Eugene Koifman created HIVE-18098:
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Summary: Add support for Export/Import for Acid tables
Key: HIVE-18098
URL: https://issues.apache.org/jira/browse/HIVE-18098
Project: Hive
Issue Type: New Feature
Components: Transactions
Reporter: Eugene Koifman
How should this work?
For regular tables export just copies the files under table root to a specified
directory.
This doesn't make sense for Acid tables:
* Some data may belong to aborted transactons
* Transaction IDs are imbedded into data/files names. You'd have export delta/
and base/ each of which may have files with the same names, e.g. bucket_00000.
* On import these IDs won't make sense in a different cluster or even a
different table (which may have delta_x_x for example for the same x (but
different data of course).
* Export creates a _metadata column types, storage format, etc. Perhaps it can
include info about aborted IDs (if the whole file can't be skipped).
* Even importing into the same table on the same cluster may be a problem. For
example delta_5_5/ existed at the time of export and was included in the
export. But 2 days later it may not exist because it was compacted and cleaned.
* If importing back into the same table on the same cluster, the data could be
imported into a different transaction (assuming per table writeIDs) w/o having
to remap the IDs in the rows themselves.
* support Import Overwrite?
* Support Import as a new txn with remapping of ROW_IDs? The new writeID can
be stored in a delta_x_x/_meta_data and ROW__IDs can be remapped at read time
(like isOriginal) and made permanent by compaction.
* It doesn't seem reasonable to import acid data into non-acid table
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