Big Data Management User Guide

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Extract Elements from Hierarchical Data

You can extract elements of a primitive or complex data type from hierarchical data. Use the

Extract from Complex Port

wizard in the Developer tool to perform the conversion.

Based on the data type of the elements in the complex port that you select, the wizard performs the following conversions:

If the elements are of primitive data types, the wizard converts the element to a relational data.

If the elements are of complex data types, the wizard converts the element to a hierarchical data.

The wizard adds an Expression transformation that contains one or more extracted ports. The number of elements that you select to extract determine the number of output ports in the transformation. The data type of the element determines the data type of the output port. The expression in the output ports use complex operators to extract elements from the complex port.

The following table describes the wizard conversions based on the data type of the complex port that you select:

Complex Port Data Type	Wizard Conversion
array	Relational data. If you specify an array index, the wizard extracts an element in the array. Default is 0. The wizard extracts the first element of the array. Hierarchical data. If you do not specify an array index, the wizard extracts the entire array.
struct	Relational data. The wizard extracts the element in the struct that you selected.
array of structs	Relational data. If you select an element in the struct, the wizard extracts the element. The wizard requires an array index value. Default is 0. Hierarchical data. If you select the array and specify an array index, the wizard extracts the struct element in the array. If you do not specify an array index, the wizard extracts the entire array.
array of maps	Relational data. If you select the key or value element in the array and specify an array index, the wizard extracts the element. Hierarchical data. If you select the array and specify an array index, the wizard extracts the map element in the array. If you do not specify an array index, the wizard extracts the entire array.
struct of structs	Relational data. If you select an element in the parent or the child struct, the wizard extracts the element. Hierarchical data. If you select the parent struct or child struct, the wizard extracts that struct.
struct of maps	Hierarchical data. If you select the map element, the wizard extracts the map data. If you select the struct, the wizard extracts the struct data in another port.

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Big Data Management User Guide

Big Data Management User Guide

Extract Elements from Hierarchical Data

Extract Elements from Hierarchical Data