Determining mapping candidates (DataStage®)
For each item in the target structure, the mapping table automatically presents a list of valid mapping candidates.
To determine the candidates to display in the mapping candidate
list and to determine which candidate to use for the Auto
Map option, the mapping algorithm uses the following process:
- Create a list that contains all of the valid mapping candidates. Valid candidates are unambiguous.
- Select only the candidates that meet the specified level of conversion accuracy. By default, the level for conversion accuracy is lossy; candidates must have a data type that can be converted to the target data type without creating a possible runtime error.
- Evaluate the similarity of the name and of the data type of the source and target items. Assign a score to each candidate, based on the similarity of the names and data types.
- Select the highest scoring candidate to use for the Auto map option.
- Select the highest scoring candidates to present on the mapping candidate list, which displays when you press the down-arrow on the source item in the mapping table. By default, the mapping candidate list displays the top 5 candidates.
To change the level of conversion accuracy and the number of mapping candidates to present on the candidate list, choose
.