tDynamoDBInput - 6.3

Talend Open Studio for Big Data Components Reference Guide

EnrichVersion
6.3
EnrichProdName
Talend Open Studio for Big Data
task
Data Governance
Data Quality and Preparation
Design and Development
EnrichPlatform
Talend Studio

Function

tDynamoDBInput retrieves items from an Amazon DynamoDB table and sends them to the component that follows for transformation.

Purpose

tDynamoDBInput allows you to retrieve data from an Amazon DynamoDB table.

tDynamoDBInput properties

Component family

Big Data/DynamoDB

Basic settings

Access Key

Enter the access key ID that uniquely identifies an AWS Account. For further information about how to get your Access Key and Secret Key, see Getting Your AWS Access Keys.

 

Secret Key

Enter the secret access key, constituting the security credentials in combination with the access Key.

To enter the secret key, click the [...] button next to the secret key field, and then in the pop-up dialog box enter the password between double quotes and click OK to save the settings.

 

Inherit credentials from AWS role

Select this check box to leverage the instance profile credentials. These credentials can be used on Amazon EC2 instances, and are delivered through the Amazon EC2 metadata service. To use this option, your Job must be running within Amazon EC2 or other services that can leverage IAM Roles for access to resources. For more information, see Using an IAM Role to Grant Permissions to Applications Running on Amazon EC2 Instances.

 

Assume role

Select this check box and specify the values for the following parameters used to create a new assumed role session.

  • Role ARN: the Amazon Resource Name (ARN) of the role to assume.

  • Role session name: an identifier for the assumed role session.

  • Session duration (minutes): the duration (in minutes) for which we want to have the assumed role session to be active.

For more information about assuming roles, see AssumeRole.

 

Use End Point

Select this check box and in the Server Url field displayed, specify the Web service URL of the DynamoDB database service.

 

Region

Specify the AWS region by selecting a region name from the list or entering a region between double quotation marks (e.g. "us-east-1") in the list. For more information about the AWS Region, see Regions and Endpoints.

 

Action

Select the operation to be performed from the drop-down list, either Query or Scan. For more information, see Query and Scan Operations in DynamoDB.

 

Schema and Edit schema

A schema is a row description. It defines the number of fields (columns) to be processed and passed on to the next component. The schema is either Built-In or stored remotely in the Repository.

  • Built-In: You create and store the schema locally for this component only. Related topic: see Talend Studio User Guide.

  • Repository: You have already created the schema and stored it in the Repository. You can reuse it in various projects and Job designs. Related topic: see Talend Studio User Guide.

Since version 5.6, both the Built-In mode and the Repository mode are available in any of the Talend solutions.

 

 

Click Edit schema to make changes to the schema. If the current schema is of the Repository type, three options are available:

  • View schema: choose this option to view the schema only.

  • Change to built-in property: choose this option to change the schema to Built-in for local changes.

  • Update repository connection: choose this option to change the schema stored in the repository and decide whether to propagate the changes to all the Jobs upon completion. If you just want to propagate the changes to the current Job, you can select No upon completion and choose this schema metadata again in the [Repository Content] window.

 

Table Name

Specify the name of the table to be queried or scanned.

 

Use advanced key condition expression

Select this check box and in the Advanced key condition expression field displayed, specify the key condition expressions used to determine the items to be read from the table or index.

 

Key condition expression

Specify the key condition expressions used to determine the items to be read. Click the [+] button to add as many rows as needed, each row for a key condition expression, and set the following attributes for each expression:

  • Key Column: Enter the name of the key column.

  • Function: Select the function for the key condition expression.

  • Value1: Specify the value used in the key condition expression.

  • Value2: Specify the second value used in the key condition expression if needed, depending on the function you selected.

Note that only the items that meet all the key conditions defined in this table can be returned.

This table is not available when the Use advanced key condition expression check box is selected.

 

Use filter expression

Select this check box to use the filter expression for the query or scan operation.

 

Use advanced filter expression

Select this check box and in the Advanced filter expression field displayed, specify the filter expressions used to refine the data after it is queried or scanned and before it is returned to you.

This check box is available when the Use filter expression check box is selected.

 

Filter expression

Specify the filter expressions used to refine the results returned to you. Click the [+] button to add as many rows as needed, each row for a filter expression, and set the following attributes for each expression:

  • Column: Enter the name of the column used to refine the results.

  • Function: Select the function for the filter expression.

  • Value1: Specify the value used in the filter expression.

  • Value2: Specify the second value used in the filter expression if needed, depending on the function you selected.

Note that only the items that meet all the filter conditions defined in this table can be returned.

This table is available when the Use filter expression check box is selected and the Use advanced filter expression check box is cleared.

 

Value mapping

Specify the placeholders for the expression attribute values.

  • value: Enter the expression attribute value.

  • placeholder: Specify the placeholder for the corresponding value.

For more information, see Expression Attribute Values.

 

Name mapping

Specify the placeholders for the attribute names that conflict with the DynamoDB reserved words.

  • name: Enter the name of the attribute that conflicts with a DynamoDB reserved word.

  • placeholder: Specify the placeholder for the corresonding attribute name.

For more information, see Expression Attribute Names.

Advanced settings

STS Endpoint

Select this check box and in the field displayed, specify the AWS Security Token Service endpoint where session credentials are retrieved from.

This check box is available only when the Assume role check box is selected.

tStatCatcher Statistics

Select this check box to gather the Job processing metadata at the Job level as well as at each component level.

Global Variables

NB_LINE: the number of rows processed. This is an After variable and it returns an integer.

QUERY: the query statement being processed. This is a Flow variable and it returns a string.

ERROR_MESSAGE: the error message generated by the component when an error occurs. This is an After variable and it returns a string. This variable functions only if the Die on error check box is cleared, if the component has this check box.

A Flow variable functions during the execution of a component while an After variable functions after the execution of the component.

To fill up a field or expression with a variable, press Ctrl + Space to access the variable list and choose the variable to use from it.

For further information about variables, see Talend Studio User Guide.

Usage

This component is usually used as a start component of a Job or Subjob and it always needs an output link.

Log4j

If you are using a subscription-based version of the Studio, the activity of this component can be logged using the log4j feature. For more information on this feature, see Talend Studio User Guide.

For more information on the log4j logging levels, see the Apache documentation at http://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/Level.html.

Related scenarios

No scenario is available for this component yet.