This PR fixes an issue #7891 in the Citus planner where an `UPDATE` on a
local table with a subquery referencing a reference table could produce
a 0-task plan. Historically, the planner sometimes failed to detect that
both the target and referenced tables were effectively “local,”
assigning `INVALID_SHARD_ID `and yielding a no-op plan.
### Root Cause
- In the Citus router logic (`PlanRouterQuery`), we relied on `shardId`
to determine whether a query should be routed to a single shard.
- If `shardId == INVALID_SHARD_ID`, but we also had not marked the query
as a “local table modification,” the code path would produce zero tasks.
- Local + reference tables do not require multi-shard routing. Failing
to detect this “purely local” scenario caused Citus to incorrectly route
to zero tasks.
### Changes
**Enhanced Local Table Detection**
- Updated `IsLocalTableModification` and related checks to consider both
local and reference tables as “local” for planning, preventing the
0-task scenario.
- Expanded `ContainsOnlyLocalOrReferenceTables` to return true if there
are no fully distributed tables in the query.
**Added Regress Test**
- Introduced a new regress test (`issue_7891.sql`) which reproduces the
scenario.
- Verifies we get a valid single- or local-task plan rather than a
0-task plan.
DESCRIPTION: Ensure that a MERGE command on a distributed table with a
`WHEN NOT MATCHED BY SOURCE` clause runs against all shards of the
distributed table.
The Postgres MERGE command updates a table using a table or a query as a
data source. It provides three ways to match the target table with the
source: `WHEN MATCHED` means that there is a row in both the target and
source; `WHEN NOT MATCHED` means that there is a row in the source that
has no match (is not present) in the target; and, as of PG17, `WHEN NOT
MATCHED BY SOURCE` means that there is a row in the target that has no
match in the source.
In Citus, when a MERGE command updates a distributed table using a
local/reference table or a distributed query as source, that source is
repartitioned, and for each repartitioned shard that has data (i.e. 1 or
more rows) the MERGE is run against the corresponding distributed table
shard. Suppose the distributed table has 32 shards, and the source
repartitions into 4 shards that have data, with the remaining 28 shards
being empty; then the MERGE command is performed on the 4 corresponding
shards of the distributed table. However, the semantics of `WHEN NOT
MATCHED BY SOURCE` are that the specified action must be performed on
the target for each row in the target that is not in the source; so if
the source is empty, all target rows should be updated. To see this,
consider the following MERGE command:
```
MERGE INTO target AS t
USING source AS s ON t.id = s.id
WHEN NOT MATCHED BY SOURCE THEN UPDATE t SET t.col1 = 100
```
If the source has zero rows then every row in the target is updated s.t.
its col1 value is 100. Currently in Citus a MERGE on a distributed table
with a local/reference table or a distributed query as source ignores
shards of the distributed table when the corresponding shard of the
repartitioned source has zero rows. However, if the MERGE command
specifies a `WHEN NOT MATCHED BY SOURCE` clause, then the MERGE should
be performed on all shards of the distributed table, to ensure that the
specified action is performed on the target for each row in the target
that is not in the source. This PR enhances Citus MERGE execution so
that when a repartitioned source shard has zero rows, and the MERGE
command specifies a `WHEN NOT MATCHED BY SOURCE` clause, the MERGE is
performed against the corresponding shard of the distributed table using
an empty (zero row) relation as source, by generating a query of the
form:
```
MERGE INTO target_shard_0002 AS t
USING (SELECT id FROM (VALUES (NULL) ) source_0002(id) WHERE FALSE) AS s ON t.id = s.id
WHEN NOT MATCHED BY SOURCE THEN UPDATE t set t.col1 = 100
```
This works because each row in the target shard will be updated, and
`WHEN MATCHED` and `WHEN NOT MATCHED`, if specified, will be no-ops
because the source has zero rows.
To implement this when the source is a local or reference table involves
teaching function `ExcuteSourceAtCoordAndRedistribution()` in
`merge_executor.c` to not prune tasks when the query has `WHEN NOT
MATCHED BY SOURCE` but to instead replace the task's query to one that
uses an empty relation as source. And when the source is a distributed
query, function
`ExecuteMergeSourcePlanIntoColocatedIntermediateResults()` (also in
`merge_executor.c`) instead of skipping empty tasks now generates a
query that uses an empty relation as source for the corresponding target
shard of the distributed table, but again only when the query has `WHEN
NOT MATCHED BY SOURCE`. A new function `BuildEmptyResultQuery()` is
added to `recursive_planning.c` and it is used by both the
aforementioned functions in `merge_executor.c` to build an empty
relation to use as the source. It applies the appropriate type to each
column of the empty relation so the join with the target makes sense to
the query compiler.
DESCRIPTION: Drops PG14 support
1. Remove "$version_num" != 'xx' from configure file
2. delete all PG_VERSION_NUM = PG_VERSION_XX references in the code
3. Look at pg_version_compat.h file, remove all _compat functions etc
defined specifically for PGXX differences
4. delete all PG_VERSION_NUM >= PG_VERSION_(XX+1), PG_VERSION_NUM <
PG_VERSION_(XX+1) ifs in the codebase
5. delete ruleutils_xx.c file
6. cleanup normalize.sed file from pg14 specific lines
7. delete all alternative output files for that particular PG version,
server_version_ge variable helps here
DESCRIPTION: Adds JSON_TABLE() support
PG17 has added basic `JSON_TABLE()` functionality
`JSON_TABLE()` allows `JSON` data to be converted into a relational view
and thus used, for example, in a `FROM` clause, like other tabular data.
We treat `JSON_TABLE` the same as correlated functions (e.g., recurring
tuples). In the end, for multi-shard `JSON_TABLE` commands, we apply the
same restrictions as reference tables (e.g., cannot perform a lateral
outer join when a distributed subquery references a (reference
table)/(json table) etc.)
Relevant PG17 commits:
[basic JSON
table](https://github.com/postgres/postgres/commit/de3600452), [nested
paths in json
table](https://github.com/postgres/postgres/commit/bb766cde6)
Onder had previously added json table support for PG15BETA1, but we
reverted that commit because json table was reverted in PG15.
ce7f1a530f
Previous relevant PG15Beta1 commit:
https://github.com/postgres/postgres/commit/4e34747c8
Therefore, I referred to Onder's commit for this commit as well, with a
few changes due to some differences between PG15/PG17:
1) In PG15Beta1, we had also `PLAN` clauses for `JSON_TABLE`
https://github.com/postgres/postgres/commit/fadb48b00, and Onder's
commit includes tests for those as well. However, `PLAN` nodes are _not_
added in PG17. Therefore, I didn't include the `json_table_select_only`
test, which had mostly queries involving `PLAN`. I only included the
last query from that test.
2) In PG15 timeline (Citus 11.1), we didn't support outer joins where
the outer rel is a recurring one and the inner one is a non-recurring
one. However, [Onur added support for that one in Citus
11.2](https://github.com/citusdata/citus/pull/6512), therefore I updated
the tests from Onder's commit accordingly.
3) PG17 json table has nested paths and columns, therefore I added a
test
with a distributed table, which is exactly the same as the one in
sqljson_jsontable in PG17.
https://github.com/postgres/postgres/commit/bb766cde6
This pull request also adds some basic tests on validation of SQL/JSON
constructor functions JSON(), JSON_SCALAR(), and JSON_SERIALIZE(),
and also SQL/JSON query functions JSON_EXISTS(), JSON_QUERY(), and
JSON_VALUE(). The relevant PG commits are the following:
[JSON(), JSON_SCALAR(),
JSON_SERIALIZE()](https://github.com/postgres/postgres/commit/03734a7fe)
[JSON_EXISTS(), JSON_VALUE(),
JSON_QUERY()](https://github.com/postgres/postgres/commit/6185c9737)
- Adapted `pgmerge.sql` tests from PostgreSQL community's `merge.sql` to
Citus by converting tables into Citus local tables.
- Identified two new PostgreSQL 17 MERGE features (`RETURNING` support
and MERGE on updatable views) not yet supported by Citus.
- Implemented changes to detect unsupported features and raise clean
exceptions, ensuring pgmerge tests pass without diffs.
- Addressed breaking changes caused by `MERGE ... WHEN NOT MATCHED BY
SOURCE` restructuring, reducing diffs in pgmerge tests.
- Segregated unsupported test cases into `merge_unsupported.sql` to
maintain clarity and avoid large diffs in test files.
- Prepared the Citus MERGE planner to handle new PostgreSQL changes,
reducing remaining test discrepancies.
All merge tests now pass cleanly, with unsupported cases clearly
isolated.
Relevant PG commits:
c649fa24a
https://github.com/postgres/postgres/commit/c649fa24a
0294df2f1
https://github.com/postgres/postgres/commit/0294df2f1
---------
Co-authored-by: naisila <nicypp@gmail.com>
This is prep work for successful compilation with PG17
PG17added foreach_ptr, foreach_int and foreach_oid macros
Relevant PG commit
14dd0f27d7cd56ffae9ecdbe324965073d01a9ff
14dd0f27d7
We already have these macros, but they are different with the
PG17 ones because our macros take a DECLARED variable, whereas
the PG16 macros declare a locally-scoped loop variable themselves.
Hence I am renaming our macros to foreach_declared_
I am separating this into its own PR since it touches many files. The
main compilation PR is https://github.com/citusdata/citus/pull/7699
DESCRIPTION: Fixes a crash that happens because of unsafe catalog access
when re-assigning the global pid after application_name changes.
When application_name changes, we don't actually need to
try re-assigning the global pid for external client backends because
application_name doesn't affect the global pid for such backends. Plus,
trying to re-assign the global pid for external client backends would
unnecessarily cause performing a catalog access when the cached local
node id is invalidated. However, accessing to the catalog tables is
dangerous in certain situations like when we're not in a transaction
block. And for the other types of backends, i.e., the Citus internal
backends, we need to re-assign the global pid when the application_name
changes because for such backends we simply extract the global pid
inherited from the originating backend from the application_name -that's
specified by originating backend when openning that connection- and this
doesn't require catalog access.
DESCRIPTION: Fix performance issue when creating distributed tables if
many already exist
This builds on the work to speed up EnsureSequenceTypeSupported, and now
does something similar for SequenceUsedInDistributedTable.
SequenceUsedInDistributedTable had a similar O(number of citus tables)
operation. This fixes that and speeds up creation of distributed tables
significantly when many distributed tables already exist.
Fixes#7022
DESCRIPTION: Fix performance issue when creating distributed tables and many already exist
EnsureSequenceTypeSupported was doing an O(number of distributed tables)
operation. This can become very slow with lots of Citus tables, which
now happens much more frequently in practice due to schema based sharding.
Partially addresses #7022
DESCRIPTION: Fixes a crash caused by some form of ALTER TABLE ADD COLUMN
statements. When adding multiple columns, if one of the ADD COLUMN
statements contains a FOREIGN constraint ommitting the referenced
columns in the statement, a SEGFAULT occurs.
For instance, the following statement results in a crash:
```
ALTER TABLE lt ADD COLUMN new_col1 bool,
ADD COLUMN new_col2 int references rt;
```
Fixes#7520.
RunPreprocessNonMainDBCommand and RunPostprocessNonMainDBCommand are
the entrypoints for this module. These functions are called from
utility_hook.c to support some of the node-wide object management
commands from non-main databases.
To add support for a new command type, one needs to define a new
NonMainDbDistributeObjectOps object and add it to
GetNonMainDbDistributeObjectOps.
In preprocess phase, we save the original database name, replace
dbname field of CreatedbStmt with a temporary name (to let Postgres
to create the database with the temporary name locally) and then
we insert a cleanup record for the temporary database name on all
nodes **(\*\*)**.
And in postprocess phase, we first rename the temporary database
back to its original name for local node and then return a list of
distributed DDL jobs i) to create the database with the temporary
name and then ii) to rename it back to its original name on other
nodes. That way, if CREATE DATABASE fails on any of the nodes, the
temporary database will be cleaned up by the cleanup records that
we inserted in preprocess phase and in case of a failure, we won't
leak any databases called as the name that user intended to use for
the database.
Solves the problem documented in
https://github.com/citusdata/citus/issues/7369
for CREATE DATABASE commands.
**(\*\*):** To ensure that we insert cleanup records on all nodes,
with this PR we also start requiring having the coordinator in the
metadata because otherwise we would skip inserting a cleanup record
for the coordinator.
DESCRIPTION: Adds support for distributed `CREATE/DROP DATABASE `
commands from the databases where Citus is not installed
---------
Co-authored-by: Onur Tirtir <onurcantirtir@gmail.com>
Rename InsertCleanupRecordInCurrentTransaction ->
InsertCleanupOnSuccessRecordInCurrentTransaction and hardcode policy
type as CLEANUP_DEFERRED_ON_SUCCESS.
Rename InsertCleanupRecordInSubtransaction ->
InsertCleanupRecordOutsideTransaction.
Moves the following functions to the Citus internal schema:
citus_internal_local_blocked_processes
citus_internal_global_blocked_processes
citus_internal_mark_node_not_synced
citus_internal_unregister_tenant_schema_globally
citus_internal_update_none_dist_table_metadata
citus_internal_update_placement_metadata
citus_internal_update_relation_colocation
citus_internal_start_replication_origin_tracking
citus_internal_stop_replication_origin_tracking
citus_internal_is_replication_origin_tracking_active
#7405
---------
Co-authored-by: Jelte Fennema-Nio <jelte.fennema@microsoft.com>
Since Postgres commit da9b580d files and directories are supposed to
be created with pg_file_create_mode and pg_dir_create_mode permissions
when default permissions are expected.
This fixes a failure of one of the postgres tests:
If we create file add.conf containing
```
shared_preload_libraries='citus'
```
and run postgres tests
```
TEMP_CONFIG=/path/to/add.conf make installcheck -C src/bin/pg_ctl/
```
then 001_start_stop.pl fails with
```
.../data/base/pgsql_job_cache mode must be 0750
```
in the log.
In passing this also stops creating directories that we haven't used
since Citus 7.4
This change explicitely doesn't change permissions of certificates/keys
that we create.
---------
Co-authored-by: Karina Litskevich <litskevichkarina@gmail.com>
This PR makes the connections to other nodes for
`mark_object_distributed` use the same user as
`execute_command_on_remote_nodes_as_user` so they'll use the same
connection.
postgres refactored newNode() in PG 17, the main point for doing this is
the original tricks is no longer neccessary for modern compilers[1].
This does the same for Citus.
This should have no backward compatibility issues since it just replaces
palloc0fast with palloc0.
This is good for forward compatibility since palloc0fast no longer
exists in PG 17.
[1]
https://www.postgresql.org/message-id/b51f1fa7-7e6a-4ecc-936d-90a8a1659e7c@iki.fi
DESCRIPTION: Adds comment on database and role propagation.
Example commands are as below
comment on database <db_name> is '<comment_text>'
comment on database <db_name> is NULL
comment on role <role_name> is '<comment_text>'
comment on role <role_name> is NULL
---------
Co-authored-by: Jelte Fennema-Nio <jelte.fennema@microsoft.com>
Running a query from a Citus non-main database that inserts to
pg_dist_object requires a new connection to the main database itself.
This PR adds that connection to the main database.
---------
Co-authored-by: Jelte Fennema-Nio <github-tech@jeltef.nl>
DESCRIPTION: Adds support for issuing `CREATE`/`DROP` DATABASE commands
from worker nodes
With this commit, we allow issuing CREATE / DROP DATABASE commands from
worker nodes too.
As in #7278, this is not allowed when the coordinator is not added to
metadata because we don't ever sync metadata changes to coordinator
when adding coordinator to the metadata via
`SELECT citus_set_coordinator_host('<hostname>')`, or equivalently, via
`SELECT citus_add_node(<coordinator_node_name>, <coordinator_node_port>, 0)`.
We serialize database management commands by acquiring a Citus specific
advisory lock on the first primary worker node if there are any workers in the
cluster. As opposed to what we've done in https://github.com/citusdata/citus/pull/7278
for role management commands, we try to avoid from running into distributed deadlocks
as much as possible. This is because, while distributed deadlocks that can happen around
role management commands can be detected by Citus, this is not the case for database
management commands because most of them cannot be run inside in a transaction block.
In that case, Citus cannot even detect the distributed deadlock because the command is not
part of a distributed transaction at all, then the command execution might not return the
control back to the user for an indefinite amount of time.
DESCRIPTION: Adds REASSIGN OWNED BY propagation
This pull request introduces the propagation of the "Reassign owned by"
statement. It accommodates both local and distributed roles for both the
old and new assignments. However, when the old role is a local role, it
undergoes filtering and is not propagated. On the other hand, if the new
role is a local role, the process involves first creating the role on
worker nodes before propagating the "Reassign owned" statement.
DESCRIPTION: Adds database connection limit, rename and set tablespace
propagation
In this PR, below statement propagations are added
alter database <database_name> with allow_connections = <boolean_value>;
alter database <database_name> rename to <database_name2>;
alter database <database_name> set TABLESPACE <table_space_name>
---------
Co-authored-by: Jelte Fennema-Nio <github-tech@jeltef.nl>
Co-authored-by: Jelte Fennema-Nio <jelte.fennema@microsoft.com>
Co-authored-by: Onur Tirtir <onurcantirtir@gmail.com>
DESCRIPTION: Adds support for 2PC from non-Citus main databases
This PR only adds support for `CREATE USER` queries, other queries need
to be added. But it should be simple because this PR creates the
underlying structure.
Citus main database is the database where the Citus extension is
created. A non-main database is all the other databases that are in the
same node with a Citus main database.
When a `CREATE USER` query is run on a non-main database we:
1. Run `start_management_transaction` on the main database. This
function saves the outer transaction's xid (the non-main database
query's transaction id) and marks the current query as main db command.
2. Run `execute_command_on_remote_nodes_as_user("CREATE USER
<username>", <username to run the command>)` on the main database. This
function creates the users in the rest of the cluster by running the
query on the other nodes. The user on the current node is created by the
query on the outer, non-main db, query to make sure consequent commands
in the same transaction can see this user.
3. Run `mark_object_distributed` on the main database. This function
adds the user to `pg_dist_object` in all of the nodes, including the
current one.
This PR also implements transaction recovery for the queries from
non-main databases.
This change adds a script to programatically group all includes in a
specific order. The script was used as a one time invocation to group
and sort all includes throught our formatted code. The grouping is as
follows:
- System includes (eg. `#include<...>`)
- Postgres.h (eg. `#include "postgres.h"`)
- Toplevel imports from postgres, not contained in a directory (eg.
`#include "miscadmin.h"`)
- General postgres includes (eg . `#include "nodes/..."`)
- Toplevel citus includes, not contained in a directory (eg. `#include
"citus_verion.h"`)
- Columnar includes (eg. `#include "columnar/..."`)
- Distributed includes (eg. `#include "distributed/..."`)
Because it is quite hard to understand the difference between toplevel
citus includes and toplevel postgres includes it hardcodes the list of
toplevel citus includes. In the same manner it assumes anything not
prefixed with `columnar/` or `distributed/` as a postgres include.
The sorting/grouping is enforced by CI. Since we do so with our own
script there are not changes required in our uncrustify configuration.
DESCRIPTION: Adds support for propagating `CREATE`/`DROP` database
In this PR, create and drop database support is added.
For CREATE DATABASE:
* "oid" option is not supported
* specifying "strategy" to be different than "wal_log" is not supported
* specifying "template" to be different than "template1" is not
supported
The last two are because those are not saved in `pg_database` and when
activating a node, we cannot assume what parameters were provided when
creating the database.
And "oid" is not supported because whether user specified an arbitrary
oid when creating the database is not saved in pg_database and we want
to avoid from oid collisions that might arise from attempting to use an
auto-assigned oid on workers.
Finally, in case of node activation, GRANTs for the database are also
propagated.
---------
Co-authored-by: Jelte Fennema-Nio <github-tech@jeltef.nl>
Co-authored-by: Jelte Fennema-Nio <jelte.fennema@microsoft.com>
Co-authored-by: Onur Tirtir <onurcantirtir@gmail.com>
We propagate `SECURITY LABEL [for provider] ON ROLE rolename IS
labelname` to the worker nodes.
We also make sure to run the relevant `SecLabelStmt` commands on a
newly added node by looking at roles found in `pg_shseclabel`.
See official docs for explanation on how this command works:
https://www.postgresql.org/docs/current/sql-security-label.html
This command stores the role label in the `pg_shseclabel` catalog table.
This commit also fixes the regex string in
`check_gucs_are_alphabetically_sorted.sh` script such that it escapes
the dot. Previously it was looking for all strings starting with "citus"
instead of "citus." as it should.
To test this feature, I currently make use of a special GUC to control
label provider registration in PG_init when creating the Citus extension.
DESCRIPTION: Adds support from issuing role management commands from worker nodes
It's unlikely to get into a distributed deadlock with role commands, we
don't care much about them at the moment.
There were several attempts to reduce the chances of a deadlock but we
didn't any of them merged into main branch yet, see:
#7325#7016#7009
I just enhanced the existing code to check if the relation is an index
belonging to a distributed table.
If so the shardId is appended to relation (index) name and the *_size
function are executed as before.
There is a change in an extern function:
`extern StringInfo GenerateSizeQueryOnMultiplePlacements(...)`
It's possible to create a new function and deprecate this one later if
compatibility is an issue.
Fixes https://github.com/citusdata/citus/issues/6496.
DESCRIPTION: Allows using Citus size functions on distributed tables
indexes.
---------
Co-authored-by: Onur Tirtir <onurcantirtir@gmail.com>
DESCRIPTION: This change starts a maintenance deamon at the time of
server start if there is a designated main database.
This is the code flow:
1. User designates a main database:
`ALTER SYSTEM SET citus.main_db = "myadmindb";`
2. When postmaster starts, in _PG_Init, citus calls
`InitializeMaintenanceDaemonForMainDb`
This function registers a background worker to run
`CitusMaintenanceDaemonMain `with `databaseOid = 0 `
3. `CitusMaintenanceDaemonMain ` takes some special actions when
databaseOid is 0:
- Gets the citus.main_db value.
- Connects to the citus.main_db
- Now the `MyDatabaseId `is available, creates a hash entry for it.
- Then follows the same control flow as for a regular db,
DESCRIPTION: Fix leaking of memory and memory contexts in Foreign
Constraint Graphs
Previously, every time we (re)created the Foreign Constraint
Relationship Graph, we created a new Memory Context while loosing a
reference to the previous context. This old context could still have
left over memory in there causing a memory leak.
With this patch we statically have one memory context that we lazily
initialize the first time we create our foreign constraint relationship
graph. On every subsequent creation, beside destroying our previous
hashmap we also reset our memory context to remove any left over
references.
DESCRIPTION: Adds support for ALTER DATABASE <db_name> SET .. statement
propagation
SET statements in Postgres has a common structure which is already being
used in Alter Function
statement.
In this PR, I added a util file; citus_setutils and made it usable for
both for
alter database<db_name>set .. and alter function ... set ... statements.
With this PR, below statements will be propagated
```sql
ALTER DATABASE name SET configuration_parameter { TO | = } { value | DEFAULT }
ALTER DATABASE name SET configuration_parameter FROM CURRENT
ALTER DATABASE name RESET configuration_parameter
ALTER DATABASE name RESET ALL
```
Additionally, there was a bug in processing float values in the common
code block.
I fixed this one as well
Previous
```C
case T_Float:
{
appendStringInfo(buf, " %s", strVal(value));
break;
}
```
Now
```C
case T_Float:
{
appendStringInfo(buf, " %s", nodeToString(value));
break;
}
```
DESCRIPTION: Adds ALTER DATABASE WITH ... and REFRESH COLLATION VERSION
support
This PR adds supports for basic ALTER DATABASE statements propagation
support. Below statements are supported:
ALTER DATABASE <database_name> with IS_TEMPLATE <true/false>;
ALTER DATABASE <database_name> with CONNECTION LIMIT <integer_value>;
ALTER DATABASE <database_name> REFRESH COLLATION VERSION;
---------
Co-authored-by: Jelte Fennema-Nio <jelte.fennema@microsoft.com>
Add citus_schema_move() that can be used to move tenant tables within a distributed
schema to another node. The function has two variations as simple wrappers around
citus_move_shard_placement() and citus_move_shard_placement_with_nodeid() respectively.
They pick a shard that belongs to the given tenant schema and resolve the source node
that contain the shards under given tenant schema. Hence their signatures are quite
similar to underlying functions:
```sql
-- citus_schema_move(), using target node name and node port
CREATE OR REPLACE FUNCTION pg_catalog.citus_schema_move(
schema_id regnamespace,
target_node_name text,
target_node_port integer,
shard_transfer_mode citus.shard_transfer_mode default 'auto')
RETURNS void
LANGUAGE C STRICT
AS 'MODULE_PATHNAME', $$citus_schema_move$$;
-- citus_schema_move(), using target node id
CREATE OR REPLACE FUNCTION pg_catalog.citus_schema_move(
schema_id regnamespace,
target_node_id integer,
shard_transfer_mode citus.shard_transfer_mode default 'auto')
RETURNS void
LANGUAGE C STRICT
AS 'MODULE_PATHNAME', $$citus_schema_move_with_nodeid$$;
```
**Problem:**
Previously we always used an outside superuser connection to overcome
permission issues for the current user while propagating dependencies.
That has mainly 2 problems:
1. Visibility issues during dependency propagation, (metadata connection
propagates some objects like a schema, and outside transaction does not
see it and tries to create it again)
2. Security issues (it is preferrable to use current user's connection
instead of extension superuser)
**Solution (high level):**
Now, we try to make a smarter decision on whether should we use an
outside superuser connection or current user's metadata connection. We
prefer using current user's connection if any of the objects, which is
already propagated in the current transaction, is a dependency for a
target object. We do that since we assume if current user has
permissions to create the dependency, then it can most probably
propagate the target as well.
Our assumption is expected to hold most of the times but it can still be
wrong. In those cases, transaction would fail and user should set the
GUC `citus.create_object_propagation` to `deferred` to work around it.
**Solution:**
1. We track all objects propagated in the current transaction (we can
handle subtransactions),
2. We propagate dependencies via the current user's metadata connection
if any dependency is created in the current transaction to address
issues listed above. Otherwise, we still use an outside superuser
connection.
DESCRIPTION: Fixes some object propagation errors seen with transaction
blocks.
Fixes https://github.com/citusdata/citus/issues/6614
---------
Co-authored-by: Nils Dijk <nils@citusdata.com>
For a database that does not create the citus extension by running
` CREATE EXTENSION citus;`
`CitusHasBeenLoaded ` function ends up querying the `pg_extension` table
every time it is invoked. This is not an ideal situation for a such a
database.
The idea in this PR is as follows:
### A new field in MetadataCache.
Add a new variable `extensionCreatedState `of the following type:
```
typedef enum ExtensionCreatedState
{
UNKNOWN = 0,
CREATED = 1,
NOTCREATED = 2,
} ExtensionCreatedState;
```
When the MetadataCache is invalidated, `ExtensionCreatedState` will be
set to UNKNOWN.
### Invalidate MetadataCache when CREATE/DROP/ALTER EXTENSION citus
commands are run.
- Register a callback function, named
`InvalidateDistRelationCacheCallback`, for relcache invalidation during
the shared library initialization for `citus.so`. This callback function
is invoked in all the backends whenever the relcache is invalidated in
one of the backends. (This could be caused many DDLs operations).
- In the cache invalidation callback,`
InvalidateDistRelationCacheCallback`, invalidate `MetadataCache` zeroing
it out.
- In `CitusHasBeenLoaded`, perform the costly citus is loaded check only
if the `MetadataCache` is not valid.
### Downsides
Any relcache invalidation (caused by various DDL operations) will case
Citus MetadataCache to get invalidated. Most of the time it will be
unnecessary. But we rely on that DDL operations on relations will not be
too frequent.
Cédric Villemain
naisila
Mehmet YILMAZ
Colm
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Teja Mupparti
Onur Tirtir
Parag Jain
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Emel Şimşek
Halil Ozan Akgül
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Karina
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Gürkan İndibay
Nils Dijk
Cédric Villemain
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