When you connect to ExactTarget the first time, dotConnect for Salesforce Marketing Cloud needs to retrieve metadata and map objects to the relational tables. This process is complex and can take some time, so to avoid retrieving the metadata each time when connecting, dotConnect for Salesforce Marketing Cloud caches the metadata.
Objects are mapped to tables; their fields, including ID, system, and calculated fields, are mapped to the table columns. Master-Detail relationships between objects are mapped to foreign keys between tables.
There are two ways to access metadata with dotConnect for Salesforce Marketing Cloud: using the GetSchema method of ExactTargetConnection or querying the information schema tables, both are described in the corresponding topics: Information Schema and Using GetSchema Method.
If you want to get fresh metadata updates from ExactTarget, use the RefreshMetadata method of the connection object. It deletes existing caches, and the metadata will be queried again next time when they are needed.