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From Edward Capriolo <edlinuxg...@gmail.com>
Subject Re: Appending to fields
Date Tue, 31 May 2011 21:22:00 GMT
On Tue, May 31, 2011 at 5:03 PM, Dan Kuebrich <dan.kuebrich@gmail.com>wrote:

>
>
> On Tue, May 31, 2011 at 4:57 PM, Victor Kabdebon <
> victor.kabdebon@gmail.com> wrote:
>
>> As Jonathan stated I believe that the insert is in O(N + M), unless there
>> are some operations that I don't know.
>>
>> There are other NoSQL database that  can be used with Cassandra as
>> "buffers" for quick access and modification and then after the content can
>> be dumped into Cassandra for long term storage. Here is an example with
>> Redis :
>>
>> http://redis.io/commands/append
>> The "append" command is said to be in O(1) but it is a little bit
>> suspicious to me...
>>
>> Best regards,
>> Victor Kabdebon
>> http://www.voxnucleus.fr
>>
>
> I think perhaps OP meant O(N * M), where N is number of rows and M is total
> bytes.
>
> Either way, won't cassandra be effectively buffering appends in memtable
> (well, also appending to commit log) until flush occurs to sstable?
>

I never learned log 0 notation. However since a write is "fast" and
cassandra "reads" are slow considering them equal for a computational
analysis is heading down the wrong path. Cassandra "appends" are normally
done by using a new TimeUUID as the column name and supplying the value in
the value. The read half of the process reads with a column slice rather
then reading a single column and joins the data client side. What you are
doing is append by inserting N columns, then reconcile on the read side.

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