Hi,
The spark-cassandra-connector does pushdown filter when there are valid
clauses. Pushdown filters go directly to cassandra so, if your model fits
your queries, you won't end up reading or scanning the full table but only
those partitions that match your query.
You can check which clauses are being pushed down when filtering a
dataframe using the df.filter("filter expression").explain() method
Check this url for more information:
https://github.com/datastax/spark-cassandra-connector/blob/master/doc/14_data_frames.md
I hope that this is of any help.
Javier García-Valdecasas Bernal
2017-10-10 15:11 GMT+02:00 Stone Fang <cnstonef...@gmail.com>:
> @kurt greaves
>
> doubt that need to read all the data.it is common that there are so many
> records in cassandra cluster.
> if loading all the data,how to analyse?
>
> On Mon, Oct 9, 2017 at 9:49 AM, kurt greaves <k...@instaclustr.com> wrote:
>
>> spark-cassandra-connector will provide the best way to achieve what you
>> want, however under the hood it's still going to result in reading all the
>> data, and because of the way Cassandra works it will essentially read the
>> same SSTables multiple times from random points. You might be able to tune
>> to make this not super bad, but pretty much reading all the data is going
>> to have horrible implications for the cache if all your data doesn't fit in
>> memory regardless of what you do.
>>
>
>
