<< Click to Display Table of Contents >> ETL > 12.6 > Implementation Guide > Tutorial and implementation guide > Steps > Mapping  Advanced topics

This chapter describes the usage of advanced features of the mapping function.

•Fallback columns
Fallback is a value, column, SQL statement or any valid column mapping which is used, if the original source does not contain the required column.

•Union mapping
Mapping can use more than one table as a source, in which case it performs a concatenation of two or more tables.

•Arbitrary column types
Database column types are inferred from usage. It is possible to customize this behavior on column-basis, by changing the required type or its length / range.

•Inferring remaining columns
Columns do not have to be all referred by their names. If you want to map them all (or all which have not been referenced explicitly) you can force the ETL engine to retrieve them automatically.