User Defined Functions Compared to SQL-MapReduce Functions - Aster Execution Engine

Teradata Aster® Developer Guide

Product
Aster Execution Engine
Release Number
7.00.02
Published
July 2017
Language
English (United States)
Last Update
2018-04-13
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Product Category
Software

You can extend the Aster Server by adding user defined functions or by adding SQL-MapReduce functions. This section presents the pros and cons of each approach and suggests some things to consider.

User Defined Functions Compare to SQL-MapReduce Functions
  User Defined Functions SQL-MapReduce Functions
API Typically simpler to write a user defined function. The framework takes care of things like iterating through the input and emitting output. Greater flexibility and capability in data processing. For example, SQL-MapReduce functions can process data from multiple input relations.
SQL User defined functions can be used in a SELECT list just like other SQL expressions. SQL-MapReduce functions can only be used in the FROM or ON clauses.
Multi-compute An Aster instance can execute multiple user defined functions. For example, those in the same SELECT list, at the same time on each vworker. An Aster instance executes one SQL-MapReduce function at a time on each vworker.