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

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

     [ https://issues.apache.org/jira/browse/IMPALA-9859?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Zoltán Borók-Nagy resolved IMPALA-9859.
---------------------------------------
    Fix Version/s: Impala 4.0
       Resolution: Fixed

> 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
>            Assignee: Zoltán Borók-Nagy
>            Priority: Major
>             Fix For: Impala 4.0
>
>
> Hive ACID supports row-level DELETE and UPDATE operations on a table. It achieves it via assigning a unique row-id for each row, and maintaining 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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