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From "Durity, Sean R" <>
Subject Massive deletes -> major compaction?
Date Thu, 21 Sep 2017 18:27:34 GMT
Cassandra version 2.0.17 (yes, it's old - waiting for new hardware/new OS to upgrade)

In a long-running system with billions of rows, TTL was not set. So a one-time purge is being
planned to reduce disk usage. Records older than a certain date will be deleted. The table
uses size-tiered compaction. Deletes are probably 25-40% of the complete data set. To actually
recover the disk space, would you recommend a major compaction after the gc_grace_seconds
time? I expect compaction would then need to be scheduled regularly (ick)...

We also plan to re-insert the remaining data with a calculated TTL, which could also benefit
from compaction.

Sean Durity


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