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Posted to user@cassandra.apache.org by mcasandra <mo...@gmail.com> on 2011/04/15 20:25:06 UTC
Key cache hit rate
How to intepret "Key cache hit rate"? What does this no mean?
Keyspace: StressKeyspace
Read Count: 87579
Read Latency: 11.792417360326105 ms.
Write Count: 179749
Write Latency: 0.009272318622078566 ms.
Pending Tasks: 0
Column Family: StressStandard
SSTable count: 59
Space used (live): 52432078035
Space used (total): 52432078035
Memtable Columns Count: 229
Memtable Data Size: 114103248
Memtable Switch Count: 375
Read Count: 87579
Read Latency: NaN ms.
Write Count: 179751
Write Latency: 0.007 ms.
Pending Tasks: 0
Key cache capacity: 1000000
Key cache size: 78576
Key cache hit rate: 3.8880248833592535E-4
Row cache: disabled
Compacted row minimum size: 182786
Compacted row maximum size: 5839588
Compacted row mean size: 532956
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Re: Key cache hit rate
Posted by Watanabe Maki <wa...@gmail.com>.
3.8E-4 means 3.8 * 10^-4, = 0.00038 = 0.038%, I think.
So your program must be using random enough keys against the key cache size.
maki
From iPhone
On 2011/04/16, at 15:17, mcasandra <mo...@gmail.com> wrote:
> You mean read it like .00038880248833592535E? I didn't quite follow why? If
> it is 3.8880248833592535E then does it mean I got only 3% hit or .0003?
>
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Re: Key cache hit rate
Posted by mcasandra <mo...@gmail.com>.
You mean read it like .00038880248833592535E? I didn't quite follow why? If
it is 3.8880248833592535E then does it mean I got only 3% hit or .0003?
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Re: Key cache hit rate
Posted by Aaron Morton <aa...@thelastpickle.com>.
Move the decimal point 4 places to the left. It's the percent of your queries that get a hit from the key cache .
Aaron
On 16/04/2011, at 6:25 AM, mcasandra <mo...@gmail.com> wrote:
>
> How to intepret "Key cache hit rate"? What does this no mean?
>
>
> Keyspace: StressKeyspace
> Read Count: 87579
> Read Latency: 11.792417360326105 ms.
> Write Count: 179749
> Write Latency: 0.009272318622078566 ms.
> Pending Tasks: 0
> Column Family: StressStandard
> SSTable count: 59
> Space used (live): 52432078035
> Space used (total): 52432078035
> Memtable Columns Count: 229
> Memtable Data Size: 114103248
> Memtable Switch Count: 375
> Read Count: 87579
> Read Latency: NaN ms.
> Write Count: 179751
> Write Latency: 0.007 ms.
> Pending Tasks: 0
> Key cache capacity: 1000000
> Key cache size: 78576
> Key cache hit rate: 3.8880248833592535E-4
> Row cache: disabled
> Compacted row minimum size: 182786
> Compacted row maximum size: 5839588
> Compacted row mean size: 532956
>
>
> --
> View this message in context: http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/Key-cache-hit-rate-tp6277236p6277236.html
> Sent from the cassandra-user@incubator.apache.org mailing list archive at Nabble.com.