* 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>
1) Remove useless columns
2) Show backends that are blocked on a DDL even before
gpid is assigned
3) One minor bugfix, where we clear distributedCommandOriginator
properly.
* [Columnar] Build columnar.so and let citus depends on it
Co-authored-by: Yanwen Jin <yanwjin@microsoft.com>
Co-authored-by: Ying Xu <32597660+yxu2162@users.noreply.github.com>
Co-authored-by: jeff-davis <Jeffrey.Davis@microsoft.com>
DESCRIPTION: Add GUC to control ddl creation behaviour in transactions
Historically we would _not_ propagate objects when we are in a transaction block. Creation of distributed tables would not always work in sequential mode, hence objects created in the same transaction as distributing a table that would use the just created object wouldn't work. The benefit was that the user could still benefit from parallelism.
Now that the creation of distributed tables is supported in sequential mode it would make sense for users to force transactional consistency of ddl commands for distributed tables. A transaction could switch more aggressively to sequential mode when creating new objects in a transaction.
We don't change the default behaviour just yet.
Also, many objects would not even propagate their creation when the transaction was already set to sequential, leaving the probability of a self deadlock. The new policy checks solve this discrepancy between objects as well.
The low-level StoreAllActiveTransactions() function filters out
backends that exited.
Before this commit, if you run a pgbench, after that you'd still
see the backends show up:
```SQL
select count(*) from get_global_active_transactions();
┌───────┐
│ count │
├───────┤
│ 538 │
└───────┘
```
After this patch, only active backends show-up:
```SQL
select count(*) from get_global_active_transactions();
┌───────┐
│ count │
├───────┤
│ 72 │
└───────┘
```
With https://github.com/citusdata/citus/pull/5657, Citus uses
a fixed application_name while connecting to remote nodes
for internal purposes.
It means that we cannot allow users to override it via
citus.node_conninfo.
Removed dependency for EnsureTableOwner. Also removed pg_fini() and columnar_tableam_finish() Still need to remove CheckCitusVersion dependency to make Columnar_tableam.h dependency free from Citus.
Replaces citus.enable_object_propagation with citus.enable_metadata_sync
Also, within Citus 11 release cycle, we added citus.enable_metadata_sync_by_default,
that is also replaced with citus.enable_metadata_sync.
In essence, when citus.enable_metadata_sync is set to true, all the objects
and the metadata is send to the remote node.
We strongly advice that the users never changes the value of
this GUC.
multi_log_hook() hook is called by EmitErrorReport() when emitting the
ereport either to frontend or to the server logs. And some callers of
EmitErrorReport() (e.g.: errfinish()) seems to assume that string fields
of given ErrorData object needs to be freed. For this reason, we copy the
message into heap here.
I don't think we have faced with such a problem before but it seems worth
fixing as it is theoretically possible due to the reasoning above.
Simply applies
```SQL
SELECT textlike(command, citus.grep_remote_commands)
```
And, if returns true, the command is logged. Else, the log is ignored.
When citus.grep_remote_commands is empty string, all commands are
logged.
- [x] Add some more regression test coverage
- [x] Make sure returning works fine in case of
local execution + remote execution
(task->partiallyLocalOrRemote works as expected, already added tests)
- [x] Implement locking properly (and add isolation tests)
- [x] We do #shardcount round-trips on `SerializeNonCommutativeWrites`.
We made it a single round-trip.
- [x] Acquire locks for subselects on the workers & add isolation tests
- [x] Add a GUC to prevent modification from the workers, hence increase the
coordinator-only throughput
- The performance slightly drops (~%15), unless
`citus.allow_modifications_from_workers_to_replicated_tables`
is set to false
Clang 13 complains about a suspicious string concatenation. It thinks we
might have missed a comma. This adds parentheses to make it clear that
concatenation is indeed what we meant.
In the past, we allowed users to manually switch to 1PC
(e.g., one phase commit). However, with this commit, we
don't. All multi-shard modifications are done via 2PC.
With Citus 9.0, we introduced `citus.single_shard_commit_protocol` which
defaults to 2PC.
With this commit, we prevent any user to set it to 1PC and drop support
for `citus.single_shard_commit_protocol`.
Although this might add some overhead for users, it is already the default
behaviour (so less likely) and marking placements as INVALID is much
worse.
Since PG14 we can now use binary encoding for arrays and composite types
that contain user defined types. This was fixed in this commit in
Postgres: 670c0a1d47
This change starts using that knowledge, by not necessarily falling back
to text encoding anymore for those types.
While doing this and testing a bit more I found various cases where
binary encoding would fail that our checks didn't cover. This fixes
those cases and adds tests for those. It also fixes EXPLAIN ANALYZE
never using binary encoding, which was a leftover of workaround that
was not necessary anymore.
Finally, it changes the default for both `citus.enable_binary_protocol`
and `citus.binary_worker_copy_format` to `true` for PG14 and up. In our
cloud offering `binary_worker_copy_format` already was true by default.
`enable_binary_protocol` had some bug with MX and user defined types,
this bug was fixed by the above mentioned fixes.
`tcp_user_timeout` is the awesome relatively unknown big brother of the
TCP keepalive related options. Instead of depending on keepalives being
sent, this determines that a socket is dead by waiting at most N seconds
for an ack of data that it has sent. It's exposed in libpq starting from
PG12.
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.
Without this change the rebalancer progress monitor gets the shard sizes
from the `shardlength` column in `pg_dist_placement`. This column needs to
be updated manually by calling `citus_update_table_statistics`.
However, `citus_update_table_statistics` could lead to distributed
deadlocks while database traffic is on-going (see #4752).
To work around this we don't use `shardlength` column anymore. Instead
for every rebalance we now fetch all shard sizes on the fly.
Two additional things this does are:
1. It adds tests for the rebalance progress function.
2. If a shard move cannot be done because a source or target node is
unreachable, then we error in stop the rebalance, instead of showing
a warning and continuing. When using the by_disk_size rebalance
strategy it's not safe to continue with other moves if a specific
move failed. It's possible that the failed move made space for the
next move, and because the failed move never happened this space now
does not exist.
3. Adds two new columns to the result of `get_rebalancer_progress` which
shows the size of the shard on the source and target node.
Fixes#4930
DESCRIPTION: Add support for ALTER DATABASE OWNER
This adds support for changing the database owner. It achieves this by marking the database as a distributed object. By marking the database as a distributed object it will look for its dependencies and order the user creation commands (enterprise only) before the alter of the database owner. This is mostly important when adding new nodes.
By having the database marked as a distributed object it can easily understand for which `ALTER DATABASE ... OWNER TO ...` commands to propagate by resolving the object address of the database and verifying it is a distributed object, and hence should propagate changes of owner ship to all workers.
Given the ownership of the database might have implications on subsequent commands in transactions we force sequential mode for transactions that have a `ALTER DATABASE ... OWNER TO ...` command in them. This will fail the transaction with meaningful help when the transaction already executed parallel statements.
By default the feature is turned off since roles are not automatically propagated, having it turned on would cause hard to understand errors for the user. It can be turned on by the user via setting the `citus.enable_alter_database_owner`.
Comment from the code:
/*
* Iterate until all the tasks are finished. Once all the tasks
* are finished, ensure that that all the connection initializations
* are also finished. Otherwise, those connections are terminated
* abruptly before they are established (or failed). Instead, we let
* the ConnectionStateMachine() to properly handle them.
*
* Note that we could have the connections that are not established
* as a side effect of slow-start algorithm. At the time the algorithm
* decides to establish new connections, the execution might have tasks
* to finish. But, the execution might finish before the new connections
* are established.
*/
Note that the abruptly terminated connections lead to the following errors:
2020-11-16 21:09:09.800 CET [16633] LOG: could not accept SSL connection: Connection reset by peer
2020-11-16 21:09:09.872 CET [16657] LOG: could not accept SSL connection: Undefined error: 0
2020-11-16 21:09:09.894 CET [16667] LOG: could not accept SSL connection: Connection reset by peer
To easily reproduce the issue:
- Create a single node Citus
- Add the coordinator to the metadata
- Create a distributed table with shards on the coordinator
- f.sql: select count(*) from test;
- pgbench -f /tmp/f.sql postgres -T 12 -c 40 -P 1 or pgbench -f /tmp/f.sql postgres -T 12 -c 40 -P 1 -C
With this commit, the executor becomes smarter about refrain to open
new connections. The very basic example is that, if the connection
establishments take 1000ms and task executions as 5 msecs, the executor
becomes smart enough to not establish new connections.
DESCRIPTION: introduce `citus.local_hostname` GUC for connections to the current node
Citus once in a while needs to connect to itself for some systems operations. This used to be hardcoded to `localhost`. The hardcoded hostname causes some issues, for example in environments where `sslmode=verify-full` is required. It is not always desirable or even feasible to get `localhost` as an alt name on the certificate.
By introducing a GUC to use when connecting to the current instance the user has more control what network path is used and what hostname is required to be present in the server certificate.
Every move in the rebalancer algorithm results in an improvement in the
balance. However, even if the improvement in the balance was very small
the move was still chosen. This is especially problematic if the shard
itself is very big and the move will take a long time.
This changes the rebalancer algorithm to take the relative size of the
balance improvement into account when choosing moves. By default a move
will not be chosen if it improves the balance by less than half of the
size of the shard. An extra argument is added to the rebalancer
functions so that the user can decide to lower the default threshold if
the ignored move is wanted anyway.
* When moving a shard to a new node ensure there is enough space
* Add WairForMiliseconds time utility
* Add more tests and increase readability
* Remove the retry loop and use a single udf for disk stats
* Address review
* address review
Co-authored-by: Jelte Fennema <github-tech@jeltef.nl>
As long as the VALUES clause contains constant values, we should not
recursively plan the queries/CTEs.
This is a follow-up work of #1805. So, we can easily apply OUTER join
checks as if VALUES clause is a reference table/immutable function.
Marco Slot
jeff-davis
Onder Kalaci
ywj
Nils Dijk
Teja Mupparti
Halil Ozan Akgul
Ying Xu
Onur Tirtir
Önder Kalacı
Ahmet Gedemenli
Jelte Fennema
Philip Dubé
SaitTalhaNisanci
Hanefi Onaldi