Perform Batch Operations with REST Data in Apache NiFi

Apache NiFi supports powerful and scalable directed graphs of data routing, transformation, and system mediation logic. When paired with the CData JDBC Driver for REST, NiFi can work with live REST data. This article shows how to read data from a CSV file and perform batch operations (INSERT/UPDATE/DELETE) using the CData JDBC Driver for REST data in Apache NiFi (version 1.9.0 or later).

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

Generate a JDBC URL

We need a JDBC URL to connect to REST data from Apachi NiFi.

Built-in Connection String Designer

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

		java -jar cdata.jdbc.rest.jar
	

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

See the Getting Started chapter in the data provider documentation to authenticate to your data source: The data provider models REST APIs as bidirectional database tables and XML/JSON files as read-only views (local files, files stored on popular cloud services, and FTP servers). The major authentication schemes are supported, including HTTP Basic, Digest, NTLM, OAuth, and FTP. See the Getting Started chapter in the data provider documentation for authentication guides.

After setting the and providing any authentication values, set to "XML" or "JSON" and set to more closely match the data representation to the structure of your data.

The property is the controlling property over how your data is represented into tables and toggles the following basic configurations.

• Document (default): Model a top-level, document view of your REST data. The data provider returns nested elements as aggregates of data.
• FlattenedDocuments: Implicitly join nested documents and their parents into a single table.
• Relational: Return individual, related tables from hierarchical data. The tables contain a primary key and a foreign key that links to the parent document.

See the Modeling REST Data chapter for more information on configuring the relational representation. You will also find the sample data used in the following examples. The data includes entries for people, the cars they own, and various maintenance services performed on those cars.

👁 Using the built-in connection string designer to generate a JDBC URL (Salesforce is shown.)

Batch Operations (INSERT/UPDATE/DELETE) in Apache NiFi

The sample flow presented below is based on the following NiFi Processors:

• ListFile - Retrieves a listing of files from the local filesystem and creates a FlowFile for each retrieved file.
• FetchFile - Reads the content of the FlowFile received from the ListFile processor.
• PutDatabaseRecord - Uses a specified RecordReader to input records from a flow file coming from the FetchFile processor. These records are translated to SQL statements and executed as a single transaction.
• LogAttribute - Emits attributes of the FlowFile at the specified log level.

This is what our finished product looks like:

👁 NiFi GUI

Disclaimers

1. The column names of the CSV file must match the column names of the data source table records to be inserted/updated/deleted.

2. Apache NiFi versions earlier than 1.9.0 do not support the Maximum Batch Size property in the PutDatabaseRecord processor.

Configurations

In order to perform batch INSERT, UPDATE or DELETE, the NiFi Processors should be configured similar to the following:

1. Configure the ListFile processor: Set the Input Directory property to the local folder path from where to pull the CSV files. Set the File Filter property to a regular expression to pick up only the files whose names match the expression. i.e., if the CSV file's full path is C:\Users\Public\Documents\InsertNiFi.csv, the properties should be configured like in the following image:
👁 config for ListFile

2. Configure the FetchFile processor
Leave the FetchFile processor's property configurations to their default values: 👁 config for FetchFile

3. Configure the PutDatabaseRecord processor

INSERT operation

Configure the PutDatabaseRecord processor similar to the following in order to perform Batch INSERT Operations:

👁 config for PutDatabaseRecord-INSERT
👁 config for PutDatabaseRecord-INSERT

• Set the Record Reader property to a CSV Reader Controller Service. Configure the CSV Reader Controller Service to match the format of your CSV file.
• Set the Statement Type property to INSERT.
• Set the Database Connection Pooling Service to the DBCPConnection Pool that holds the driver configuration. Please note that the driver should be configured to use Bulk API.

  Property	Value
  Database Connection URL	jdbc:rest:DataModel=Relational;URI=C:/people.xml;Format=XML;
  Database Driver Class Name	cdata.jdbc.rest.RESTDriver

• Set the Catalog Name property to the name of the catalog that your table is part of.
• Set the Schema Name property to the name of the schema that your table is part of.
• Set the Table Name property to the name of the table that you want to INSERT into.
• Set the Maximum Batch Size property to the maximum number of records that you want to be included in a single batch. 👁 config for PutDatabaseRecord-INSERT
  

UPDATE Operation

Configure the PutDatabaseRecord processor similar to the following in order to perform Batch UPDATE Operations:

• Set the Record Reader property to a CSV Reader Controller Service. Configure the CSV Reader Controller Service to match the format of your CSV file. 👁 config for PutDatabaseRecord-INSERT
  👁 config for PutDatabaseRecord-INSERT
  
• Set the Statement Type property to UPDATE.
• Set the Database Connection Pooling Service to the DBCPConnection Pool that holds the driver configuration. Please note that the driver should be configured to use Bulk API. Use the same Database Connection URL format as seen above.
• Set the Catalog Name property to the name of the catalog that your table is part of.
• Set the Schema Name property to the name of the schema that your table is part of.
• Set the Table Name property to the name of the table that you want to UPDATE.
• Set the Update Keys property to the name of the columns that are required for an UPDATE.
• Set the Maximum Batch Size property to the maximum number of records that you want to be included in a single batch. 👁 config for PutDatabaseRecord-UPDATE
  

DELETE Operation

Configure the PutDatabaseRecord processor similar to the following in order to perform Batch DELETE Operations:

• Set the Record Reader property to a CSV Reader Controller Service. Configure the CSV Reader Controller Service to match the format of your CSV file. 👁 config for PutDatabaseRecord-UPDATE
  👁 config for PutDatabaseRecord-UPDATE
  
• Set the Statement Type property to DELETE.
• Set the Database Connection Pooling Service to the DBCPConnection Pool that holds the driver configuration. Please note that the driver should be configured to use Bulk API. Use the same Database Connection URL format as seen above.
• Set the Catalog Name property to the name of the catalog that your table is part of.
• Set the Schema Name property to the name of the schema that your table is part of.
• Set the Table Name property to the name of the table that you want to UPDATE.
• In comparison to INSERT and UPDATE statement types, the DELETE operation does not expose a Maximum Batch Size property. However, the operations are still processed in batches. If not changed, the maximum number of records per batch is 2000, adhering to the default value. In order to change the value of the Maximum Batch Size used for DELETE operations, change the statement type to INSERT or UPDATE, then change the value of the Maximum Batch Size property, and click Apply Changes. Finally, reopen the processor's configuration, change the Statement Type back to DELETE, and click Apply Changes.
👁 config for PutDatabaseRecord-DELETE

4. Configure the LogAttribute processor

   Finally, configure the LogAttribute processor by specifying the Attributes that you would like to log or ignore, as well as the log level, based on your use case.

Free Trial & More Information

Download a free, 30-day trial of the CData JDBC Driver for REST and start working with your live REST data in Apache NiFi. Reach out to our Support Team if you have any questions.