TAJO-1644: When inserting empty data into a partitioned table, existing data would be removed.

[blrunner]

When inserting empty data into a partitioned table, existing data would be removed. Tajo provides column value partition which is hive-style partition. In hive, when inserting empty data into a partition, there are two cases. If you use dynamic partitions, existing data never would be removed. But if you don't use dynamic partitions, existing data would be removed. When inserting a data to partition, tajo user don't specify each column and each column value. So, it is similar to dynamic partition of hive. It seems to update deletion logic of partitioned table.

[hyunsik]

It would be better if you rename verifyMaintainExistingData to verifyKeptExistingData.

[blrunner]

Thanks @hyunsik

I've just updated the patch using your comments. :)

[hyunsik]

Hi @blrunner,

Thank you for your work. How about the insert overwrite behavior for not partitioned table? Does that the same semantic?

[blrunner]

Hi @hyunsik

Thank you for your review. I also agree with you. But when inserting empty data into a non partitioned table in hive, existing data would be removed always. I'm a bit anxious about user's confusion between hive and tajo.

[hyunsik]

How about TABLE_PARTITION_NO_RESULT_OVERWRITE_ENABLED for the config name? It seems to be more intuitive for me.

[blrunner]

@hyunsik

Thank you for your detailed review.
I've just updated the patch using your comments.

[hyunsik]

I have one more suggestion. It would be great if you use PARTITION instead of TABLE_PARTITION. It is still clear because we only use the term 'partition' to indicate table partition.

[hyunsik]

+1
Looks good to me. I leaved one trivial comment. If you agree, you can commit the patch after you reflect my comment.