Map runtime considerations
When a map is executed at runtime (in the absence of Talend Data Mapper) it is normally not validated against its structures as all of the data associated with the structures are stored in the map's metadata. The reason for this is the validation against large structures can consume quite a bit of memory in the initial map startup.
However, for this optimization to work correctly, the validation results of the map with the structures must be completely clean: there must be no errors or warnings. If there are errors or warnings in the last validation of the map in Talend Data Mapper, the map is marked such that it will require validation against the structures at runtime to make sure any problems are correctly reported and the runtime execution results of the map are the same as they would be in Talend Data Mapper.