I am using Cassandra 2.2.4 and I am struggling to get the cassandra-stress tool
to work for my test scenario. I have followed the example on
http://www.datastax.com/dev/blog/improved-cassandra-2-1-stress-tool-benchmark-any-schema
<http://www.datastax.com/dev/blog/improved-cassandra-2-1-stress-tool-benchmark-any-schema>
to create a yaml file describing my test.
I am collecting events per user id (text, partition key). Events have a session
type (text), event type (text), and creation time (timestamp) (clustering keys,
in that order). Plus some more attributes required for rendering the events in
a UI. For testing purposes I ended up with the following column spec and insert
distribution:
columnspec:
- name: created_at
cluster: uniform(10..10000)
- name: event_type
size: uniform(5..10)
population: uniform(1..30)
cluster: uniform(1..30)
- name: session_type
size: fixed(5)
population: uniform(1..4)
cluster: uniform(1..4)
- name: user_id
size: fixed(15)
population: uniform(1..1000000)
- name: message
size: uniform(10..100)
population: uniform(1..100B)
insert:
partitions: fixed(1)
batchtype: UNLOGGED
select: fixed(1)/1200000
Running stress tool for just the insert prints
Generating batches with [1..1] partitions and [0..1] rows (of [10..1200000]
total rows in the partitions)
and then immediately starts flooding me with
"com.datastax.driver.core.exceptions.InvalidQueryException: Batch too large”.
Why I should be exceeding the "batch_size_fail_threshold_in_kb: 50” in the
cassandra.yaml I do not understand. My understanding is that the stress tool
should generate one row per batch. The size of a single row should not exceed
8+10*3+5*3+15*3+100*3 = 398 bytes. Assuming a worst case of all text characters
being 3 byte unicode characters.
How come I end up with batches that exceed the 50kb threshold? Am I missing the
point about the “select” attribute?
Thanks!
Ralf
