# tAggregateRow Standard properties These properties are used to configure tAggregateRow running in the Standard Job framework. The Standard tAggregateRow component belongs to the Processing family. The component in this framework is available in all Talend products. ## 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:

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. | | | Repository: You have already created the schema and stored it in the
Repository. You can reuse it in various projects and Job designs. | | Group by | Define the aggregation sets, the values of which will be
used for calculations. | | | Output Column: Select the column
label in the list offered based on the schema structure you defined. You
can add as many output columns as you wish to make more precise
aggregations.

Ex: Select Country to calculate an average of values for
each country of a list or select Country and Region if you want to
compare one country's regions with another country' regions. | | | Input Column: Match the input
column label with your output columns, in case the output label of the
aggregation set needs to be different. | | Operations | Select the type of operation along with the value to use
for the calculation and the output field. | | | Output Column: Select the
destination field in the list. | | | Function: Select the operator among:

count: calculates the number of rows
min: selects the minimum value
max: selects the maximum value
avg: calculates the average
sum: calculates the sum
first: returns the first value
last: returns the last value
list: lists values of an aggregation by multiple keys.
list (object): lists Java values of an aggregation by multiple keys
count (distinct): counts the number of the distinct rows
standard deviation: calculates the variability of a set of value.
union (geometry): makes the union of a set of Geometry objects
population standard deviation: calculates the spread of a data distribution. Use this function if the data to be calculated is considered a population on its own. This calculation supports 39 decimal places.
sample standard deviation: calculates the spread of a data distribution. Use this function if the data to be calculated is considered a sample from a larger population. This calculation supports 39 decimal places.

| | | Input column: Select the input
column from which the values are taken to be aggregated. | | | Ignore null values: Select the
check boxes corresponding to the names of the columns for which you want
the NULL value to be ignored. | ## Advanced settings | Delimiter(only for list
operation) | Enter the delimiter you want to use to separate the
different operations. | | --- | --- | | Use financial precision, this is the max
precision for "sum" and "avg" operations, checked option heaps more
memory and slower than unchecked. | Select this check box to use a financial precision. This
is a max precision but consumes more memory and slows the
processing.

Information noteWarning:

*We advise you to use the BigDecimal type for the
output in order to obtain precise results.* | | Check type overflow (slower) | Checks the type of data to ensure that the Job doesn't
crash. | | Check ULP (Unit in the Last Place), ensure
that a value will be incremented or decremented correctly, only
float and double types. (slower) | Select this check box to ensure the most precise results
possible for the Float and Double types. | | tStatCatcher Statistics | Check this box to collect the log data at component level. Note that this
check box is not available in the Map/Reduce version of the component. | ## 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 handles flow of data therefore it requires
input and output, hence is defined as an intermediary step. Usually the
use of tAggregateRow is combined
with the tSortRow component. | | --- | --- |