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Jonathan Ellis commented on CASSANDRA-6106: ------------------------------------------- I dunno. If it's a problem, then don't paper over it ("less likely" is a synonym for "still possible"); use LWT or fix your data model. > QueryState.getTimestamp() & FBUtilities.timestampMicros() reads current > timestamp with System.currentTimeMillis() * 1000 instead of System.nanoTime() > / 1000 > ------------------------------------------------------------------------------------------------------------------------------------------------------------ > > Key: CASSANDRA-6106 > URL: https://issues.apache.org/jira/browse/CASSANDRA-6106 > Project: Cassandra > Issue Type: Bug > Components: Core > Environment: DSE Cassandra 3.1, but also HEAD > Reporter: Christopher Smith > Priority: Minor > Labels: collision, conflict, timestamp > Attachments: microtimstamp.patch > > > I noticed this blog post: http://aphyr.com/posts/294-call-me-maybe-cassandra > mentioned issues with millisecond rounding in timestamps and was able to > reproduce the issue. If I specify a timestamp in a mutating query, I get > microsecond precision, but if I don't, I get timestamps rounded to the > nearest millisecond, at least for my first query on a given connection, which > substantially increases the possibilities of collision. > I believe I found the offending code, though I am by no means sure this is > comprehensive. I think we probably need a fairly comprehensive replacement of > all uses of System.currentTimeMillis() with System.nanoTime(). > There seems to be some confusion here, so I'd like to clarify: the purpose of > this patch is NOT to improve the precision of ordering guarantees for > concurrent writes to cells. The purpose of this patch is to reduce the > probability that concurrent writes to cells are deemed as having occurred at > *the same time*, which is when Cassandra violates its atomicity guarantee. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira