August 16, 2023

tLogRow MapReduce properties – Docs for ESB 6.x

tLogRow MapReduce properties

These properties are used to configure tLogRow running in the MapReduce Job framework.

The MapReduce
tLogRow component belongs to the Logs & Errors family.

The component in this framework is available only if you have subscribed to one
of the
solutions with Big Data.

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.

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.

This component offers the
advantage of the dynamic schema feature. This allows you to retrieve unknown columns
from source files or to copy batches of columns from a source without mapping each
column individually. For further information about dynamic schemas, see
Talend Studio

User Guide.

This dynamic schema
feature is designed for the purpose of retrieving unknown columns of a table and is
recommended to be used for this purpose only; it is not recommended for the use of
creating tables.


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.

Sync columns Click to synchronize the output file schema with the
input file schema. The Sync function is available only when the
component is linked with the preceding component using a Row connection.
Basic Displays the output flow in basic mode.
Table Displays the output flow in table cells.

Displays each row of the output flow as a key-value list.

With this mode selected, you can choose to show either the unique
name or the label of component, or both of them, for each output


(For Basic mode only)

Enter the separator which will delimit data on the Log

Print header

(For Basic mode only)

Select this check box to include the header of the input
flow in the output display.

Print component unique name in front of each
output row

(For Basic mode only)

Select this check box to show the unique name the component in
front of each output row to differentiate outputs in case several
tLogRow components are

Print schema column name in front of each

(For Basic mode only)

Select this check box to retrieve column labels from output

Use fixed length for values

(For Basic mode only)

Select this check box to set a fixed width for the value

Global Variables

Global Variables

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 +
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 can be used as intermediate step in a data flow or
as a n end object in the Job flowchart.

In a
Map/Reduce Job, this component is used as an intermediate or
an end step. It generates native Map/Reduce code that can be executed directly in

You need to use the Hadoop Configuration tab in the
Run view to define the connection to a given Hadoop
distribution for the whole Job.

This connection is effective on a per-Job basis.

For further information about a
Map/Reduce Job, see the sections
describing how to create, convert and configure a
Map/Reduce Job of the

Talend Open Studio for Big Data Getting Started


Note that in this documentation, unless otherwise
explicitly stated, a scenario presents only Standard Jobs,
that is to say traditional
data integration Jobs, and non Map/Reduce Jobs.

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