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From: Stefano Ortolani <ostefano@gmail.com>
Date: Thu, 11 May 2017 15:15:54 +0100
Message-ID: <CAKy_EwZ=eVAkDwBY12Vcw4chjjp7=0hiK4RwT2t_7SU5E_9SGA@mail.gmail.com>
Subject: LCS, range tombstones, and eviction
To: user@cassandra.apache.org
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archived-at: Thu, 11 May 2017 14:16:18 -0000

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Hi all,

I am trying to wrap my head around how C* evicts tombstones when using LCS.
Based on what I understood reading the docs, if the ratio of garbage
collectable tomstones exceeds the "tombstone_threshold", C* should start
compacting and evicting.

I am quite puzzled however by what might happen when dealing with range
tombstones. In that case a single tombstone might actually stand for an
arbitrary number of normal tombstones. In other words, do range tombstones
contribute to the "tombstone_threshold"? If so, how?

I am also a bit confused by the "tombstone_compaction_interval". If I am
dealing with a big partition in LCS which is receiving new records every
day,
and a weekly incremental repair job continously anticompacting the data and
thus creating SStables, what is the likelhood of the default interval
(10 days) to be actually hit?

Hopefully somebody will be able to shed some lights here!

Thanks in advance!
Stefano

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<div dir=3D"ltr"><div>Hi all,</div><div><br></div><div>I am trying to wrap =
my head around how C* evicts tombstones when using LCS.</div><div>Based on =
what I understood reading the docs, if the ratio of garbage=C2=A0</div><div=
>collectable tomstones exceeds the &quot;tombstone_threshold&quot;, C* shou=
ld start=C2=A0</div><div>compacting and evicting.</div><div><br></div><div>=
I am quite puzzled however by what might happen when dealing with range=C2=
=A0</div><div>tombstones. In that case a single tombstone might actually st=
and for an=C2=A0</div><div>arbitrary number of normal tombstones. In other =
words, do range tombstones=C2=A0</div><div>contribute to the &quot;tombston=
e_threshold&quot;? If so, how?</div><div><br></div><div>I am also a bit con=
fused by the &quot;tombstone_compaction_<wbr>interval&quot;. If I am=C2=A0<=
/div><div>dealing with a big partition in LCS which is receiving new record=
s every day,=C2=A0</div><div>and a weekly incremental repair job continousl=
y anticompacting the data and=C2=A0</div><div>thus creating SStables, what =
is the likelhood of the default interval=C2=A0</div><div>(10 days) to be ac=
tually hit?</div><div><br></div><div>Hopefully somebody will be able to she=
d some lights here!</div><div><br></div><div>Thanks in advance!=C2=A0</div>=
<div>Stefano=C2=A0</div><div><br></div></div>

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