Connections

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The Connections page lists all of the database connections that you have configured for Looker use.

Viewing Connections

This page shows basic information about the connections you’ve defined and lets you test the status of those connections:

Column Definition
Name The name of the connection, which you define, and is used in the connection LookML parameter. A list of status checks is also included, described below.
Host : Port The host path where your database is located, and the port that Looker will use to connect to that host
Username The username that Looker will use to connect to the database
Database The name of the database that Looker will query when using this connection
SSL Whether or not you are using SSL encryption to protect the data traveling between Looker and your database (please note there are other secure options that are not SSL)
Type The SQL dialect of the database connection
Actions Actions you can take for a connection: test a connection, edit a connection, view other information about a connection, jump to a list of links to the connection’s Explores, or delete a connection.

Testing Connections

Looker allows you to test your connections to make sure they are functioning properly. Each connection test includes a list of status checks to tell you whether or not Looker can successfully use the database connection. For example:

Potential issues are shown in yellow, while errors are shown in red.

You can check the status of:

  • a single connection by clicking Test to the far right of that connection.
  • all connections by clicking the Test All Connections button at the top of the page.

Two common checks are cause for confusion:

  • Can find temp schema
  • Can use persistent derived tables

These checks do not need to pass in order for Looker to function, however, you will need them to pass in order to use persistent derived tables, which are a very valuable modeling feature.

Adding Connections

To add a connection, simply click the New Database Connection button in the upper left of the page.

The fields that you will need to fill in change depending upon the SQL Dialect that you choose. However, there are a set of fields that apply to almost everyone:

Name

The name of the connection as you want to refer to it. You should not use spaces. This value does not need to match anything in your database, it is just a label that you assign. You’ll use it in the connection parameter of your LookML model.

Dialect

The SQL dialect that matches your connection. It’s important to choose the correct value so that you are presented with the proper connection options, and so Looker can translate your LookML into SQL properly.

Host : Port

The hostname of your database host, and the port that Looker should use to connect to your database host.

To set the value of the host or port to an user attribute, click the person icon to the right of the host or port field, then choose the user attribute from the dropdown menu. Please note that this will disable persistent derived tables on this connection!

Database

The name of the database on your host. For example, you might have a hostname of my-instance.us-east-1.redshift.amazonaws.com on which there is a database called sales_info. You would enter sales_info in this field. If you have multiple databases on the same host, you may need to create multiple connections to use them (with the exception of MySQL, in which the word “database” means something a little bit different than most SQL dialects).

To set the value of the database to an user attribute, click the person icon to the right of the database field, then choose the user attribute from the dropdown menu. Please note that this will disable persistent derived tables on this connection!

Username

The username that Looker should use to connect to your database. You should configure the user ahead of time according to the instructions in our database configuration instructions.

To set the value of the username to an user attribute, click the person icon to the right of the username field, then choose the user attribute from the dropdown menu. Please note that this will disable persistent derived tables on this connection! Also, for models based on this connection, you will not be able to specify a caching policy or when to rebuild PDTs using datagroups .

Password

The password that Looker should use to connect to your database. You should configure the password ahead of time according to the instructions in our database configuration instructions.

To set the value of the password to an user attribute, click the Change Password button, then click the person icon to the right of the password field. Finally, choose the user attribute from the dropdown menu. Please note that this will disable persistent derived tables on this connection!

Persistent Derived Tables

Check this box to enable persistent derived tables. Doing so will reveal the Temp Database field. Looker displays this option only if the database dialect you chose supports using PDTs.

Temp Database

Though labeled “temp database”, you’ll enter either the database name or schema name — as appropriate for your SQL dialect — that Looker should use to create persistent derived tables. You should configure this database or schema ahead of time, with the appropriate write permissions. On the Database Configuration Instructions page, select your database dialect to see the instructions for that dialect.

PDT Maintenance Schedule

This setting accepts a cron expression that indicates when Looker should check persistent derived tables (that are based on sql_trigger_value) to be regenerated or dropped. The default value of */5 * * * * means “check every 5 minutes”.

For additional details, read our Discourse article about this feature.

SSL

Choose whether or not you want to use SSL encryption to protect data as it passes between Looker and your database. SSL is only one option that can be used to protect your data; other secure options are described here.

Max Connections

Here you can set the maximum number of connections that Looker can establish with your database. For the most part, you are setting the number of simultaneous queries that Looker can run against your database. You should set this value carefully. If it is too low, queries may be slow for your users as they wait for other user’s queries to return. If it is too high, you may overwhelm your database. The default value (which varies depending upon your SQL dialect) is typically a reasonable starting point.

Most databases also have their own settings for the maximum number of connections they will accept. You should check to see that Looker is set equal to or lower than your database’s configuration.

Connection Pool Timeout

If your users do request more connections than the Max Connections setting, the requests will wait for others to finish before they are executed. The maximum amount of time that a request will wait is configured here. You should set this value carefully. If it is too low, users may find their queries get cancelled because there isn’t enough time for other user’s queries to finish. If it is too high, large numbers of queries may build up causing users to wait for a very long time. The default value is typically a reasonable starting point.

SQL Runner Precache

In SQL Runner, all table information is pre-loaded as soon as you select a connection and schema. This enables SQL Runner to quickly display table columns as soon as you click on a table name. However, for connections and schema with many tables or with very large tables, you may not want SQL Runner to pre-load all of the information.

If you prefer SQL Runner to load table information only when a table is selected, you can uncheck the SQL Runner Precache option to disable SQL Runner pre-loading for the connection.

Database Time Zone

The time zone in which your database stores time information. Looker needs to know this so that it can convert time values for users, making it easier to understand and use time-related data. Users can use their preferred time zone in filter values and view query results converted to their preferred time zone.

Time data is converted depending on how these options are set:

  • If User Specific Time Zones are disabled,

    Looker converts time values in filter values and query results between the Database Time Zone and the Query Time Zone.
  • If the User Specific Time Zone setting is enabled, then:

Looker’s ability to provide time zone conversion depends on the database dialect’s ability to support this functionality. The list below shows which dialects support time zone in the most recent Looker release

Query Time Zone

The Query Time Zone option is visible only if you have disabled User Specific Time Zones.

When User Specific Time Zones are disabled, the Query Time Zone is the time zone that is displayed to your users when they pull time data, and the time zone into which Looker will convert time data from the Database Time Zone.

Additional Params

You can include additional JDBC parameters for your queries here, if needed.

If you want to use an user attribute in a JDBC parameter, you can use liquid templating. The syntax is _user_attributes['name_of_your_user_attribute'].

Editing Connections

To edit an existing connection, click the Edit button to the far right of a connection. You’ll be brought to same page that you use to create a connection (described above), but with the relevant information already filled out. Make any changes you need to, then click Update Connection.

Other Connection Options

You’ll notice there is also a gear dropdown menu to the far right of a connection. It offers the following options:

Show Tables

This option brings you to a Looker explore page that lets you create Looker reports based on the metadata of your connection. Although this option begins with the schema name, table name, and column count selected, you can manipulate it just like any other Looker report.

Show Databases

This option brings you to a Looker explore page that lets you create Looker reports based on the metadata of your connection. Although this option begins with the schema name, catalog name, table count, and column count selected, you can manipulate it just like any other Looker report.

Show Processes

This option brings you to a Looker explore page that lets you create Looker reports based on the processes running on this connection, the state they are in, how long they have been running, and other info. This can be useful in helping determine the cause if Looker is running slow, or if a query is not running at all.

Show PDT Event Log

This option brings you to a Looker explore page that lets you create Looker reports based on the derived table activity for this connection. The available fields are described in more detail on our PDTs page.

SQL Runner

This option brings you to Looker’s SQL Runner, with the proper connection and schema already selected.

Explore

This option brings you to a list of basic, automatically generated Explore options for your connection. These are not based on your customized data models, but they enable some quick reporting on the raw data in your connection’s tables. This is typically only useful for getting an idea of table contents before modeling, rather than for actual data analysis purposes.

Deleting Connections

To delete an existing connection, click the gear dropdown menu to the far right of a connection and select Delete. You’ll be given the opportunity to confirm the deletion but, once you do so, it cannot be undone. Accidentally deleting a connection will disable any queries that use it. However, as long you re-create a new connection with the same name, functionality will be restored.

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