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  1. Apache Cassandra
  2. CASSANDRA-14918

multiget_slice returning inconsistent results when performed with CL higher than ONE

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Details

    • Bug
    • Status: Resolved
    • Normal
    • Resolution: Duplicate
    • None
    • Legacy/Coordination
    • None
    • 9 node ring, cassandra 3.11.2, RF of 3.

      Ring is not upgraded from any previous version.

    • Normal

    Description

      I'm on cassandra 3.11.2. On a number of CFs I'm observing that multiget_slice sometimes returns inconsistent, partially-empty results for the exact same request, despite the underlying data not changing. This behaviour is only observed when I perform the multiget with a CL higher than `ONE` - all `ONE` requests work as expected.

      I was able to create a test table in a lab environment and after fiddling with the data enough was able to repro. I was unable to perform a very basic repro with only a few rows present. To repro, I inserted a couple million rows, deleted a subset of those rows, and the performed a multiget slice on a list of partitions which included living and deleted partitions. The result is that sometimes, when performing a multiget on this data, I get a thrift struct back with partition info, but no column names or values - the thrift LIST that is generated contains 0 elements. If I issue this exact same request 5 times I might get the appropriate data back once or twice. I have verified on the wire that the request being made is identical - only the results are different.

      The repro case described above is rather meandering so I'm working to break it down into a simple of a case as I can. It is unclear if deletions need to occur to reproduce this or not.

      Edit: Just confirmed I'm observing this behaviour on multiple distinct 3.11.2 rings.

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              Unassigned Unassigned
              alienth Jason Harvey
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