When synchronizing a HanDBase database with an external data source, such as MS Access or an ODBC data source, Sync Exchange needs a way to keep track of the records in that other data source.
Using MS Access as an example, MS Access does not have a concept of synchronization. Thus, there is no concept of which records have been added since a certain point of time, which records have been deleted since that point in time, or which records have been changed since that point in time.
Sync Exchange adds two fields to a table in an external data source called rhdrinfo_ and rhdrid_ to keep track of what has changed in the external data source since the last synchronization.
Those two fields have to be in the table in the external data source for Sync Exchange to work
properly. Under normal circumstances, you will want to
completely ignore them. You should not modify the values in those fields,
and normally you would not want to delete or remove the fields. If you remove those fields or modify the values in those fields, and still sync through Sync Exchange with that data source, you will very likely end up with duplicate records in the HanDBase database, the external data source, or both.
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