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From aaron morton <>
Subject Re: 54 memtable flushes in hour at peaktime
Date Mon, 10 Oct 2011 07:49:06 GMT
It's not a problem by it's self, compaction will do it's thing. It you are also seeing read
latency increase it may be something you want to look it.  

What version are you using ? The tuning is different (i.e. it gets easier) between versions
0.7, 0.8 and 1.0. 

It's probably just the case that you are writing a lot of data. Look for log messages from
ColumnFamilyStore that start with "Enqueuing flush of Memtable…" They will tell you how
many serialized bytes and operations the memtable soaked up before been flushed. 


Aaron Morton
Freelance Cassandra Developer

On 10/10/2011, at 6:56 AM, Tomer B wrote:

> Hi
> at highest traffic hours i get 54 memtable flushes, this happens for a few hours during
the day and at the rest of hours its ranging from 0 to 10 .
> Should I be doing anything about it? is that number on critical level? can i live with
54 memtable flushes per hour during peak hours? (I might expect higher peaks coming during
this year).
> (The rest of my memtables with lower traffic range at about 1-4 memtable flushes per
> thanks

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