Apache Hive

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This page contains information about connecting Looker to Apache Hive.

Introduction

Looker is architected to connect to a database server via JDBC. In the case of Hive, this is the thrift server (HiveServer2). See the Apache documentation for more information.

By default, this server will listen on port 10000.

Looker is an interactive querying tool, so it expects to work with an interactive SQL engine. If Hive is running on MapReduce -- hive.execution.engine is set to mr -- then Hive will return query results too slowly to be practical.

Looker was tested with Hive on Tez (hive.execution.engine=tez), although it is also possible to run Looker against Hive on Spark. Spark support was added in Hive version 1.1. (Looker supports Hive 1.2.1+.)

Persistent derived tables (PDTs)

To enable persistent derived tables (PDTs) in Looker using a Hive connection, create a scratch schema for Looker to use. Here is an example of a command you can use to create a looker_scratch schema:

 CREATE SCHEMA looker_scratch;

The user account that Looker uses to connect to Hive (which can be anonymous if no authentication is used) must have the following abilities in the scratch schema:

  • Create tables
  • Alter tables
  • Drop tables

Test this with a JDBC client before attempting to create PDTs with Hive.

Queues

If you want queries from Looker to go into a specific queue, enter the queue name parameter in the Additional Params field on the Connection Settings page:

?tez.queue.name=the_bi_queue

Other Hive parameters can be set this way in the Additional Params field on the Connection Settings page.

Using user attributes, it is possible for queries from different users or different groups of users to go into different queues. To do this, create a user attribute named something like queue_name, then in the Additional Params field, add:

?tez.queue.name={{ _user_attributes['queue_name'] }}

You can use this to customize other hive-site.xml parameters on a per-user or per-group basis as well.

Adding the connection

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

Fill out the connection details (see the Connecting Looker to your database documentation page for more information):

  • Name: Specify the name of the connection. This is how you will refer to the connection in LookML projects.
  • Dialect: Specify the dialect: Apache Hive 2, Apache Hive 2.3+, or Apache Hive 3.1.2+.

    For Apache Hive 3.1.2+, Looker can fully integrate with Apache Hive 3 databases only on versions specifically 3.1.2+. This is because of a query parsing issue from Hive versions 2.4.0 - 3.1.2 that resulted in extremely long parsing times for Looker-generated SQL.

  • Host: Specify the hostname.

  • Port: Specify the database port.

  • Database: Specify the database name.

  • Username: Specify the database username.

  • Password: Specify the database user password.

  • Persistent Derived Tables: Check this box to enable persistent derived tables. This setting reveals the Temp Database field and the PDT Overrides column.

  • Temp Database: Specify the name of the scratch schema created in the PDTs section above.

  • Max PDT Builder Connections: Specify the number of possible concurrent PDT builds on this connection. Setting this value too high could negatively impact query times. For more information, see the Connecting Looker to your database documentation page.

  • Additional Params: Specify any additional JDBC string parameters.

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

  • SSL: Check to use SSL connections.

  • Verify SSL Cert: Check for hostname verification.

  • Max Connections: This setting can be left at the default value initially. Read more about this setting in the Max Connections section of the Connecting Looker to your database documentation page.

  • Connection Pool Timeout: This setting can be left at the default value initially. Read more about this setting in the Connection Pool Timeout section of the Connecting Looker to your database documentation page.

  • SQL Runner Precache: To cause SQL Runner not to preload table information and to load table information only when a table is selected, uncheck this option. Read more about this setting in the SQL Runner Precache section of the Connecting Looker to your database documentation page.

  • Database Time Zone: Specify the time zone used in the database. Leave this field blank if you do not want time zone conversion. See the Using time zone settings documentation page for more information.

Feature support

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

In the latest release of Looker, Apache Hive 2 supports the following Looker features:

In the latest release of Looker, Apache Hive 2.3+ supports the following Looker features:

In the latest release of Looker, Apache Hive 3.1.2+ supports the following Looker features:

Next steps

After you have connected your database to Looker, configure sign-in options for your users.