Custom payloads

Starting with Cassandra v2.2+, every request can include custom payload. This payload is meant to be processed by custom query handlers on Cassandra. Default handlers simply ignore it.

Background

Given

a running cassandra cluster

Sending custom payload

Given

the following example:

require 'cassandra'
cluster = Cassandra.cluster
session = cluster.connect

result = session.execute('SELECT unixTimestampOf(NOW()) as date FROM system.local',
                         payload: {'some_key' => 'some_value'})

delta = Time.now.to_i - result.first['date'] / 1000
if delta < 0 || delta > 1
  puts "failure"
else
  puts "success"
end

When

it is executed

Then

its output should contain:

success

Mirroring a sent custom payload

Given

the following schema:

CREATE KEYSPACE simplex WITH replication = {'class': 'SimpleStrategy', 'replication_factor': 1};
USE simplex;
CREATE TABLE test (k int, v int, PRIMARY KEY (k, v));

And

the following example:

require 'cassandra'
cluster = Cassandra.cluster
session = cluster.connect("simplex")

result = session.execute('SELECT * FROM test', payload: {'first_key' => 'first_value'})
puts result.execution_info.payload

select = session.prepare('SELECT * FROM test WHERE k=?')
result = session.execute(select, arguments: [0], payload: {'second_key' => 'second_value'})
puts result.execution_info.payload

batch = session.batch do |b|
  b.add("INSERT INTO test (k, v) VALUES (1, 1)")
end
result = session.execute(batch, payload: {'third_key' => 'third_value', 'fourth_key' => 'fourth_value'})
puts result.execution_info.payload

When

payload mirroring query handler is enabled

And

it is executed

Then

its output should contain:

{"first_key"=>"first_value"}
{"second_key"=>"second_value"}
{"fourth_key"=>"fourth_value", "third_key"=>"third_value"}