This adds a replication_model GUC which is used as the replication
model for any new distributed table that is not a reference table.
With this change, tables with replication factor 1 are no longer
implicitly MX tables.
The GUC is similarly respected during empty shard creation for e.g.
existing append-partitioned tables. If the model is set to streaming
while replication factor is greater than one, table and shard creation
routines will error until this invalid combination is corrected.
Changing this parameter requires superuser permissions.
If any placements fail it doesn't update shard statistics on those placements.
A minor enabling refactor: Make CoordinatedTransactionUses2PC public (it used to be CoordinatedTransactionUse2PC but that symbol already existed, so renamed it as well)
We changed error message which appears when user tries to execute outer join command and
that command requires repartitioning. Old error message mentioned about 1-to-1 shard
partitioning which may not be clear to user.
This enables proper transactional behaviour for copy and relaxes some
restrictions like combining COPY with single-row modifications. It
also provides the basis for relaxing restrictions further, and for
optionally allowing connection caching.
Instead use pg_plan_query() like the normal explain does, and use that
to explain the query. That's important because it allows to remove
the duplicated planner logic from multi_explain - and that logic is
about to get more complicated.
They make fixing explain for prepared statement harder, and they don't
really fit into EXPLAIN in the first place. Additionally they're
currently not exercised in any tests.
This change adds support for serial columns to be used with MX tables.
Prior to this change, sequences of serial columns were created in all
workers (for being able to create shards) but never used. With MX, we
need to set the sequences so that sequences in each worker create
unique values. This is done by setting the MINVALUE, MAXVALUE and
START values of the sequence.
A small refactor which pulls some code out of `RecoverWorkerTransactions`
and into `remote_commands.c`. This code block currently only occurs in
`RecoverWorkerTransactions` but will be useful to other functions
shortly.
Unfortunately we couldn't call it `ExecuteRemoteCommand`, that name was
already taken.
Because of foreign keys and similar concerns there should only be a
single modifying/DDL connection for a set of colocated placements to a
node. To enforce placement_connection.c now has an additional
hash-table keeping track of the connections to a set of colocated
placements. In addition to enforcing per placement restrictions on
connections, there's now very similar restrictions for sets of
colocated placements.