To read data from an Amazon DynamoDB table, configure an Amazon DynamoDB V2 object as the Source transformation in a mapping.
Specify the name and description of the Amazon DynamoDB V2 source. Configure the source properties for the source object. You can also parameterize the Amazon DynamoDB V2 source object with values specified in a parameter file when you configure a mapping in advanced mode.
When you configure a Source transformation, you can add or remove source fields of primitive data types.
The following table describes the source properties that you can configure in a Source transformation:
Property
Description
Connection
Name of the source connection.
You can select an existing connection or create a new connection. You can also select New Parameter to define a parameter for the source connection.
If you want to overwrite the source connection properties at runtime, select the Allow parameter to be overridden at run time option. Specify the parameter file directory and name in the advanced session properties.
Source Type
Type of the source object.
Select Single Object or Parameter.
Object
Name of the DynamoDB V2 source object based on the source type selected.
The following table describes the Amazon DynamoDB V2 advanced source property that you can configure in a Source transformation:
Property
Description
Refresh duration for Assume Role Session
Generates a new set of credentials for the assume role after the specified duration and refreshes the assume role session after fixed intervals.
You can configure Refresh duration for Assume Role Session when you configure assume role in the connection properties.
The default value is 900 seconds. The maximum value is 12 hours depending upon the maximum session duration that you set for the role.
Schema inference for Amazon DynamoDB V2 sources
The schema of the Amazon DynamoDB source is inferred by sampling rows from the Amazon DynamoDB table.
The data that you read from an Amazon DynamoDB table using a mapping must have a strict schema. Amazon DynamoDB V2 Connector picks the most common data types from the sample for mixed columns, sub-columns, and lists.
Consider the following rules and guidelines to infer the schema of an Amazon DynamoDB V2 source:
•Amazon DynamoDB V2 Connector chooses the string data type when all the rows in a sample have a null value for a particular column.
•If a row has an extra top-level column or nested column that does not appear in the schema, this extra column is dropped.
•If a row is missing a top-level column or nested column, the source uses a null value for that column.
•If a row has a column with a type that does not match the schema, the source tries to cast the value to the type in the schema. If this cast fails, the source uses a null value for that column.
Adding and removing source fields
You can configure the source fields that you want to use in the data flow.
You can add fields to a mapping source and retrieve a field from the source object that is not displayed in the list.
For more information on how to add or remove source fields, see the topic "Add and remove fields" in Source transformation in the Data Integration documentation.
