We're in the processes of totally changing the shard rebalancer
experience and infrastructure. Soon the shard rebalancer will include
retries, crash recovery and support for running in the background.
These improvements come at a cost though, the way the
get_rebalance_progress UDF currently works is very hard to replicate
with this new structure. This is mostly because the old behaviour
doesn't really make sense anymore with this new infrastructure. A new
and better way to track the progress will be included as part of the new
infrastructure.
This PR is in preparation of the new code rebalancer experience.
It changes the get_rebalance_progress UDF to only display the moves that
are in progress at the moment, not the ones that happened in the past or
that are planned in the future. Another option would have been to
completely remove the current get_rebalance_progress functionality and
point people to the new way of tracking progress. But old blogposts
still reference the old UDF and users might have some automation on top
of it. Showing the progress of the current moves is fairly simple to
achieve, even with the new infrastructure.
So this PR is a kind of compromise: It doesn't have complete feature
parity with the old get_rebalance_progress, but the most common use
cases will still work.
There's also an advantage of the change: You can now see progress of
shard moves that were triggered by calling citus_move_shard_placement
manually. Instead of only being able to see progress of moves that were
initiated using get_rebalance_table_shards.
We used to rely on a seperate session to add the coordinator.
However, that might prevent the existing sessions to get
assigned proper gpids, which causes flaky tests.
This removes a flaky test that I introduced in #3868 after I fixed the
issue described in #3622. This test is sometimes fails randomly in CI.
The way it fails indicates that there might be some bug: A connection
breaks after rolling back to a savepoint.
I tried reproducing this issue locally, but I wasn't able to. I don't
understand what causes the failure.
Things that I tried were:
1. Running the test with:
```sql
SET citus.force_max_query_parallelization = true;
```
2. Running the test with:
```sql
SET citus.max_adaptive_executor_pool_size = 1;
```
3. Running the test in parallel with the same tests that it is run in
parallel with in multi_schedule.
None of these allowed me to reproduce the issue locally.
So I think it's time to give on fixing this test and simply remove the
test. The regression that this test protects against seems very unlikely
to reappear, since in #3868 I also added a big comment about the need
for the newly added `UnclaimConnection` call. So, I think the need for
the test is quite small, and removing it will make our CI less flaky.
In case the cause of the bug ever gets found, I tracked the bug in #6189
Example of a failing CI run:
https://app.circleci.com/pipelines/github/citusdata/citus/26098/workflows/f84741d9-13b1-4ae7-9155-c21ed3466951/jobs/736424
For reference the unexpected diff is this (so both warnings and an error):
```diff
INSERT INTO t SELECT i FROM generate_series(1, 100) i;
+WARNING: connection to the remote node localhost:57638 failed with the following error:
+WARNING:
+CONTEXT: while executing command on localhost:57638
+ERROR: connection to the remote node localhost:57638 failed with the following error:
ROLLBACK;
```
This test is also mentioned as the most failing regression test in #5975
There are 3 different ways that a sequence can be interacting
with tables. (1) and (2) are already supported. This commit adds
support for (3).
(1) column DEFAULT nextval('seq'):
The dependency is roughly like below,
and ExpandCitusSupportedTypes() is responsible
for finding the depending sequences.
schema <--- table <--- column <---- default value
^ |
|------------------ sequence <--------|
(2) serial columns: Bigserial/small serial etc:
The dependency is roughly like below,
and ExpandCitusSupportedTypes() is responsible
for finding the depending sequences.
schema <--- table <--- column <---- default value
^ |
| |
sequence <--------|
(3) Sequence OWNED BY table.column: Added support for
this type of resolution in this commit.
The dependency is almost like the following, and
ExpandCitusSupportedTypes() is NOT responsible for finding
the dependency.
schema <--- table <--- column
^
|
sequence
Object type ids have changed in PG15 because of at least two added
objects in the list: OBJECT_PARAMETER_ACL, OBJECT_PUBLICATION_NAMESPACE
To avoid different output between pg versions, let's use the object
name in the error, and put the object id in the error detail.
Relevant PG commits:
a0ffa885e478f5eeacc4e250e35ce25a4740c487
5a2832465fd8984d089e8c44c094e6900d987fcd
DESCRIPTION: Fix reference table lock contention
Dropping and creating reference tables unintentionally blocked on each other due to the use of an ExclusiveLock for both the Drop and conditionally copying existing reference tables to (new) nodes.
The patch does the following:
- Lower lock lever for dropping (reference) tables to `ShareLock` so they don't self conflict
- Treat reference tables and distributed tables equally and acquire the colocation lock when dropping any table that is in a colocation group
- Perform the precondition check for copying reference tables twice, first time with a lower lock that doesn't conflict with anything. Could have been a NoLock, however, in preparation for dropping a colocation group, it is an `AccessShareLock`
During normal operation the first check will always pass and we don't have to escalate that lock. Making it that we won't be blocked on adding and remove reference tables. Only after a node addition the first `create_reference_table` will still need to acquire an `ExclusiveLock` on the colocation group to perform the copy.
This is a refactoring PR that starts using our new hash table creation
helper function. It adds a few more macros for ease of use, because C
doesn't have default arguments. It also adds a macro to check if a
struct contains automatic padding bytes. No struct that is hashed using
tag_hash should have automatic padding bytes, because those bytes are
undefined and thus using them to create a hash will result in undefined
behaviour (usually a random hash).
Nitish Upreti
Jelte Fennema
Önder Kalacı
Naisila Puka
Ying Xu
Nils Dijk
Ahmet Gedemenli
aykut-bozkurt