The tdload command has the intelligence to determine the most appropriate load operator (for example, Load, Update, Stream or Inserter) or export operator (for example, Export) to be used for the Easy Loader job based on the status of the target table. For example,
- If the target table is empty and has no secondary indexes, tdload knows to use the Load operator to load data.
- If the target table is not empty, tdload may use the Update operator to load data.
- If a value is specified for either the --SourceTable option or --SelectStmt option, tdload knows to use the Export operator to extract data from Teradata table(s).
Any attributes not supported as part of the allowed set of tdload command line options (specified above) must be specified in the job variables file. Because tdload internally calls tbuild, these attributes get passed as part of the job variables file to the tbuild command.
If values are specified for both the --SourceTable option and the --SelectStmt option, tdload ignores the value of --SourceTable option. A warning message is returned to the console and the job continues with the schema inferred from the SELECT statement.