Commit 4909b38af0 introduced logic to distribute invalidation messages
from catalog-modifying transactions to all concurrent in-progress
transactions. However, since each transaction distributes not only its
original invalidation messages but also previously distributed
messages to other transactions, this leads to an exponential increase
in allocation request size for invalidation messages, ultimately
causing memory allocation failure.
This commit fixes this issue by tracking distributed invalidation
messages separately per decoded transaction and not redistributing
these messages to other in-progress transactions. The maximum size of
distributed invalidation messages that one transaction can store is
limited to MAX_DISTR_INVAL_MSG_PER_TXN (8MB). Once the size of the
distributed invalidation messages exceeds this threshold, we
invalidate all caches in locations where distributed invalidation
messages need to be executed.
Back-patch to all supported versions where we introduced the fix by
commit 4909b38af0.
Note that this commit adds two new fields to ReorderBufferTXN to store
the distributed transactions. This change breaks ABI compatibility in
back branches, affecting third-party extensions that depend on the
size of the ReorderBufferTXN struct, though this scenario seems
unlikely.
Additionally, it adds a new flag to the txn_flags field of
ReorderBufferTXN to indicate distributed invalidation message
overflow. This should not affect existing implementations, as it is
unlikely that third-party extensions use unused bits in the txn_flags
field.
Bug: #18938#18942
Author: vignesh C <vignesh21@gmail.com>
Reported-by: Duncan Sands <duncan.sands@deepbluecap.com>
Reported-by: John Hutchins <john.hutchins@wicourts.gov>
Reported-by: Laurence Parry <greenreaper@hotmail.com>
Reported-by: Max Madden <maxmmadden@gmail.com>
Reported-by: Braulio Fdo Gonzalez <brauliofg@gmail.com>
Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Reviewed-by: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Discussion: https://postgr.es/m/680bdaf6-f7d1-4536-b580-05c2760c67c6@deepbluecap.com
Discussion: https://postgr.es/m/18942-0ab1e5ae156613ad@postgresql.org
Discussion: https://postgr.es/m/18938-57c9a1c463b68ce0@postgresql.org
Discussion: https://postgr.es/m/CAD1FGCT2sYrP_70RTuo56QTizyc+J3wJdtn2gtO3VttQFpdMZg@mail.gmail.com
Discussion: https://postgr.es/m/CANO2=B=2BT1hSYCE=nuuTnVTnjidMg0+-FfnRnqM6kd23qoygg@mail.gmail.com
Backpatch-through: 13
During logical decoding, we advance catalog_xmin of logical too early in
fast_forward mode, resulting in required catalog data being removed by
vacuum. This mode is normally used to advance the slot without processing
the changes, but we still can't let the slot's xmin to advance to an
incorrect value.
Commit f49a80c481 fixed a similar issue where the logical slot's
catalog_xmin was getting advanced prematurely during non-fast-forward
mode. During xl_running_xacts processing, instead of directly advancing
the slot's xmin to the oldest running xid in the record, it allowed the
xmin to be held back for snapshots that can be used for
not-yet-replayed transactions, as those might consider older txns as
running too. However, it missed the fact that the same problem can happen
during fast_forward mode decoding, as we won't build a base snapshot in
that mode, and the future call to get_changes from the same slot can miss
seeing the required catalog changes leading to incorrect reslts.
This commit allows building the base snapshot even in fast_forward mode to
prevent the early advancement of xmin.
Reported-by: Amit Kapila <amit.kapila16@gmail.com>
Author: Zhijie Hou <houzj.fnst@fujitsu.com>
Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
Reviewed-by: shveta malik <shveta.malik@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Backpatch-through: 13
Discussion: https://postgr.es/m/CAA4eK1LqWncUOqKijiafe+Ypt1gQAQRjctKLMY953J79xDBgAg@mail.gmail.com
Discussion: https://postgr.es/m/OS0PR01MB57163087F86621D44D9A72BF94BB2@OS0PR01MB5716.jpnprd01.prod.outlook.com
Data loss can happen when the DDLs like ALTER PUBLICATION ... ADD TABLE ...
or ALTER TYPE ... that don't take a strong lock on table happens
concurrently to DMLs on the tables involved in the DDL. This happens
because logical decoding doesn't distribute invalidations to concurrent
transactions and those transactions use stale cache data to decode the
changes. The problem becomes bigger because we keep using the stale cache
even after those in-progress transactions are finished and skip the
changes required to be sent to the client.
This commit fixes the issue by distributing invalidation messages from
catalog-modifying transactions to all concurrent in-progress transactions.
This allows the necessary rebuild of the catalog cache when decoding new
changes after concurrent DDL.
We observed performance regression primarily during frequent execution of
*publication DDL* statements that modify the published tables. The
regression is minor or nearly nonexistent for DDLs that do not affect the
published tables or occur infrequently, making this a worthwhile cost to
resolve a longstanding data loss issue.
An alternative approach considered was to take a strong lock on each
affected table during publication modification. However, this would only
address issues related to publication DDLs (but not the ALTER TYPE ...)
and require locking every relation in the database for publications
created as FOR ALL TABLES, which is impractical.
The bug exists in all supported branches, but we are backpatching till 14.
The fix for 13 requires somewhat bigger changes than this fix, so the fix
for that branch is still under discussion.
Reported-by: hubert depesz lubaczewski <depesz@depesz.com>
Reported-by: Tomas Vondra <tomas.vondra@enterprisedb.com>
Author: Shlok Kyal <shlok.kyal.oss@gmail.com>
Author: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Reviewed-by: Zhijie Hou <houzj.fnst@fujitsu.com>
Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Tested-by: Benoit Lobréau <benoit.lobreau@dalibo.com>
Backpatch-through: 14
Discussion: https://postgr.es/m/de52b282-1166-1180-45a2-8d8917ca74c6@enterprisedb.com
Discussion: https://postgr.es/m/CAD21AoAenVqiMjpN-PvGHL1N9DWnHSq673bfgr6phmBUzx=kLQ@mail.gmail.com
The test was unstable in branches 14 and 15 as we were relying on the
number of changes in the table having a toast column to start streaming.
On branches >= 16, we have a GUC debug_logical_replication_streaming which
can stream each change, so the test was stable in those branches.
Change the test to use PREPARE TRANSACTION as that should make the result
consistent and test the code changed in 022564f60c.
Reported-by: Daniel Gustafsson as per buildfarm
Author: Hou Zhijie, Amit Kapila
Backpatch-through: 14
Discussion: https://postgr.es/m/8C2F86AA-981E-4803-B14D-E264C0255330@yesql.se
During logical decoding of in-progress transactions, we perform the toast
table scan while fetching the default toast value for an attribute. We
forgot to initialize the flag during this scan to indicate that the system
table scan is in progress. We need this flag to ensure that during logical
decoding we never directly access the tableam or heap APIs because we check
for concurrent aborts only in systable_* APIs.
Reported-by: Alexander Lakhin
Author: Takeshi Ideriha, Hou Zhijie
Reviewed-by: Amit Kapila, Hou Zhijie
Backpatch-through: 14
Discussion: https://postgr.es/m/18641-6687273b7f15269d@postgresql.org
When creating and initializing a logical slot, the restart_lsn is set
to the latest WAL insertion point (or the latest replay point on
standbys). Subsequently, WAL records are decoded from that point to
find the start point for extracting changes in the
DecodingContextFindStartpoint() function. Since the initial
restart_lsn could be in the middle of a transaction, the start point
must be a consistent point where we won't see the data for partial
transactions.
Previously, when not building a full snapshot, serialized snapshots
were restored, and the SnapBuild jumps to the consistent state even
while finding the start point. Consequently, the slot's restart_lsn
and confirmed_flush could be set to the middle of a transaction. This
could lead to various unexpected consequences. Specifically, there
were reports of logical decoding decoding partial transactions, and
assertion failures occurred because only subtransactions were decoded
without decoding their top-level transaction until decoding the commit
record.
To resolve this issue, the changes prevent restoring the serialized
snapshot and jumping to the consistent state while finding the start
point.
On v17 and HEAD, a flag indicating whether snapshot restores should be
skipped has been added to the SnapBuild struct, and SNAPBUILD_VERSION
has been bumpded.
On backbranches, the flag is stored in the LogicalDecodingContext
instead, preserving on-disk compatibility.
Backpatch to all supported versions.
Reported-by: Drew Callahan
Reviewed-by: Amit Kapila, Hayato Kuroda
Discussion: https://postgr.es/m/2444AA15-D21B-4CCE-8052-52C7C2DAFE5C%40amazon.com
Backpatch-through: 12
In commit 272248a0c, we fixed the catalog lookup due to the wrong snapshot
for transactions and subtransactions during decoding. We failed to
consider the case where top-level xact is already marked as containing
catalog change but its subtransaction is not yet marked as containing
catalog change even though it contained such a change.
This can happen when during decoding, none of the WAL records from the
subtransaction was decoded and top-level xact contains a DDL.
We fix it by marking the transaction and all its subtransactions as
containing catalog changes if the top-level xact contains any catalog
change and it is present in the initial running xacts array.
This fix is required only for 14 and 15 because in prior branches we
already always mark the transaction and all its subtransactions as
containing catalog changes in the same case. In 16 and above, we preserve
the list of transaction IDs and sub-transaction IDs, that have modified
catalogs and are running during snapshot serialization, to the serialized
snapshot (see commit 7f13ac8123).
Author: Fei Changhong
Reviewed-by: Amit Kapila, Hayato Kuroda, Andy Fan
Discussion: https://postgr.es/m/18280-4c8060178cb41750@postgresql.org
Some of the test_decoding test output was extremely wide, because it
deals with massive toasted values, and the aligned mode causes psql to
produce 200kB of whitespace and dashes. Change to unaligned mode
temporarily to avoid that behavior.
Backpatch to 14, where it applies cleanly.
Discussion: https://postgr.es/m/20230405103953.sxleixp3uz5lazst@alvherre.pgsql
This problem has been introduced by commit 272248a0c1 where we started
assigning the subtransactions to the top-level transaction when we mark
both the top-level transaction and its subtransactions as containing
catalog changes. After we assign subtransactions to the top-level
transaction, we were not allowed to execute any invalidations associated
with it when we decide to skip the transaction.
The reason to assign the subtransactions to the top-level transaction was
to avoid the assertion failure in AssertTXNLsnOrder() as they have the
same LSN when we sometimes start accumulating transaction changes for
partial transactions after the restart. Now that with commit 64ff0fe4e8,
we skip this assertion check until we reach the LSN at which we start
decoding the contents of the transaction, so, there is no reason for such
an assignment anymore.
The assignment change was introduced in 15 and prior versions but this bug
doesn't exist in branches prior to 14 since we don't add invalidation
messages to subtransactions. We decided to backpatch through 11 for
consistency but not for 10 since its final release is near.
Reported-by: Kuroda Hayato
Author: Masahiko Sawada
Reviewed-by: Amit Kapila
Backpatch-through: 11
Discussion: https://postgr.es/m/TYAPR01MB58660803BCAA7849C8584AA4F57E9%40TYAPR01MB5866.jpnprd01.prod.outlook.com
Discussion: https://postgr.es/m/a89b46b6-0239-2fd5-71a9-b19b1f7a7145%40enterprisedb.com
When the logical decoding restarts from NEW_CID, since there is no
association between the top transaction and its subtransaction, both are
created as top transactions and have the same LSN. This caused the
assertion failure in AssertTXNLsnOrder().
This patch skips the assertion check until we reach the LSN at which we
start decoding the contents of the transaction, specifically
start_decoding_at LSN in SnapBuild. This is okay because we don't
guarantee to make the association between top transaction and
subtransaction until we try to decode the actual contents of transaction.
The ordering of the records prior to the start_decoding_at LSN should have
been checked before the restart.
The other assertion failure is due to the reason that we forgot to track
that we have considered top-level transaction id in the list of catalog
changing transactions that were committed when one of its subtransactions
is marked as containing catalog change.
Reported-by: Tomas Vondra, Osumi Takamichi
Author: Masahiko Sawada, Kuroda Hayato
Reviewed-by: Amit Kapila, Dilip Kumar, Kuroda Hayato, Kyotaro Horiguchi, Masahiko Sawada
Backpatch-through: 10
Discussion: https://postgr.es/m/a89b46b6-0239-2fd5-71a9-b19b1f7a7145%40enterprisedb.com
Discussion: https://postgr.es/m/TYCPR01MB83733C6CEAE47D0280814D5AED7A9%40TYCPR01MB8373.jpnprd01.prod.outlook.com
Previously, we relied on HEAP2_NEW_CID records and XACT_INVALIDATION
records to know if the transaction has modified the catalog, and that
information is not serialized to snapshot. Therefore, after the restart,
if the logical decoding decodes only the commit record of the transaction
that has actually modified a catalog, we will miss adding its XID to the
snapshot. Thus, we will end up looking at catalogs with the wrong
snapshot.
To fix this problem, this changes the snapshot builder so that it
remembers the last-running-xacts list of the decoded RUNNING_XACTS record
after restoring the previously serialized snapshot. Then, we mark the
transaction as containing catalog changes if it's in the list of initial
running transactions and its commit record has XACT_XINFO_HAS_INVALS. To
avoid ABI breakage, we store the array of the initial running transactions
in the static variables InitialRunningXacts and NInitialRunningXacts,
instead of storing those in SnapBuild or ReorderBuffer.
This approach has a false positive; we could end up adding the transaction
that didn't change catalog to the snapshot since we cannot distinguish
whether the transaction has catalog changes only by checking the COMMIT
record. It doesn't have the information on which (sub) transaction has
catalog changes, and XACT_XINFO_HAS_INVALS doesn't necessarily indicate
that the transaction has catalog change. But that won't be a problem since
we use snapshot built during decoding only to read system catalogs.
On the master branch, we took a more future-proof approach by writing
catalog modifying transactions to the serialized snapshot which avoids the
above false positive. But we cannot backpatch it because of a change in
the SnapBuild.
Reported-by: Mike Oh
Author: Masahiko Sawada
Reviewed-by: Amit Kapila, Shi yu, Takamichi Osumi, Kyotaro Horiguchi, Bertrand Drouvot, Ahsan Hadi
Backpatch-through: 10
Discussion: https://postgr.es/m/81D0D8B0-E7C4-4999-B616-1E5004DBDCD2%40amazon.com
We have some streaming tests that rely on the size of changes which can
fail if there are additional changes like invalidation messages by
background activity like auto analyze. Avoid such failures by increasing
autovacuum_naptime to a reasonably high value (1d).
Author: Dilip Kumar
Backpatch-through: 14
Discussion: https://postgr.es/m/1958043.1650129119@sss.pgh.pa.us
Currently, during UPDATE, the unchanged replica identity key attributes
are not logged separately because they are getting logged as part of the
new tuple. But if they are stored externally then the untoasted values are
not getting logged as part of the new tuple and logical replication won't
be able to replicate such UPDATEs. So we need to log such attributes as
part of the old_key_tuple during UPDATE.
Reported-by: Haiying Tang
Author: Dilip Kumar and Amit Kapila
Reviewed-by: Alvaro Herrera, Haiying Tang, Andres Freund
Backpatch-through: 10
Discussion: https://postgr.es/m/OS0PR01MB611342D0A92D4F4BF26C0F47FB229@OS0PR01MB6113.jpnprd01.prod.outlook.com
When using replication origins, pg_replication_origin_xact_setup() is an
optional choice to be able to set a LSN and a timestamp to mark the
origin, which would be additionally added to WAL for transaction commits
or aborts (including 2PC transactions). An assertion in the code path
of PREPARE TRANSACTION assumed that this data should always be set, so
it would trigger when using replication origins without setting up an
origin LSN. Some tests are added to cover more this kind of scenario.
Oversight in commit 1eb6d65.
Per discussion with Amit Kapila and Masahiko Sawada.
Discussion: https://postgr.es/m/YbbBfNSvMm5nIINV@paquier.xyz
Backpatch-through: 11
Incrementing the level of the call stack reported is useful for
debugging purposes as it allows to control which part of the test is
exactly failing, especially if a test is structured with subroutines
that call routines from Test::More.
This adds more incrementations of $Test::Builder::Level where debugging
gets improved (for example it does not make sense for some paths like
pg_rewind where long subroutines are used).
A note is added to src/test/perl/README about that, based on a
suggestion from Andrew Dunstan and a wording coming from both of us.
Usage of Test::Builder::Level has spread in 12, so a backpatch down to
this version is done.
Reviewed-by: Andrew Dunstan, Peter Eisentraut, Daniel Gustafsson
Discussion: https://postgr.es/m/YV1CCFwgM1RV1LeS@paquier.xyz
Backpatch-through: 12
Commit 325f2ec555 introduced pg_class.relwrite to skip operations on
tables created as part of a heap rewrite during DDL. It links such
transient heaps to the original relation OID via this new field in
pg_class but forgot to do anything about toast tables. So, logical
decoding was not able to skip operations on internally created toast
tables. This leads to an error when we tried to decode the WAL for the
next operation for which it appeared that there is a toast data where
actually it didn't have any toast data.
To fix this, we set pg_class.relwrite for internally created toast tables
as well which allowed skipping operations on them during logical decoding.
Author: Bertrand Drouvot
Reviewed-by: David Zhang, Amit Kapila
Backpatch-through: 11, where it was introduced
Discussion: https://postgr.es/m/b5146fb1-ad9e-7d6e-f980-98ed68744a7c@amazon.com
For no obvious reason, isolationtester has always insisted that
session and step names be written with double quotes. This is
fairly tedious and does little for test readability, especially
since the names that people actually choose almost always look
like normal identifiers. Hence, let's tweak the lexer to allow
SQL-like identifiers not only double-quoted strings.
(They're SQL-like, not exactly SQL, because I didn't add any
case-folding logic. Also there's no provision for U&"..." names,
not that anyone's likely to care.)
There is one incompatibility introduced by this change: if you write
"foo""bar" with no space, that used to be taken as two identifiers,
but now it's just one identifier with an embedded quote mark.
I converted all the src/test/isolation/ specfiles to remove
unnecessary double quotes, but stopped there because my
eyes were glazing over already.
Like 741d7f104, back-patch to all supported branches, so that this
isn't a stumbling block for back-patching isolation test changes.
Discussion: https://postgr.es/m/759113.1623861959@sss.pgh.pa.us
Previously, isolationtester displayed SQL query results using some
ad-hoc code that clearly hadn't had much effort expended on it.
Field values longer than 14 characters weren't separated from
the next field, and usually caused misalignment of the columns
too. Also there was no visual separation of a query's result
from subsequent isolationtester output. This made test result
files confusing and hard to read.
To improve matters, let's use libpq's PQprint() function. Although
that's long since unused by psql, it's still plenty good enough
for the purpose here.
Like 741d7f104, back-patch to all supported branches, so that this
isn't a stumbling block for back-patching isolation test changes.
Discussion: https://postgr.es/m/582362.1623798221@sss.pgh.pa.us
We've long contended with isolation test results that aren't entirely
stable. Some test scripts insert long delays to try to force stable
results, which is not terribly desirable; but other erratic failure
modes remain, causing unrepeatable buildfarm failures. I've spent a
fair amount of time trying to solve this by improving the server-side
support code, without much success: that way is fundamentally unable
to cope with diffs that stem from chance ordering of arrival of
messages from different server processes.
We can improve matters on the client side, however, by annotating
the test scripts themselves to show the desired reporting order
of events that might occur in different orders. This patch adds
three types of annotations to deal with (a) test steps that might or
might not complete their waits before the isolationtester can see them
waiting; (b) test steps in different sessions that can legitimately
complete in either order; and (c) NOTIFY messages that might arrive
before or after the completion of a step in another session. We might
need more annotation types later, but this seems to be enough to deal
with the instabilities we've seen in the buildfarm. It also lets us
get rid of all the long delays that were previously used, cutting more
than a minute off the runtime of the isolation tests.
Back-patch to all supported branches, because the buildfarm
instabilities affect all the branches, and because it seems desirable
to keep isolationtester's capabilities the same across all branches
to simplify possible future back-patching of tests.
Discussion: https://postgr.es/m/327948.1623725828@sss.pgh.pa.us
While decoding the multi-insert WAL we can't clean the toast untill we get
the last insert of that WAL record. Now if we stream the changes before we
get the last change, the memory for toast chunks won't be released and we
expect the txn to have streamed all changes after streaming. This
restriction is mainly to ensure the correctness of streamed transactions
and it doesn't seem worth uplifting such a restriction just to allow this
case because anyway we will stream the transaction once such an insert is
complete.
Previously we were using two different flags (one for toast tuples and
another for speculative inserts) to indicate partial changes. Now instead
we replaced both of them with a single flag to indicate partial changes.
Reported-by: Pavan Deolasee
Author: Dilip Kumar
Reviewed-by: Pavan Deolasee, Amit Kapila
Discussion: https://postgr.es/m/CABOikdN-_858zojYN-2tNcHiVTw-nhxPwoQS4quExeweQfG1Ug@mail.gmail.com
Some of the tests were not considering that the slot's spill stats could be
received by the stats collector after we have reset the stats. Remove
those tests and don't check total bytes decoded and sent to output plugin
in the spilled stats test as we can send the spilled stats to the stats
collector before actually sending the changes to output plugin.
Reported-by: Tom Lane as per buildfarm
Author: Vignesh C, Sawada Masahiko
Reviewed-by: Amit Kapila
Discussion: https://postgr.es/m/20210319185247.ldebgpdaxsowiflw@alap3.anarazel.de
As per analysis, it appears that the 'drop slot' message from the previous
test and 'create slot' message of the new test are either missed or not
yet delivered to the stats collector due to which we will still see the
stats from the old slot. This can happen rarely which could be the reason
that we are seeing some failures in the buildfarm randomly. To avoid that
we are using a different slot name for the tests in
test_decoding/sql/stats.sql.
Reported-by: Tom Lane based on buildfarm reports
Author: Sawada Masahiko
Reviewed-by: Amit Kapila, Vignesh C
Discussion: https://postgr.es/m/20210319185247.ldebgpdaxsowiflw@alap3.anarazel.de
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
In the new test after resetting the stats, we were not waiting for the
stats message to be delivered. Also, we need to decode the results for
the new test, otherwise, it will show the old stats.
In passing,
a. Change docs added by commit f5fc2f5b23 as per suggestion by
Justin Pryzby.
b. Bump the PGSTAT_FILE_FORMAT_ID as commit f5fc2f5b23 changes the file
format of stats.
Reported-by: Tom Lane based on buildfarm reports
Author: Vignesh C, Justin Pryzby
Reviewed-by: Amit Kapila
Discussion: https://postgr.es/m/20210319185247.ldebgpdaxsowiflw@alap3.anarazel.de
This adds the statistics about total transactions count and total
transaction data logically sent to the decoding output plugin from
ReorderBuffer. Users can query the pg_stat_replication_slots view to check
these stats.
Suggested-by: Andres Freund
Author: Vignesh C and Amit Kapila
Reviewed-by: Sawada Masahiko, Amit Kapila
Discussion: https://postgr.es/m/20210319185247.ldebgpdaxsowiflw@alap3.anarazel.de
Along with gid, this provides a different way to identify the transaction.
The users that use xid in some way to prepare the transactions can use it
to filter prepare transactions. The later commands COMMIT PREPARED or
ROLLBACK PREPARED carries both identifiers, providing an output plugin the
choice of what to use.
Author: Markus Wanner
Reviewed-by: Vignesh C, Amit Kapila
Discussion: https://postgr.es/m/ee280000-7355-c4dc-e47b-2436e7be959c@enterprisedb.com
When accessing replication slot stats, introduced in 9868167500,
pgstat_read_statsfiles() reads the data into newly allocated
memory. Unfortunately the current memory context at that point is the
callers, leading to leaks and use-after-free dangers.
The fix is trivial, explicitly use pgStatLocalContext. There's some
potential for further improvements, but that's outside of the scope of
this bugfix.
No backpatch necessary, feature is only in HEAD.
Author: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i@alap3.anarazel.de
Commit 0aa8a01d04 extends the output plugin API to allow decoding of
prepared xacts and allowed the user to enable/disable the two-phase option
via pg_logical_slot_get_changes(). This can lead to a problem such that
the first time when it gets changes via pg_logical_slot_get_changes()
without two_phase option enabled it will not get the prepared even though
prepare is after consistent snapshot. Now next time during getting changes,
if the two_phase option is enabled it can skip prepare because by that
time start decoding point has been moved. So the user will only get commit
prepared.
Allow to enable/disable this option at the create slot time and default
will be false. It will break the existing slots which is fine in a major
release.
Author: Ajin Cherian
Reviewed-by: Amit Kapila and Vignesh C
Discussion: https://postgr.es/m/d0f60d60-133d-bf8d-bd70-47784d8fabf3@enterprisedb.com
In commit a271a1b50e, we allowed decoding at prepare time and the prepare
was decoded again if there is a restart after decoding it. It was done
that way because we can't distinguish between the cases where we have not
decoded the prepare because it was prior to consistent snapshot or we have
decoded it earlier but restarted. To distinguish between these two cases,
we have introduced an initial_consistent_point at the slot level which is
an LSN at which we found a consistent point at the time of slot creation.
This is also the point where we have exported a snapshot for the initial
copy. So, prepare transaction prior to this point are sent along with
commit prepared.
This commit bumps SNAPBUILD_VERSION because of change in SnapBuild. It
will break existing slots which is fine in a major release.
Author: Ajin Cherian, based on idea by Andres Freund
Reviewed-by: Amit Kapila and Vignesh C
Discussion: https://postgr.es/m/d0f60d60-133d-bf8d-bd70-47784d8fabf3@enterprisedb.com
Commit 5a3574d7b3 added the test for decoding of two-phase transactions
during the build of a consistent snapshot. The test forgot to skip empty
xacts which can lead to decoding of extra empty transactions due to
background activity by autovacuum.
Per report by buildfarm.
Reported-by: Tom Lane
Discussion: https://postgr.es/m/363512.1610171267@sss.pgh.pa.us
This patch allows PREPARE-time decoding of two-phase transactions (if the
output plugin supports this capability), in which case the transactions
are replayed at PREPARE and then committed later when COMMIT PREPARED
arrives.
Now that we decode the changes before the commit, the concurrent aborts
may cause failures when the output plugin consults catalogs (both system
and user-defined).
We detect such failures with a special sqlerrcode
ERRCODE_TRANSACTION_ROLLBACK introduced by commit 7259736a6e and stop
decoding the remaining changes. Then we rollback the changes when rollback
prepared is encountered.
Author: Ajin Cherian and Amit Kapila based on previous work by Nikhil Sontakke and Stas Kelvich
Reviewed-by: Amit Kapila, Peter Smith, Sawada Masahiko, Arseny Sher, and Dilip Kumar
Tested-by: Takamichi Osumi
Discussion:
https://postgr.es/m/02DA5F5E-CECE-4D9C-8B4B-418077E2C010@postgrespro.ruhttps://postgr.es/m/CAMGcDxeqEpWj3fTXwqhSwBdXd2RS9jzwWscO-XbeCfso6ts3+Q@mail.gmail.com
This adds six methods to the output plugin API, adding support for
streaming changes of two-phase transactions at prepare time.
* begin_prepare
* filter_prepare
* prepare
* commit_prepared
* rollback_prepared
* stream_prepare
Most of this is a simple extension of the existing methods, with the
semantic difference that the transaction is not yet committed and maybe
aborted later.
Until now two-phase transactions were translated into regular transactions
on the subscriber, and the GID was not forwarded to it. None of the
two-phase commands were communicated to the subscriber.
This patch provides the infrastructure for logical decoding plugins to be
informed of two-phase commands Like PREPARE TRANSACTION, COMMIT PREPARED
and ROLLBACK PREPARED commands with the corresponding GID.
This also extends the 'test_decoding' plugin, implementing these new
methods.
This commit simply adds these new APIs and the upcoming patch to "allow
the decoding at prepare time in ReorderBuffer" will use these APIs.
Author: Ajin Cherian and Amit Kapila based on previous work by Nikhil Sontakke and Stas Kelvich
Reviewed-by: Amit Kapila, Peter Smith, Sawada Masahiko, and Dilip Kumar
Discussion:
https://postgr.es/m/02DA5F5E-CECE-4D9C-8B4B-418077E2C010@postgrespro.ruhttps://postgr.es/m/CAMGcDxeqEpWj3fTXwqhSwBdXd2RS9jzwWscO-XbeCfso6ts3+Q@mail.gmail.com
In streaming mode, the transaction can be decoded in multiple streams and
those streams can be interleaved with streams of other transactions. So,
we can't remember the transaction's write status in the logical decoding
context because that might get changed due to some other transactions and
lead to wrong answers for 'skip-empty-xacts' option. We decided to keep
each transaction's write status in the ReorderBufferTxn to avoid
interleaved streams changing the status of some unrelated transactions.
Diagnosed-by: Amit Kapila
Author: Dilip Kumar
Reviewed-by: Amit Kapila
Discussion: https://postgr.es/m/CAA4eK1LR7=XNM_TLmpZMFuV8ZQpoxkem--NZJYf8YXmesbvwLA@mail.gmail.com
Change the attribute 'name' to 'slot_name' in pg_stat_replication_slots
view to make it clear and that way we will be consistent with the other
places like pg_stat_wal_receiver view where we display the same attribute.
In the passing, fix the typo in one of the macros in the related code.
Bump the catversion as we have modified the name in the catalog as well.
Reported-by: Noriyoshi Shinoda
Author: Noriyoshi Shinoda
Reviewed-by: Sawada Masahiko and Amit Kapila
Discussion: https://postgr.es/m/CA+fd4k5_pPAYRTDrO2PbtTOe0eHQpBvuqmCr8ic39uTNmR49Eg@mail.gmail.com
A number of places were using appendStringInfo() when they could have been
using appendStringInfoString() instead. While there's no functionality
change there, it's just more efficient to use appendStringInfoString()
when no formatting is required. Likewise for some
appendStringInfoString() calls which were just appending a single char.
We can just use appendStringInfoChar() for that.
Additionally, many places were using appendPQExpBuffer() when they could
have used appendPQExpBufferStr(). Change those too.
Patch by Zhijie Hou, but further searching by me found significantly more
places that deserved the same treatment.
Author: Zhijie Hou, David Rowley
Discussion: https://postgr.es/m/cb172cf4361e4c7ba7167429070979d4@G08CNEXMBPEKD05.g08.fujitsu.local
The test cases added by that commit were trying to test the exact number of
times a particular transaction has spilled. However, that number can vary if
any background transaction (say by autovacuum) happens in parallel to the main
transaction. So let's not try to verify the exact count.
Author: Amit Kapila
Reviewed-by: Sawada Masahiko
Discussion: https://postgr.es/m/CA+fd4k5_pPAYRTDrO2PbtTOe0eHQpBvuqmCr8ic39uTNmR49Eg@mail.gmail.com
We were decoding empty transactions via streaming APIs added in commit
45fdc9738b even when the user used the option 'skip-empty-xacts'. The APIs
makes no effort to skip empty xacts under the assumption that we will
never try to stream such transactions. However, that is not true because
we can pick to stream a transaction that has change messages for
REORDER_BUFFER_CHANGE_INTERNAL_SNAPSHOT and we don't send such messages to
downstream rather they are just to update the internal state. So, we need
to skip such xacts when plugin uses the option 'skip-empty-xacts'.
Diagnosed-By: Amit Kapila
Author: Dilip Kumar
Reviewed-by: Amit Kapila
Discussion: https://postgr.es/m/CAA4eK1+OqgFNZkf7=ETe_y5ntjgDk3T0wcdkd4Sot_u1hySGfw@mail.gmail.com
REPLICA IDENTITY USING INDEX behaves the same way as NOTHING if the
associated index is dropped, even if there is a primary key that could
be used as a fallback for the changes generated. There have never been
any tests to cover such scenarios, so this commit closes the gap.
Author: Michael Paquier
Reviewed-by: Masahiko Sawada, Rahila Syed, Euler Taveira
Discussion: https://postgr.es/m/20200522035028.GO2355@paquier.xyz
Commit 7259736a6e added the capability to stream changes in ReorderBuffer
which has some tests to test the streaming mode. It is quite possible that
while this test is running a parallel transaction could be logged by
autovacuum. Such a transaction won't perform any insert/update/delete to
non-catalog tables so will be shown as an empty transaction. Fix it by
skipping the empty transactions during this test.
Per report by buildfarm.
Instead of serializing the transaction to disk after reaching the
logical_decoding_work_mem limit in memory, we consume the changes we have
in memory and invoke stream API methods added by commit 45fdc9738b.
However, sometimes if we have incomplete toast or speculative insert we
spill to the disk because we can't generate the complete tuple and stream.
And, as soon as we get the complete tuple we stream the transaction
including the serialized changes.
We can do this incremental processing thanks to having assignments
(associating subxact with toplevel xacts) in WAL right away, and
thanks to logging the invalidation messages at each command end. These
features are added by commits 0bead9af48 and c55040ccd0 respectively.
Now that we can stream in-progress transactions, the concurrent aborts
may cause failures when the output plugin consults catalogs (both system
and user-defined).
We handle such failures by returning ERRCODE_TRANSACTION_ROLLBACK
sqlerrcode from system table scan APIs to the backend or WALSender
decoding a specific uncommitted transaction. The decoding logic on the
receipt of such a sqlerrcode aborts the decoding of the current
transaction and continue with the decoding of other transactions.
We have ReorderBufferTXN pointer in each ReorderBufferChange by which we
know which xact it belongs to. The output plugin can use this to decide
which changes to discard in case of stream_abort_cb (e.g. when a subxact
gets discarded).
We also provide a new option via SQL APIs to fetch the changes being
streamed.
Author: Dilip Kumar, Tomas Vondra, Amit Kapila, Nikhil Sontakke
Reviewed-by: Amit Kapila, Kuntal Ghosh, Ajin Cherian
Tested-by: Neha Sharma, Mahendra Singh Thalor and Ajin Cherian
Discussion: https://postgr.es/m/688b0b7f-2f6c-d827-c27b-216a8e3ea700@2ndquadrant.com
This adds seven methods to the output plugin API, adding support for
streaming changes of large in-progress transactions.
* stream_start
* stream_stop
* stream_abort
* stream_commit
* stream_change
* stream_message
* stream_truncate
Most of this is a simple extension of the existing methods, with
the semantic difference that the transaction (or subtransaction)
is incomplete and may be aborted later (which is something the
regular API does not really need to deal with).
This also extends the 'test_decoding' plugin, implementing these
new stream methods.
The stream_start/start_stop are used to demarcate a chunk of changes
streamed for a particular toplevel transaction.
This commit simply adds these new APIs and the upcoming patch to "allow
the streaming mode in ReorderBuffer" will use these APIs.
Author: Tomas Vondra, Dilip Kumar, Amit Kapila
Reviewed-by: Amit Kapila
Tested-by: Neha Sharma and Mahendra Singh Thalor
Discussion: https://postgr.es/m/688b0b7f-2f6c-d827-c27b-216a8e3ea700@2ndquadrant.com
This patch removes the hardcoded check for superuser privileges when
executing replication origin functions. Instead, execution is revoked
from public, meaning that those functions can be executed by a superuser
and that access to them can be granted.
Author: Martín Marqués
Reviewed-by: Kyotaro Horiguchi, Michael Paquier, Masahiko Sawada
Discussion: https:/postgr.es/m/CAPdiE1xJMZOKQL3dgHMUrPqysZkgwzSMXETfKkHYnBAB7-0VRQ@mail.gmail.com
Masahiko Sawada