This engine is designed for rollup (thinning and aggregating/averaging) [Graphite](http://graphite.readthedocs.io/en/latest/index.html) data. It may be helpful to developers who want to use ClickHouse as a data store for Graphite.
The engine inherits properties from MergeTree. The settings for thinning data are defined by the [graphite_rollup](../server_settings/settings.md#server_settings-graphite_rollup) parameter in the server configuration.
When processing a record, ClickHouse will check the rules in the `pattern`clause. If the metric name matches the `regexp`, the rules from `pattern` are applied; otherwise, the rules from `default` are used.
Fields in the pattern.
-`age`– The minimum age of the data in seconds.
-`function`– The name of the aggregating function to apply to data whose age falls within the range `[age, age + precision]`.
-`precision`– How precisely to define the age of the data in seconds.