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TSBS Supplemental Guide: Cassandra

Cassandra is a general column store database. This supplemental guide explains how the data generated for TSBS is stored, additional flags available when using the data importer (tsbs_load_cassandra), and additional flags available for the query runner (tsbs_run_queries_cassandra). This should be read after the main README.

Data format

Data generated by tsbs_generate_data for Cassandra is a "pseudo-CSV" format. Each reading is a single line where the first comma-separated element with the following elements:

  • first, the table the reading belongs to (based on data type, e.g., series_double for doubles);
  • then, the data source (e.g., cpu for cpu-only);
  • then, several elements of the form <label>=<value> for tags;
  • then, the field label;
  • then, the date of the reading in YYYY-MM-DD form;
  • then, the timestamp in nanoseconds;
  • and finally, the reading itself.

An example from cpu-only:

series_double,cpu,hostname=host_0,region=eu-west-1,datacenter=eu-west-1b,rack=67,os=Ubuntu16.10,arch=x86,team=NYC,service=7,service_version=0,service_environment=production,usage_guest_nice,2016-01-01,1451606400000000000,38.2431182911542820

When stored, the elements starting with the data source (e.g. cpu) through the date of the reading are concatenated to serve as the primary key.

tsbs_load_cassandra Additional Flags

Database related

-consistency (type: string, default: ALL)

Consistency level for writes to the database. Options are ALL, ANY, ONE, TWO, THREE, or QUORUM. Applies for multi-node cluster.

-hosts (type: string, default: localhost:9042)

Comma-separated list of hostname and port combinations for nodes in the cluster.

-replication-factor (type: int, default: 1)

Level of replication for each write, i.e., number of nodes to store the data on. Only applies a multi-node cluster.

-write-timeout (type: duration, default: 10s)

Length of the timeout for writes. It is expressed as a Golang time.Duration string, meaning a number followed by a unit abbreviation (s = seconds, m = minutes, h = hours), e.g., the default 10s is ten seconds.

tsbs_run_queries_cassandra Additional Flags

Database related

-aggregation-plan (type: string, default: client)

Method for doing aggregations in queries. Due to limitations in Cassandra's SQL-like language CQL, aggregations can be painful and slow if done on the server itself. Therefore the default is client (with the other valid option being server), where the client Go program handles the aggregation.

-client-side-index-timeout (type: duration, default: 10s)

Length of the timeout when setting up the client side index, a data structure used to speed up queries by storing the tagsets/primary keys in memory on the client. It is expressed as a Golang time.Duration string, meaning a number followed by a unit abbreviation (s = seconds, m = minutes, h = hours), e.g., the default 10s is ten seconds.

-host (type: string, default: localhost:9042)

Hostname and port combination of at least one node in the cluster. The library used will discover the other nodes for queries.

-read-timeout (type: duration, default: 10s)

Length of the timeout for reads. It is expressed as a Golang time.Duration string, meaning a number followed by a unit abbreviation (s = seconds, m = minutes, h = hours), e.g., the default 10s is ten seconds.