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From "Eugene Koifman (JIRA)" <>
Subject [jira] [Updated] (HIVE-18814) Support Add Partition For Acid tables
Date Sun, 01 Apr 2018 16:27:00 GMT


Eugene Koifman updated HIVE-18814:
    Attachment: HIVE-18814.04.patch

> Support Add Partition For Acid tables
> -------------------------------------
>                 Key: HIVE-18814
>                 URL:
>             Project: Hive
>          Issue Type: New Feature
>          Components: Transactions
>            Reporter: Eugene Koifman
>            Assignee: Eugene Koifman
>            Priority: Major
>         Attachments: HIVE-18814.01.patch, HIVE-18814.02.patch, HIVE-18814.03.patch, HIVE-18814.04.patch
> []
> Add Partition command creates a {{Partition}} metadata object and sets the location to
the directory containing data files.
> In current master (Hive 3.0), Add partition on an acid table doesn't fail and at read
time the data is decorated with row__id but the original transaction is 0.  I suspect in
earlier Hive versions this will throw or return no data.
> Since this new partition didn't have data before, assigning txnid:0 isn't going to generate
duplicate IDs but it could violate Snapshot Isolation in multi stmt txns.  Suppose txnid:7
runs {{select * from T}}.  Then txnid:8 adds a partition to T.  Now if txnid:7 runs the same
query again, it will see the data in the new partition.
> This can't be release like this since a delete on this data (added via Add partition)
will use row_ids with txnid:0 so a later upgrade that sees un-compacted may generate row_ids
with different txnid (assuming this is fixed by then)
> One option is follow Load Data approach and create a new delta_x_x/ and move/copy the
data there.
> Another is to allocate a new writeid and save it in Partition metadata.  This could
then be used to decorate data with ROW__IDs.  This avoids move/copy but retains data "outside"
of the table tree which make it more likely that this data will be modified in some way which
can really break things if done after and SQL update/delete on this data have happened. 
> It performs no validations on add (except for partition spec) so any file with any format
can be added.  It allows add to bucketed tables as well.
> Seems like a very dangerous command.  Maybe a better option is to block it and advise
using Load Data.  Alternatively, make this do Add partition metadata op followed by Load Data. 

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