Skip to content

Glossary

  • Bootstrapping: Process by which an M3DB node is brought up. Bootstrapping consists of determining the integrity of data that the node has, replay writes from the commit log, and/or stream missing data from its peers.

  • Cardinality: The number of unique metrics within the M3DB index. Cardinality increases with the number of unique tag/value combinations that are being emitted.

  • Datapoint: A single timestamp/value. Timeseries are composed of multiple datapoints and a series of tag/value pairs.

  • Labels: Pairs of descriptive words that give meaning to a metric. Tags and Labels are interchangeable terms.

  • Metric: A collection of uniquely identifiable tags.

  • M3: Highly scalable, distributed metrics platform that is comprised of a native, distributed time series database, a highly-dynamic and performant aggregation service, a query engine, and other supporting infrastructure.

  • M3Coordinator: A service within M3 that coordinates reads and writes between upstream systems, such as Prometheus, and downstream systems, such as M3DB.

  • M3DB: Distributed time series database influenced by Gorilla and Cassandra released as open source by Uber Technologies.

  • M3Query: A distributed query engine for M3DB. Unlike M3Coordinator, M3Query only provides supports for reads.

  • Namespace: Similar to a table in other types of databases, namespaces in M3DB have a unique name and a set of configuration options, such as data retention and block size.

  • Placement: Map of the M3DB cluster's shard replicas to nodes. Each M3DB cluster has only one placement. Placement and Topology are interchangeable terms.

  • Shard: Effectively the same as a "virtual shard" in Cassandra in that it provides an arbitrary distribution of time series data via a simple hash of the series ID.

  • Tags: Pairs of descriptive words that give meaning to a metric. Tags and Labels are interchangeable terms.

  • Timeseries: A series of data points tracking a particular metric over time.

  • Topology: Map of the M3DB cluster's shard replicas to nodes. Each M3DB cluster has only one placement. Placement and Topology are interchangeable terms.