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

lavaraja.padala_150810 avatar image
lavaraja.padala_150810 asked ·

Does a node with UTC timezone in a cluster of EDT nodes corrupt the data?

We have observed that one of the node is showing timezone as UTC while other nodes are running EDT time. What is the way to correct the problem?. Should changing time zone on the faulty node will resolve issue? If we run run repair on this node will it corrupt the data on other nodes since EDT time is behind UTC?.

cassandratimezonecurated
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1 Answer

Erick Ramirez avatar image
Erick Ramirez answered ·

The node's timezone has no effect whatsoever on the state of the data that Cassandra stores.

In Cassandra, timestamps are timezone-naive since timestamps are encoded microseconds since Unix epoch -- the number of microseconds which have elapsed since midnight (00:00 UTC/GMT) January 1, 1970.

Regardless of the timezone of a server, the data is encoded with timestamps (microseconds since Unix epoch). The only difference a timezone makes is displaying the timestamps in local time.

For example, the timestamp 1596501496772880 is equivalent to the following dates/times in the following timezones:

  • UTC (GMT+0:00) - August 4, 2020 12:38:16.772 AM
  • PDT (GMT-7:00) - August 3, 2020 05:38:16.772 PM
  • BST (GMT+1:00) - August 4, 2020 01:38:16.772 AM
  • IST (GMT+5:30) - August 4, 2020 06:08:16.772 AM
  • AEST (GMT+10:00) - August 4, 2020 10:38:16.772 AM

In other words, timezones are a representation of the same underlying universal time displayed in a particular local time. Cheers!

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