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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: Key cache capacity: 1 when using KeysCached="50%"
Date Tue, 25 May 2010 12:42:43 GMT
That does look like a bug.  Can you create a ticket and upload a
(preferably small-ish) sstable that illustrates the problem?

On Mon, May 24, 2010 at 12:07 PM, Ran Tavory <rantav@gmail.com> wrote:
> 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
>
>



-- 
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support
http://riptano.com

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