Permalink
Fetching contributors…
Cannot retrieve contributors at this time
68 lines (51 sloc) 3.07 KB

Graphite Terminology

Graphite uses many terms that can have ambiguous meaning. The following definitions are what these terms mean in the context of Graphite.

.. glossary::

    datapoint
      A :term:`value` stored at a :term:`timestamp bucket`. If no value is recorded at a particular
      timestamp bucket in a :term:`series`, the value will be None (null).

    function
      A time-series function which transforms, combines, or performs computations on one or more :term:`series`.
      See :doc:`functions`

    metric
      See :term:`series`

    metric series
      See :term:`series`

    precision
      See :term:`resolution`

    resolution
      The number of seconds per datapoint in a :term:`series`. Series are created with a resolution
      which determines how often a :term:`datapoint` may be stored. This resolution is represented
      as the number of seconds in time that each datapoint covers. A series which stores one datapoint
      per minute has a resolution of 60 seconds. Similarly, a series which stores one datapoint per
      second has a resolution of 1 second.

    retention
      The number of datapoints retained in a :term:`series`. Alternatively: The length of time datapoints
      are stored in a series.

    series
      A named set of datapoints. A series is identified by a unique name, which is composed of
      elements separated by periods (``.``) which are used to display the collection of series
      into a hierarchical tree. A series storing system load average on a server called ``apache02``
      in datacenter ``metro_east`` might be named as ``metro_east.servers.apache02.system.load_average``

    series list
      A series name or wildcard which matches one or more :term:`series`. Series lists are received by
      :term:`functions <function>` as a list of matching series. From a user perspective, a series list is
      merely the name of a metric. For example, each of these would be considered a single series list:

      * ``metro_east.servers.apache02.system.load_average.1_min``,
      * ``metro_east.servers.apache0{1,2,3}.system.load_average.1_min``
      * ``metro_east.servers.apache01.system.load_average.*``

    target
      A source of data used as input for a Graph. A target can be a single metric name, a metric wildcard,
      or either of these enclosed within one or more :term:`functions <function>`

    timestamp
      A point in time in which :term:`values <value>` can be associated. Time in Graphite is represented
      as `epoch time <http://en.wikipedia.org/wiki/Epoch_time>`_ with a maximum resolution of 1-second.

    timestamp bucket
      A :term:`timestamp` after rounding down to the nearest multiple of a :term:`series's <series>` :term:`resolution`.

    value
      A numeric or null value. Values are stored as double-precision floats. Values are parsed using
      the python :py:func:`float` constructor and can also be None (null). The range and precision of
      values is system dependent and can be found by executing (with Python 2.6 or later)::
      python -c 'import sys; print sys.float_info'