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From aaron morton <aa...@thelastpickle.com>
Subject Re: live ratio counting
Date Mon, 14 May 2012 10:32:37 GMT
> liveratio calc should do nothing if memtable has 0 columns.
Sounds reasonable, as counting with zero columns may dramatically change the live ratio and
it may take some time to be counted again. 
Please create a ticket on https://issues.apache.org/jira/browse/CASSANDRA

> liveratio calculation logic also needs to be changed because it is based on assumption
that workloads do not change.
Can you give an example of the sort of workload change you are thinking of ? 

> raise maximum liveratio from 64 to at least 80.
Have you seen examples in your logs where the calculated live ratio was between 64 and 80
?
Are you experiencing memory pressure you think may be attributed to memtables not being flushed
frequently enough ? 

Cheers
 
-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com

On 11/05/2012, at 12:07 AM, Radim Kolar wrote:

> liveratio calc should do nothing if memtable has 0 columns. I did manual flush before
this.
> 
> WARN [MemoryMeter:1] 2012-05-10 13:21:19,430 Memtable.java (line 181) setting live ratio
to maximum of 64 instead of Infinity
> INFO [MemoryMeter:1] 2012-05-10 13:21:19,431 Memtable.java (line 186) CFS(Keyspace='rapidshare',
ColumnFamily='resultcache') liveRatio is 64.0 (just-counted was 64.0).  calculation took 1ms
for 0 columns
> 
> liveratio calculation logic also needs to be changed because it is based on assumption
that workloads do not change. I propose to get configuration option (per node is enough) for
maximum interval between liveratio calculation and raise maximum liveratio from 64 to at least
80.


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