[jira] [Created] (IMPALA-9859) Milestone 4: Read updated tables

["Zoltán Borók-Nagy (Jira)" <ji...@apache.org>]

Zoltán Borók-Nagy created IMPALA-9859:
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             Summary: Milestone 4: Read updated tables
                 Key: IMPALA-9859
                 URL: https://issues.apache.org/jira/browse/IMPALA-9859
             Project: IMPALA
          Issue Type: Sub-task
            Reporter: Zoltán Borók-Nagy


Hive ACID supports row-level DELETE and UPDATE operatations on a table. It achieves it via assigning a unique row-id for each row, and maintinaining two sets of files in a table. The first set is in the delta directories, they contain the INSERTed rows. The second set of files are in the delete-delta directories, they contain the DELETEd rows.

_Note: UPDATE operations are implemented via DELETE+INSERT._

In the filesystem it looks like e.g.:

 
{noformat}
full_acid/delta_0000001_0000001_0000/0000_0
full_acid/delete_delta_0000002_0000002_0000/0000_0
{noformat}
During scanning we need to return INSERTed rows minus DELETEd rows. One way of doing that is to create an ANTI JOIN between INSERT and DELETE events.



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