Exasol

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.

The Exasol JDBC drivers support encrypted connections. If you're interested, see Exasol's documentation.

Create a Looker user

First, create a designated Looker user and give it the ability to create sessions:

CREATE USER LOOKER IDENTIFIED BY "<password>";
GRANT CREATE SESSION TO LOOKER;

Give the Looker user the appropriate SELECT permissions for the schema or tables that you plan to access from Looker:

GRANT SELECT ON <tables that will be used by LOOKER>;

Alternatively, you can grant all privileges:

GRANT ALL PRIVILEGES ON SCHEMA <YOUR_SCHEMA> TO LOOKER;

Alternatively, if you do not want to have to re-run GRANT statements on newly created tables in the future:

GRANT SELECT ANY TABLE TO LOOKER;

Persistent derived tables

If you want to enable PDTs for your Looker connection to Exasol, run this command:

CREATE SCHEMA LOOKER_SCRATCH;
ALTER SCHEMA LOOKER_SCRATCH CHANGE OWNER LOOKER;

Alternatively, you can grant all privileges:

GRANT ALL PRIVILEGES ON SCHEMA LOOKER_SCRATCH TO LOOKER;

Enable symmetric aggregates

To allow Exasol to take advantage of symmetric aggregates, create the hexstring2dec function:

OPEN SCHEMA <YOUR_SCHEMA>;

create or replace function hexstring2dec(hexstring in varchar(32)) return decimal(36,0)
is
    pos smallint;
    current_hexstring char(1);
    current_hexstring_dec smallint;
    hexstring_length smallint;
    res decimal(36,0);
begin
    if hexstring is null then
        return null;
    end if;
    hexstring_length := length(hexstring);
    res := 0;
    pos := 1;
    while  pos <= hexstring_length
    do
        current_hexstring := substr(hexstring,pos,1);
        if current_hexstring in ('A','B','C','D','E','F') then
            current_hexstring_dec := ascii(current_hexstring) - ascii('A') + 10;
        else
            current_hexstring_dec := to_number(current_hexstring);
        end if;
        res := (res * 16) + current_hexstring_dec;
        pos := pos + 1;
    end while;
    return res;
end hexstring2dec;
/

GRANT EXECUTE ON FUNCTION hexstring2dec;

Creating the Looker connection to your database

Follow these steps to create the connection from Looker to your database:

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

  2. Select Exasol from the Dialect drop-down menu.

  3. 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.

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

  5. To save these settings, click Connect.

Feature support

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

Exasol supports the following features as of Looker 24.20:

Feature Supported?
Support Level
Supported
Looker (Google Cloud core)
No
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
No
SSL
Yes
Subtotals
No
JDBC Additional Params
Yes
Case Sensitive
Yes
Location Type
Yes
List Type
Yes
Percentile
Yes
Distinct Percentile
No
SQL Runner Show Processes
No
SQL Runner Describe Table
Yes
SQL Runner Show Indexes
No
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
No
Materialized Views
No
Approximate Count Distinct
No