tAggregateSortedRow Standard properties - Cloud - 8.0

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.

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.

Click Sync columns to retrieve the schema from the previous component connected in the Job.

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: The schema will be created and stored locally for this component only. Related topic: see Talend Studio User Guide.

Repository: The schema already exists and is stored in the Repository, hence can be reused in various projects and Job flowcharts. Related topic: see Talend Studio User Guide.

Input rows count

Specify the number of rows that are sent to the tAggregateSortedRow component.

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.

tStatCatcher Statistics

Check this box to collect the log data at component level.

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.

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.

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 more information about variables, see Talend Studio User Guide.

Usage rule

This component handles flow of data therefore it requires input and output, hence is defined as an intermediary step.