# 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 in all subscription-based Talend products with Big Data and Talend Data Fabric. ## 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. When you create a Spark
Job, avoid the reserved word line when naming the
fields.

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



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. | | | Repository: You have already created the schema and stored it in the
Repository. You can reuse it in various projects and Job designs. | | 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. | | Vertical | 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
row. | | Separator

(For Basic mode only) | Enter the separator which will delimit data on the Log
display. | | 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 used. | | Print schema column name in front of each
value

(For Basic mode only) | Select this check box to retrieve column labels from output
schema. | | Use fixed length for values

(For Basic mode only) | Select this check box to set a fixed width for the value
display. | ## Advanced settings | Use local timezone for date | Select this check box to use the local date of the machine in which your Job is executed. If leaving this check box clear, UTC is automatically used to format the Date-type data. | | --- | --- | ## 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 + 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 | **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
Talend
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
Hadoop.

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
Talend
Map/Reduce Job, see the sections
describing how to create, convert and configure a
Talend
Map/Reduce Job of the
**Talend Open Studio for Big Data Getting Started Guide**.

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