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Component family
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Processing
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Function
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tAggregateSortedRow receives a
sorted flow and aggregates it based on one or more columns. For each
output line, are provided the aggregation key and the relevant
result of set operations (min, max, sum…).
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Purpose
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Helps to provide a set of metrics based on values or calculations.
As the input flow is meant to be sorted already, the performance are
hence greatly optimized.
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Basic settings
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Schema and Edit
Schema
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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.
Since version 5.6, both the Built-In mode and the Repository mode are
available in any of the Talend solutions.
Click Edit schema to make changes to the schema. If the
current schema is of the Repository type, three options are
available:
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View schema: choose this option to view the
schema only.
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Change to built-in property: choose this option
to change the schema to Built-in for local
changes.
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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.
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Built-in: The schema will be
created and stored locally for this component only. Related topic:
see Talend Studio User Guide.
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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.
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Input rows count
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Specify the number of rows that are sent to the tAggregateSortedRow component.
Note
If you specified a Limit for
the number of rows to be processed in the input component, you
will have to use that same limit in the Input rows count field.
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Group by
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Define the aggregation sets, the values of which will be used for
calculations.
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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.
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Input Column: Match the input
column label with your output columns, in case the output label of
the aggregation set needs to be different.
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Operations
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Select the type of operation along with the value to use for the
calculation and the output field.
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Output Column: Select the
destination field in the list.
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Function: Select the operator
among: count, min, max, avg, first, last.
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Input column: Select the input
column from which the values are taken to be aggregated.
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Ignore null values: Select the
check boxes corresponding to the names of the columns for which you
want the NULL value to be ignored.
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Advanced settings
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tStatCatcher Statistics
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Check this box to collect the log data at component level.
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Global Variables
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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 further information about variables, see Talend Studio
User Guide.
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Usage
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This component handles flow of data therefore it requires input
and output, hence is defined as an intermediary step.
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Log4j
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The activity of this component can be logged using the log4j feature. For more information on this feature, see Talend Studio User
Guide.
For more information on the log4j logging levels, see the Apache documentation at http://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/Level.html.
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Limitation
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n/a
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