We need to rewind the tuplestorestate's tuple index to get correct
results on fetching scrollable with hold cursors.
`PersistHoldablePortal` is responsible for persisting out
tuplestorestate inside a with hold cursor before commiting a
transaction.
It rewinds the cursor like below (`ExecutorRewindcalls` calls `rescan`):
```c
if (portal->cursorOptions & CURSOR_OPT_SCROLL)
{
ExecutorRewind(queryDesc);
}
```
At the end, it adjusts tuple index for holdStore in the portal properly.
```c
if (portal->cursorOptions & CURSOR_OPT_SCROLL)
{
if (!tuplestore_skiptuples(portal->holdStore,
portal->portalPos,
true))
elog(ERROR, "unexpected end of tuple stream");
}
```
DESCRIPTION: Fixes incorrect results on fetching scrollable with hold
cursors.
Fixes https://github.com/citusdata/citus/issues/7010
(cherry picked from commit f667f14029)
We need to break sequence dependency for a table while creating the
table during non-transactional metadata sync to ensure idempotency of
the creation of the table.
**Problem:**
When we send `SELECT
pg_catalog.worker_drop_sequence_dependency(logicalrelid::regclass::text)
FROM pg_dist_partition` to workers during the non-transactional sync,
table might not be in `pg_dist_partition` at worker, and sequence
dependency is not broken at the worker.
**Solution:**
We break sequence dependency via `SELECT
pg_catalog.worker_drop_sequence_dependency(logicalrelid::regclass::text)`
for each table while creating it at the workers. It is safe to send
since the udf is a no-op when there is no sequence dependency.
DESCRIPTION: Fixes a bug related to sequence idempotency at
non-transactional sync.
Fixes https://github.com/citusdata/citus/issues/6888.
(cherry picked from commit 8cb69cfd13)
Add new metadata sync methods which uses MemorySyncContext api so that during the sync we can
- free memory to prevent OOM,
- use either transactional or nontransactional modes according to the GUC .
This pull request proposes a change to the logic used for propagating
identity columns to worker nodes in citus. Instead of creating a
dependent sequence for each identity column and changing its default
value to `nextval(seq)/worker_nextval(seq)`, this update will pass the
identity columns as-is to the worker nodes.
Please note that there are a few limitations to this change.
1. Only bigint identity columns will be allowed in distributed tables to
ensure compatibility with the DDL from any node functionality. Our
current distributed sequence implementation only allows insert
statements from all nodes for bigint sequences.
2. `alter_distributed_table` and `undistribute_table` operations will
not be allowed for tables with identity columns. This is because we do
not have a proper way of keeping sequence states consistent across the
cluster.
DESCRIPTION: Prevents using identity columns on data types other than
`bigint` on distributed tables
DESCRIPTION: Prevents using `alter_distributed_table` and
`undistribute_table` UDFs when a table has identity columns
DESCRIPTION: Fixes a bug that prevents enforcing identity column
restrictions on worker nodes
Depends on #6740Fixes#6694
Description:
Implementing CDC changes using Logical Replication to avoid
re-publishing events multiple times by setting up replication origin
session, which will add "DoNotReplicateId" to every WAL entry.
- shard splits
- shard moves
- create distributed table
- undistribute table
- alter distributed tables (for some cases)
- reference table operations
The citus decoder which will be decoding WAL events for CDC clients,
ignores any WAL entry with replication origin that is not zero.
It also maps the shard names to distributed table names.
Decide core distribution params in CreateCitusTable to reduce the
chances of
creating Citus tables based on incorrect combinations of distribution
method
and replication model params.
Also introduce DistributedTableParams struct to encapsulate the
parameters
that are specific to distributed tables.
Now that we will soon add another table type having DISTRIBUTE_BY_NONE
as distribution method and that we want the code to interpret such
tables mostly as distributed tables, let's make the definition of those
other two table types more strict by removing
CITUS_TABLE_WITH_NO_DIST_KEY
macro.
And instead, use HasDistributionKey() check in the places where the
logic applies to all table types that have / don't have a distribution
key. In future PRs, we might want to convert some of those
HasDistributionKey() checks if logic only applies to Citus local /
reference tables, not the others.
And adding HasDistributionKey() also allows us to consider having
DISTRIBUTE_BY_NONE as the distribution method as a "table attribute"
that can apply to distributed tables too, rather something that
determines the table type.
Split the main logic that allows creating a Citus table into the
internal function CreateCitusTable().
Old CreateDistributedTable() function was assuming that it's creating
a reference table when the distribution method is DISTRIBUTE_BY_NONE.
However, soon this won't be the case when adding support for creating
single-shard distributed tables because their distribution method would
also be the same.
Now the internal method CreateCitusTable() doesn't make any assumptions
about table's replication model or such. Instead, it expects callers to
properly set all such metadata bits.
Even more, some of the parameters the old CreateDistributedTable() takes
--such as the shard count-- were not meaningful for a reference table,
and would be the same as for new table type.
2 improvements to prevent memory leaks during altering or undistributing
distributed tables with a lot of partitions and shards:
1. Free memory for each call to ConvertTable so that colocated and partition tables at
`AlterDistributedTable`, `UndistributeTable`, or
`AlterTableSetAccessMethod` will not cause an increase
in memory usage,
2. Free memory while executing attach partition commands for each partition table at
`AlterDistributedTable` to prevent an increase in memory usage.
DESCRIPTION: Fixes memory leak issue during altering distributed table
with a lot of partition and shards.
Fixes https://github.com/citusdata/citus/issues/6503.
We have memory leak during distribution of a table with a lot of
partitions as we do not release memory at ExprContext until all
partitions are not distributed. We improved 2 things to resolve the
issue:
1. We create and delete MemoryContext for each call to
`CreateDistributedTable` by partitions,
2. We rebuild the cache after we insert all the placements instead of
each placement for a shard.
DESCRIPTION: Fixes memory leak during distribution of a table with a lot
of partitions and shards.
Fixes https://github.com/citusdata/citus/issues/6572.
Prevents memory leak during ConvertTable call for a table with a lot of
partitions.
DESCRIPTION: Fixes memory leak during undistribution and alteration of a
table with a lot of partitions.
We should disallow dropping table_name option if foreign table is in
metadata. Otherwise, we get table not found error which contains
shardid.
DESCRIPTION: Fixes an unexpected foreign table error by disallowing to drop the table_name option.
Fixes#6663
DESCRIPTION: Fix foreign key validation skip at the end of shard move
In eadc88a we started completely skipping foreign key constraint
validation at the end of a non blocking shard move, instead of only for
foreign keys to reference tables. However, it turns out that this didn't
work at all because of a hard to notice bug: By resetting the
SkipConstraintValidation flag at the end of our utility hook, we
actually make the SET command that sets it a no-op.
This fixes that bug by removing the code that resets it. This is fine
because #6543 removed the only place where we set the flag in C code. So
the resetting of the flag has no purpose anymore. This PR also adds a
regression test, because it turned out we didn't have any otherwise we
would have caught that the feature was completely broken.
It also moves the constraint validation skipping to the utility hook.
The reason is that #6550 showed us that this is the better place to skip
it, because it will also skip the planning phase and not just the
execution.
Fixes#6655.
heap_modify_tuple() fetches values[i] if replace[i] is set true,
regardless of the fact that whether isnull[i] is true or false. So
similar to replace[], let's init values[] & isnull[] too.
DESCRIPTION: Fixes an uninitialized memory access in
create_distributed_function()
This change allows creating a constraint without a name using an index.
The index name will be used as the constraint name the same way postgres
handles it.
Fixes issue #6644
This commit also cleans up some leftovers from nameless constraint checks.
With this commit, we now fully support adding all nameless constraints
directly to a table.
Co-authored-by: naisila <nicypp@gmail.com>
DESCRIPTION: Fix regression in allowed foreign keys on distributed
tables
In commit eadc88a we changed how we skip foreign key validation. The
goal was to skip it in more cases. However, one change had the
unintended regression of introducing failures when trying to create
certain foreign keys. This reverts that part of the change.
The way of skipping validation of foreign keys that was introduced in
eadc88a was skipping validation during execution. The reason that
this caused this regression was because some foreign key validation
queries already fail during planning. In those cases it never gets to
the execution step where it would later be skipped.
Fixes#6543
DESCRIPTION: Enable adding FOREIGN KEY constraints on Citus tables
without a name
This PR enables adding a foreign key to a distributed/reference/Citus
local table without specifying the name of the constraint, e.g. `ALTER
TABLE items ADD FOREIGN KEY (user_id) REFERENCES users (id);`
DESCRIPTION: Enable adding CHECK constraints on distributed tables
without the client having to provide a constraint name.
This PR enables the following command syntax for adding check
constraints to distributed tables.
ALTER TABLE ... ADD CHECK ...
by creating a default constraint name and transforming the command into
the below syntax before sending it to workers.
ALTER TABLE ... ADD CONSTRAINT \<conname> CHECK ...
DESCRIPTION: Adds support for creating table constraints UNIQUE and
EXCLUDE via ALTER TABLE command without client having to specify a name.
ALTER TABLE ... ADD CONSTRAINT <conname> UNIQUE ...
ALTER TABLE ... ADD CONSTRAINT <conname> EXCLUDE ...
commands require the client to provide an explicit constraint name.
However, in postgres it is possible for clients not to provide a name
and let the postgres generate it using the following commands
ALTER TABLE ... ADD UNIQUE ...
ALTER TABLE ... ADD EXCLUDE ...
This PR enables the same functionality for citus tables.
DESCRIPTION: Support ALTER TABLE .. ADD PRIMARY KEY ... command
Before processing
> **ALTER TABLE ... ADD PRIMARY KEY ...**
command
1. Create a primary key name to use as the constraint name.
2. Change the **ALTER TABLE ... ADD PRIMARY KEY ...** command to into
**ALTER TABLE ... ADD CONSTRAINT \<constraint name> PRIMARY KEY ...**
form.
This is the only form we can specify a name for a primary key. If we run
ALTER TABLE .. ADD PRIMARY KEY, postgres
would create a constraint name internally in its own scheme. But the
problem is that we need to create constraint names
for shards in our own scheme which is \<constraint name>_\<shardid>.
Hence we need to create a name and send it to workers so that the
workers can append the shardid.
4. Run the changed command on the coordinator to make sure we are using
the same constraint name across the board.
5. Send the changed command to workers such that it is executed for the
main table as well as for the shards.
Fixes#6515.
DESCRIPTION: Extend cleanup process for replication artifacts
This PR adds new cleanup record types for:
* Subscriptions
* Replication slots
* Publications
* Users created for subscriptions
We add records for these object types, to `pg_dist_cleanup` during
creation phase. Once the operation is done, in case of success or
failure, we iterate those records and drop the objects. With this PR we
will not be dropping any of these objects during the operation. In
short, we will always be deferring the drop.
One thing that's worth mentioning is that we sort cleanup records before
processing (dropping) them, because of dependency relations among those
objects, e.g a subscription might depend on a publication. Therefore, we
always drop subscriptions before publications.
We have some renames in this PR:
* `TryDropOrphanedShards` -> `TryDropOrphanedResources`
* `DropOrphanedShardsForCleanup` -> `DropOrphanedResourcesForCleanup`
* `run_try_drop_marked_shards` -> `run_try_drop_marked_resources`
as these functions now process replication artifacts as well.
This PR drops function `DropAllLogicalReplicationLeftovers` and its all
usages, since now we rely on the deferring drop mechanism.
DESCRIPTION: Makes sure to disallow triggers that depend on extensions
We were already doing so for `ALTER trigger DEPENDS ON EXTENSION`
commands. However, we also need to disallow creating Citus tables
having such triggers already, so this PR fixes that.
This didn't cause any bugs since today we're always calling
UpdateAutoConvertedForConnectedRelations with autoconverted=false, so we
don't need to backport this to anywhere.
DESCRIPTION: Don't leak search_path to workers on DDL
For DDL we have to set the `search_path` on workers to the same as on
the coordinator for some DDL to work. Previously this search_path would
leak outside of the transaction that was used for the DDL. This fixes
that by using `SET LOCAL` instead of `SET`. The only place where we
still use plain `SET` is for DDL commands that are not allowed within
transactions, such as `CREATE INDEX CONCURRENLTY`.
This fixes this flaky test:
```diff
CONTEXT: SQL statement "SELECT change_id FROM distributed_triggers.data_changes
WHERE shard_key_value = NEW.shard_key_value AND object_id = NEW.object_id
ORDER BY change_id DESC LIMIT 1"
-PL/pgSQL function record_change() line XX at SQL statement
+PL/pgSQL function distributed_triggers.record_change() line 17 at SQL statement
while executing command on localhost:57638
DELETE FROM data_ref_table where shard_key_value = 'hello';
```
Source:
https://app.circleci.com/pipelines/github/citusdata/citus/27849/workflows/75ae5f1a-100b-4b7a-b991-7de069f39ee1/jobs/831429
I had tried to fix this flaky test in #5894 and then I tried
implementing a better fix in #5896, where @marcocitus suggested this
better fix. This change reverts the fix from #5894 and implements the
fix suggested by Marco.
Our multi_mx_alter_distributed_table test actually depended on the old
buggy search_path leaking behavior. After fixing the bug that test would
fail like this:
```diff
CALL proc_0(1.0);
DEBUG: pushing down the procedure
-NOTICE: Res: 3
-DETAIL: from localhost:xxxxx
+ERROR: relation "test_proc_colocation_0" does not exist
+CONTEXT: PL/pgSQL function mx_alter_distributed_table.proc_0(double precision) line 5 at SQL statement
+while executing command on localhost:57637
RESET client_min_messages;
```
I fixed this test by fully qualifying the table names used in the
procedure. I think it's quite unlikely that actual users depend
on this behavior though. Since it would require first doing
DDL before calling a procedure in a session where the
search_path was changed after connecting.
Fixes https://github.com/citusdata/citus/issues/6394.
DESCRIPTION: Fixes a bug that causes creating disabled-triggers on
shards as enabled
Since CREATE TRIGGER doesn't have syntax support to specify
whether the trigger should be enabled/disabled, the underlying
PG function (`pg_get_triggerdef()`) that we use to generate the
command to create the trigger is not enough. For this reason, we
append a second command to enable/disable trigger, right after
creating it.
We don't retain explicit extension dependencies set by using
`ALTER trigger DEPENDS ON EXTENSION` commands too, but apparently
right fix for that is to throw an error as in
`PreprocessAlterTriggerDependsStmt()`; so, opened a separate PR
to fix that #6399.
During alter_distributed_table, we create a new table like the
original table but with the altered options.
To retrieve the name of the distribution column, we were using
the attribute syscache of the new table, since we already created
the new table as identical to the original table.
However, the attribute syscaches of these two tables are not
the same if the original table has dropped columns. The reason
is that dropped columns are all still present in the cache.
Hence, for example, the attnos would be different in the syscaches.
So, let's use the attribute syscache of the original table.
Given that we drop DEFAULT nextval('sequence') expressions from
shard relation columns, allowing `ON DELETE/UPDATE SET DEFAULT`
on such columns might cause inserting NULL values as a result
of a delete/update operation.
For this reason, we disallow ON DELETE/UPDATE SET DEFAULT actions
on columns that default to sequences.
DESCRIPTION: Disallows having ON DELETE/UPDATE SET DEFAULT actions on
columns that default to sequences
Fixes#6339.
As we did for GENERATED STORED columns in #4613, we should not drop
column
default expressions that are not based on sequences from shard relation
since
such expressions need to exist e.g. for foreign key actions.
For the column default expressions that are based on sequences we cannot
do much, so we need to disallow having ON DELETE SET DEFAULT actions on
such columns in a separate PR, see #6339.
Fixes#6318.
DESCRIPTION: Fixes a bug that might cause inserting incorrect DEFAULT
values when applying foreign key actions
DESCRIPTION: Fixes floating exception during
create_distributed_table_concurrently.
Fixes#6332.
During create_distributed_table_concurrently, when there is no active
primary node, it fails with floating exception. We added similar check
with create_distributed_table. It will fail with proper message if
current active node is less than replication factor.
We can now do the following:
- Distribute sequence with logged/unlogged option
- ALTER TABLE my_sequence SET LOGGED/UNLOGGED
- ALTER SEQUENCE my_sequence SET LOGGED/UNLOGGED
Relevant PG commit
344d62fb9a
Onur Tirtir
aykut-bozkurt
Marco Slot
aykutbozkurt
Gokhan Gulbiz
Marco Slot
rajeshkt78
Jelte Fennema
Emel Şimşek
Naisila Puka
Gürkan İndibay
songjinzhou
Ahmet Gedemenli
Philip Dubé