There are two integration methods that can be specified for downloading object data:
Delete – when using this method for an object when a download is run all object rows are downloaded from Salesforce, the current object data on SQL is deleted and replaced with the downloaded data. No history is kept of changes.
Incremental – when using this method for an object when a download is run only object rows that have changed since the last download are extracted from Salesforce. These changes are saved in the object history table to maintain a history of changes.
Because the Salesforce Bulk Query API cannot extract deleted records the Bulk and Batched download methods should not be used on objects that are using the incremental integration method.
Similarly objects that do not have an IsDeleted column cannot track deleted records and so cannot be used with Incremental downloads.