Audit action field optionality

[fvaleye]

Description

Audit Action attributes using https://github.com/delta-io/delta/blob/master/core/src/main/scala/org/apache/spark/sql/delta/actions/actions.scala file

Related Issue(s)

closes #372

[fvaleye]

@houqp based on my investigation, tell me what you think about:

• Keeping optional fields in Actions and Metadata when there are null by default in delta (examples from Metadata: names and description).
  Option will be used to avoid serialization/deserialization errors when reading the delta transaction log.
  I encountered several issues when reading older delta table versions <1.0 (these fields were not in the transaction logs).

• Setting created_time in Metadata as Optional

• Settting deletion_timestamp in Remove as Optional

• Setting the values of data_change and extended_file_metadata with their default values when reading delta table transaction log for Remove actions

[houqp]

Sorry for the late response @fvaleye , catch up on notifications after getting back from vacation :)

What you proposed makes total sense to me 👍

[fvaleye]

Sorry for the late response @fvaleye , catch up on notifications after getting back from vacation :)

What you proposed makes total sense to me 👍

@houqp Oh, no worries at all! I hope you enjoyed it 🏖️