02 YAML Organization
It is best to keep every workload self-contained within a single YAML file, including schema, data rampup, and the main phase of testing. The phases of testing are controlled by tags as described below.
NOTE: The phase names described below have been adopted as a convention within the built-in workloads. It is strongly advised that new workload YAMLs use the same tagging scheme so that workload are more plugable across YAMLs.
The schema phase is simply a phase of your test which creates the necessary schema on your target system. For CQL, this generally consists of a keyspace and one ore more table statements. There is no special schema layer in nosqlbench. All statements executed are simply statements. This provides the greatest flexibility in testing since every activity type is allowed to control its DDL and DML using the same machinery.
The schema phase is normally executed with defaults for most parameters. This means that statements will execute in the order specified in the YAML, in serialized form, exactly once. This is a welcome side-effect of how the initial parameters like cycles is set from the statements which are activated by tagging.
You can mark operations for the schema phase by adding this set of tags to the op templates, either directly, or by block:
tags: phase: schema
When you run a performance test, it is very important to be aware of how much data is present. Higher density tests are more realistic for systems which accumulate data over time, or which have a large working set of data. The amount of data on the system you are testing should recreate a realistic amount of data that you would run in production, ideally. In general, there is a triangular trade-off between service time, op rate, and data density.
It is the purpose of the rampup phase to create the backdrop data on a target system that makes a test meaningful for some level of data density. Data density is normally discussed as average per node, but it is also important to consider distribution of data as it varies from the least dense to the most dense nodes.
Because it is useful to be able to add data to a target cluster in an incremental way, the bindings
which are used with a rampup phase may actually be different from the ones used for a main
phase. In most cases, you want the rampup phase to create data in a way that incrementally adds to
the population of data in the cluster. This allows you to add some data to a cluster
cycles=0..1M and then decide whether to continue adding data using the next contiguous range
of cycles, with
cycles=1M..2M and so on.
You can mark operations for the rampup phase by adding this set of tags to the op templates, either directly, or by block:
tags: phase: rampup
The main phase of a NoSQLBench scenario is the one during which you really care about recording the metrics. This is the actual test that everything else has prepared your system for.
You can mark operations for the main phase by adding this set of tags to the op templates, either directly, or by block:
tags: phase: main