Table of Contents

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  1. Preface
  2. Introduction to Data Engineering Streaming
  3. Data Engineering Streaming Administration
  4. Sources in a Streaming Mapping
  5. Targets in a Streaming Mapping
  6. Streaming Mappings
  7. Window Transformation
  8. Appendix A: Connections
  9. Appendix B: Monitoring REST API Reference
  10. Appendix C: Sample Files

Refresh Schema

Refresh Schema

You can refresh the source or target schema at run time when you enable a streaming mapping to run dynamically. You can refresh the imported metadata before you run the dynamic streaming mapping.
You can enable a streaming mapping to run dynamically using the
At runtime, get data object columns from data source
option in the
Data Object
tab of the Read and Write transformations when you create a mapping.
When you add or override the metadata dynamically, you can include all the existing source and target objects in a single mapping and run the mapping. You do not have to change the source schema to update the data objects and mappings manually to incorporate all the new changes in the mapping.
You can use the mapping template rules to tune the behavior of the execution of such pipeline mapping.
When the Read or Write transformation contains updated ports, such as changes in the port names, data types, precision, or scale, the Data Integration Service fetches the updated ports and runs the mapping dynamically. You must ensure that at least one of the column name in the source or target file is the same as before refreshing the schema to run the dynamic mapping successfully.
Even though the original order of the source or target ports in the table changes, the Data Integration Service displays the original order of the ports in the table when you refresh the schemas at run time.
If there are more columns in the source file as compared to the target file, the Data Integration Service does not map the extra column to the target file and loads null data for all the unmapped columns in the target file.
If the Source transformation contains updated columns that do not match the Target transformation, the Data Integration Service does not link the new ports by default when you refresh the source or target schema. You must create a run-time link between the transformations to link ports at run time based on a parameter or link policy in the
Run-time Linking
tab and update the target schema manually. For information about run-time linking, see the
Informatica Developer Mapping Guide
.