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From Ran Tavory <ran...@gmail.com>
Subject Re: Key cache capacity: 1 when using KeysCached="50%"
Date Mon, 24 May 2010 17:07:23 GMT
I'd like to have 100% keys cached. Sorry if my example of Super2 wasn't
correct, but I do think there's a problem. Here's with my own data:

When using actual numbers (in this case for RowsCached) it works as
expected, however when specifying KeysCached="100%" I get only 1.

      <ColumnFamily CompareWith="BytesType" Name="KvAds"
        KeysCached="100%"
        RowsCached="10000"
        />


                Column Family: KvAds
                SSTable count: 7
                Space used (live): 797535964
                Space used (total): 797535964
                Memtable Columns Count: 42292
                Memtable Data Size: 10514176
                Memtable Switch Count: 24
                Read Count: 2563704
                Read Latency: 4.590 ms.
                Write Count: 1963804
                Write Latency: 0.025 ms.
                Pending Tasks: 0
                Key cache capacity: 1
                Key cache size: 1
                Key cache hit rate: 0.0
                Row cache capacity: 10000
                Row cache size: 10000
                Row cache hit rate: 0.2206178354382234
                Compacted row minimum size: 386
                Compacted row maximum size: 9808
                Compacted row mean size: 616


On Mon, May 24, 2010 at 6:30 PM, Jonathan Ellis <jbellis@gmail.com> wrote:

> If you really want a cache capacity of 0 then you need to use 0
> explicitly, otherwise the % versions will give you at least 1.
>
> On Mon, May 24, 2010 at 12:34 AM, Ran Tavory <rantav@gmail.com> wrote:
> > I've noticed that when defining KeysCached="50%" (or KeysCached="100%"
> and I
> > didn't test other values with %) then cfstats reports Key cache capacity:
> 1
> > This looks weird... is this expected? (version 0.6.1)
> > For example, in the default configuration:
> >       <ColumnFamily Name="Super2"
> >                     ColumnType="Super"
> >                     CompareWith="UTF8Type"
> >                     CompareSubcolumnsWith="UTF8Type"
> >                     RowsCached="10000"
> >                     KeysCached="50%"/>
> >
> > ----------------
> > Keyspace: Keyspace1
> >         Read Count: 0
> >         Read Latency: NaN ms.
> >         Write Count: 0
> >         Write Latency: NaN ms.
> >         Pending Tasks: 0
> >                 Column Family: Super1
> >                 SSTable count: 0
> >                 Space used (live): 0
> >                 Space used (total): 0
> >                 Memtable Columns Count: 0
> >                 Memtable Data Size: 0
> >                 Memtable Switch Count: 0
> >                 Read Count: 0
> >                 Read Latency: NaN ms.
> >                 Write Count: 0
> >                 Write Latency: NaN ms.
> >                 Pending Tasks: 0
> >                 Key cache capacity: 200000
> >                 Key cache size: 0
> >                 Key cache hit rate: NaN
> >                 Row cache: disabled
> >                 Compacted row minimum size: 0
> >                 Compacted row maximum size: 0
> >                 Compacted row mean size: 0
> >                 Column Family: Super2
> >                 SSTable count: 0
> >                 Space used (live): 0
> >                 Space used (total): 0
> >                 Memtable Columns Count: 0
> >                 Memtable Data Size: 0
> >                 Memtable Switch Count: 0
> >                 Read Count: 0
> >                 Read Latency: NaN ms.
> >                 Write Count: 0
> >                 Write Latency: NaN ms.
> >                 Pending Tasks: 0
> >                 Key cache capacity: 1
> >                 Key cache size: 0
> >                 Key cache hit rate: NaN
> >                 Row cache capacity: 10000
> >                 Row cache size: 0
> >                 Row cache hit rate: NaN
> >                 Compacted row minimum size: 0
> >                 Compacted row maximum size: 0
> >                 Compacted row mean size: 0
> >
>
>
>
> --
> Jonathan Ellis
> Project Chair, Apache Cassandra
> co-founder of Riptano, the source for professional Cassandra support
> http://riptano.com
>

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