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From Anuj Wadehra <>
Subject Re: Minor Compactions Not Triggered
Date Mon, 01 Jun 2015 18:25:46 GMT
Thanks Robert !!!

As per the algorithm shared in the CASSANDRA 6654, I understand that tombstone_threshold property
only comes into picture if you have expirying columns and it wont have any effect if you have
manually deleted rows in cf. Is my understanding correct?

According to you What would be the expected behavior of following steps??

I inserted x rows

I deleted x rows

Ran major compaction to make sure that one big sstable contains all tombstones

Waited for gc grace period to see whether that big sstable formed after major compaction is
compacted on its own without finding any other sstable



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From:"Robert Coli" <>
Date:Mon, 1 Jun, 2015 at 10:56 pm
Subject:Re: Minor Compactions Not Triggered

On Sun, May 31, 2015 at 11:37 AM, Anuj Wadehra <> wrote:

2. We thought that CQL compaction subproperty of tombstone_threshold will help us after major
compactions. This property will ensure that even if we have one huge sstable, once tombstone
threshold of 20% has reached, sstables will be compacted and tombstones will be dropped after
gc_grace_periods (even if there no similar sized sstables as need by STCS). But in our initial
testing, single huge sstable is not getting compacted even if we drop all rows in it and gc_grace_period
has passed.  Why tombstone_threshold is behaving like that? ?


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