Adds support for propagation ALTER VIEW commands to
- Change owner of view
- SET/RESET option
- Rename view and view's column name
- Change schema of the view
Since PG also supports targeting views with ALTER TABLE
commands, related code also added to direct such ALTER TABLE
commands to ALTER VIEW commands while sending them to workers.
Breaking down #5899 into smaller PR-s
This particular PR changes the way TRUNCATE acquires distributed locks on the relations it is truncating to use the LOCK command instead of lock_relation_if_exists. This has the benefit of using pg's recursive locking logic it implements for the LOCK command instead of us having to resolve relation dependencies and lock them explicitly. While this does not directly affect truncate, it will allow us to generalize this locking logic to then log different relations where the pg recursive locking will become useful (e.g. locking views).
This implementation is a bit more complex that it needs to be due to pg not supporting locking foreign tables. We can however, still lock foreign tables with lock_relation_if_exists. So for a command:
TRUNCATE dist_table_1, dist_table_2, foreign_table_1, foreign_table_2, dist_table_3;
We generate and send the following command to all the workers in metadata:
```sql
SEL citus.enable_ddl_propagation TO FALSE;
LOCK dist_table_1, dist_table_2 IN ACCESS EXCLUSIVE MODE;
SELECT lock_relation_if_exists('foreign_table_1', 'ACCESS EXCLUSIVE');
SELECT lock_relation_if_exists('foreign_table_2', 'ACCESS EXCLUSIVE');
LOCK dist_table_3 IN ACCESS EXCLUSIVE MODE;
SEL citus.enable_ddl_propagation TO TRUE;
```
Note that we need to alternate between the lock command and lock_table_if_exists in order to preserve the TRUNCATE order of relations.
When pg supports locking foreign tables, we will be able to massive simplify this logic and send a single LOCK command.
Adds support for propagating create/drop view commands and views to
worker node while scaling out the cluster. Since views are dropped while
converting the table type, metadata connection will be used while
propagating view commands to not switch to sequential mode.
Here is a flaky test output that is quite hard to fix:
```diff
diff -dU10 -w /home/circleci/project/src/test/regress/expected/isolation_master_update_node_1.out /home/circleci/project/src/test/regress/results/isolation_master_update_node.out
--- /home/circleci/project/src/test/regress/expected/isolation_master_update_node_1.out.modified 2022-03-21 19:03:54.237042562 +0000
+++ /home/circleci/project/src/test/regress/results/isolation_master_update_node.out.modified 2022-03-21 19:03:54.257043084 +0000
@@ -49,18 +49,20 @@
<waiting ...>
step s2-update-node-1-force: <... completed>
master_update_node
------------------
(1 row)
step s2-abort: ABORT;
step s1-abort: ABORT;
FATAL: terminating connection due to administrator command
-SSL connection has been closed unexpectedly
+server closed the connection unexpectedly
+ This probably means the server terminated abnormally
+ before or while processing the request.
```
I could not come up with a solution that would decrease the flakiness in the test outputs. We already have 3 output files for the same test and now I introduced a 4th one.
I can also add complex regular expressions that span multiple lines, and normalize these error messages. Feel free to suggest a normalized error message in a comment here.
## Current alternative file contents
`isolation_master_update_node.out`
```
step s1-abort: ABORT;
FATAL: terminating connection due to administrator command
FATAL: terminating connection due to administrator command
SSL connection has been closed unexpectedly
```
`isolation_master_update_node_0.out`
```
step s1-abort: ABORT;
WARNING: this step had a leftover error message
FATAL: terminating connection due to administrator command
server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
```
`isolation_master_update_node_1.out`
```
step s1-abort: ABORT;
FATAL: terminating connection due to administrator command
SSL connection has been closed unexpectedly
```
new file: `isolation_master_update_node_2.out`
```
step s1-abort: ABORT;
FATAL: terminating connection due to administrator command
server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
```
In the past, for all modifications on the local execution,
we enabled 2PC (with 6a7ed7b309).
This also required us to enable coordinated transactions
via https://github.com/citusdata/citus/pull/4831 .
However, it does have a very substantial impact on the
distributed deadlock detection. The distributed deadlock
detection is designed to avoid single-statement transactions
because they cannot lead to any actual deadlocks.
The implementation is to skip backends without distributed
transactions are assigned. Now that we assign single
statement local executions in the lock graphs, we are
conflicting with the design of distributed deadlock
detection.
In general, we should fix it. However, one might
think that it is not a big deal, even if the processes
show up in the lock graphs, the deadlock detection
should not be causing any false positives. That is
false, unless https://github.com/citusdata/citus/issues/1803
is fixed. Now that local processes are considered as a single
distributed backend, the lock graphs might find:
local execution 1 [tx id: 1] -> any local process [tx id: 0]
any local process [tx id: 0] -> local execution 2 [tx id: 2]
And, decides that there is a distributed deadlock.
This commit is:
(a) right thing to do, as local execuion should not need any
distributed tx id
(b) Eliminates performance issues that might come up with
deadlock detection does a lot of unncessary checks
(c) After moving local execution after the remote execution
via https://github.com/citusdata/citus/pull/4301, the
vauge requirement for assigning distributed tx ids are
already gone.
For some reason search_path is not always set correctly on the worker
when calling a distributed function, this shows up when calling
`insert_document` in our distributed_triggers test. The underlying
reason is currently unknown and warrants deeper investigation.
Currently this test is one of the main causes for random CI failures. So
this change sets the search_path of each function explicitly, to reduce
these failures. So other devs can be more efficient, while I continue
investigating the root cause of this issue.
Also changes explicit `SET citus.enable_unsafe_triggers = false` to
`RESET citus.enable_unsafe_triggers` in passing.
* Separate build of citus.so and citus_columnar.so.
Because columnar code is statically-linked to both modules, it doesn't
make sense to load them both at once.
A subsequent commit will make the modules entirely separate and allow
loading them both simultaneously.
Author: Yanwen Jin
* Separate citus and citus_columnar modules.
Now the modules are independent. Columnar can be loaded by itself, or
along with citus.
Co-authored-by: Jeff Davis <jefdavi@microsoft.com>
The aim of hiding shards is to hide shards from client applications.
Certain bg workers (such as pg_cron or Citus maintanince daemon)
should be treated like client applications because users can run
queries from such bg workers. And, these bg workers should follow
the similar application_name checks as client backeends.
Certain other bg workers, such as logical replication or postgres'
parallel workers, should never hide shards. They are internal
operations.
Similarly the other backend types like the walsender or
checkpointer or autovacuum should never hide shards.
Since now we don't throw an error for enums that user attempts creating
in temp schema, the preprocess / DDL job that contains the prepared
statement (to idempotently create the enum type) gets executed. As a
result, we were emitting the following warning because of the error the
underlying worker connection throws:
```sql
WARNING: cannot PREPARE a transaction that has operated on temporary objects
CONTEXT: while executing command on localhost:xxxxx
WARNING: connection to the remote node localhost:xxxxx failed with the following error: another command is already in progress
ERROR: cannot PREPARE a transaction that has operated on temporary objects
CONTEXT: while executing command on localhost:xxxxx
```
We were already doing so for functions & types believing that
this cannot be the case for other object types.
However, as in #5830, we cannot distribute an object that user
attempts creating in temp schema. Even more, this doesn't only
apply to functions and types but also to many other object types.
So with this commit, we teach preprocess/postprocess functions
(that need to create dependencies on worker nodes) how to skip
trying to distribute such objects.
We also start identifying temp schemas as the objects that we
don't know how to propagate to worker nodes so that we can
simply create objects locally if user attempts creating them
in a temp schema.
There are 36 callers of `EnsureDependenciesExistOnAllNodes` in
the codebase atm and for the most we still need to throw a hard
error (i.e.: not use `DeferErrorIfHasUnsupportedDependency`
beforehand), such as:
i) user explicitly wants to create a distributed object
* CreateCitusLocalTable
* CreateDistributedTable
* master_create_worker_shards
* master_create_empty_shard
* create_distributed_function
* EnsureExtensionFunctionCanBeDistributed
ii) we don't want to skip altering distributed table on worker nodes
* PostprocessIndexStmt
* PostprocessCreateTriggerStmt
* PostprocessCreateStatisticsStmt
iii) object is already distributed / handled by Citus before, so we
aren't okay with not propagating the ALTER command
* PostprocessAlterTableSchemaStmt
* PostprocessAlterCollationOwnerStmt
* PostprocessAlterCollationSchemaStmt
* PostprocessAlterDatabaseOwnerStmt
* PostprocessAlterExtensionSchemaStmt
* PostprocessAlterFunctionOwnerStmt
* PostprocessAlterFunctionSchemaStmt
* PostprocessAlterSequenceOwnerStmt
* PostprocessAlterSequenceSchemaStmt
* PostprocessAlterStatisticsSchemaStmt
* PostprocessAlterStatisticsOwnerStmt
* PostprocessAlterTextSearchConfigurationSchemaStmt
* PostprocessAlterTextSearchDictionarySchemaStmt
* PostprocessAlterTextSearchConfigurationOwnerStmt
* PostprocessAlterTextSearchDictionaryOwnerStmt
* PostprocessAlterTypeSchemaStmt
* PostprocessAlterForeignServerOwnerStmt
iv) we already cannot create those objects in temp schemas, so skipping
for now
* PostprocessCreateExtensionStmt
* PostprocessCreateForeignServerStmt
Also note that there are 3 more callers of
`EnsureDependenciesExistOnAllNodes` in enterprise in addition to those
36 but we don't need to do anything specific about them due to the same
reasoning given in iii).
In `pg_regress_multi.pl` we're running `initdb` with some options that
the `common.py` `initdb` is currently not using. All these flags seem
reasonable, so this brings `common.py` in line with
`pg_regress_multi.pl`.
In passing change the `--nosync` flag to `--no-sync`, since that's what
the PG documentation lists as the official option name (but both work).
Burak Velioglu
Marco Slot
Ahmet Gedemenli
Gledis Zeneli
Hanefi Onaldi
Onder Kalaci
Nils Dijk
Jelte Fennema
jeff-davis
Halil Ozan Akgul
Onur Tirtir