Fastest way? Stop cassandra, use sstablemetadata to remove any files with 
maxTimestamp > 2 days. Start cassandra. Works better with some compaction 
strategies than others (probably find a few droppable sstables with either DTCS 
/ STCS, but not perfect). 

Cleanest way? One by one (starting with oldest sstables first), use 
forceUserDefinedCompaction on each sstable and let it purge out the droppable 
garbage. This is what the tombstone sub properties would do.




From:  Anubhav Kale
Reply-To:  "user@cassandra.apache.org"
Date:  Tuesday, May 17, 2016 at 4:17 PM
To:  "user@cassandra.apache.org"
Subject:  Applying TTL Change quickly

Hello,

 

We use STCS and DTCS on our tables and recently made a TTL change (reduced from 
8 days to 2) on a table with large amounts of data. What is the best way to 
quickly purge old data ? I am playing with tombstone_compaction_interval at the 
moment, but would like some suggestions on what else can be done to reclaim the 
space as quick as possible.

 

Thanks !

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