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From Jonathan Ellis <>
Subject Re: size tiered compaction - improvement
Date Wed, 18 Apr 2012 02:53:52 GMT
On Sat, Apr 14, 2012 at 4:08 AM, Igor <> wrote:
> Assume I insert all my data with TTL=2weeks and let we have sstable A which
> was created week ago at the time T, so I know that right now it contain:
> 1) some data that were inserted not later than T and may-be not expired yet
> 2) some amount of data that were already close to expiration due TTL at the
> time T, but still had no chances to be wiped out because up to the current
> moment size-tiered compaction did not involve A into compactions.
> Large amount of data from 2) became expired in a week after time T and
> probably passed gc_grace period, so it shoould be wiped at any compaction on
> table A.

Any compaction pass over A will first convert the TTL data into tombstones.

Then, any subsequent pass that includes A *and all other sstables
containing rows with the same key* will drop the tombstones.

Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of DataStax, the source for professional Cassandra support

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