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Using Multiple OLAP Engines

Overview​

If you have access to another OLAP engine (such as ClickHouse or Druid), you have the option to either:

  • Create dedicated projects that are powered by one specific OLAP engine (default)
  • Use different OLAP engines in the same project to power separate dashboards

On this page, we will walk through how to configure the latter.

Why Multiple OLAP Engines?​

There could be reasons why you wish to configure multiple OLAP engines within the same project.

  • You have datasources that differ greatly in size but which you want to use within the same project. As a rule of thumb, DuckDB handles datasets up to 50GB quite well and is performant. Much larger though, you may want a more enterprise-grade OLAP engine powering specific dashboards.
  • You have existing datasets / tables from other OLAP stores that you wish to use in Rill, which may already be optimized, and which you do not want to separately ingest into Rill. Instead, you would like to create dashboards off these tables directly and have the OLAP engine power it.
Don't see an OLAP engine?

If there's an OLAP engine you're interested that isn't available, please don't hesitate to contact us. We'd love to hear from you and learn more!

Enabling Multiple OLAP Engines​

To configure multiple OLAP engines, you'll want to leave the default OLAP engine as DuckDB in your project and configure dashboards that are powered by other OLAP engines individually (more on this below).

Setting up your OLAP Engine connection string (DSN)​

Before getting started, you'll need to first configure the appopriate connection string for each OLAP engine that you plan to use in Rill. Besides the built-in DuckDB OLAP engine, each OLAP engine should have it's own connector.<olap-engine>.dsn variable that needs to be configured.

For Rill Developer:

  • You can set these variables in your project's .env file or try pulling existing credentials locally using rill env pull if the project has already been deployed to Rill Cloud
  • Alternatively, you can pass in these connector DSN variables to rill start directly when starting Rill (e.g. rill start --env connector.druid.dsn=... --env connector.clickhouse.dsn=...)
Getting DSN errors in dashboards after setting .env?

There might be instances where you've configured the project's .env file with the appropriate connection DSN strings but dashboards are still throwing errors. In these situations, try restarting Rill using the rill start --reset command.

For Rill Cloud:

  • You can pass in the appropriate DSN connection string for each required OLAP engine by using the rill env configure command
  • Alternatively, if the required connector.<olap-engine>.dsn parameters have been set in your project's .env, you can "push" these updated variables to your deployed project directly using rill env push
info

Note that you must cd into the Git repository that your project was deployed from before running rill env configure.

Configuring DuckDB as the default OLAP engine​

Not much needs to be done here as DuckDB as the inherent default OLAP engine that is used by Rill. However, in case a different olap_connector is set in the project's rill.yaml file, this property should either be removed and/or set back to duckdb.

olap_connector: duckdb
rill.yaml

For more information about available configurations for rill.yaml, please see our Project YAML reference documentation.

Setting the OLAP Engine in the dashboard YAML​

For each dashboard that is using a separate OLAP engine (than the default), you'll want to set the connector and table properties in the underlying dashboard YAML configuration to the OLAP engine and corresponding external table that exists in your OLAP store respectively.

type: metrics_view
title: <dashboard_name>
connector: <olap_engine>
table: <external_table_in_olap>
...