Jark Wu created FLINK-12971:
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Summary: Remove the constraint that lookup join needs a primary
key or index key
Key: FLINK-12971
URL: https://issues.apache.org/jira/browse/FLINK-12971
Project: Flink
Issue Type: Improvement
Components: Table SQL / Planner
Reporter: Jark Wu
Assignee: Jark Wu
Currently, we add a constraint in dimension table lookup join that the lookup
fields must be a primary key or index key. This is not a logic constraint but a
performance constraint. Because if there are no indexes on the lookup key, the
lookup performance will be poor.
We will remove this constraint because not every table have a primary key or
indexes (e.g. Hive tables). It's the user's responsibility if the lookup fields
are not keys and get a bad performance. In this case, users should add indexes
on these fields. In the future, we can also propagate out these tuning
information before SQL is executed.
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