This commit aims to add a comprehensive guide that covers all
essential aspects of Citus, including planning, execution,
locking mechanisms, shard moves, 2PC, and many other major
components of Citus.
Co-authored-by: Marco Slot <marco.slot@gmail.com>
Co-authored-by: Onder Kalaci <onderkalaci@gmail.com>
When cdc got added the makefiles hardcoded the `.so` extension instead
of using the platform specifc `$(DLSUFFIX)` variable used by `pgxs.mk`.
Also don't remove installed cdc artifacts on `make clean`.
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>
We currently don't support propagating these options in Citus
Relevant PG commits:
https://github.com/postgres/postgres/commit/e3ce2dehttps://github.com/postgres/postgres/commit/3d14e17
Limitation:
We also need to take care of generated GRANT statements by dependencies
in attempt to distribute something else. Specifically, this part of the
code in `GenerateGrantRoleStmtsOfRole`:
```
grantRoleStmt->admin_opt = membership->admin_option;
```
In PG16, membership also has `inherit_option` and `set_option` which
need to properly be part of the `grantRoleStmt`. We can skip for now
since #7164 will take care of this soon, and also this is not an
expected use-case.
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', $$citus_schema_move_with_nodeid$$;
```
Since in PG16, truncate triggers are supported on foreign tables, we add
the citus_truncate_trigger to Citus foreign tables as well, such that the TRUNCATE
command is propagated to the table's single local shard as well.
Note that TRUNCATE command was working for foreign tables even before this
commit: see https://github.com/citusdata/citus/pull/7170#issuecomment-1706240593 for details
This commit also adds tests with user-enabled truncate triggers on Citus foreign tables:
both trigger on the shell table and on its single foreign local shard.
Relevant PG commit:
https://github.com/postgres/postgres/commit/3b00a94
**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.
When braking a colocation, we need to create a new colocation group
record in pg_dist_colocation for the relation. It is not sufficient to
have a new colocationid value in pg_dist_partition only.
This patch also fixes a bug when deleting a colocation group if no
tables are left in it. Previously we passed a relation id as a parameter
to DeleteColocationGroupIfNoTablesBelong function, where we should have
passed a colocation id.
onderkalaci
Marco Slot
Marco Slot
Onur Tirtir
Nils Dijk
Gürkan İndibay
aykut-bozkurt
Naisila Puka
zhjwpku
Emel Şimşek
Hanefi Onaldi
Ivan Vyazmitinov