convert to delta, add support for overwrite existing Table

[djouallah]

I have an external process that produce Parquet files incrementally, basically it just add files , I want to convert it to Delta Table , which currently works the first time but errors the second time as the table exists.

two current workaround

• delete the log ( seems like hack)

• use arrow to write the delta table, I notice there is an overhead when transfering big volume of data and using batch next is slow

[ion-elgreco]

You likely want to just manually add a transaction commit for these append actions if they are appends.

You could take a look at a tool @rtyler build: https://github.com/buoyant-data/oxbow