Apache Druid

Encrypting network traffic

It is a best practice to encrypt network traffic between the Looker application and your database. Consider one of the options described on the Enabling secure database access documentation page.

Configuring your Apache Druid cluster

<DRUID_BASE_DIR> refers to the base directory in which the Apache Druid cluster is installed on a server.

Enabling SQL

To enable SQL on your Druid database, add this line to the broker/runtime.properties configuration file:

<DRUID_BASE_DIR>/conf/druid/broker/runtime.properties

druid.sql.enable=true

Turning off COUNT DISTINCT approximation (optional)

By default, Druid approximates COUNT DISTINCT. For precise results, add this line to the broker/runtime.properties configuration file:

<DRUID_BASE_DIR>/conf/druid/broker/runtime.properties

`druid.sql.planner.useApproximateCountDistinct=false`

Creating the Looker connection to your database

In the Admin section of Looker, select Connections, and then click Add Connection.

Fill out the connection details. The majority of the settings are common to most database dialects. See the Connecting Looker to your database documentation page for information. Some of the settings are described next:

  • Name: The name of the connection.

  • Dialect: Apache Druid, Apache Druid 0.13+, or Apache Druid 0.18+.

  • Host: DNS or IP address of the cluster Broker. You can find this in your broker/runtime.properties file.

  • Port: The port of the Broker. The default port is 8082. If your cluster is secured by SSL, the default port is 8182.

  • Database: The name of your database. The default is druid.

  • Username: The database username if your Apache Druid cluster is configured to use Druid Basic Security. If it is not, then you can specify any string.

  • Password: The user password. If your cluster is not configured to use Druid Basic Security, then you can specify any string.

  • Schema: The default schema to use when there is no schema specified. Entering a schema is optional.

  • Additional JDBC parameters: Semicolon delimited Avatica JDBC parameters.

    • These properties can be set as connection properties:
      • useApproximateCountDistinct
      • useApproximateTopN
      • useFallback
      • sqlTimeZone

    Example: none useApproximateCountDistinct=false;truststore=/path/to/truststore.jks;truststore_password=changeit

  • Datagroup and PDT Maintenance Schedule: A cron expression that indicates when Looker should check datagroups and persistent derived tables. Read more about this setting in the Datagroup and PDT Maintenance Schedule documentation.

  • SSL: Check if your Apache Druid cluster is configured to use Druid TLS.

  • Verify SSL: Check to enforce strict hostname verification.

  • Max connections per node: The default is 25. This setting can be left at the default value initially. See the Connecting Looker to your database documentation page for more information.

  • Connection Pool Timeout: The default is 120 seconds.

  • SQL Runner Precache: To cause SQL Runner not to preload table information and to load table information only when a table is selected, clear this option. Read more about this setting in the SQL Runner Precache documentation.

  • Database Time Zone: Database timezone. Supported in Apache Druid 0.13+ and Apache Druid 0.18+.

To verify that the connection is successful, click Test. See the Testing database connectivity documentation page for troubleshooting information.

Looker runs a SELECT 1 query to verify a basic connection and perform a query test. It does not validate that the catalog and schema combination exist or that the user has the required access to that schema.

If you have any issues, check out our Testing Connections documentation.

To save these settings, click Connect.

Test the connection in SQL Runner. Navigate to SQL Runner, select your connection and schema, then check if you can see your database tables.

Feature support

For Looker to support some features, your database dialect must also support them.

Apache Druid

Apache Druid supports the following features as of Looker 24.20:

Feature Supported?
Support Level
Supported
Looker (Google Cloud core)
No
Symmetric Aggregates
No
Derived Tables
Yes
Persistent SQL Derived Tables
No
Persistent Native Derived Tables
No
Stable Views
No
Query Killing
No
SQL-based Pivots
No
Timezones
No
SSL
Yes
Subtotals
No
JDBC Additional Params
Yes
Case Sensitive
Yes
Location Type
Yes
List Type
No
Percentile
No
Distinct Percentile
No
SQL Runner Show Processes
No
SQL Runner Describe Table
No
SQL Runner Show Indexes
No
SQL Runner Select 10
Yes
SQL Runner Count
Yes
SQL Explain
Yes
Oauth Credentials
No
Context Comments
Yes
Connection Pooling
No
HLL Sketches
No
Aggregate Awareness
No
Incremental PDTs
No
Milliseconds
Yes
Microseconds
No
Materialized Views
No
Approximate Count Distinct
No

Apache Druid 0.13+

Apache Druid 0.13+ supports the following features as of Looker 24.20:

Feature Supported?
Support Level
Supported
Looker (Google Cloud core)
No
Symmetric Aggregates
No
Derived Tables
Yes
Persistent SQL Derived Tables
No
Persistent Native Derived Tables
No
Stable Views
No
Query Killing
No
SQL-based Pivots
No
Timezones
Yes
SSL
Yes
Subtotals
No
JDBC Additional Params
Yes
Case Sensitive
Yes
Location Type
No
List Type
No
Percentile
No
Distinct Percentile
No
SQL Runner Show Processes
No
SQL Runner Describe Table
No
SQL Runner Show Indexes
No
SQL Runner Select 10
Yes
SQL Runner Count
Yes
SQL Explain
Yes
Oauth Credentials
No
Context Comments
Yes
Connection Pooling
No
HLL Sketches
No
Aggregate Awareness
No
Incremental PDTs
No
Milliseconds
Yes
Microseconds
No
Materialized Views
No
Approximate Count Distinct
No

Apache Druid 0.18+

Apache Druid 0.18+ supports the following features as of Looker 24.20:

Feature Supported?
Support Level
Supported
Looker (Google Cloud core)
Yes
Symmetric Aggregates
No
Derived Tables
Yes
Persistent SQL Derived Tables
No
Persistent Native Derived Tables
No
Stable Views
No
Query Killing
No
SQL-based Pivots
No
Timezones
Yes
SSL
Yes
Subtotals
No
JDBC Additional Params
Yes
Case Sensitive
Yes
Location Type
Yes
List Type
No
Percentile
No
Distinct Percentile
No
SQL Runner Show Processes
No
SQL Runner Describe Table
No
SQL Runner Show Indexes
No
SQL Runner Select 10
Yes
SQL Runner Count
Yes
SQL Explain
Yes
Oauth Credentials
No
Context Comments
Yes
Connection Pooling
No
HLL Sketches
No
Aggregate Awareness
No
Incremental PDTs
No
Milliseconds
Yes
Microseconds
No
Materialized Views
No
Approximate Count Distinct
No

Next steps

After you have completed the database connection, configure authentication options.