CNDB-16886: Reject BM25 queries in validation when the coordinator is…#2459
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pkolaczk
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scottfines
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… before EC (#2459) Reject BM25 queries on `Index.validate(ReadCommand)` if the current index version doesn't support them. That way they would be rejected on the coordinator before execution, which is faster and produces a descriptive error message, rather than the generic per-replica error codes. The replicas still will do their own validation if the query gets past the coordinator.
djatnieks
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… before EC (#2459) Reject BM25 queries on `Index.validate(ReadCommand)` if the current index version doesn't support them. That way they would be rejected on the coordinator before execution, which is faster and produces a descriptive error message, rather than the generic per-replica error codes. The replicas still will do their own validation if the query gets past the coordinator.
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What is the issue
Writers reject BM25 queries when the index version if before
Version.BM25_EARLIEST, or when the index doesn't have the needed components. They do that by sendingRequestFailureReason.FEATURE_NEEDS_INDEX_UPGRADE. If the query succeeds in the writers, there are still more version checks in the coordinator, so everything should be in the right version.While that behaviour is correct and manages index version issues in a controlled manner, we could also check the current index version at the query validation step done by the coordinator, before actually executing the query. That would allow us to throw a better error message than the obscure
ReadFailureExceptionwith named error codes, and save us some round trips, in case the coordinator is in the wrong version. TheReadFailureExceptionwith named error codes would still be used for cases when only some of the writers or the sstables is in the wrong version.What does this PR fix and why was it fixed
Reject BM25 queries on
Index.validate(ReadCommand)if the current index version doesn't support them. That way they would be rejected on the coordinator before execution, which is faster and produces a descriptive error message, rather than the generic per-replica error codes. The replicas still will do their own validation if the query gets past the coordinator.