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From Benjamin Heiskell <>
Subject TWCS decommission and cleanups
Date Wed, 15 Nov 2017 15:57:33 GMT
Hello all,

How does TWCS work when decommissioning a node? Does the data distribute
across the other nodes to the current time window's sstable (like
read-repairs)? Or will it compact into the sstables for the prior windows?
If that's how it works, how does it decide what sstable to compact with?
E.g.., if I ran a major compaction on one node (pushing everything into a
few sstables), then decommissioned it, what would you expect to see on
other nodes? Would the data distribute across all sstables based on the
row's timestamp?

I'm also a little unclear on how cleanups work. If I run a nodetool
cleanup, will that actually re-write the old, but not completely expired
sstables of prior time windows? Or are those sstables truly immutable?

I've read through the documentation (
and a few other resources (, but I still
don't have a clear understanding of how it works.

Any clarification would be greatly appreciated. Thanks!

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