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.
Before this commit, we erroneously converted the sequence
type to the column's type it is used. However, it is possible
that the sequence is used in an expression which then converted
to a type that cannot be a sequence, such as text.
With this commit, we only try this conversion if the column
type is a supported sequence type (e.g., smallint, int and bigint).
Note that we do this conversion because if the column type is a
bigint and the sequence is NOT a bigint, users would be in trouble
because sequences would generate values that are out of the range
of the column. (The other ways are already not supported such as
the column is int and the sequence is bigint would fail on the worker.)
In other words, with this commit, we scope this optimization only
when the target column type is a supported sequence type. Otherwise,
we let users to more freely use the sequences.
(cherry picked from commit db529facab)
Conflicts:
- src/backend/distributed/commands/create_distributed_table.c
- src/include/distributed/metadata_utility.h
EnsureSequenceTypeSupported did not have the third parameter prior
to Citus 11. I removed the references to ownerRelationId.
- src/test/regress/multi_schedule
Trivial conflict for the newly introduced test files. This conflict
was easy to resolve, but I modified the tests to prevent failures
due to the following:
a) MX is not on by default on 10.2 contrary to Citus 11
b) We set replication factor = 2 here contrary to 1 in Citus 11
In addition to starting a new transaction, we also need to tell other
backends --including the ones spawned for connections opened to
localhost to build indexes on shards of this relation-- that concurrent
index builds can safely ignore us.
Normally, DefineIndex() only does that if index doesn't have any
predicates (i.e.: where clause) and no index expressions at all.
However, now that we already called standard process utility, index
build on the shell table is finished anyway.
The reason behind doing so is that we cannot guarantee not grabbing any
snapshots via adaptive executor, and the backends creating indexes on
local shards (if any) might block on waiting for current xact of the
current backend to finish, which would cause self deadlocks that are not
detectable.
(cherry picked from commit 3cc44ed8b3)
Conflicts:
src/backend/distributed/commands/utility_hook.c
make_simple_restrictinfo and pull_varnos functions now have a new parameter
These new macros give us the ability to use this new parameter for PG14 and they don't give the parameter for previous versions
Relevant PG commit:
55dc86eca70b1dc18a79c141b3567efed910329d
get_partition_parent and RelationGetPartitionDesc functions now have new parameters to also include detached partitions
Thess new macros give us the ability to use these new parameter for PG14 and they don't give the parameters for previous versions
Existing parameters are set to not accept detached partitions
Relevant PG commit:
71f4c8c6f74ba021e55d35b1128d22fb8c6e1629
In two commits vacuumFlags in PGXACT is moved and then renamed to status flags
This macro uses the appropriate version of the flag
Relevant PG commits:
5788e258bb26495fab65ff3aa486268d1c50b123
cd9c1b3e197a9b53b840dcc87eb41b04d601a5f9
SetTuplestoreDestReceiverParams function now has two new parameters
This new macro give us the ability to use this new parameter for PG14 and it doesn't give the parameter for previous versions
Existing parameters are set to NULL to keep previous behavior
Relevant PG commit:
2f48ede080f42b97b594fb14102c82ca1001b80c
Some Copy related functions copied from Postgres had support for both old and new protocols
Postgres removed support for old version so we remove it too
Relevant PG commit:
3174d69fb96a66173224e60ec7053b988d5ed4d9
New macros: standard_ProcessUtility_compat, ProcessUtility_compat, ColumnarProcessUtility_compat, PrevProcessUtilityHook_compat
The functions now have a new bool parameter: readOnlyTree
These new macros give us the ability to use this new parameter for PG14 and it doesn't give the parameter for previous versions
In multi_ProcessUtility and ColumnarProcessUtility, before doing anything else, we check if readOnlyTree parameter is true and create a copy of pstmt
Existing readOnlyTree parameters are set to false since we already handle the read only case at multi_ProcessUtility and ColumnarProcessUtility
Relevant PG commit:
7c337b6b527b7052e6a751f966d5734c56f668b5
BeginCopyFrom function now has a new whereClause parameter.
In the function this parameter is assigned to the whereClause field of the CopyFromState returned
Currently in Postgres there is only one place where this argument isn't NULL, and in previous PG version the whereClause argument of copy state is set right after the function call
Since we don't have such example all current whereClause parameters are set to NULL
Relevant PG commit:
c532d15dddff14b01fe9ef1d465013cb8ef186df
CopyState struct is divided into parts and one of them is CopyFromState
This macro uses the appropriate one for PG versions
Relevant PG commit:
c532d15dddff14b01fe9ef1d465013cb8ef186df
In ReindexStmt concurrent field is moved to options and then options are converted to params list.
This macro uses previous fields for previous versions and the new params list with a new function named IsReindexWithParam for PG14
Relevant PG commits:
844c05abc3f1c1703bf17cf44ab66351ed9711d2
b5913f6120792465f4394b93c15c2e2ac0c08376
VacOptTernaryValue enum is renamed to VacOptValue.
In the enum there were three values, VACOPT_TERNARY_DEFAULT, VACOPT_TERNARY_DISABLED, and VACOPT_TERNARY_ENABLED
Now there are four values VACOPTVALUE_UNSPECIFIED, VACOPTVALUE_AUTO, VACOPTVALUE_DISABLED, and VACOPTVALUE_ENABLED
New macros are VacOptValue_compat, VACOPTVALUE_UNSPECIFIED_COMPAT, VACOPTVALUE_DISABLED_COMPAT, and VACOPTVALUE_ENABLED_COMPAT
The VACOPTVALUE_UNSPECIFIED_COMPAT matches VACOPT_TERNARY_DEFAULT and VACOPTVALUE_UNSPECIFIED. And there are no macro for VACOPTVALUE_AUTO.
Relevant PG commit:
3499df0dee8c4ea51d264a674df5b5e31991319a
New macros: FuncnameGetCandidates_compat and expand_function_arguments_compat
The functions (the ones without _compat) now have a new bool include_out_arguments parameter
These new macros give us the ability to use this new parameter for PG14 and it doesn't give the parameter for previous versions
Existing include_out_arguments parameters are set to 'false' to keep current behavior
Relevant PG commit:
e56bce5d43789cce95d099554ae9593ada92b3b7
stats function now have a new bool print_to_stderr parameter
This new macro gives us the ability to use this new parameter for PG14 and it doesn't give the parameter for previous versions
Existing print_to_stderr parameter is set to true to keep current behavior
Relevant PG commit:
43620e328617c1f41a2a54c8cee01723064e3ffa
getObjectTypeDescription and getObjectIdentity functions now have a new bool missing_ok parameter
These new macros give us the ability to use this new parameter for PG14 and they don't give the parameter for previous versions
Currently all missing_ok parameters are set to false to keep current behavior
Relevant PG commit:
2a10fdc4307a667883f7a3369cb93a721ade9680
The STATUS_WAITING define is removed and an enum with PROC_WAIT_STATUS_WAITING is added instead
This macro uses appropriate one
Relevant PG commit:
a513f1dfbf2c29a51b0f7cbd5913ce2d2ee452c5
AlterTableStmt's relkind field is changed into objtype
New AlterTableStmtObjType macro uses the appropriate one
Relevant PG commit:
cc35d8933a211d9965eb1c1d2749a903d5735db2
* Synchronize hasmetadata flag on mx workers
* Switch to sequential execution
* Add test
* Use SetWorkerColumn
* Add test for stop_sync
* Remove usage of UpdateHasmetadataOnWorkersWithMetadata
* Remove MarkNodeMetadataSynced
* Fix test for metadatasynced
* Remove MarkNodeMetadataSynced
* Style
* Remove MarkNodeHasMetadata
* Remove UpdateDistNodeBoolAttr
* Refactor SetWorkerColumn
* Use SetWorkerColumnLocalOnly when setting up dependencies
* Use SetWorkerColumnLocalOnly in TriggerSyncMetadataToPrimaryNodes
* Style
* Make update command generator functions static
* Set metadatasynced before syncing
* Call SetWorkerColumn only if the sync is successful
* Try to sync all nodes
* Fix indexno
* Update metadatasynced locally first
* Break if a node fails to sync metadata
* Send worker commands optional
* Style & Rebase
* Add raiseOnError param to SetWorkerColumn
* Style
* Set metadatasynced for all metadata nodes
* Style
* Introduce SetWorkerColumnOptional
* Polish
* Style
* Dont send set command to not synced metadata nodes
* Style
* Polish
* Add test for stop_sync
* Add test for shouldhaveshards
* Add test for isactive flag
* Sort by placementid in the function verify_metadata
* Cover edge cases for failing nodes
* Add comments
* Add nodeport to isactive test
* Add warning if metadata out of sync
* Update warning message
As we use the current user to sync the metadata to the nodes
with #5105 (and many other PRs), there is no reason that
prevents us to use the coordinated transaction for metadata syncing.
This commit also renames few functions to reflect their actual
implementation.
Before this commit, creating a partition after a DROP column
on the parent (position before dist. key) was leading to
partition to have the wrong distribution column.
update_distributed_table_colocation can be called by the relation
owner, and internally it updates pg_dist_partition. With this
commit, update_distributed_table_colocation uses an internal
UDF to access pg_dist_partition.
As a result, this operation can now be done by regular users
on MX.
* Fix UNION not being pushdown
Postgres optimizes column fields that are not needed in the output. We
were relying on these fields to understand if it is safe to push down a
union query.
This fix looks at the parse query, which has the original column fields
to detect if it is safe to push down a union query.
* Add more tests
* Simplify code and make it more robust
* Process varlevelsup > 0 in FindReferencedTableColumn
* Only look for outers vars in union path
* Add more comments
* Remove UNION ALL specific logic for pulling up childvars
These two options were not included when creating the sequences on the
workers as part of metadata syncing.
The missing `data_type` part of the definition made finding the cause
of #5126 harder than necessary, because of confusing errors.
Before this commit, we always synced the metadata with superuser.
However, that creates various edge cases such as visibility errors
or self distributed deadlocks or complicates user access checks.
Instead, with this commit, we use the current user to sync the metadata.
Note that, `start_metadata_sync_to_node` still requires super user
because accessing certain metadata (like pg_dist_node) always require
superuser (e.g., the current user should be a superuser).
However, metadata syncing operations regarding the distributed
tables can now be done with regular users, as long as the user
is the owner of the table. A table owner can still insert non-sense
metadata, however it'd only affect its own table. So, we cannot do
anything about that.
Ignore orphaned shards in more places
Only use active shard placements in RouterInsertTaskList
Use IncludingOrphanedPlacements in some more places
Fix comment
Add tests
* Alter seq type when we first use the seq in a dist table
* Don't allow type changes when seq is used in dist table
* ALTER SEQUENCE propagation
* Tests for ALTER SEQUENCE propagation
* Relocate AlterSequenceType and ensure dependencies for sequence
* Support for citus local tables, and other fixes
* Final formatting
Moving shards of reference tables was possible in at least one case:
```sql
select citus_disable_node('localhost', 9702);
create table r(x int);
select create_reference_table('r');
set citus.replicate_reference_tables_on_activate = off;
select citus_activate_node('localhost', 9702);
select citus_move_shard_placement(102008, 'localhost', 9701, 'localhost', 9702);
```
This would then remove the reference table shard on the source, causing
all kinds of issues. This fixes that by disallowing all shard moves
except for shards of distributed tables.
Co-authored-by: Onur Tirtir <onurcantirtir@gmail.com>
The first and main issue was that we were putting absolute pointers into
shared memory for the `steps` field of the `ProgressMonitorData`. This
pointer was being overwritten every time a process requested the monitor
steps, which is the only reason why this even worked in the first place.
To quote a part of a relevant stack overflow answer:
> First of all, putting absolute pointers in shared memory segments is
> terrible terible idea - those pointers would only be valid in the
> process that filled in their values. Shared memory segments are not
> guaranteed to attach at the same virtual address in every process.
> On the contrary - they attach where the system deems it possible when
> `shmaddr == NULL` is specified on call to `shmat()`
Source: https://stackoverflow.com/a/10781921/2570866
In this case a race condition occurred when a second process overwrote
the pointer in between the first process its write and read of the steps
field.
This issue is fixed by not storing the pointer in shared memory anymore.
Instead we now calculate it's position every time we need it.
The second race condition I have not been able to trigger, but I found
it while investigating this. This issue was that we published the handle
of the shared memory segment, before we initialized the data in the
steps. This means that during initialization of the data, a call to
`get_rebalance_progress()` could read partial data in an unsynchronized
manner.
With local query caching, we try to avoid deparse/parse stages as the
operation is too costly.
However, we can do deparse/parse operations once per cached queries, right
before we put the plan into the cache. With that, we avoid edge
cases like (4239) or (5038).
In a sense, we are making the local plan caching behave similar for non-cached
local/remote queries, by forcing to deparse the query once.
Nils Dijk
Marco Slot
Ahmet Gedemenli
Halil Ozan Akgul
Onder Kalaci
Onur Tirtir
Sait Talha Nisanci
Naisila Puka
Hanefi Onaldi
Jelte Fennema