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From Igor <>
Subject Re: size tiered compaction - improvement
Date Wed, 18 Apr 2012 04:26:19 GMT
Thank you Jonatathan, I missed this point about converting TTL data to 
tombstones first.

When you say:

    You absolutely can.  That's what the "user defined" part is: you give
    it the exact list of sstables you want compacted.

does it mean that I can use list (not just one) of sstables as second 
parameter for userDefinedCompaction?

On 04/18/2012 05:53 AM, Jonathan Ellis wrote:
> 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.

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