Support DELETE and INSERT operations in Query-to-File

[vogti]

Note that this issue is rather difficult and requires taking time to understand the whole architecture of the Query-to-File project.

The Query-to-File interface does not support deleting and inserting new rows. The semantics of deleting a row could be to delete all files belonging to a row, or only the files that belong to the primary key columns. The insertion of a row could be realized by providing an insert-folder where a user can put new files inside. Every new row could be placed in a new folder.

In the Query-to-File project the important places to understand are the getBatchUpdateRequest method in the ResultFS class and the commit method in the QueryInterface-class.

The support for deletes can be integrated without changing Polypheny-DB, using the deleteRow method of the REST interface. For the inserts, Polypheny-DB has to be extended. The important code to understand is the batchUpdate method in the Crud-class and the BatchUpdateRequest-class.