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From aaron morton <>
Subject Re: Running repair negatively impacts read performance?
Date Wed, 26 Sep 2012 21:51:55 GMT
Sounds very odd. 

Is read performance degrading _after_ repair and compactions that normally result have completed
What Compaction Strategy ?
What OS and JVM ? 

What are are the bloom filter false positive stats from cf stats ?

Do you have some read latency numbers from cfstats ?
Also, could you take a look at cfhistograms  ? 


Aaron Morton
Freelance Developer

On 26/09/2012, at 3:05 AM, Charles Brophy <> wrote:

> Hey guys,
> I've begun to notice that read operations take a performance nose-dive after a standard
(full) repair of a fairly large column family: ~11 million records. Interestingly, I've then
noticed that read performance returns to normal after a full scrub of the column family. Is
it possible that the repair operation is not correctly establishing the bloom filter afterwards?
I've noticed an interesting note of the scrub operation is that it will "rebuild sstables
with correct bloom filters" which is what is leading me to this conclusion. Does this make
> I'm using 1.1.3 and Oracle JDK 1.6.31
> The column family is a stanard type and I've noticed this exact behavior regardless of
the key/column/value serializers in use.
> Charles

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