Corentin Chary created CASSANDRA-12910:
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Summary: SASI: calculatePrimary() always returns null
Key: CASSANDRA-12910
URL: https://issues.apache.org/jira/browse/CASSANDRA-12910
Project: Cassandra
Issue Type: Bug
Components: sasi
Reporter: Corentin Chary
While investigating performance issues with SASI
(https://github.com/criteo/biggraphite/issues/174 if you want to know more) I
ended finding calculatePrimary() in QueryController.java which apparently
should return the "primary index".
It lacks documentation, and I'm unsure what the "primary index" should be, but
apparently this function never returns one because primaryIndexes.size() is
always 0.
https://github.com/apache/cassandra/blob/81f6c784ce967fadb6ed7f58de1328e713eaf53c/src/java/org/apache/cassandra/index/sasi/plan/QueryController.java#L237
I'm unsure if the proper fix is checking if the collection is empty or
reversing the operator (selecting the index with higher cardinality versus the
one with lower cardinality).
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