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From aaron morton <aa...@thelastpickle.com>
Subject Re: live ratio counting
Date Mon, 14 May 2012 21:25:34 GMT
>> Are you experiencing memory pressure you think may be attributed to memtables not
being flushed frequently enough ?
> 
Try reducing memtable_total_space_in_mb config setting. If the problem is incorrect memory
metering that should help. 

> i have 3 workload types running in batch. Delete only workload, insert only and heavy
update (lot of overwrites)
Are you saying you do a lot of deletes, followed by a lot of inserts and then updates all
for the same CF ? 

> yes. Record is about 120, but it is rare. 80 should be good enough. Default 10 (if not
jusing jamm) is way too low.
Can you provide some information on what is stored in the CF and what sort of workload. It
would be interesting to understand why the real memory usage is 120 times the serialised size.


Cheers


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

On 15/05/2012, at 1:50 AM, Radim Kolar wrote:

> 
> 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 ?
> i have 3 workload types running in batch. Delete only workload, insert only and heavy
update (lot of overwrites)
> 
>>> 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 ?
> yes. Record is about 120, but it is rare. 80 should be good enough. Default 10 (if not
jusing jamm) is way too low.
>> Are you experiencing memory pressure you think may be attributed to memtables not
being flushed frequently enough ?
> yes


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