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From Jimmy Lin <y2klyf+w...@gmail.com>
Subject Re: row caching for frequently updated column
Date Tue, 29 Apr 2014 16:30:00 GMT
hi,
>>> writing a new value to a row will invalidate the row cache for that
value
do you mean the entire row will be invalidate ? or just the column it was
being updated ?

I was reading through
http://planetcassandra.org/blog/post/cassandra-11-tuning-for-frequent-column-updates/
that seems to indicate it just write through it and not invalidate the
entire row.

if Cassandra invalidate the  row cache upon a single column update to that
row, that seems very inefficient.





On Tue, Apr 29, 2014 at 4:43 AM, Jonathan Lacefield <jlacefield@datastax.com
> wrote:

> Hello,
>
>
>   Iirc writing a new value to a row will invalidate the row cache for that
> value.  Row cache is only populated after a read operation.
> http://www.datastax.com/documentation/cassandra/2.0/cassandra/operations/ops_configuring_caches_c.html?scroll=concept_ds_n35_nnr_ck
>
>   Cassandra provides the ability to "preheat" key and page cache, but I
> don't believe this is possible for row cache.
>
>   Hope that helps.
>
> Jonathan
>
>
> Jonathan Lacefield
> Solutions Architect, DataStax
> (404) 822 3487
> <http://www.linkedin.com/in/jlacefield>
>
> <http://www.datastax.com/cassandrasummit14>
>
>
>
> On Mon, Apr 28, 2014 at 10:27 PM, Jimmy Lin <y2klyf+work@gmail.com> wrote:
>
>> I am wondering if there is any negative impact on Cassandra write
>> operation, if I turn on row caching for a table that has mostly 'static
>> columns' but few frequently write columns (like timestamp).
>>
>> The application will frequently write to a few columns, and the
>> application will also frequently query entire row.
>>
>> How Cassandra handle update column to a cached row?
>> does it update both memtables value and also the row cached row's
>> column(which dealing with memory update so it is very fast) ?
>> or in order to update the cached row, entire row need to read back from
>> sstable?
>>
>>
>> thanks
>>
>>
>

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