ValidateExternalMetadata Property
Indicates whether the component validates its column metadata against it external data source at design time. When the "is true", the component connects to its external data source during design time and validates the column s in it input or output collections against the columns at the external data source. When set to False, the component does isn't perform this "connected" validation.
The ValidateExternalMetadata property is an attribute of componet, and in VS, the component that appears on the Data Flow tab has this property.
By default, thevalidateexternalmetadata property is set to True , so any time we open a package, add a component, or run a package,SSIS is linked to the data source and validates the external metadata. When the ValidateExternalMetadata property is set to False ,SSIS validates the data source when it runs to the component, in Desgin Time does not validate the source data.
The applicable case is that a staging table does not exist in design time, and when the package runtime, the high component of the component creates the staging table, and when the package runs to that component, because the staging table already exists, the component validates the , to be able to run successfully.
ValidateExternalMetadata Properties for SSIS component