cloud-fan commented on issue #24129: [SPARK-27190][SQL] add table capability 
for streaming
URL: https://github.com/apache/spark/pull/24129#issuecomment-483484108
 
 
   @rdblue `V2WriteSupportCheck` only checks write capability not scan.
   
   > For any streaming scan of a V2Relation, validate that the underlying table 
supports either micro-batch or continuous mode.
   
   This needs to create an unresolved streaming DS v2 relation, and ask 
`DataStreamReader` to create this unresolved relation, instead of checking the 
scan capability and creating a resolved relation. I don't agree that we HAVE TO 
do it in this PR while the PR that adds batch scan ability did not.
   
   > For any streaming write to a V2Relation, validate that the underlying 
table supports streaming writes.
   
   This needs to move the creation of streaming writing logical plan from 
`MicroBatchExecution`/`ContinuousExecution` to `DataStreamWriter`. The writing 
logical plan is different between micro-batch and continuous, we also need an 
unresolved writing plan, and resolve it when we know the streaming execution 
mode. This is a major refactor
   
   > For the set of streaming scans in the plan, validate that the intersection 
of supported modes is non-empty. For example, fail if s1 supports only 
microbatch and s2 supports only continuous.
   
   Same as the first point.
   
   I don't understand why you think this PR is incomplete. It adds streaming 
scan/write capability and checks them correctly. It's a different story to 
centralize the check, which can be done in a followup.

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