User Guide : Designing and Executing Map : Refreshing Map Connection Schema
 
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Refreshing Map Connection Schema
You can refresh the map connection schema in the following scenarios:
When a map is created, the source, lookup, join, or target details are stored in a connection file. If this file changes (fields are added or removed, field names are changed, and so on), then when you refresh the schema, the engine re-reads the schema.
If you change a connector property that changes the schema, then when you refresh the schema, the engine re-reads the schema.
If the external schema file is updated, then when you refresh the schema the updated schema is applied.
If you change the connection information, click to prompt Map Editor to read the structure of the data from the new file. The following message is displayed:
Refresh can result in invalid expressions or lost event/actions due to field name changes. Do you want to continue?
Select or deselect the Save the map before continuing option and click OK to save the map.
Sometimes, when the connection file or database schema changes and if you reload the map and establish the source or target connection, the "Schema Mismatch" error message is displayed. To resolve this:
1. Change the Schema Mismatch property to Use Connection or Match by Name.
2. Click . The engine re-reads the connection from the file or database and displays the updated schema from the data.
Note:  
The icon is not enabled until you establish the source or target connection.
For connectors that does not have a schema (example, Binary or ASCII (Fixed)), the icon removes the existing schema and rebuilds the schema from the connection.
For Multimode connectors, the icon remains disabled even after connecting to the target.
Since the target expressions (target side) and events (source side) are associated with the records or fields in the schema, they will be saved before refreshing the schema. After refreshing the schema, if the records and fields still exists, then an attempt is made to add the target expressions and source events associated with the records or fields.
Refreshing a source removes the target expressions. After refreshing the schema, expressions with source record or field names that no longer exist will not be valid. You can validate or run the map to check the location of these invalid expressions.
In case the external schema file is updated, then in the Confirm Schema section, click to apply the updated schema.