# GraphiteMergeTree 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. Graphite stores full data in ClickHouse, and data can be retrieved in the following ways: - Without thinning. Uses the [MergeTree](mergetree.md#table_engines-mergetree) engine. - With thinning. Using the `GraphiteMergeTree` engine. 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. ## Using the engine The Graphite data table must contain the following fields at minimum: - `Path` – The metric name (Graphite sensor). - `Time` – The time for measuring the metric. - `Value` – The value of the metric at the time set in Time. - `Version` – Determines which value of the metric with the same Path and Time will remain in the database. Rollup pattern: ```text pattern regexp function age -> precision ... pattern ... default function age -> precision ... ``` 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. - `regexp`– A pattern for the metric name. Example of settings: ```xml click_cost any 0 5 86400 60 max 0 60 3600 300 86400 3600 ```