Fixes issue #258
Prior to this change, Citus gives a deceptive NOTICE message when a query
including ANY or ALL on a non-partition column is issued on a hash
partitioned table.
Let the github_events table be hash-distributed on repo_id column. Then,
issuing this query:
SELECT count(*) FROM github_events WHERE event_id = ANY ('{1,2,3}')
Gives this message:
NOTICE: cannot use shard pruning with ANY (array expression)
HINT: Consider rewriting the expression with OR clauses.
Note that since event_id is not the partition column, shard pruning would
not be applied in any case. However, the NOTICE message would be valid
and be given if the ANY clause would have been applied on repo_id column.
Reviewer: Murat Tuncer
All citusdb references in
- extension, binary names
- file headers
- all configuration name prefixes
- error/warning messages
- some functions names
- regression tests
are changed to be citus.
Previously we used, for historical reasons, MessageContext.
That is problematic if a single message from the client
causes a lot of statements to be planned. E.g. for the
copy_to_distributed_table script one insert statement
is planned for each row inserted via COPY, and only freed
when COPY has finished.
This entirely removes any restriction on the type of partitioning
during DML planning and execution. Though there aren't actually any
technical limitations preventing DML commands against append- (or even
range-) partitioned tables, we had initially forbidden this, as any
future stage operation could cause shards to overlap, banning all
subsequent DML operations to partition values contained within more
than one shards. This ended up mostly restricting us, so we're now
removing that restriction.
When two data types have the same binary representation, PostgreSQL may
add an implicit coercion between them by wrapping a node in a relabel
type. This wrapper signals that the wrapped value is completely binary
compatible with the designated "final type" of the relabel node. As an
example, the varchar type is often relabeled to text, since functions
provided for use with text (comparisons, hashes, etc.) are completely
compatible with varchar as well.
The hash-partitioned codepath contains functions that verify queries
actually contain an equality constraint on the partition column, but
those functions expect such constraints to be comparison operations
between a Var and Const. The RelabelType wrapper node causes these
functions to always return false, which bypasses shard pruning.
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Jason Petersen
Murat Tuncer
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Jason Petersen