The functions with the prefix TD are a new generation of advanced analytic functions that use the SQL-MapReduce framework and keep the resource usage under budget.
MapReduce is a framework for operating on large sets of data using massively parallel processing (MPP) systems. MapReduce enables complex analysis to be performed efficiently on extremely large sets of data, such as those obtained from weblogs and clickstreams. Its application areas include machine learning, scientific data analysis, and document classification.
The syntax of corresponding TD and non-TD functions may differ, but given the same inputs and syntax element values, they produce the same results (with the minor exceptions noted in specific functions).