Graphite uses many terms that can have ambiguous meaning. The following definitions are what these
terms mean in the context of Graphite.
- A value stored at a timestamp bucket. If no value is recorded at a particular
timestamp bucket in a series, the value will be None (null).
- A time-series function which transforms, combines, or performs computations on one or more series.
- See series
- metric series
- See series
- See resolution
- The number of seconds per datapoint in a series. Series are created with a resolution
which determines how often a 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.
- The number of datapoints retained in a series. Alternatively: The length of time datapoints
are stored in a 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 heirarchical 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 series. Series lists are received by
functions 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:
- 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 functions
- A point in time in which values can be associated. Time in Graphite is represented
as epoch time with a maximum resolution of 1-second.
- timestamp bucket
- A timestamp after rounding down to the nearest multiple of a series’s resolution.
- A numeric or null value. Values are stored as double-precision floats. Values are parsed using
the python float() constructor and can also be None (null). The range and precision of
values is system dependant and can be found by executing (with Python 2.6 or later)::
python -c ‘import sys; print sys.float_info’