Pretty straightforward. Had some concerns about locking, but due to the
fact that all distributed operations use either some level of deparsing
or need to enumerate column names, they all block during any concurrent
column renames (due to the AccessExclusive lock).
In addition, I had some misgivings about permitting renames of the dis-
tribution column, but nothing bad comes from just allowing them.
Finally, I tried to trigger any sort of error using prepared statements
and could not trigger any errors not also exhibited by plain PostgreSQL
tables.
This was getting pretty long and complex in the context of the main
utility hook. Moved out the checks for what should skip Citus process-
ing and what should have version checks performed.
With this change, we start to error out if loaded citus binaries does not match
the available major version or installed citus extension version. In this case
we force user to restart the server or run ALTER EXTENSION depending on the
situation
Thought this looked slightly nicer than the default behavior.
Changed preventTransaction to concurrent to be clearer that this code
path presently affects CONCURRENTLY code only.
Coordinator code marks index as invalid as a base, set it as valid in a
transactional layer atop that base, then proceeds with worker commands.
If a worker command has problems, the rollback results in an index with
isvalid = false. If everything succeeds, the user sees a valid index.
Some tests relied on worker errors though local commands were invalid.
Fixed those by ensuring preconditions were met to have command work
correctly. Otherwise most test changes are related to slight changes
in local/remote error ordering.
We have one replication of reference table for each node. Therefore all problems with
replication factor > 1 also applies to reference table. As a solution we will not allow
foreign keys on reference tables. It is not possible to define foreign key from, to or
between reference tables.
With this commit, we implemented some basic features of reference tables.
To start with, a reference table is
* a distributed table whithout a distribution column defined on it
* the distributed table is single sharded
* and the shard is replicated to all nodes
Reference tables follows the same code-path with a single sharded
tables. Thus, broadcast JOINs are applicable to reference tables.
But, since the table is replicated to all nodes, table fetching is
not required any more.
Reference tables support the uniqueness constraints for any column.
Reference tables can be used in INSERT INTO .. SELECT queries with
the following rules:
* If a reference table is in the SELECT part of the query, it is
safe join with another reference table and/or hash partitioned
tables.
* If a reference table is in the INSERT part of the query, all
other participating tables should be reference tables.
Reference tables follow the regular co-location structure. Since
all reference tables are single sharded and replicated to all nodes,
they are always co-located with each other.
Queries involving only reference tables always follows router planner
and executor.
Reference tables can have composite typed columns and there is no need
to create/define the necessary support functions.
All modification queries, master_* UDFs, EXPLAIN, DDLs, TRUNCATE,
sequences, transactions, COPY, schema support works on reference
tables as expected. Plus, all the pre-requisites associated with
distribution columns are dismissed.
Adds support for VACUUM and ANALYZE commands which target a specific
distributed table. After grabbing the appropriate locks, this imple-
mentation sends VACUUM commands to each placement (using one connec-
tion per placement). These commands are sent in parallel, so users
with large tables will benefit from sharding. Except for VERBOSE, all
VACUUM and ANALYZE options are supported, including the explicit
column list used by ANALYZE.
As with many of our utility commands, the local command also runs. In
the VACUUM/ANALYZE case, the local command is executed before any re-
mote propagation. Because error handling is managed after local proc-
essing, this can result in a VACUUM completing locally but erroring
out when distributed processing commences: a minor technicality in all
cases, as there isn't really much reason to ever roll back a VACUUM (an
impossibility in any case, as VACUUM cannot run within a transaction).
Remote propagation of targeted VACUUM/ANALYZE is controlled by the
enable_ddl_propagation setting; warnings are emitted if such a command
is attempted when DDL propagation is disabled. Unqualified VACUUM or
ANALYZE is not handled, but a warning message informs the user of this.
Implementation note: this commit adds a "BARE" value to MultiShard-
CommitProtocol. When active, no BEGIN command is ever sent to remote
nodes, useful for commands such as VACUUM/ANALYZE which must not run in
a transaction block. This value is not user-facing and is reset at
transaction end.
With this PR, we add foreign key support to ALTER TABLE commands. For now,
we only support foreign constraint creation via ALTER TABLE query, if it
is only subcommand in ALTER TABLE subcommand list.
We also only allow foreign key creation if replication factor is 1.
Previously, we threw an error when we ran CREATE INDEX IF NOT EXISTS
with an already existing index. This change enables expected behavior by
checking if the statement has IF NOT EXISTS before throwing the error.
We also ensure that we don't execute the command on the workers, if an
index already exists on the master.
Fixcitusdata/citus#886
The way postgres' explain hook is designed means that our hook is never
called during EXPLAIN EXECUTE. So, we special-case EXPLAIN EXECUTE by
catching it in the utility hook. We then replace the EXECUTE with the
original query and pass it back to Citus.
Three changes here to get to true multi-statement, multi-relation DDL
transactions (same functionality pre-5.2, with benefits of atomicity):
1. Changed the multi-shard utility hook to always run (consistency
with router executor hook, removes ad-hoc "installed" boolean)
2. Change the global connection list in multi_shard_transaction to
instead be a hash; update related functions to operate on global
hash instead of local hash/global list
3. Remove check within DDL code to prevent subsequent DDL commands;
place unset/reset guard around call to ConnectToNode to permit
connecting to additional nodes after DDL transaction has begun
In addition, code has been added to raise an error if a ROLLBACK TO
SAVEPOINT is attempted (similar to router executor), and comprehensive
tests execute all multi-DDL scenarios (full success, user ROLLBACK, any
actual errors (say, duplicate index), partial failure (duplicate index
on one node but not others), partial COMMIT (one node fails), and 2PC
partial PREPARE (one node fails)). Interleavings with other commands
(DML, \copy) are similarly all covered.
Recent changes to DDL and transaction logic resulted in a "regression"
from the viewpoint of users. Previously, DDL commands were allowed in
multi-command transaction blocks, though they were not processed in any
actual transactional manner. We improved the atomicity of our DDL code,
but added a restriction that DDL commands themselves must not occur in
any BEGIN/END transaction block.
To give users back the original functionality (and improved atomicity)
we now keep track of whether a multi-command transaction has modified
data (DML) or schema (DDL). Interleaving the two modification types in
a single transaction is disallowed.
This first step simply permits a single DDL command in such a block,
admittedly an incomplete solution, but one which will permit us to add
full multi-DDL command support in a subsequent commit.
Fixes#679
This change sets the default commit protocol for distributed DDL
commands to '1pc'. If the user issues a distributed DDL command with
this default setting, then once in a session, a NOTICE message is
shown about using '2pc' being extra safe.
Marco Slot
velioglu
Jason Petersen
Burak Yucesoy
Metin Doslu
Andres Freund
Onder Kalaci
Brian Cloutier
Eren Basak
Jason Petersen
Sumedh Pathak
Samay Sharma
Brian Cloutier
Murat Tuncer