Jingsong Lee created FLINK-22901:
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Summary: Introduce getChangeLogUpsertKeys in FlinkRelMetadataQuery
Key: FLINK-22901
URL: https://issues.apache.org/jira/browse/FLINK-22901
Project: Flink
Issue Type: Improvement
Components: Table SQL / Planner
Reporter: Jingsong Lee
Assignee: Jingsong Lee
Fix For: 1.14.0
{code:java}
/**
* Determines the set of change log upsert minimal keys for this expression. A
key is
* represented as an {@link org.apache.calcite.util.ImmutableBitSet}, where
each bit position
* represents a 0-based output column ordinal.
*
* <p>Different from the unique keys: In distributed streaming computing, one
record may be
* divided into RowKind.UPDATE_BEFORE and RowKind.UPDATE_AFTER. If a key
changing join is
* connected downstream, the two records will be divided into different tasks,
resulting in
* disorder. In this case, the downstream cannot rely on the order of the
original key. So in
* this case, it has unique keys in the traditional sense, but it doesn't have
change log upsert
* keys.
*
* @return set of keys, or null if this information cannot be determined
(whereas empty set
* indicates definitely no keys at all)
*/
public Set<ImmutableBitSet> getChangeLogUpsertKeys(RelNode rel);
{code}
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