Work with CouchDB Data in Apache Spark Using SQL

Apache Spark is a fast and general engine for large-scale data processing. When paired with the CData JDBC Driver for CouchDB, Spark can work with live CouchDB data. This article describes how to connect to and query CouchDB data from a Spark shell.

The CData JDBC Driver offers unmatched performance for interacting with live CouchDB data due to optimized data processing built into the driver. When you issue complex SQL queries to CouchDB, the driver pushes supported SQL operations, like filters and aggregations, directly to CouchDB and utilizes the embedded SQL engine to process unsupported operations (often SQL functions and JOIN operations) client-side. With built-in dynamic metadata querying, you can work with and analyze CouchDB data using native data types.

Install the CData JDBC Driver for CouchDB

Download the CData JDBC Driver for CouchDB installer, unzip the package, and run the JAR file to install the driver.

Start a Spark Shell and Connect to CouchDB Data

1. Open a terminal and start the Spark shell with the CData JDBC Driver for CouchDB JAR file as the jars parameter: $ spark-shell --jars /CData/CData JDBC Driver for CouchDB/lib/cdata.jdbc.apachecouchdb.jar
2. With the shell running, you can connect to CouchDB with a JDBC URL and use the SQL Context load() function to read a table.

   Set the following to connect:

   • Url: The Url of your instance. For example: http://localhost:5984
   • User The Apache CouchDB user account used to authenticate.
   • Password The Apache CouchDB password associated with the authenticating user.

   Built-in Connection String Designer

   For assistance in constructing the JDBC URL, use the connection string designer built into the CouchDB JDBC Driver. Either double-click the JAR file or execute the jar file from the command-line.

   java -jar cdata.jdbc.apachecouchdb.jar

   Fill in the connection properties and copy the connection string to the clipboard.

   Configure the connection to CouchDB, using the connection string generated above.

   scala> val apachecouchdb_df = spark.sqlContext.read.format("jdbc").option("url", "jdbc:apachecouchdb:Url=http://localhost:5984;User=abc123;Password=abcdef;").option("dbtable","Movies").option("driver","cdata.jdbc.apachecouchdb.ApacheCouchDBDriver").load()
3. Once you connect and the data is loaded you will see the table schema displayed.

4. Register the CouchDB data as a temporary table:

   scala> apachecouchdb_df.registerTable("movies")

5. Perform custom SQL queries against the Data using commands like the one below:

   scala> apachecouchdb_df.sqlContext.sql("SELECT MovieRuntime, MovieRating FROM Movies WHERE MovieRating = R").collect.foreach(println)

   You will see the results displayed in the console, similar to the following:

Using the CData JDBC Driver for CouchDB in Apache Spark, you are able to perform fast and complex analytics on CouchDB data, combining the power and utility of Spark with your data. Download a free, 30 day trial of any of the 200+ CData JDBC Drivers and get started today.