Oracle

Note: Looker support for Oracle is implemented using standard Oracle deployments. If your Oracle database is an Oracle RAC deployment, Looker can connect successfully but it may encounter issues with killing queries because of a difference in metadata for retrieving query connection IDs from nodes.

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.

If you're interested in using SSL encryption, see the Oracle documentation.

Creating a Looker user

First, create a designated Looker user:

-- connect / as sysdba;
CREATE USER LOOKER IDENTIFIED BY <password>
DEFAULT TABLESPACE USERS
TEMPORARY TABLESPACE TEMP;

Next, give the new Looker user the ability to create sessions:

GRANT CREATE SESSION TO LOOKER;

Finally, give the Looker user the appropriate SELECT permissions for the data tables that you plan to access from Looker. If you want to access additional tables in the future, you will need to grant SELECT on those new tables as well.

GRANT SELECT ON -- <all tables that will be used by looker>;

Ensuring Looker can see all tables

Looker may not be able to identify tables (especially empty tables) without first collecting statistics in Oracle. If tables you need do not appear in generated LookML or SQL Runner, try executing:

EXEC DBMS_STATS.GATHER_DATABASE_STATS;

For alternative methods, consult your Oracle documentation.

Setting up main database objects

Your Oracle DBA must set up the following objects and permissions on Oracle. The following commands create LOOKER_SESSION and LOOKER_SQL as synonyms for V$SESSION and V$SQL.

Run the following commands as the root user to complete this setup. These examples assume that the Looker user's name is LOOKER.

CREATE OR REPLACE VIEW LOOKER_SQL
AS
  SELECT
    sql.SQL_ID,
    sql.SQL_TEXT
  FROM
    V$SQL sql,
    v$session sess
  WHERE
    sess.SQL_ADDRESS = sql.ADDRESS AND
    sess.username='LOOKER';

CREATE OR REPLACE SYNONYM LOOKER.LOOKER_SQL FOR LOOKER_SQL;

GRANT SELECT ON LOOKER.LOOKER_SQL TO LOOKER;

-- Pay special attention to the following comments:
-- the following view will be different for clustered Oracle deployments
CREATE OR REPLACE VIEW LOOKER_SESSION
AS
  SELECT
    SID,
    USERNAME,
    TYPE,
    STATUS,
    SQL_ID,
    -- If using a single node Oracle deployment
    "SERIAL#",
    -- If using a clustered Oracle deployment, like Oracle Real Application Clusters
    (SERIAL# || ',' || INST_ID) AS "SERIAL#",
    AUDSID
  -- If using a single node Oracle deployment
  FROM V$SESSION
  -- If using a clustered Oracle deployment, like Oracle Real Application Clusters
  FROM GV$SESSION
  WHERE
    USERNAME='LOOKER';

CREATE OR REPLACE SYNONYM LOOKER.LOOKER_SESSION FOR LOOKER_SESSION;

GRANT SELECT ON LOOKER.LOOKER_SESSION TO LOOKER;

Setting up symmetric aggregates

Your Oracle DBA must set up the LOOKER_HASH function to enable symmetric aggregates. The LOOKER_HASH function is a synonym for the Oracle dbms_crypto.hash function. The DBA must also create the associated synonym and privileges. The following commands assume that the Looker user's name is LOOKER:

CREATE OR REPLACE FUNCTION LOOKER_HASH(bytes raw, prec number)
  RETURN raw AS
  BEGIN
    return(dbms_crypto.HASH(bytes, prec));
  END;

CREATE OR REPLACE SYNONYM LOOKER.LOOKER_HASH FOR LOOKER_HASH;

GRANT EXECUTE ON LOOKER.LOOKER_HASH TO LOOKER;

GRANT EXECUTE ON SYS.LOOKER_HASH TO LOOKER;

Depending on your Oracle database configuration, the SYS prefix may be SYSDBA, ADMIN, or unnecessary.

Setting up persistent derived tables

To enable persistent derived tables, give the Looker user the UNLIMITED TABLESPACE and CREATE TABLE permissions. The following commands assume that the Looker user's name is LOOKER:

GRANT UNLIMITED TABLESPACE TO LOOKER;
GRANT CREATE TABLE TO LOOKER;

Setting up query killing

Follow these instructions to configure query killing for either a standard Oracle deployment or an Amazon RDS deployment.

Standard Oracle deployments

To set up query killing in standard Oracle deployments, the Oracle DBA must create the LOOKER_KILL_QUERY procedure as a synonym of ALTER SYSTEM KILL SESSION. To do this, execute the following command:

CREATE OR REPLACE PROCEDURE LOOKER_KILL_QUERY(p_sid in varchar2,
                                              p_serial# in varchar2)
IS
  cursor_name pls_integer default dbms_sql.open_cursor;
  ignore pls_integer;

BEGIN
  SELECT
    COUNT(*) INTO ignore
  -- If using a single node Oracle deployment
  FROM V$SESSION
  -- If using a clustered Oracle deployment, like Oracle Real Application Clusters
  FROM GV$SESSION
  WHERE
    username = USER
    AND sid = p_sid
    -- If using a single node Oracle deployment
    AND serial# = p_serial#;
    -- If using a clustered Oracle deployment, like Oracle Real Application Clusters
    AND (SERIAL# || ',' || INST_ID) = p_serial#;

  IF (ignore = 1)
  THEN
    dbms_sql.parse(cursor_name,
                   'ALTER SYSTEM KILL SESSION '''
                   || p_sid || ',' || p_serial# || '''',
                   dbms_sql.native);
    ignore := dbms_sql.execute(cursor_name);
  ELSE
    raise_application_error(-20001,
                            'You do not own session ''' ||
                            p_sid || ',' || p_serial# ||
                            '''');
  END IF;
END;

The DBA will also need to run these related commands:

CREATE OR REPLACE SYNONYM LOOKER.LOOKER_KILL_QUERY FOR SYS.LOOKER_KILL_QUERY;
GRANT EXECUTE ON SYS.LOOKER_KILL_QUERY TO LOOKER;

Depending on your Oracle database configuration, the SYS prefix may be SYSDBA, ADMIN, or unnecessary.

Amazon RDS deployments

In Amazon RDS Oracle deployments, the rdsadmin.rdsadmin_util.kill procedure is used to kill queries. To use this procedure, the Looker database user must have the DBA role assigned.

Because DBA is an elevated database role, you might consider skipping this step and forgoing query killing in Looker.

To give the Looker database user query killing abilities, run the following command:

GRANT DBA TO LOOKER;

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. The following settings are specific to Oracle:

• Name: Specify the name of the connection. This is how you will refer to the connection in LookML projects.
• Dialect: Oracle.
• Use TNS: Enable Transparent Network Substrate (TNS) connections.
• Host: Hostname or TNS alias.
• Port: Database port.
• Database: Database name (if not using TNS).
• Service Name: Service name (if using TNS).
• Username: Database username or Temp Database if PDTs are enabled.
• Password: Database user password.
• Enable PDTs: Use this toggle to enable persistent derived tables. When PDTs are enabled, the Connection window reveals additional PDT settings and the PDT Overrides section.
• Temp Database: In Oracle a user is a schema, so this should be specified as the name of the database user. For this example, you would use the temp schema value LOOKER.
• Max number of 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 JDBC parameters: Leave this blank, since Oracle does not support additional JDBC parameters.
• 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 to use SSL connections.
• Verify SSL: Ignore this field. Oracle will use the default Java Truststore to verify SSL.
• Max connections per node: This setting can be left at the default value initially. Read more about this setting in the Max connections per node 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.

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

To save these settings, click Connect. In the Admin section of Looker, select Connections, and then click Add Connection.

Feature support

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

Oracle supports the following features as of Looker 24.20:

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