tCouchDBInput properties - 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

Component family

Big Data / CouchDB

 

Basic settings

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.

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.

The columns in the schema may vary depending on your configuration:

  • If you select the Query by view check box and the Is reduce check box at the same time and specify a group level after selecting the Group check box, only the key and value columns are available in the schema.

  • If you select the Include docs check box but do not select the Is reduce check box, the id, key, value and JSONDoc columns are available in the schema.

  • If you keep both the Is reduce check box and Include docs check box clear, the id, key, and value columns are available in the schema.

Connection

Use existing connection

Select this check box and in the Component List click the relevant connection component to reuse the connection details you already defined.

 

DB Version

Select the CouchDB version that you are using.

 

Server

Hostname or IP address of the CouchDB server.

 

Port

Listening port number of the CouchDB server.

 

Database

Specify the database that you want to use.

Authentication

Required authentication

Select this check box to provide credentials for the CouchDB authentication.

  • Username: Type in the user name for the CouchDB authentication.

  • Password: Type in the password for the CouchDB authentication.

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

Replication

Use trigger replication

Select this check box to trigger replication between databases.

Warning

This check box appears only if you do not select the Use an existing connection check box.

 

Target DB name

Specify the target database to which the documents will be copied. It can be a local database name or a remote database URL.

 

Continuous

Select this check box to continue a replication upon the server restart.

 Create target DB

Select this check box to create the target database if it does not exist.

 

IS Canceled

Select this check box to cancel the existing replication between the specified source database and target database at the end of the Job.

Querying options

Query by view

Select this check box to specify query conditions based on a view which involves one map function and one optional reduce function.

 

Design Document

Type in the name of the design document from which you want to read data.

 

Action on design document

Select the operation you want to perform on the design document of interest:

  • None: No operation is carried out.

  • Drop and create design document: The design document is removed and created again.

  • Create design document: A new design document is created.

  • Create design document if not exists: A design document is created if it does not exist.

  • Drop design document if exists and create: The design document is removed if it exists and gets created again.

 

View

Type in the name of the view from which you want to read data.

 

Action on view

Select the operation you want to perform on the view of interest:

  • None: No operation is carried out.

  • Create view: A new view is created.

 

Map

Enter the map function in this field.

Warning

This field appears only if you select Create view from the Action on view drop-down list.

 

Reduce

Enter the reduce function in this field.

Warning

This field appears only if you select Create view from the Action on view drop-down list and select the Is reduce check box.

 

Start key

Type in the start key.

 

End key

Type in the end key.

 

Start key docid

Type in the start key document id.

 

End key docid

Type in the end key document id.

 

Is reduce

Select this check box to make the reduce function take effect.

 

Group

Select this check box to make the reduce function reduce to a set of distinct keys or to a single result row.

Warning

This check box appears only if you select the Is reduce check box.

 

Group level

Enter the specific group level in this field after you select the Group check box.

 

Include docs

Select this check box to include the document which emitted each view entry.

Warning

This check box appears only if you do not select the Is reduce check box.

 

Descending

Select this check box to reverse the query order.

 

Add options

Select this check box to add more query options and define the parameters as needed.

 

Extract JSON field

Select this check box to extract the desired JSON data based on XPath query.

 

JSON field

List of JSON fields to be extracted.

Warning

Make sure you select a JSON field whose value is a JSON document. Otherwise, errors may occur unexpectedly.

 

Loop XPath query

Node within the JSON field, on which the loop is based.

 

Mapping

Schema output column: schema defined to hold the data extracted from the JSON field.

XPath query: XPath query to specify the node within the JSON field to be extracted.

Get Nodes: select this check box if you need to get values from a nested node within the JSON field.

 

Limit

Enter the maximum number of rows to process.
 

Die on error

This check box is cleared by default, meaning to skip the row on error and to complete the process for error-free rows.

Advanced settings

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 read by an input component or transferred to an output component. This is an After variable and it returns an integer.

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 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.

Limitation

n/a