nazir Bilal Yavuz
"meson test" used to ignore the PG_TEST_EXTRA environment variable,
which meant that in order to run additional tests, you had to run
"meson setup -DPG_TEST_EXTRA=...". That's somewhat expensive, and not
consistent with autoconf builds. Allow PG_TEST_EXTRA environment
variable to override the setup-time option at run time, so that you
can do "PG_TEST_EXTRA=... meson test".
To implement this, the configuration time value is passed as an extra
"--pg-test-extra" argument to testwrap instead of adding it to the
test environment. If the environment variable is set at the time of
running test, testwrap uses the value from the environment variable
and ignores the --pg-test-extra option.
Now that "meson test" obeys the environment variable, we can remove it
from the "meson setup" steps in the CI script. It will now be picked
up from the environment variable like with "make check".
Author: Nazir Bilal Yavuzk, Ashutosh Bapat
Reviewed-by: Ashutosh Bapat with inputs from Tom Lane and Andrew Dunstan
arrays.sql was already missing it before 49d6c7d8da, and I have just
noticed it thanks to this commit. The second one in test_slru has been
introduced by 768a9fd553.
A CacheInvalidateHeapTuple* callee might call
CatalogCacheInitializeCache(), which needs a relcache entry. Acquiring
a valid relcache entry might scan pg_class. Hence, to prevent
undetected LWLock self-deadlock, CacheInvalidateHeapTuple* callers must
not hold BUFFER_LOCK_EXCLUSIVE on buffers of pg_class. Move the
CacheInvalidateHeapTupleInplace() before the BUFFER_LOCK_EXCLUSIVE. No
back-patch, since I've reverted commit
243e9b40f1 from non-master branches.
Reported by Alexander Lakhin. Reviewed by Alexander Lakhin.
Discussion: https://postgr.es/m/10ec0bc3-5933-1189-6bb8-5dec4114558e@gmail.com
Commit a07e03fd8f enlarged the work done
here under the pg_class heap buffer lock. Two preexisting actions are
best done before holding that lock. Both RelationGetNumberOfBlocks()
and visibilitymap_count() do I/O, and the latter might exclusive-lock a
visibility map buffer. Moving these reduces contention and risk of
undetected LWLock deadlock. Back-patch to v12, like that commit.
Discussion: https://postgr.es/m/20241031200139.b4@rfd.leadboat.com
Instead of talking about setting latches, which is a pretty low-level
mechanism, emphasize that they wake up other processes.
This is in preparation for replacing Latches with a new abstraction.
That's still work in progress, but this seems a little tidier anyway,
so let's get this refactoring out of the way already.
Discussion: https://www.postgresql.org/message-id/391abe21-413e-4d91-a650-b663af49500c%40iki.fi
After a closer lookup, this makes the all-zero check of the page more
expensive, so let's remove the new function call in bufpage.c. The
maths of the check were also incorrect, checking that the page was full
of zeros only for the first 1kB.
This brings back the code to the state it was at 49d6c7d8da.
Per discussion with David Rowley and Bertrand Drouvot.
Discussion: https://postgr.es/m/CAApHDvrXzPAr3FxoBuB7b3D-okNoNA2jxLun1rW8Yw5wkbqusw@mail.gmail.com
This new function tests if a memory region starting at a given location
for a defined length is made only of zeroes. This unifies in a single
path the all-zero checks that were happening in a couple of places of
the backend code:
- For pgstats entries of relation, checkpointer and bgwriter, where
some "all_zeroes" variables were previously used with memcpy().
- For all-zero buffer pages in PageIsVerifiedExtended().
This new function uses the same forward scan as the check for all-zero
buffer pages, applying it to the three pgstats paths mentioned above.
Author: Bertrand Drouvot
Reviewed-by: Peter Eisentraut, Heikki Linnakangas, Peter Smith
Discussion: https://postgr.es/m/ZupUDDyf1hHI4ibn@ip-10-97-1-34.eu-west-3.compute.internal
This function takes in input an array, and reverses the position of all
its elements. This operation only affects the first dimension of the
array, like array_shuffle().
The implementation structure is inspired by array_shuffle(), with a
subroutine called array_reverse_n() that may come in handy in the
future, should more functions able to reverse portions of arrays be
introduced.
Bump catalog version.
Author: Aleksander Alekseev
Reviewed-by: Ashutosh Bapat, Tom Lane, Vladlen Popolitov
Discussion: https://postgr.es/m/CAJ7c6TMpeO_ke+QGOaAx9xdJuxa7r=49-anMh3G5476e3CX1CA@mail.gmail.com
This patch responds to a comment that I (tgl) made in the
discussion leading up to 774171c4f, that really all errors
occurring during raw parsing should provide error cursors.
Syntax errors reported by Bison will have one, and most of
the handwritten ereport's in gram.y already provide one,
but there were a few stragglers.
(It is not claimed that this handles every failure reachable
during raw parsing --- out-of-memory is an obvious exception.
But this makes a good start on cases that are likely to occur.)
While we're at it, clean up the reported positions for errors
associated with LIMIT/OFFSET clauses. Previously we were
relying on applying exprLocation() to the contained expressions,
but that leads to slightly odd cursor placement, e.g.
regression=# (select * from foo limit 10) limit 10;
ERROR: multiple LIMIT clauses not allowed
LINE 1: (select * from foo limit 10) limit 10;
^
We can afford to keep a little more state in the transient
SelectLimit structs in order to make that better.
Jian He and Tom Lane (extracted from a larger patch by Jian,
with some additional work by me)
Discussion: https://postgr.es/m/CACJufxEmONE3P2En=jopZy1m=cCCUs65M4+1o52MW5og9oaUPA@mail.gmail.com
This allows an error cursor to be supplied for a bunch of
bad-function-definition errors that previously lacked one,
or that cheated a bit by pointing at the contained type name
when the error isn't really about that.
Bump catversion from an abundance of caution --- I don't think
this node type can actually appear in stored views/rules, but
better safe than sorry.
Jian He and Tom Lane (extracted from a larger patch by Jian,
with some additional work by me)
Discussion: https://postgr.es/m/CACJufxEmONE3P2En=jopZy1m=cCCUs65M4+1o52MW5og9oaUPA@mail.gmail.com
Buildfarm member 'prion', which is configured with
-DRELCACHE_FORCE_RELEASE -DCATCACHE_FORCE_RELEASE, failed with errors
like this:
ERROR: could not read blocks 0..0 in file "global/2672": read only 0 of 8192 bytes
while running a parallel test group that includes VACUUM FULL on some
catalog tables among other things. I was not able to reproduce that
just by running the tests with -DRELCACHE_FORCE_RELEASE
-DCATCACHE_FORCE_RELEASE, even though 'prion' hit it on first run
after commit 2b9b8ebbf8, so there might be something else that makes
it more susceptible to the race. However, I was able to reproduce it
by adding another test to the same test group that runs "vacuum full
pg_database" repeatedly.
The problem is that RelationReloadIndexInfo() no longer calls
RelationInitPhysicalAddr() on a nailed, shared index, when an
invalidation happens early during backend startup, before the critical
relcaches have been built. Before commit 2b9b8ebbf8, that was done by
RelationReloadNailed(), but it went missing from that path. Add it
back as an explicit step.
Broken by commit 2b9b8ebbf8, which refactored these functions.
Discussion: https://www.postgresql.org/message-id/db876575-8f5b-4193-a538-df7e1f92d47a%40iki.fi
The old RelationClearRelation function did different things depending
on the arguments and circumstances. It could:
a) remove the relation completely from relcache (rebuild == false),
b) mark the entry as invalid (rebuild == true, but not in xact), or
c) rebuild the entry (rebuild == true).
Different callers used it for different purposes, and often assumed a
particular behavior, which was confusing. Split it into three
different functions, one for each of the above actions (one of them,
RelationInvalidateRelation, was already added in commit e6cd857726).
Move the responsibility of choosing the action and calling the right
function to the callers.
Reviewed-by: jian he <jian.universality@gmail.com>
Discussion: https://www.postgresql.org/message-id/9c9e8908-7b3e-4ce7-85a8-00c0e165a3d6%40iki.fi
RelationClearRelation(rebuild == true) calls RelationReloadIndexInfo()
for indexes. We can rely on that in RelationIdGetRelation(), instead
of calling RelationReloadIndexInfo() directly. That simplifies the
code a little.
In the passing, add a comment in RelationBuildLocalRelation()
explaining why it doesn't call RelationInitIndexAccessInfo(). It's
because at index creation, it's called before the pg_index row has
been created. That's also the reason that RelationClearRelation()
still needs a special case to go through the full-blown rebuild if the
index support information in the relcache entry hasn't been populated
yet.
Reviewed-by: jian he <jian.universality@gmail.com>
Discussion: https://www.postgresql.org/message-id/9c9e8908-7b3e-4ce7-85a8-00c0e165a3d6%40iki.fi
9f00edc228 has disabled a permutation due to failures in the CI for
FreeBSD environments, but this is a matter of timing. Let's document
properly why this type of permutation is a bad idea if relying on a wait
done in a SQL function, so as this can be avoided when implementing new
tests (this spec is also a template).
Reviewed-by: Bertrand Drouvot
Discussion: https://postgr.es/m/ZyCa2qsopKaw3W3K@paquier.xyz
Follow-up to bugfix commit 763d65ae. Technically this new assertion is
redundant with the assertion recently added to _bt_readpage by that same
commit, but it seems like a good idea to have both.
The new assertion makes it clear that we expect to call _bt_readnextpage
when there's another primitive index scan scheduled, though only when
needed as the final step of ending the current primitive scan.
Strictly speaking, we only need to make sure to leave the scan's array
keys in their final positions (final for the current scan direction) to
handle SAOP array exhaustion because btgettuple might only return a
subset of the items for the final page (final for the current scan
direction), before the scan changes direction. While it's typical for
so->currPos to be invalidated shortly after the scan's arrays are first
exhausted, and while so->currPos invalidation does obviate the need to
leave the scan's arrays in any particular state, we can't rely on any of
that actually happening when handling array exhaustion. Adjust comments
to make all of that a lot clearer.
Oversight in commit 5bf748b8, which enhanced nbtree ScalarArrayOp
execution.
Presently, each iteration of the loop in sift_down() will perform
3 comparisons if both children are larger than the parent node (2
for comparing each child to the parent node, and a third to compare
the children to each other). By first comparing the children to
each other and then comparing the larger child to the parent node,
we can accomplish the same thing with just 2 comparisons (while
also not affecting the number of comparisons in any other case).
Author: ChangAo Chen
Reviewed-by: Robert Haas
Discussion: https://postgr.es/m/tencent_0142D8DA90940B9930BCC08348BBD6D0BB07%40qq.com
An operation like '12:34:56'::time_tz takes the UTC offset from
the prevailing time zone, which means that the results change
across DST transitions. One of the test cases added in ed055d249
failed to consider this.
Per report from Bernhard Wiedemann. Back-patch to v17, as the
test case was.
Discussion: https://postgr.es/m/ba8e1bc0-8a99-45b7-8397-3f2e94415e03@suse.de
A bug in nbtree's handling of primitive index scan scheduling could lead
to wrong answers when a scrollable cursor was used with an index scan
that had a SAOP index qual. Wrong answers were only possible when the
scan direction changed after a primitive scan was scheduled, but before
_bt_next was asked to fetch the next tuple in line (i.e. for things to
break, _bt_next had to be denied the opportunity to step off the page in
the same direction as the one used when the primscan was scheduled).
Furthermore, the issue only occurred when the page in question happened
to be the first page to be visited by the entire top-level scan; the
issue hinged upon the cursor backing up to the absolute beginning of the
key space that it returns tuples from (fetching in the opposite scan
direction across a "primitive scan boundary" always worked correctly).
To fix, make _bt_next unset the "needs primitive index scan" flag when
it detects that the current scan direction is not the one that was used
by _bt_readpage back when the primitive scan in question was scheduled.
This fixes the cases that are known to be faulty, and also seems like a
good idea on general robustness grounds.
Affected scrollable cursor cases now avoid a spurious primitive index
scan when they fetch backwards to the absolute start of the key space to
be visited by their cursor. Fetching backwards now only returns those
tuples at the start of the scan, as expected. It'll also be okay to
once again fetch forwards from the start at that point, since the scan
will be left in a state that's exactly consistent with the state it was
in before any tuples were ever fetched, as expected.
Oversight in commit 5bf748b8, which enhanced nbtree ScalarArrayOp
execution.
Author: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAH2-Wznv49bFsE2jkt4GuZ0tU2C91dEST=50egzjY2FeOcHL4Q@mail.gmail.com
Backpatch: 17-, where commit 5bf748b8 first appears.
Amit Kapila