Increase request timeout for CQL from NiFi

Question

I am using QueryCassandra processor in NiFi to fetch data from Cassandra but my query is getting timedoutexception. I want to increase the request time out while running the CQL query from the processor. Is there a way to do that or I will have to write a custom processor?

Answer 1

Most probably you're getting an exception because you're performing query on non-partition key - in this case, the query is distributed to the all nodes, and requires to go through all available data, and this is very slow if you have big data set.

In Cassandra queries are fast only when you're performing them on (at least) partition key. If you need to search on non-partition column, then you need to re-model your tables to match your queries. I recommend to take DS220 course on DataStax Academy for better understanding how Cassandra works.

Answer 2

As @Alex ott said, it is not recommended to query on non partition key. If you still want to do so and increase the timeout for the query, just property Max Wait Time to whatever timeout you want.

EDIT:

tl;dr: Apache's timeout wrapper doesn't really let you use the timeout option.

Now that you mentioned that this is a DataStax exception and not java.util.concurrent.TimeoutException, I can tell you that I've looked into QueryCassandra processor's source code and it seems like Apache just wrapped the query function with a Future to achieve a timeout instead of using DataStax's built-in timeout option. This results in a default non-changeable timeout by the DataStax driver. It should be reported to Apache as a bug.