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.

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.

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.

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.

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.

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.

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.

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 rule

This component always needs an output link.