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Commit Graph

40420 Commits

Author SHA1 Message Date
Fujii Masao
8e9ea08bae Don't pass "ONLY" options specified in TRUNCATE to foreign data wrapper.
Commit 8ff1c94649 allowed TRUNCATE command to truncate foreign tables.
Previously the information about "ONLY" options specified in TRUNCATE
command were passed to the foreign data wrapper. Then postgres_fdw
constructed the TRUNCATE command to issue the remote server and
included "ONLY" options in it based on the passed information.

On the other hand, "ONLY" options specified in SELECT, UPDATE or DELETE
have no effect when accessing or modifying the remote table, i.e.,
are not passed to the foreign data wrapper. So it's inconsistent to
make only TRUNCATE command pass the "ONLY" options to the foreign data
wrapper. Therefore this commit changes the TRUNCATE command so that
it doesn't pass the "ONLY" options to the foreign data wrapper,
for the consistency with other statements. Also this commit changes
postgres_fdw so that it always doesn't include "ONLY" options in
the TRUNCATE command that it constructs.

Author: Fujii Masao
Reviewed-by: Bharath Rupireddy, Kyotaro Horiguchi, Justin Pryzby, Zhihong Yu
Discussion: https://postgr.es/m/551ed8c1-f531-818b-664a-2cecdab99cd8@oss.nttdata.com
2021-04-27 14:41:27 +09:00
Amit Kapila
3fa17d3771 Use HTAB for replication slot statistics.
Previously, we used to use the array of size max_replication_slots to
store stats for replication slots. But that had two problems in the cases
where a message for dropping a slot gets lost: 1) the stats for the new
slot are not recorded if the array is full and 2) writing beyond the end
of the array if the user reduces the max_replication_slots.

This commit uses HTAB for replication slot statistics, resolving both
problems. Now, pgstat_vacuum_stat() search for all the dead replication
slots in stats hashtable and tell the collector to remove them. To avoid
showing the stats for the already-dropped slots, pg_stat_replication_slots
view searches slot stats by the slot name taken from pg_replication_slots.

Also, we send a message for creating a slot at slot creation, initializing
the stats. This reduces the possibility that the stats are accumulated
into the old slot stats when a message for dropping a slot gets lost.

Reported-by: Andres Freund
Author: Sawada Masahiko, test case by Vignesh C
Reviewed-by: Amit Kapila, Vignesh C, Dilip Kumar
Discussion: https://postgr.es/m/20210319185247.ldebgpdaxsowiflw@alap3.anarazel.de
2021-04-27 09:09:11 +05:30
Amit Kapila
e7eea52b2d Fix Logical Replication of Truncate in synchronous commit mode.
The Truncate operation acquires an exclusive lock on the target relation
and indexes. It then waits for logical replication of the operation to
finish at commit. Now because we are acquiring the shared lock on the
target index to get index attributes in pgoutput while sending the
changes for the Truncate operation, it leads to a deadlock.

Actually, we don't need to acquire a lock on the target index as we build
the cache entry using a historic snapshot and all the later changes are
absorbed while decoding WAL. So, we wrote a special purpose function for
logical replication to get a bitmap of replica identity attribute numbers
where we get that information without locking the target index.

We decided not to backpatch this as there doesn't seem to be any field
complaint about this issue since it was introduced in commit 5dfd1e5a in
v11.

Reported-by: Haiying Tang
Author: Takamichi Osumi, test case by Li Japin
Reviewed-by: Amit Kapila, Ajin Cherian
Discussion: https://postgr.es/m/OS0PR01MB6113C2499C7DC70EE55ADB82FB759@OS0PR01MB6113.jpnprd01.prod.outlook.com
2021-04-27 08:28:26 +05:30
Alvaro Herrera
6dd1042eda psql: tab-complete ALTER ... DETACH CONCURRENTLY / FINALIZE
New keywords per 71f4c8c6f7.

Discussion: https://postgr.es/m/20210422204035.GA25929@alvherre.pgsql
2021-04-26 16:14:10 -04:00
Tom Lane
04942bffd0 Remove rewriteTargetListIU's expansion of view targetlists in UPDATE.
Commit 2ec993a7c, which added triggers on views, modified the rewriter
to add dummy entries like "SET x = x" for all columns that weren't
actually being updated by the user in any UPDATE directed at a view.
That was needed at the time to produce a complete "NEW" row to pass
to the trigger.  Later it was found to cause problems for ordinary
updatable views, so commit cab5dc5da restricted it to happen only for
trigger-updatable views.  But in the wake of commit 86dc90056, we
really don't need it at all.  nodeModifyTable.c populates the trigger
"OLD" row from the whole-row variable that is generated for the view,
and then it computes the "NEW" row using that old row and the UPDATE
targetlist.  So there is no need for the UPDATE tlist to have dummy
entries, any more than it needs them for regular tables or other
types of views.

(The comments for rewriteTargetListIU suggest that we must do this
for correct expansion of NEW references in rules, but I now think
that that was just lazy comment editing in 2ec993a7c.  If we didn't
need it for rules on views before there were triggers, we don't need
it after that.)

This essentially propagates 86dc90056's decision that we don't need
dummy column updates into the view case.  Aside from making the
different cases more uniform and hence possibly forestalling future
bugs, it ought to save a little bit of rewriter/planner effort.

Discussion: https://postgr.es/m/2181213.1619397634@sss.pgh.pa.us
2021-04-26 13:58:00 -04:00
Peter Eisentraut
38c9a5938a Fix pg_upgrade test on Cygwin
The verification of permissions doesn't succeed on Cygwin, because the
required feature is not implemented for Cygwin at the moment.  So skip
this part of the test, like MinGW already does.
2021-04-26 12:10:46 +02:00
Michael Paquier
2ecfeda3e9 Add more tests with triggers on partitions for logical replication
The tuple routing logic used by a logical replication worker can fire
triggers on relations part of a partition tree, but there was no test
coverage in this area.  The existing script 003_constraints.pl included
something, but nothing when a tuple is applied across partitioned tables
on a subscriber.

Author: Amit Langote
Discussion: https://postgr.es/m/OS0PR01MB611383FA0FE92EB9DE21946AFB769@OS0PR01MB6113.jpnprd01.prod.outlook.com
2021-04-26 15:22:48 +09:00
Amit Kapila
f25a4584c6 Avoid sending prepare multiple times while decoding.
We send the prepare for the concurrently aborted xacts so that later when
rollback prepared is decoded and sent, the downstream should be able to
rollback such a xact. For 'streaming' case (when we send changes for
in-progress transactions), we were sending prepare twice when concurrent
abort was detected.

Author: Peter Smith
Reviewed-by: Amit Kapila
Discussion: https://postgr.es/m/f82133c6-6055-b400-7922-97dae9f2b50b@enterprisedb.com
2021-04-26 11:27:44 +05:30
Peter Eisentraut
3cbea581c7 Remove unused function argument
This was already unused in the initial commit
257836a755.  Apparently, it was used in
an earlier proposed patch version.
2021-04-26 07:05:21 +02:00
Amit Kapila
6d2e87a077 Fix typo in reorderbuffer.c.
Author: Peter Smith
Discussion: https://postgr.es/m/CAHut+PtvzuYY0zu=dVRK_WVz5WGos1+otZWgEWqjha1ncoSRag@mail.gmail.com
2021-04-26 08:42:46 +05:30
Tom Lane
08a9869665 Update comments for rewriteTargetListIU().
This function's behavior for UPDATE on a trigger-updatable view was
justified by analogy to what preptlist.c used to do for UPDATE on
regular tables.  Since preptlist.c hasn't done that since 86dc90056,
that argument is no longer sensible, let alone convincing.  I think
we do still need it to act that way, so update the comment to explain
why.
2021-04-25 18:02:03 -04:00
Noah Misch
59773da2b1 Make a test endure log_error_verbosity=verbose. 2021-04-25 01:08:05 -07:00
Andrew Dunstan
b859d94c63 Provide pg_amcheck with an --install-missing option
This will install amcheck in the database if not present. The default
schema is for the extension is pg_catalog, but this can be overridden by
providing a value for the option.

Mark Dilger, slightly editorialized by me.

(rather divergent)
Discussion: https://postgr.es/m/bdc0f7c2-09e3-ee57-8471-569dfb509234@dunslane.net
2021-04-24 10:13:07 -04:00
Andrew Dunstan
aa271209f6 Teach PostgresVersion all the ways to mark non-release code
As well as 'devel' version_stamp.pl provides for 'alphaN'
'betaN' and 'rcN', so teach PostgresVersion about those.

Also stash the version string instead of trying to reconstruct it during
stringification.

Discussion: https://postgr.es/m/YIHlw5nSgAHs4dK1@paquier.xyz
2021-04-24 09:37:20 -04:00
Michael Paquier
9b5558e7ad Fix come comments in execMain.c
1375422 has refactored this area of the executor code, and some comments
went out-of-sync.

Author: Yukun Wang
Reviewed-by: Amul Sul
Discussion: https://postgr.es/m/OS0PR01MB60033394FCAEF79B98F078F5B4459@OS0PR01MB6003.jpnprd01.prod.outlook.com
2021-04-24 15:07:04 +09:00
Michael Paquier
4aba61b870 Add some forgotten LSN_FORMAT_ARGS() in xlogreader.c
6f6f284 has introduced a specific macro to make printf()-ing of LSNs
easier.  This takes care of what looks like the remaining code paths
that did not get the call.

Author: Michael Paquier
Reviewed-by: Kyotaro Horiguchi, Tom Lane
Discussion: https://postgr.es/m/YIJS9x6K8ruizN7j@paquier.xyz
2021-04-24 09:09:02 +09:00
Peter Eisentraut
82c3cd9741 Factor out system call names from error messages
Instead, put them in via a format placeholder.  This reduces the
number of distinct translatable messages and also reduces the chances
of typos during translation.  We already did this for the system call
arguments in a number of cases, so this is just the same thing taken a
bit further.

Discussion: https://www.postgresql.org/message-id/flat/92d6f545-5102-65d8-3c87-489f71ea0a37%40enterprisedb.com
2021-04-23 14:21:37 +02:00
Peter Eisentraut
9486844f30 Use correct format placeholder for WSAGetLastError()
Some code thought this was unsigned, but it's signed int.
2021-04-23 14:21:37 +02:00
Alexander Korotkov
6bbcff096f Mark multirange_constructor0() and multirange_constructor2() strict
These functions shouldn't receive null arguments: multirange_constructor0()
doesn't have any arguments while multirange_constructor2() has a single array
argument, which is never null.

But mark them strict anyway for the sake of uniformity.

Also, make checks for null arguments use elog() instead of ereport() as these
errors should normally be never thrown.  And adjust corresponding comments.

Catversion is bumped.

Reported-by: Peter Eisentraut
Discussion: https://postgr.es/m/0f783a96-8d67-9e71-996b-f34a7352eeef%40enterprisedb.com
2021-04-23 13:25:45 +03:00
Fujii Masao
3f20d5f370 Reorder COMPRESSION option in gram.y and parsenodes.h into alphabetical order.
Commit bbe0a81db6 introduced "INCLUDING COMPRESSION" option
in CREATE TABLE command, but previously TableLikeOption in gram.y and
parsenodes.h didn't classify this new option in alphabetical order
with the rest.

Author: Fujii Masao
Reviewed-by: Michael Paquier
Discussion: https://postgr.es/m/YHerAixOhfR1ryXa@paquier.xyz
2021-04-23 19:10:24 +09:00
Peter Eisentraut
add5fad78a pg_amcheck: Use logging functions
This was already mostly done, but some error messages were printed the
long way.
2021-04-23 09:55:23 +02:00
Peter Eisentraut
7776a23a4b Fix incorrect format placeholder 2021-04-23 07:21:13 +02:00
Michael Paquier
45c0c5f70e Fix some comments in fmgr.c
Oversight in 2a0faed.

Author: Hou Zhijie
Discussion: https://postgr.es/m/OS0PR01MB5716405E2464D85E6DB6DC0794469@OS0PR01MB5716.jpnprd01.prod.outlook.com
2021-04-23 13:34:02 +09:00
Michael Paquier
62aa2bb293 Remove use of [U]INT64_FORMAT in some translatable strings
%lld with (long long), or %llu with (unsigned long long) are more
adapted.  This is similar to 3286065.

Author: Kyotaro Horiguchi
Discussion: https://postgr.es/m/20210421.200000.1462448394029407895.horikyota.ntt@gmail.com
2021-04-23 13:25:49 +09:00
Etsuro Fujita
bb684c82f7 Minor code cleanup in asynchronous execution support.
This is cleanup for commit 27e1f1456:

* ExecAppendAsyncEventWait(), which was modified a bit further by commit
  a8af856d3, duplicated the same nevents calculation.  Simplify the code
  a little bit to avoid the duplication.  Update comments there.
* Add an assertion to ExecAppendAsyncRequest().
* Update a comment about merging the async_capable options from input
  relations in merge_fdw_options(), per complaint from Kyotaro Horiguchi.
* Add a comment for fetch_more_data_begin().

Author: Etsuro Fujita
Discussion: https://postgr.es/m/CAPmGK1637W30Wx3MnrReewhafn6F_0J76mrJGoFXFnpPq4QfvA%40mail.gmail.com
2021-04-23 12:00:00 +09:00
Tom Lane
d479d00285 Don't crash on reference to an un-available system column.
Adopt a more consistent policy about what slot-type-specific
getsysattr functions should do when system attributes are not
available.  To wit, they should all throw the same user-oriented
error, rather than variously crashing or emitting developer-oriented
messages.

This closes a identifiable problem in commits a71cfc56b and
3fb93103a (in v13 and v12), so back-patch into those branches,
along with a test case to try to ensure we don't break it again.
It is not known that any of the former crash cases are reachable
in HEAD, but this seems like a good safety improvement in any case.

Discussion: https://postgr.es/m/141051591267657@mail.yandex.ru
2021-04-22 17:30:55 -04:00
Alvaro Herrera
43b55ec4bc Fix uninitialized memory bug
Have interested callers of find_inheritance_children set the
detached_exist value to false prior to calling it, so that that routine
only has to set it true in the rare cases where it is necessary.  Don't
touch it otherwise.

Per buildfarm member thorntail (which reported a UBSan failure here).
2021-04-22 16:04:48 -04:00
Andrew Dunstan
502dc6df8f Make PostgresVersion code a bit more robust and simple.
per gripe from Alvaro Herrera.
2021-04-22 15:27:05 -04:00
Alvaro Herrera
8aba932251 Fix relcache inconsistency hazard in partition detach
During queries coming from ri_triggers.c, we need to omit partitions
that are marked pending detach -- otherwise, the RI query is tricked
into allowing a row into the referencing table whose corresponding row
is in the detached partition.  Which is bogus: once the detach operation
completes, the row becomes an orphan.

However, the code was not doing that in repeatable-read transactions,
because relcache kept a copy of the partition descriptor that included
the partition, and used it in the RI query.  This commit changes the
partdesc cache code to only keep descriptors that aren't dependent on
a snapshot (namely: those where no detached partition exist, and those
where detached partitions are included).  When a partdesc-without-
detached-partitions is requested, we create one afresh each time; also,
those partdescs are stored in PortalContext instead of
CacheMemoryContext.

find_inheritance_children gets a new output *detached_exist boolean,
which indicates whether any partition marked pending-detach is found.
Its "include_detached" input flag is changed to "omit_detached", because
that name captures desired the semantics more naturally.
CreatePartitionDirectory() and RelationGetPartitionDesc() arguments are
identically renamed.

This was noticed because a buildfarm member that runs with relcache
clobbering, which would not keep the improperly cached partdesc, broke
one test, which led us to realize that the expected output of that test
was bogus.  This commit also corrects that expected output.

Author: Amit Langote <amitlangote09@gmail.com>
Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/3269784.1617215412@sss.pgh.pa.us
2021-04-22 15:13:25 -04:00
Andrew Dunstan
4c4eaf3d19 Make PostgresNode version aware
A new PostgresVersion object type is created and this is used in
PostgresNode using the output of `pg_config --version` and the result
stored in the PostgresNode object.  This object can be compared to other
PostgresVersion objects, or to a number or string.

PostgresNode is currently believed to be compatible with versions down
to release 12, so PostgresNode will issue a warning if used with a
version prior to that.

No attempt has been made to deal with incompatibilities in older
versions - that remains work to be undertaken in a subsequent
development cycle.

Based on code from Mark Dilger and Jehan-Guillaume de Rorthais.

Discussion: https://postgr.es/m/a80421c0-3d7e-def1-bcfe-24777f15e344@dunslane.net
2021-04-22 10:56:28 -04:00
Michael Paquier
f3b141c482 Fix relation leak for subscribers firing triggers in logical replication
Creating a trigger on a relation to which an apply operation is
triggered would cause a relation leak once the change gets committed,
as the executor would miss that the relation needs to be closed
beforehand.  This issue got introduced with the refactoring done in
1375422c, where it becomes necessary to track relations within
es_opened_result_relations to make sure that they are closed.

We have discussed using ExecInitResultRelation() coupled with
ExecCloseResultRelations() for the relations in need of tracking by the
apply operations in the subscribers, which would simplify greatly the
opening and closing of indexes, but this requires a larger rework and
reorganization of the worker code, particularly for the tuple routing
part.  And that's not really welcome post feature freeze.  So, for now,
settle down to the same solution as TRUNCATE which is to fill in
es_opened_result_relations with the relation opened, to make sure that
ExecGetTriggerResultRel() finds them and that they get closed.

The code is lightly refactored so as a relation is not registered three
times for each DML code path, making the whole a bit easier to follow.

Reported-by: Tang Haiying, Shi Yu, Hou Zhijie
Author: Amit Langote, Masahiko Sawada, Hou Zhijie
Reviewed-by: Amit Kapila, Michael Paquier
Discussion: https://postgr.es/m/OS0PR01MB611383FA0FE92EB9DE21946AFB769@OS0PR01MB6113.jpnprd01.prod.outlook.com
2021-04-22 12:48:54 +09:00
Alvaro Herrera
7c298c6573 Add comment about extract_autovac_opts not holding lock
Per observation from Tom Lane.

Discussion: https://postgr.es/m/1901125.1617904665@sss.pgh.pa.us
2021-04-21 18:36:12 -04:00
Alvaro Herrera
7b357cc6ae Don't add a redundant constraint when detaching a partition
On ALTER TABLE .. DETACH CONCURRENTLY, we add a new table constraint
that duplicates the partition constraint.  But if the partition already
has another constraint that implies that one, then that's unnecessary.
We were already avoiding the addition of a duplicate constraint if there
was an exact 'equal' match -- this just improves the quality of the check.

Author: Justin Pryzby <pryzby@telsasoft.com>
Reviewed-by: Álvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/20210410184226.GY6592@telsasoft.com
2021-04-21 18:12:05 -04:00
Andrew Dunstan
e014d25dea fix silly perl error in commit d064afc720 2021-04-21 11:17:29 -04:00
Andrew Dunstan
d064afc720 Only ever test for non-127.0.0.1 addresses on Windows in PostgresNode
This has been found to cause hangs where tcp usage is forced.

Alexey Kodratov

Discussion: https://postgr.es/m/82e271a9a11928337fcb5b5e57b423c0@postgrespro.ru

Backpatch to all live branches
2021-04-21 10:21:22 -04:00
Peter Eisentraut
d84ffffe58 Add DISTINCT to information schema usage views
Since pg_depend can contain duplicate entries, we need to eliminate
those in information schema views that build on pg_depend, using
DISTINCT.  Some of the older views already did that correctly, but
some of the more recently added ones didn't.  (In some of these views,
it might not be possible to reproduce the issue because of how the
implementation happens to deduplicate dependencies while recording
them, but it seems better to keep this consistent in all cases.)
2021-04-21 11:54:47 +02:00
Peter Eisentraut
39d0928a0e Use correct format placeholder for timeline IDs
Should be %u rather than %d.
2021-04-21 08:26:18 +02:00
Peter Eisentraut
544b28088f doc: Improve hyphenation consistency 2021-04-21 08:14:43 +02:00
Peter Eisentraut
3286065651 Don't use INT64_FORMAT inside message strings
Use %lld and cast to long long int instead.
2021-04-21 08:07:37 +02:00
Peter Eisentraut
f0ec598b43 Fix typo 2021-04-21 08:07:37 +02:00
Michael Paquier
22b2dec31b Add CURRENT_ROLE to list of roles for tab completion of GRANT in psql
This compatibility has been added in 45b9805, but psql forgot the call.

Author: Wei Wang
Reviewed-by: Aleksander Alekseev
Discussion: https://postgr.es/m/OS3PR01MB6275935F62E161BCD393D6559E489@OS3PR01MB6275.jpnprd01.prod.outlook.com
2021-04-21 10:34:43 +09:00
Tom Lane
783be78ca9 Improve WAL record descriptions for SP-GiST records.
While tracking down the bug fixed in the preceding commit, I got quite
annoyed by the low quality of spg_desc's output.  Add missing fields,
try to make the formatting consistent.
2021-04-20 17:01:49 -04:00
Tom Lane
9e41148229 Fix under-parenthesized XLogRecHasBlockRef() macro.
Commit f003d9f87 left this macro with inadequate (or, one could say,
too much) parenthesization.  Which was catastrophic to the correctness
of calls such as "if (!XLogRecHasBlockRef(record, 1)) ...".  There
are only a few of those, which perhaps explains why we didn't notice
immediately (with our general weakness of WAL replay testing being
another factor).  I found it by debugging intermittent replay failures
like

2021-04-08 14:33:30.191 EDT [29463] PANIC:  failed to locate backup block with ID 1
2021-04-08 14:33:30.191 EDT [29463] CONTEXT:  WAL redo at 0/95D3438 for SPGist/ADD_NODE: off 1; blkref #0: rel 1663/16384/25998, blk 1
2021-04-20 17:01:49 -04:00
Bruce Momjian
db01f797dd Fix interaction of log_line_prefix's query_id and log_statement
log_statement is issued before query_id can be computed, so properly
clear the value, and document the interaction.

Reported-by: Fujii Masao, Michael Paquier

Discussion: https://postgr.es/m/YHPkU8hFi4no4NSw@paquier.xyz

Author: Julien Rouhaud
2021-04-20 12:57:59 -04:00
Bruce Momjian
9660834dd8 adjust query id feature to use pg_stat_activity.query_id
Previously, it was pg_stat_activity.queryid to match the
pg_stat_statements queryid column.  This is an adjustment to patch
4f0b0966c8.  This also adjusts some of the internal function calls to
match.  Catversion bumped.

Reported-by: Álvaro Herrera, Julien Rouhaud

Discussion: https://postgr.es/m/20210408032704.GA7498@alvherre.pgsql
2021-04-20 12:22:26 -04:00
Tom Lane
7645376774 Rename find_em_expr_usable_for_sorting_rel.
I didn't particularly like this function name, as it fails to
express what's going on.  Also, returning the sort expression
alone isn't too helpful --- typically, a caller would also
need some other fields of the EquivalenceMember.  But the
sole caller really only needs a bool result, so let's make
it "bool relation_can_be_sorted_early()".

Discussion: https://postgr.es/m/91f3ec99-85a4-fa55-ea74-33f85a5c651f@swarm64.com
2021-04-20 11:37:36 -04:00
Tom Lane
3753982441 Fix planner failure in some cases of sorting by an aggregate.
An oversight introduced by the incremental-sort patches caused
"could not find pathkey item to sort" errors in some situations
where a sort key involves an aggregate or window function.

The basic problem here is that find_em_expr_usable_for_sorting_rel
isn't properly modeling what prepare_sort_from_pathkeys will do
later.  Rather than hoping we can keep those functions in sync,
let's refactor so that they actually share the code for
identifying a suitable sort expression.

With this refactoring, tlist.c's tlist_member_ignore_relabel
is unused.  I removed it in HEAD but left it in place in v13,
in case any extensions are using it.

Per report from Luc Vlaming.  Back-patch to v13 where the
problem arose.

James Coleman and Tom Lane

Discussion: https://postgr.es/m/91f3ec99-85a4-fa55-ea74-33f85a5c651f@swarm64.com
2021-04-20 11:32:02 -04:00
Andrew Dunstan
95c3a1956e Avoid unfortunate IPC::Run path caching in PostgresNode
Commit b34ca595ab provided for installation-aware instances of
PostgresNode. However, it turns out that IPC::Run works against this by
caching the path to a binary and not consulting the path again, even if
it has changed. We work around this by calling Postgres binaries with
the installed path rather than just a bare name to be looked up in the
environment path, if there is an installed path. For the common case
where there is no installed path we continue to use the bare command
name.

Diagnosis and solution from Mark Dilger

Discussion: https://postgr.es/m/E8F512F8-B4D6-4514-BA8D-2E671439DA92@enterprisedb.com
2021-04-20 10:36:10 -04:00
Magnus Hagander
8b4b5669cd Fix typo in comment
Author: Julien Rouhaud
Backpatch-through: 11
Discussion: https://postgr.es/m/20210420121659.odjueyd4rpilorn5@nol
2021-04-20 14:35:16 +02:00
Peter Geoghegan
7136bf34f2 Document LP_DEAD accounting issues in VACUUM.
Document VACUUM's soft assumption that any LP_DEAD items encountered
during pruning will become LP_UNUSED items before VACUUM finishes up.
This is integral to the accounting used by VACUUM to generate its final
report on the table to the stats collector.  It also affects how VACUUM
determines which heap pages are truncatable.  In both cases VACUUM is
concerned with the likely contents of the page in the near future, not
the current contents of the page.

This state of affairs created the false impression that VACUUM's dead
tuple accounting had significant difference with similar accounting used
during ANALYZE.  There were and are no substantive differences, at least
when the soft assumption completely works out.  This is far clearer now.

Also document cases where things don't quite work out for VACUUM's dead
tuple accounting.  It's possible that a significant number of LP_DEAD
items will be left behind by VACUUM, and won't be recorded as remaining
dead tuples in VACUUM's statistics collector report.  This behavior
dates back to commit a96c41fe, which taught VACUUM to run without index
and heap vacuuming at the user's request.  The failsafe mechanism added
to VACUUM more recently by commit 1e55e7d1 takes the same approach to
dead tuple accounting.

Reported-By: Masahiko Sawada <sawada.mshk@gmail.com>
Discussion: https://postgr.es/m/CAH2-Wz=Jmtu18PrsYq3EvvZJGOmZqSO2u3bvKpx9xJa5uhNp=Q@mail.gmail.com
2021-04-19 18:55:31 -07:00