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From Aaron Morton <>
Subject Re: Calculating the size of rows in KBs
Date Thu, 10 Feb 2011 21:12:02 GMT
If you are thinking about column_index_size_in_kb in Cassandra.yaml then yes. 


On 11/02/2011, at 9:39 AM, Aditya Narayan <> wrote:

> Thank you Aaron!!
> But, If you are reading partial rows(that otherwise contain several
> thousands of **valueless** columns) then do the column indexes help in
> making the reads faster & more efficient than if they were not
> valueless?
> Perhaps, because they would only need to  look up whether the asked
> column names exist in indexes for that row/key & they dont need to
> deserialize the blocks in SST tables searching for column values. Am I
> thinking right way??
> -Aditya
> On Fri, Feb 11, 2011 at 1:54 AM, Aaron Morton <> wrote:
>> If you want to get the byte size of a particular row you will need to read it all
>> If you connect with JConsole at look at you column families, there are attributes
for the max, min and mean row sizes.
>> In general the entire row only exists in memory when it is contained in the first
Memtable it's written to. It may then be partially or fully read from disk during subsequent
reads or compactions.
>> On disk format  described here may help
>> Hope that helps
>> Aaron
>> On 10/02/2011, at 11:56 PM, Aditya Narayan <> wrote:
>>> How can I get or calculate the size of  rows/ columns ? what are the
>>> any overheads on memory for each column/row ?

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