tCouchDBInput – Docs for ESB 5.x

Component family

Big Data / CouchDB

Function

tCouchDBInput allows you to read
data from CouchDB and send data in the Talend flow.

Purpose

tCouchDBInput is used to extract
the desired JSON data out of a CouchDB database to make
transformation to it, migrate it to another target format, or
process it before inserting it to the same database.

Basic settings

Schema and Edit Schema

A schema is a row description. It defines the number of fields 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:

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

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.

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.

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.

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:

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:

Map

Enter the map function in this field.

Reduce

Enter the reduce function in this field.

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.

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.

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.

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

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

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