Tutorial: Configuring data retention

    For this tutorial, we’ll assume you’ve already downloaded Apache Druid as described in the single-machine quickstart and have it running on your local machine.

    It will also be helpful to have finished and Tutorial: Querying data.

    For this tutorial, we’ll be using the Wikipedia edits sample data, with an ingestion task spec that will create a separate segment for each hour in the input data.

    The ingestion spec can be found at . Let’s submit that spec, which will create a datasource called retention-tutorial:

    After the ingestion completes, go to http://localhost:8888/unified-console.html#datasources in a browser to access the web console’s datasource view.

    This view shows the available datasources and a summary of the retention rules for each datasource:

    Currently there are no rules set for the retention-tutorial datasource. Note that there are default rules for the cluster: load forever with 2 replicas in _default_tier.

    This means that all data will be loaded regardless of timestamp, and each segment will be replicated to two Historical processes in the default tier.

    In this tutorial, we will ignore the tiering and redundancy concepts for now.

    Let’s view the segments for the retention-tutorial datasource by clicking the “24 Segments” link next to “Fully Available”.

    Original segments

    Suppose we want to drop data for the first 12 hours of 2015-09-12 and keep data for the later 12 hours of 2015-09-12.

    Go to the datasources view and click the blue pencil icon next to Cluster default: loadForever for the retention-tutorial datasource.

    A rule configuration window will appear:

    Now click the button twice.

    In the upper rule box, select Load and by interval, and then enter 2015-09-12T12:00:00.000Z/2015-09-13T00:00:00.000Z in field next to by interval. Replicas can remain at 2 in the _default_tier.

    In the lower rule box, select Drop and .

    The rules should look like this:

    Set rules

    Now click Next. The rule configuration process will ask for a user name and comment, for change logging purposes. You can enter tutorial for both.

    Give the cluster a few minutes to apply the rule change, and go to the in the web console. The segments for the first 12 hours of 2015-09-12 are now gone:

    New segments

    The resulting retention rule chain is the following:

    1. dropForever

    The rule chain is evaluated from top to bottom, with the default rule chain always added at the bottom.

    The tutorial rule chain we just created loads data if it is within the specified 12 hour interval.

    If data is not within the 12 hour interval, the rule chain evaluates dropForever next, which will drop any data.

    The dropForever terminates the rule chain, effectively overriding the default loadForever rule, which will never be reached in this rule chain.

    If instead you want to retain data based on how old it is (e.g., retain data that ranges from 3 months in the past to the present time), you would define a Period load rule instead.