Good PR descriptions for flaky tests are quite helpful when reviewing.
Although obviously no PR description is the same, there's a few common
pieces of information that are useful for all PRs that fix flaky tests.
We should not introduce breaking sql changes to upgrade files after they
are released. We did that for worker_fetch_foreign_file in v9.0.0 and
worker_repartition_cleanup in v9.2.0. Later when we try to drop those
udfs, they were missing for some clients unexpectedly due to breaking
change in an old upgrade script. For that case, the fix is to add DROP
IF EXISTS for those 2 udfs in 11.0-4--11.1-1.
This crash happens with recursively planned queries. For such queries,
subplans are explained via the ExplainOnePlan function of postgresql.
This function reconstructs the query description from the plan therefore
it expects the ActiveSnaphot for the query be available. This fix makes
sure that the snapshot is in the stack before calling ExplainOnePlan.
Fixes#2920.
DESCRIPTION: Don't leak search_path to workers on DDL
For DDL we have to set the `search_path` on workers to the same as on
the coordinator for some DDL to work. Previously this search_path would
leak outside of the transaction that was used for the DDL. This fixes
that by using `SET LOCAL` instead of `SET`. The only place where we
still use plain `SET` is for DDL commands that are not allowed within
transactions, such as `CREATE INDEX CONCURRENLTY`.
This fixes this flaky test:
```diff
CONTEXT: SQL statement "SELECT change_id FROM distributed_triggers.data_changes
WHERE shard_key_value = NEW.shard_key_value AND object_id = NEW.object_id
ORDER BY change_id DESC LIMIT 1"
-PL/pgSQL function record_change() line XX at SQL statement
+PL/pgSQL function distributed_triggers.record_change() line 17 at SQL statement
while executing command on localhost:57638
DELETE FROM data_ref_table where shard_key_value = 'hello';
```
Source:
https://app.circleci.com/pipelines/github/citusdata/citus/27849/workflows/75ae5f1a-100b-4b7a-b991-7de069f39ee1/jobs/831429
I had tried to fix this flaky test in #5894 and then I tried
implementing a better fix in #5896, where @marcocitus suggested this
better fix. This change reverts the fix from #5894 and implements the
fix suggested by Marco.
Our multi_mx_alter_distributed_table test actually depended on the old
buggy search_path leaking behavior. After fixing the bug that test would
fail like this:
```diff
CALL proc_0(1.0);
DEBUG: pushing down the procedure
-NOTICE: Res: 3
-DETAIL: from localhost:xxxxx
+ERROR: relation "test_proc_colocation_0" does not exist
+CONTEXT: PL/pgSQL function mx_alter_distributed_table.proc_0(double precision) line 5 at SQL statement
+while executing command on localhost:57637
RESET client_min_messages;
```
I fixed this test by fully qualifying the table names used in the
procedure. I think it's quite unlikely that actual users depend
on this behavior though. Since it would require first doing
DDL before calling a procedure in a session where the
search_path was changed after connecting.
DESCRIPTION: Adds failure test for shard move
DESCRIPTION: Remove function `WaitForAllSubscriptionsToBecomeReady` and
related tests
Adding some failure tests for shard moves.
Dropping the not-needed-anymore function
`WaitForAllSubscriptionsToBecomeReady`, as the subscriptions now start
as ready from the beginning because we don't use logical replication
table sync workers anymore.
fixes: #6260
In CI shard_rebalancer sometimes fails with this error:
```diff
SET citus.node_connection_timeout to 60;
BEGIN;
SET LOCAL citus.shard_replication_factor TO 2;
SET citus.log_remote_commands TO ON;
SET SESSION citus.max_adaptive_executor_pool_size TO 5;
SELECT replicate_table_shards('dist_table_test_2', max_shard_copies := 4, shard_transfer_mode:='block_writes');
+WARNING: could not establish connection after 60 ms
```
Source
https://app.circleci.com/pipelines/github/citusdata/citus/28128/workflows/38eeacc4-4191-4366-87ed-9a628414965a/jobs/847458?invite=true#step-107-21
This PR avoids this issue by increasing
```citus.node_connection_timeout``` to 35s.
I fixed a lot of flaky tests recently and I found some patterns in the
type of issues and type of fixes. This adds a document that lists
these types of issues and explains how to fix them.
To be able to test non-blocking shard moves we take an advisory lock, so
we can pause the shard move at an interesting moment. Originally this
was during the logical replication catch up phase. But when I added
tests for the rebalancer progress I moved this lock before the initial
data copy. This allowed testing of the rebalance progress, but
inadvertently made our non-blocking tests not actually test if we held
unintended locks during logical replication catch up.
This fixes that by creating two types of advisory locks, one before the
copy and one after. This causes the tests to actually test their
intended scenario again.
Furthermore it starts using one of these locks for blocking shard moves
too. Which allowed me to reduce the complexity of the rebalance progress
test suite quite a bit. It also allowed enabling some flaky tests again,
because this stopped them from being flaky. And finally it allowed
testing of rebalance progress for blocking shard copy operations as
well.
In passing it fixes a flaky test during parallel blocking shard moves by
ordering the output.
DESCRIPTION: Adds status column to get_rebalance_progress()
Introduces a new column named `status` for the function
`get_rebalance_progress()`. For each ongoing shard move, this column
will reveal information about that shard move operation's current
status.
For now, candidate status messages could be one of the below.
* Not Started
* Setting Up
* Copying Data
* Catching Up
* Creating Constraints
* Final Catchup
* Creating Foreign Keys
* Completing
* Completed
Deparser function set_relation_column_names() knows that it needs to
re-evaluate column names based on relation's tuple descriptor when
the rte belongs to a relation (RTE_RELATION).
However before this commit, it didn't know about the fact that citus
might wrap such an rte with an rte that points to
citus_extradata_container() placeholder.
And because of this, it was simply taking the column aliases
(e.g., "bar" in "foo AS bar") into the account and this might result in
an incorrectly deparsed query as in below case:
* Say, if we had view based on following query:
```sql
SELECT a FROM table;
```
* And if we rename column "a" to "b", the view query normally becomes:
```sql
SELECT b AS a FROM table;
```
* So before this commit, deparsing a query based on that view was
resulting in such a query due to deparsing based on the column aliases,
which is not correct:
```sql
SELECT a FROM table;
```
Fixes#5932.
DESCRIPTION: Fixes a bug that might cause failing to query the views
based on tables that have renamed columns
PostgreSQL 15 exposes WL_SOCKET_CLOSED in WaitEventSet API, which is
useful for detecting closed remote sockets. In this patch, we use this
new event and try to detect closed remote sockets in the executor.
When a closed socket is detected, the executor now has the ability to
retry the connection establishment. Note that, the executor can retry
connection establishments only for the connection that has not been
used. Basically, this patch is mostly useful for preventing the executor
to fail if a cached connection is closed because of the worker node
restart (or worker failover).
In other words, the executor cannot retry connection establishment if we
are in a distributed transaction AND any command has been sent over the
connection. That requires more sophisticated retry mechanisms. For now,
fixing the above use case is enough.
Fixes#5538
Earlier discussions: #5908, #6259 and #6283
### Summary of the current approach regards to earlier trials
As noted, we explored some alternatives before getting into this.
https://github.com/citusdata/citus/pull/6283 is simple, but lacks an
important property. We should be checking for `WL_SOCKET_CLOSED`
_before_ sending anything over the wire. Otherwise, it becomes very
tricky to understand which connection is actually safe to retry. For
example, in the current patch, we can safely check
`transaction->transactionState == REMOTE_TRANS_NOT_STARTED` before
restarting a connection.
#6259 does what we intent here (e.g., check for sending any command).
However, as @marcocitus noted, it is very tricky to handle
`WaitEventSets` in multiple places. And, the executor is designed such
that it reacts to the events. So, adding anything `pre-executor` seemed
too ugly.
In the end, I converged into this patch. This patch relies on the
simplicity of #6283 and also does a very limited handling of
`WaitEventSets`, just for our purpose. Just before we add any connection
to the execution, we check if the remote session has already closed.
With that, we do a brief interaction of multiple wait event processing,
but with different purposes. The new wait event processing we added does
not even consider cancellations. We let that handled by the main event
processing loop.
Co-authored-by: Marco Slot <marco.slot@gmail.com>
In #6405 I added better improved blocked process detection for isolation
tests. But when cleaning up unnecessary code I cleaned up a bit too
much. This actually includes the new function definition in our
migrations.
In CI multi_partitioning sometimes fails with this error:
```diff
SELECT citus_remove_node('localhost', :master_port);
- citus_remove_node
----------------------------------------------------------------------
-
-(1 row)
-
+ERROR: tuple concurrently deleted
-- d) invalid tables for helper UDFs
```
Source:
https://app.circleci.com/pipelines/github/citusdata/citus/27993/workflows/685e5b20-c923-43e5-8a0d-b932ef4c4914/jobs/839466
This PR avoids this concurrency issue by not running the
multi_partitioning test in parallel with other tests.
If an operation requires having coordinator in pg_dist_node and if that
is not the case, then we automatically add the coordinator into
pg_dist_node if user didn't add any worker nodes yet.
However, if user have already added some worker nodes before, we throw
an error. With this commit, we improve the error thrown in that case.
Closes#6423 based on the discussion made there.
Sometimes our CI randomly fails on a test in a way similar to this:
```diff
step s2-drop:
DROP TABLE cancel_table;
-
+ <waiting ...>
+step s2-drop: <... completed>
starting permutation: s1-timeout s1-begin s1-sleep10000 s1-rollback s1-reset s1-drop
```
Source:
https://app.circleci.com/pipelines/github/citusdata/citus/26524/workflows/5415b84f-13a3-482f-bef9-648314c79a67/jobs/756377
I tried to fix that already in #6252 by disabling the maintenance daemon
during isolation tests. But it seems that hasn't fixed all cases of
these errors. This is another attempt at fixing these issues that seems
to have better results.
What it does is that it starts using the pInterestingPids parameter that
citus_isolation_test_session_is_blocked receives. With this change we
start filter out block-edges that are not caused by any of these pids.
In passing this change also makes it possible to run
`isolation_create_distributed_table_concurrently` with
`check-isolation-base`
PG15 introduced a function called ReplicationSlotName that causes
conflicts with our function with the same name. I solved this issue by
renaming our function to ReplicationSlotNameForNodeAndOwner
Relevant PG commit:
c3b5992b91
DESCRIPTION: Fix bug in global PID assignment for rebalancer
sub-connections
In CI our isolation_shard_rebalancer_progress test would sometimes fail
like this:
```diff
+isolationtester: canceling step s1-rebalance-c1-block-writes after 60 seconds
step s1-rebalance-c1-block-writes:
SELECT rebalance_table_shards('colocated1', shard_transfer_mode:='block_writes');
- <waiting ...>
+
+ERROR: canceling statement due to user request
step s7-get-progress:
```
Source:
https://app.circleci.com/pipelines/github/citusdata/citus/27855/workflows/2a7e335a-f3e8-46ed-b6bd-6920d42f7214/jobs/831710
It turned out this was an actual bug in the way our assigning of global
PIDs interacts with the way we connect to ourselves as the shard
rebalancer. The first command the shard rebalancer sends is a SET
ommand to change the application_name to `citus_rebalancer`. If
`StartupCitusBackend` is called after this command is processed, then it
overwrites the global PID that was extracted from the previous
application_name. This makes sure that we don't do that, and continue to
use the original global PID. While it might seem that we only call
`StartupCitusBackend` once for each query backend, this isn't actually
the case. Whenever pg_dist_partition gets ANALYZEd by autovacuum
we indirectly call `StartupCitusBackend` again, because we invalidate
the cache then.
In passing this fixes two other things as well:
1. It sets `distributedCommandOriginator` correctly in
`AssignGlobalPID`, by using IsExternalClientBackend(). This doesn't
matter much anymore, since AssignGlobalPID effectively becomes a
no-op in this PR for any non-external client backends.
2. It passes the application_name to InitializeBackendData in
StartupCitusBackend, instead of INVALID_CITUS_INTERNAL_BACKEND_GPID
(which effectively got casted to NULL). In practice this doesn't
change the behaviour of the call, since the call is a no-op for every
backend except the maintenance daemon. And the behaviour of the call
is the same for NULL as for the application_name of the maintenance
daemon.
We decrease verbosity level here to avoid the flaky output
https://app.circleci.com/pipelines/github/citusdata/citus/27936/workflows/dc63128a-1570-41a0-8722-08f3e3cfe301/jobs/836153
```diff
select alter_table_set_access_method('ref','heap');
NOTICE: creating a new table for alter_table_set_access_method.ref
NOTICE: moving the data of alter_table_set_access_method.ref
NOTICE: dropping the old alter_table_set_access_method.ref
NOTICE: drop cascades to 2 other objects
-DETAIL: drop cascades to materialized view m_ref
-drop cascades to view v_ref
+DETAIL: drop cascades to view v_ref
+drop cascades to materialized view m_ref
CONTEXT: SQL statement "DROP TABLE alter_table_set_access_method.ref CASCADE"
NOTICE: renaming the new table to alter_table_set_access_method.ref
alter_table_set_access_method
-------------------------------
(1 row)
```
DESCRIPTION: Raises memory limits in columnar from 256MB to 1GB for
reads and writes
This doesn't completely fix#5918 but at least increases the
buffer limits that might cause throwing an error when reading
from or writing into into columnar storage. A way better approach
to fix this is documented in #6420.
Replacing memcpy_s with memcpy is quite safe in those places
since we anyway make sure to allocate enough amount of memory
before writing into related buffers.
When you run vanilla tests in your local environment, some of the tests
tries to find path for regress.so which is not in default lib path. That
is why we need to specify regress.so path as dlpath option.
Example failure:
```
LOAD :'regresslib';
+ERROR: could not access file "/home/aykutbozkurt/.pgenv/pgsql-15beta4/lib/regress.so": No such file or directory
```
It is actually in
`~/.pgenv/src/postgresql-15beta4/src/test/regress/regress.so` which is
found by `$regresslibdir`.
PG15 introduced an optimization on GROUP BY keys that is now reverted on
RC2.
Relevant PG commit:
Revert "Optimize order of GROUP BY keys".
443df6e2db932a7cd6d85ddfb67e11a43345130d
Fixes https://github.com/citusdata/citus/issues/6394.
DESCRIPTION: Fixes a bug that causes creating disabled-triggers on
shards as enabled
Since CREATE TRIGGER doesn't have syntax support to specify
whether the trigger should be enabled/disabled, the underlying
PG function (`pg_get_triggerdef()`) that we use to generate the
command to create the trigger is not enough. For this reason, we
append a second command to enable/disable trigger, right after
creating it.
We don't retain explicit extension dependencies set by using
`ALTER trigger DEPENDS ON EXTENSION` commands too, but apparently
right fix for that is to throw an error as in
`PreprocessAlterTriggerDependsStmt()`; so, opened a separate PR
to fix that #6399.
During alter_distributed_table, we create a new table like the
original table but with the altered options.
To retrieve the name of the distribution column, we were using
the attribute syscache of the new table, since we already created
the new table as identical to the original table.
However, the attribute syscaches of these two tables are not
the same if the original table has dropped columns. The reason
is that dropped columns are all still present in the cache.
Hence, for example, the attnos would be different in the syscaches.
So, let's use the attribute syscache of the original table.
DESCRIPTION: Fixes a bug that prevents retaining columnar table options after a table-rewrite
A fix for this issue: Columnar: options ignored during ALTER TABLE
rewrite #5927
The OID for the temporary table created during ALTER TABLE was not the
same as the original table's OID so the columnar options were not being
applied during rewrite.
The change is that I applied the original table's columnar options to
the new table so that it has the correct options during write. I also
added a test.
DESCRIPTION: Adds source_lsn and target_lsn fields into
get_rebalance_progress
Adding two fields named `source_lsn` and `target_lsn` to the function
`get_rebalance_progress`.
Target lsn data is fetched in `GetShardStatistics`, by expanding the
query sent to workers (joining with pg_subscription_rel and
pg_stat_subscription). Then put into the hashmap, for each shard.
Source lsn data is fetched in `BuildWorkerShardStatististicsHash`, in
the loop that iterate each node, by sending a pg_current_wal_lsn query
to each node. Then put into the hashmap, for each node.
On our CI our isolation_shard_rebalancer_progress would sometimes
randomly fail like this:
```diff
table_name|shardid|shard_size|sourcename|sourceport|source_shard_size|targetname|targetport|target_shard_size|progress|operation_type
----------+-------+----------+----------+----------+-----------------+----------+----------+-----------------+--------+--------------
-colocated1|1500001| 49152|localhost | 57637| 49152|localhost | 57638| 73728| 1|move
-colocated2|1500005| 376832|localhost | 57637| 376832|localhost | 57638| 401408| 1|move
+colocated1|1500001| 49152|localhost | 57637| 49152|localhost | 57638| 81920| 1|move
+colocated2|1500005| 376832|localhost | 57637| 376832|localhost | 57638| 409600| 1|move
(2 rows)
```
Source:
https://app.circleci.com/pipelines/github/citusdata/citus/27688/workflows/8c5ca443-5f21-4f21-b74f-0ca7bde69648/jobs/823648/parallel-runs/1
The shard sizes would be slightly larger or smaller than expected. This
fixes this by fixing the output to the nearest expected shard size. To
do so I used a trick described in this stack overflow answer:
https://stackoverflow.com/a/33147437/2570866
When investigating I ran into one more random failure:
```diff
-step s1-shard-move-c1-block-writes: <... completed>
+step s4-shard-move-sep-block-writes: <... completed>
citus_move_shard_placement
--------------------------
(1 row)
-step s4-shard-move-sep-block-writes: <... completed>
+step s1-shard-move-c1-block-writes: <... completed>
citus_move_shard_placement
--------------------------
```
Source:
https://app.circleci.com/pipelines/github/citusdata/citus/27707/workflows/c3ff4fc7-5068-4096-ab9f-803c941ddac0/jobs/824622/parallel-runs/29?filterBy=FAILED
This random failure happens, because the two parallel moves can complete
at the same time. So, it's non-deterministic which one finishes first. To
make this deterministic I used the "marker" feature from the isolation
tester.
And finally I ran into a third random failure:
```diff
table_name|shardid|shard_size|sourcename|sourceport|source_shard_size|targetname|targetport|target_shard_size|progress|operation_type
----------+-------+----------+----------+----------+-----------------+----------+----------+-----------------+--------+--------------
-colocated1|1500001| 50000|localhost | 57637| 50000|localhost | 57638| 50000| 1|move
-colocated2|1500005| 400000|localhost | 57637| 400000|localhost | 57638| 400000| 1|move
+colocated1|1500001| 50000|localhost | 57637| 50000|localhost | 57638| 8000| 1|move
+colocated2|1500005| 400000|localhost | 57637| 400000|localhost | 57638| 8000| 1|move
colocated1|1500002| 200000|localhost | 57637| 200000|localhost | 57638| 0| 0|move
colocated2|1500006| 8000|localhost | 57637| 8000|localhost | 57638| 0| 0|move
```
Source:
https://app.circleci.com/pipelines/github/citusdata/citus/27707/workflows/c3ff4fc7-5068-4096-ab9f-803c941ddac0/jobs/824622/parallel-runs/30?filterBy=FAILED
This happened in two of the tests only. For now I commented these tests
out. I have some ideas on how to fix these, but these ideas require more
impactful changes than I would like in this PR. One of these tests had a
copy paste error too, in passing I fixed that in the commented out line.
This test used to contain some utility commands that Citus did not
support. However we added support for most of the commands, and this
test got outdated.
We used to error out on community when user attempted to use pooler
options. Now that we open sourced all enterprise features, the test can
now be removed.
Sometimes our CI randomly fails on a test in a way similar to this:
```diff
step s2-drop:
DROP TABLE cancel_table;
-
+ <waiting ...>
+step s2-drop: <... completed>
starting permutation: s1-timeout s1-begin s1-sleep10000 s1-rollback s1-reset s1-drop
```
Source:
https://app.circleci.com/pipelines/github/citusdata/citus/26524/workflows/5415b84f-13a3-482f-bef9-648314c79a67/jobs/756377
Another example of a failure like this:
```diff
stop_session_level_connection_to_node
-------------------------------------
(1 row)
step s3-display:
SELECT * FROM ref_table ORDER BY id, value;
SELECT * FROM dist_table ORDER BY id, value;
-
+ <waiting ...>
+step s3-display: <... completed>
id|value
--+-----
```
Source: https://app.circleci.com/pipelines/github/citusdata/citus/26551/workflows/91dca4b2-bb1c-4cae-b2ef-ce3f9c689ce5/jobs/757781
A step that shouldn't be blocked is detected as "waiting..." temporarily
and then gets unblocked automatically immediately after. I'm not
certain of the reason for this, but one explanation is that the
maintenance daemon is doing something that blocks the query. In the
shown case my hunch is that it could be the deferred shard deletion.
This PR disables all the features of the maintenance daemon during
isolation testing to try and prevent process from randomly being
detected as blocking.
NOTE: I'm not certain that this will actually fix this issue. If the
issue persists even after this change, at least we know that it's not
the maintenance daemon that's blocking it.
For the sake of documentation, here is a failing diff:
```diff
step s2-view-dist:
SELECT query, citus_nodename_for_nodeid(citus_nodeid_for_gpid(global_pid)), citus_nodeport_for_nodeid(citus_nodeid_for_gpid(global_pid)), state, wait_event_type, wait_event, usename, datname FROM citus_dist_stat_activity WHERE query NOT ILIKE ALL(VALUES('%pg_prepared_xacts%'), ('%COMMIT%'), ('%BEGIN%'), ('%pg_catalog.pg_isolation_test_session_is_blocked%'), ('%citus_add_node%')) AND backend_type = 'client backend' ORDER BY query DESC;
query |citus_nodename_for_nodeid|citus_nodeport_for_nodeid|state |wait_event_type|wait_event|usename |datname
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------------------+-------------------------+-------------------+---------------+----------+--------+----------
ALTER TABLE test_table ADD COLUMN x INT;
|localhost | 57636|idle in transaction|Client |ClientRead|postgres|regression
-(1 row)
+
+ SELECT coalesce(to_jsonb(array_agg(csa_from_one_node.*)), '[{}]'::JSONB)
+ FROM (
+ SELECT global_pid, worker_query AS is_worker_query, pg_stat_activity.* FROM
+ pg_stat_activity LEFT JOIN get_all_active_transactions() ON process_id = pid
+ ) AS csa_from_one_node;
+ |localhost | 57638|active | | |postgres|regression
+(2 rows)
```
This failure can be seen at [this CI
run](https://app.circleci.com/pipelines/github/citusdata/citus/27653/workflows/d769701c-8f6e-4f97-a412-16f7b9b288a6/jobs/821416)
PG15 now allows users to specify oids when creating databases. This
feature is a side effect of a bigger feature in pg_upgrade.
Relevant PG Commit:
pg_upgrade: Preserve database OIDs.
aa01051418f10afbdfa781b8dc109615ca785ff9
Depends on https://github.com/citusdata/the-process/pull/92Closes: #6371
Updates test dependencies to not rely on a known vulnerable dependency
Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
PG15 has suppressed some casts on constants when querying foreign
tables.
For example, we can use text to represent a type that's an enum on the
remote side.
A comparison on such a column will get shipped as "var = 'foo'::text".
But there's no enum = text operator on the remote side.
If we leave off the explicit cast, the comparison will work.
Test we behave in the same way with a Citus foreign table
Reminder: foreign tables cannot be distributed/reference, can only be
Citus local
Relevant PG commit:
f8abb0f5e1
PostgreSQL 15 had some changes to jsonpath to conform with ECMA-262
referenced by SQL standard. This commit adds tests to make sure Citus
also supports the same standards.
Relevant pg commit:
e26114c817b610424010cfbe91a743f591246ff1
In Split, Logical replication logic and ShardCleaner we call
`SendCommandListToWorkerOutsideTransaction` and
`SendOptionalCommandListToWorkerOutsideTransaction` frequently. This
opens new connection for each of those calls, even though we already
have a perfectly good connection lying around.
This PR adds two new APIs
`SendCommandListToWorkerOutsideTransactionWithConnection` and
`SendOptionalCommandListToWorkerOutsideTransactionWithConnection` that
allow sending a list of queries in a transaction over an existing
connection. We also update the callers (Split, ShardCleaner, Logical
Replication) to use these new APIs instead.
Co-authored-by: Nitish Upreti <niupre@microsoft.com>
Co-authored-by: Onder Kalaci <onderkalaci@gmail.com>
In Citus 11.1.0 we changed the order of doing the initial data copy and
the replica identity creation when doing a non blocking shard move. This
was done to try and increase the speed with which shard moves could be
done. But after doing more extensive performance testing this change
turned out to have a negative impact on the speed of moves on the setups
that I tested.
Looking at the resource usage metrics of the VMs the reason for this
seems to be that these shard moves were bottlenecked by disk bandwidth.
While creating replica identities in bulk after the initial copy will
reduce CPU usage a bit, it does require an additional sequence scan of
the just written data. So when a VM is bottlenecked on disk, it makes
sense to spend a little bit more CPU to avoid an additional scan. Since
PKs are usually simple indexes that don't require lots of CPU to update,
as opposed to e.g. GiST indexes.
This reverts the order change to avoid a regression on shard move speed
in these cases.
For future releases we might consider re-evaluating our index creation
order for other indexes too, and create "simple" indexes before the
copy.
Given that we drop DEFAULT nextval('sequence') expressions from
shard relation columns, allowing `ON DELETE/UPDATE SET DEFAULT`
on such columns might cause inserting NULL values as a result
of a delete/update operation.
For this reason, we disallow ON DELETE/UPDATE SET DEFAULT actions
on columns that default to sequences.
DESCRIPTION: Disallows having ON DELETE/UPDATE SET DEFAULT actions on
columns that default to sequences
Fixes#6339.
As we did for GENERATED STORED columns in #4613, we should not drop
column
default expressions that are not based on sequences from shard relation
since
such expressions need to exist e.g. for foreign key actions.
For the column default expressions that are based on sequences we cannot
do much, so we need to disallow having ON DELETE SET DEFAULT actions on
such columns in a separate PR, see #6339.
Fixes#6318.
DESCRIPTION: Fixes a bug that might cause inserting incorrect DEFAULT
values when applying foreign key actions
PG15 added support for security invoker views. Relevant PG conmit:
7faa5fc84b
These views check the permissions for the underlying tables of the view
invoker user, not the view definer user.
When the view has underlying distributed tables, the queries to the
shards are sent by opening connections with the current user, which is
the view invoker, no matter what the type of the view is. This means
that, for distributed views, they were always behaving like security
invoker views. Check the following issue for more details:
https://github.com/citusdata/citus/issues/6161
So, Citus doesn't fully support security definer views.
However Citus does fully support security invoker views. We add tests to
make sure we cover different cases.
DESCRIPTION: Fixes dropping replication slots
As detected by a flaky test, Citus sometimes fails to drop replication
slots, possibly due to a race condition, at the end of a shard split.
With this PR, we retry to drop them in case of an `OBJECT_IN_USE` error,
consistently for 20 seconds.
fixes: #6326
Both tests include pushdown and pull to coordinator type of aggregate
execution.
Relevant PG commits:
Add min() and max() aggregates for xid8
400fc6b6487ddf16aa82c9d76e5cfbe64d94f660
Add range_agg with multirange inputs
7ae1619bc5b1794938c7387a766b8cae34e38d8a
Co-authored-by: Onder Kalaci <onderkalaci@gmail.com>
DESCRIPTION: Improve logging during shard split and resource cleanup
### DESCRIPTION
This PR makes logging improvements to Shard Split :
1. Update confusing logging to fix#6312
2. Added new `ereport(LOG` to make debugging easier as part of telemetry review.
Comment from the code is clear on this:
/*
* The statistics objects of the distributed table are not relevant
* for the distributed planning, so we can override it.
*
* Normally, we should not need this. However, the combination of
* Postgres commit 269b532aef55a579ae02a3e8e8df14101570dfd9 and
* Citus function AdjustPartitioningForDistributedPlanning()
* forces us to do this. The commit expects statistics objects
* of partitions to have "inh" flag set properly. Whereas, the
* function overrides "inh" flag. To avoid Postgres to throw error,
* we override statlist such that Postgres does not try to process
* any statistics objects during the standard_planner() on the
* coordinator. In the end, we do not need the standard_planner()
* on the coordinator to generate an optimized plan. We call
* into standard_planner() for other purposes, such as generating the
* relationRestrictionContext here.
*
* AdjustPartitioningForDistributedPlanning() is a hack that we use
* to prevent Postgres' standard_planner() to expand all the partitions
* for the distributed planning when a distributed partitioned table
* is queried. It is required for both correctness and performance
* reasons. Although we can eliminate the use of the function for
* the correctness (e.g., make sure that rest of the planner can handle
* partitions), it's performance implication is hard to avoid. Certain
* planning logic of Citus (such as router or query pushdown) relies
* heavily on the relationRestrictionList. If
* AdjustPartitioningForDistributedPlanning() is removed, all the
* partitions show up in the, causing high planning times for
* such queries.
*/
DESCRIPTION: Fixes floating exception during
create_distributed_table_concurrently.
Fixes#6332.
During create_distributed_table_concurrently, when there is no active
primary node, it fails with floating exception. We added similar check
with create_distributed_table. It will fail with proper message if
current active node is less than replication factor.
The PR introduces code changes to fix Issue
[6303](https://github.com/citusdata/citus/issues/6303)
`create_distributed_table_concurrently` following drop column, creates a
buggy situation in split decoder.
* Consider the below scenario:
* Session1 : Drop column followed by
create_distributed_table_concurrently
* Session2 : Concurrent insert workload
The child shards created by `create_distributed_table_concurrently` will
have less columns than the source shard because some column were
dropped. The incoming tuple from session2 will have more columns as the
writes happened on source shard. But now the tuple needs to be applied
on child shard. So we need to format existing tuple according to child
schema and skip dropped column values.
The PR fixes this by reformatting the tuple according the target child
schema.
Test:
1) isolation_create_distributed_concurrently_after_drop_column - Repros
the issue and tests on the same.
No need for description, fixing issue introduced with new feature for
11.1
Fixes#6333
Due to Postgres' C api being o-indexed and postgres' attributes being
1-indexed, we were reading the wrong Datum as the Task owner when
cancelling. Here we add a test to show the error and fix the off-by-one
error.
When I built Citus on PG15beta4 locally, I get a warning message.
```
utils/background_jobs.c:902:5: warning: declaration does not declare anything
[-Wmissing-declarations]
__attribute__((fallthrough));
^
1 warning generated.
```
This is a hint to the compiler that we are deliberately falling through
in a switch-case block.
DESCRIPTION: Show citus_copy_shard_placement progress in
get_rebalance_progress
When rebalancing to a new node that does not have reference tables yet
the rebalancer will first copy the reference tables to the nodes.
Depending on the size of the reference tables, this might take a long
time. However, there's no indication of what's happening at this stage
of the rebalance.
This PR improves this situation by also showing the progress of any
citus_copy_shard_placement calls when calling get_rebalance_progress.
We can now do the following:
- Distribute sequence with logged/unlogged option
- ALTER TABLE my_sequence SET LOGGED/UNLOGGED
- ALTER SEQUENCE my_sequence SET LOGGED/UNLOGGED
Relevant PG commit
344d62fb9a
PG15 introduces `CLUSTER` commands for partitioned tables. Similar to a
`CLUSTER` command with no supplied table names, these commands also can
not be run inside transaction blocks and therefore can not be propagated
in a distributed transaction block with ease. Therefore we raise warnings.
Relevant PG commit: cfdd03f45e6afc632fbe70519250ec19167d6765
DESCRIPTION: Add a rebalancer that uses background tasks for its
execution
Based on the baclground jobs and tasks introduced in #6296 we implement
a new rebalancer on top of the primitives of background execution. This
allows the user to initiate a rebalance and let Citus execute the long
running steps in the background until completion.
Users can invoke the new background rebalancer with `SELECT
citus_rebalance_start();`. It will output information on its job id and
how to track progress. Also it returns its job id for automation
purposes. If you simply want to wait till the rebalance is done you can
use `SELECT citus_rebalance_wait();`
A running rebalance can be canelled/stopped with `SELECT
citus_rebalance_stop();`.
Reverting the following commits:
977ddaae564a5cf06def9ae19c181f30447117e5f9c43f433221dba4ed08262932da3e
We have to manually make changes to this file.
Follow the relevant PG commit in ruleutils.c & make the exact same changes in ruleutils_15.c
Relevant PG commit:
96ef3237bf741c12390003e90a4d7115c0c854b7
PG 15 added support for that (d6f96ed94e73052f99a2e545ed17a8b2fdc1fb8a).
We also add support, but we already do not support ON DELETE SET NULL/DEFAULT
for distribution column. So, in essence, we add support for reference tables
and Citus local tables.
The logical replication catchup part for shard splits and shard moves is
very similar. This abstracts most of that similarity away into a single
function. This also improves the logic for non blocking shard splits a
bit, by using faster foreign key creation. It also parallelizes index creation
which shard moves were already doing, but shard splits did not.
DESCRIPTION: Add infrastructure to run long running management operations in background
This infrastructure introduces the primitives of jobs and tasks.
A task consists of a sql statement and an owner. Tasks belong to a
Job and can depend on other tasks from the same job.
When there are either runnable or running tasks we would like to
make sure a bacgrkound task queue monitor process is running. A Task
could be in running state while there is actually no monitor present
due to a database restart or failover. Once the monitor starts it
will reset any running task to its runnable state.
To make sure only one background task queue monitor is ever running
at once it will acquire an advisory lock that self conflicts.
Once a task is done it will find all tasks depending on this task.
After checking that the task doesn't have unmet dependencies it will
transition the task from blocked to runnable state for the task to
be picked up on a subsequent task start.
Currently only one task can be running at a time. This can be
improved upon in later releases without changes to the higher level
API.
The initial goal for this background tasks is to allow a rebalance
to run in the background. This will be implemented in a subsequent PR.
Previously we would create foreign keys to reference table in an extra
fast way at the end of a shard move. This uses that same logic to also
do it for foreign keys between distributed tables.
Fixes#6141
Introduces a new GUC named citus.skip_constraint_validation, which basically skips constraint validation when set to on.
For some several places that we hack to skip the foreign key validation phase, now we use this GUC.
When introducing our overrides of pg_cancel_backend and
pg_terminate_backend we accidentally did that in such a way that we
cannot call the original pg_cancel_backend and pg_terminate_backend from
C anymore. This happened because we defined the exact same symbols in
our shared library as postgres does in its own binary.
This fixes that by using a different names for the C function than for
the SQL function.
Making this work in all upgrade and downgrade scenarios is not trivial
though, because we actually need to remove the C function definition.
Postgres errors in two different times when the symbol that a C function
wants to call is not defined in the library it expects it in:
1. When creating the SQL function definition
2. When calling the SQL function
Item 1 causes an issue when creating our extension for the first time.
We then go execute all the migrations that we have. So if the 11.0
migration contains a SQL function definition that still references the
pg_cancel_backend symbol, that migration will fail. This issue is solved
by actually changing the SQL definition in the old migration.
This is not enough to fix all issues though. Item 2 causes an issue
after an upgrade to 11.1, because it won't have the new definition of
the SQL function. This is solved by recreating the SQL functions in the
migration to 11.1. That way it gets the new definition.
Then finally there's the case of downgrades. To continue to make our
pg_cancel_backend SQL function work after downgrading, we will need to
make a patch release for 11.0 that includes the new citus_cancel_backend
symbol. This is done in a separate commit.
DESCRIPTION:
This PR adds support for 'Deferred Drop' and robust 'Shard Cleanup' for Splits.
Common Infrastructure
This PR introduces new common infrastructure so as any operation that wants robust cleanup of resources can register with the cleaner and have the resources cleaned appropriately based on a specified policy. 'Shard Split' is the first consumer using this new infrastructure.
Note : We only support adding 'shards' as resources to be cleaned-up right now but the framework will be extended to support other resources in future.
Deferred Drop for Split
Deferred Drop Support ensures that shards undergoing split are not dropped inline as part of operation but dropped later when no active read queries are running on shard. This helps with :
Avoids any potential deadlock scenarios that can cause long running Split operation to rollback.
Avoids Split operation blocking writes and then getting blocked (due to running queries on the shard) when trying to drop shards.
Deferred drop is the new default behavior going forward.
Shard Cleaner Extension
Shard Cleaner is a background task responsible for deferred drops in case of 'Move' operations.
The cleaner has been extended to ensure robust cleanup of shards (dummy shards and split children) in case of a failure based on the new infrastructure mentioned above. The cleaner also handles deferred drop for 'Splits'.
TESTING:
New test ''citus_split_shard_by_split_points_deferred_drop' to test deferred drop support.
New test 'failure_split_cleanup' to test shard cleanup with failures in different stages.
Update 'isolation_blocking_shard_split and isolation_non_blocking_shard_split' for deferred drop.
Added non-deferred drop version of existing tests : 'citus_split_shard_no_deferred_drop' and 'citus_non_blocking_splits_no_deferred_drop'
* Fix issue : 6109 Segfault or (assertion failure) is possible when using a SQL function
* DESCRIPTION: Ensures disallowing the usage of SQL functions referencing to a distributed table and prevents a segfault.
Using a SQL function may result in segmentation fault in some cases.
This change fixes the issue by throwing an error message when a SQL function cannot be handled.
Fixes#6109.
* DESCRIPTION: Ensures disallowing the usage of SQL functions referencing to a distributed table and prevents a segfault.
Using a SQL function may result in segmentation fault in some cases. This change fixes the issue by throwing an error message when a SQL function cannot be handled.
Fixes#6109.
Co-authored-by: Emel Simsek <emel.simsek@microsoft.com>
PG15 allows numeric scale to be negative or greater than precision. This
causes issues and we may end up routing queries to a wrong shard due to
differing hash results after rounding.
Formerly, when specifying NUMERIC(precision, scale), the scale had to be
in the range [0, precision], which was per SQL spec. PG15 extends the
range of allowed scales to [-1000, 1000].
A negative scale implies rounding before the decimal point. For
example, a column might be declared with a scale of -3 to round values
to the nearest thousand. Note that the display scale remains
non-negative, so in this case the display scale will be zero, and all
digits before the decimal point will be displayed.
Relevant PG commit: 085f931f52494e1f304e35571924efa6fcdc2b44
Pre PG15, renaming child triggers on partitions is allowed. When
creating a trigger in a distributed parent partitioned table, the
triggers on the shards of the partitions have the same name with
the triggers on the corresponding parent shards of the parent
table. Therefore, they don't have the same appended shard id as
the shard id of the partition. Hence, when trying to rename a
child trigger on a partition of a distributed table, we can't
correctly find the triggers on the shards of the partition in
order to rename them since we append a different shard id to the
name of the trigger. Since we can't find the trigger we get a
misleading error of inexistent trigger.
In this commit we prohibit renaming child triggers on distributed
partitions altogether.
Sometimes in CI our isolation_citus_dist_activity test fails randomly
like this:
```diff
step s2-view-dist:
SELECT query, citus_nodename_for_nodeid(citus_nodeid_for_gpid(global_pid)), citus_nodeport_for_nodeid(citus_nodeid_for_gpid(global_pid)), state, wait_event_type, wait_event, usename, datname FROM citus_dist_stat_activity WHERE query NOT ILIKE ALL(VALUES('%pg_prepared_xacts%'), ('%COMMIT%'), ('%BEGIN%'), ('%pg_catalog.pg_isolation_test_session_is_blocked%'), ('%citus_add_node%')) AND backend_type = 'client backend' ORDER BY query DESC;
query |citus_nodename_for_nodeid|citus_nodeport_for_nodeid|state |wait_event_type|wait_event|usename |datname
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------------------+-------------------------+-------------------+---------------+----------+--------+----------
INSERT INTO test_table VALUES (100, 100);
|localhost | 57636|idle in transaction|Client |ClientRead|postgres|regression
-(1 row)
+
+ SELECT coalesce(to_jsonb(array_agg(csa_from_one_node.*)), '[{}]'::JSONB)
+ FROM (
+ SELECT global_pid, worker_query AS is_worker_query, pg_stat_activity.* FROM
+ pg_stat_activity LEFT JOIN get_all_active_transactions() ON process_id = pid
+ ) AS csa_from_one_node;
+ |localhost | 57636|active | | |postgres|regression
+(2 rows)
step s3-view-worker:
```
Source: https://app.circleci.com/pipelines/github/citusdata/citus/26692/workflows/3406e4b4-b686-4667-bec6-8253ee0809b1/jobs/765119
I intended to fix this with #6263, but the fix turned out to be
insufficient. This PR tries to address the issue by setting
distributedCommandOriginator correctly in more situations. However, even
with this change it's still possible to reproduce the flaky test in CI.
In any case this should fix at least some instances of this issue.
In passing this changes the isolation_citus_dist_activity test to allow
running it multiple times in a row.
PRE PG15, Renaming the parent triggers on partitioned tables doesn't
recurse to renaming the child triggers on the partitions as well.
In PG15, Renaming triggers on partitioned tables
recurses to renaming the triggers on the partitions as well.
Add an upgrade test to make sure we are not breaking anything
with distributed triggers on distributed partitioned tables.
Relevant PG commit:
80ba4bb383538a2ee846fece6a7b8da9518b6866
pg_dist_node and pg_dist_colocation have a primary key index, not a replica identity index.
Citus catalog tables are created in public schema, which has replica identity index by default
as primary key index. Later the citus catalog tables are moved to pg_catalog schema.
During pg_upgrade, all tables are recreated, and given that pg_dist_colocation is found in
pg_catalog schema, it is recreated in that schema, and when it is recreated it doesn't
have a replica identity index, because catalog tables have no replica identity.
Further action:
Do we even need to acquire this lock on the primary key index?
Postgres doesn't acquire such locks on indexes before deleting catalog tuples.
Also, catalog tuples don't have replica identities by definition.
In commit 31faa88a4e I removed some features of the rebalance progress
monitor. I did this because the plan was to remove the foreground shard
rebalancer later in the PR that would add the background shard
rebalancer. So, I didn't want to spend time fixing something that we
would throw away anyway.
As it turns out we're not removing the foreground shard rebalancer after
all, so it made sens to fix the stuff that I broke. This PR does that.
For the most part this commit reverts the changes in commit 31faa88a4e.
It's not a full revert though, because it keeps the improved tests and
the changes to `citus_move_shard_placement`.
Jelte Fennema
aykut-bozkurt
Emel Şimşek
Ahmet Gedemenli
Gokhan Gulbiz
Onur Tirtir
Naisila Puka
Önder Kalacı
Hanefi Onaldi
Ying Xu
Nils Dijk
Nitish Upreti
Marco Slot
Sameer Awasekar
Jelte Fennema
naisila