Connect to Live Presto Data in PostGresSQL Interface through CData Connect Cloud

There are a vast number of PostgreSQL clients available on the Internet. PostgreSQL is a popular interface for data access. When you pair PostgreSQL with CData Connect Cloud, you gain database-like access to live Presto data from PostgreSQL. In this article, we walk through the process of connecting to Presto data in Connect Cloud and establishing a connection between Connect Cloud and PostgreSQL using a TDS foreign data wrapper (FDW).

CData Connect Cloud provides a pure SQL Server interface for Presto, allowing you to query data from Presto without replicating the data to a natively supported database. Using optimized data processing out of the box, CData Connect Cloud pushes all supported SQL operations (filters, JOINs, etc.) directly to Presto, leveraging server-side processing to return the requested Presto data quickly.

Getting Started

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Connect to Presto in Connect Cloud

CData Connect Cloud uses a straightforward, point-and-click interface to connect to data sources.

1. Log into Connect Cloud, click Sources, and then click Add Connection

2. Select "Presto" from the Add Connection panel

3. Enter the necessary authentication properties to connect to Presto.

   Set the Server and Port connection properties to connect, in addition to any authentication properties that may be required.

   To enable TLS/SSL, set UseSSL to true.

   Authenticating with LDAP

   In order to authenticate with LDAP, set the following connection properties:

   • AuthScheme: Set this to LDAP.
   • User: The username being authenticated with in LDAP.
   • Password: The password associated with the User you are authenticating against LDAP with.

   Authenticating with Kerberos

   In order to authenticate with KERBEROS, set the following connection properties:

   • AuthScheme: Set this to KERBEROS.
   • KerberosKDC: The Kerberos Key Distribution Center (KDC) service used to authenticate the user.
   • KerberosRealm: The Kerberos Realm used to authenticate the user with.
   • KerberosSPN: The Service Principal Name for the Kerberos Domain Controller.
   • KerberosKeytabFile: The Keytab file containing your pairs of Kerberos principals and encrypted keys.
   • User: The user who is authenticating to Kerberos.
   • Password: The password used to authenticate to Kerberos.
   
4. Click Create & Test
5. Navigate to the Permissions tab in the Add Presto Connection page and update the User-based permissions.

Add a Personal Access Token

When connecting to Connect Cloud through the REST API, the OData API, or the Virtual SQL Server, a Personal Access Token (PAT) is used to authenticate the connection to Connect Cloud. It is best practice to create a separate PAT for each service to maintain granularity of access.

1. Click on the Gear icon () at the top right of the Connect Cloud app to open the settings page.
2. On the Settings page, go to the Access Tokens section and click Create PAT.
3. Give the PAT a name and click Create.
4. The personal access token is only visible at creation, so be sure to copy it and store it securely for future use.

With the connection configured and a PAT generated, you are ready to connect to Presto data from PostgreSQL.

Build the TDS Foreign Data Wrapper

The Foreign Data Wrapper can be installed as an extension to PostgreSQL, without recompiling PostgreSQL. The tds_fdw extension is used as an example (https://github.com/tds-fdw/tds_fdw).

1. You can clone and build the git repository via something like the following view source:

   sudo apt-get install git
   git clone https://github.com/tds-fdw/tds_fdw.git
   cd tds_fdw
   make USE_PGXS=1
   sudo make USE_PGXS=1 install
   

   Note: If you have several PostgreSQL versions and you do not want to build for the default one, first locate where the binary for pg_config is, take note of the full path, and then append PG_CONFIG= after USE_PGXS=1 at the make commands.
2. After you finish the installation, then start the server:

   sudo service postgresql start
   

3. Then go inside the Postgres database

   psql -h localhost -U postgres -d postgres
   

   Note: Instead of localhost you can put the IP where your PostgreSQL is hosted.

Connect to Presto data as a PostgreSQL Database and query the data!

After you have installed the extension, follow the steps below to start executing queries to Presto data:

1. Log into your database.
2. Load the extension for the database:

   CREATE EXTENSION tds_fdw;
   

3. Create a server object for Presto data:

   CREATE SERVER "Presto1" FOREIGN DATA WRAPPER tds_fdw OPTIONS (servername'tds.cdata.com', port '14333', database 'Presto1');
   

4. Configure user mapping with your email and Personal Access Token from your Connect Cloud account:

   CREATE USER MAPPING for postgres SERVER "Presto1" OPTIONS (username '[email protected]', password 'your_personal_access_token' );
   

5. Create the local schema:

   CREATE SCHEMA "Presto1";
   

6. Create a foreign table in your local database:

   #Using a table_name definition:
   
   CREATE FOREIGN TABLE "Presto1".Customer  (      
   id varchar,      
   LastName varchar)      
   SERVER "Presto1"
   OPTIONS(table_name 'Presto.Customer', row_estimate_method 'showplan_all');
   
   #Or using a schema_name and table_name definition:
   
   CREATE FOREIGN TABLE "Presto1".Customer (      
   id varchar,      
   LastName varchar)      
   SERVER "Presto1"
   OPTIONS (schema_name 'Presto', table_name 'Customer', row_estimate_method 'showplan_all');
   
   #Or using a query definition:
   
   CREATE FOREIGN TABLE  "Presto1".Customer (
   id varchar,      
   LastName varchar)      
   SERVER "Presto1"
   OPTIONS (query 'SELECT * FROM Presto.Customer', row_estimate_method 'showplan_all');
   
   #Or setting a remote column name:
   
   CREATE FOREIGN TABLE "Presto1".Customer (
   id varchar,
   col2 varchar OPTIONS (column_name 'LastName'))
   SERVER "Presto1"
   OPTIONS (schema_name 'Presto', table_name 'Customer', row_estimate_method 'showplan_all');
   

7. You can now execute read/write commands to Presto:

   SELECT id, LastName
   FROM "Presto1".Customer;
   

More Information & Free Trial

Now, you have created a simple query from live Presto data. For more information on connecting to Presto (and more than 200 other data sources), visit the Connect Cloud page. Sign up for a free trial and start working with live Presto data in PostgreSQL.