DataStax Academy FAQ

DataStax Academy migrated to a new learning management system (LMS) in July 2020. We are also moving to a new Cassandra Certification process so there are changes to exam bookings, voucher system and issuing of certificates.

Check out the Academy FAQ pages for answers to your questions:


question

satvantsingh_190085 avatar image
satvantsingh_190085 asked ·

What happens when the coordinator goes down while servicing a long-running query?

What will happen for long running query -

If coordinator nodes goes down suddenly ?

If any node goes down from which query was fetching data ?



cassandra
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1 Answer

Erick Ramirez avatar image
Erick Ramirez answered ·

If the coordinator node goes down before the query completes, the driver will never get a response back and will eventually timeout with (for example) a DriverTimeoutException.

If a node that was requested data goes down, what happens next depends on how the cluster is configured. By default if speculative_retry is configured on the table, the coordinator will retry the request with another replica node.

For more information, see How read requests are accomplished. Cheers!

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