[jira] [Comment Edited] (HIVE-13479) Relax sorting requirement in ACID tables

["Abhishek Somani (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-13479?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16795678#comment-16795678 ] 

Abhishek Somani edited comment on HIVE-13479 at 3/19/19 5:01 AM:
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[~ekoifman] [~vgumashta] [~gopalv]

Do we have any plans to work on this?

As I understand it, this might not be a restriction on Insert Only tables as there are no row_ids there, but will need work on Orc readers because of the assumption of records sorted on row_ids for a sort merge of delete events. Is that correct?


was (Author: asomani):
[~ekoifman] [~vgumashta] [~gopalv]

Do we have any plans to work on this?

> Relax sorting requirement in ACID tables
> ----------------------------------------
>
>                 Key: HIVE-13479
>                 URL: https://issues.apache.org/jira/browse/HIVE-13479
>             Project: Hive
>          Issue Type: New Feature
>          Components: Transactions
>    Affects Versions: 1.2.0
>            Reporter: Eugene Koifman
>            Assignee: Eugene Koifman
>            Priority: Major
>   Original Estimate: 160h
>  Remaining Estimate: 160h
>
> Currently ACID tables require data to be sorted according to internal primary key.  This is that base + delta files can be efficiently sort/merged to produce the snapshot for current transaction.
> This prevents the user to make the table sorted based on any other criteria which can be useful.  One example is using dynamic partition insert (which also occurs for update/delete SQL).  This may create lots of writers (buckets*partitions) and tax cluster resources.
> The usual solution is hive.optimize.sort.dynamic.partition=true which won't be honored for ACID tables.
> We could rely on hash table based algorithm to merge delta files and then not require any particular sort on Acid tables.  One way to do that is to treat each update event as an Insert (new internal PK) + delete (old PK).  Delete events are very small since they just need to contain PKs.  So the hash table would just need to contain Delete events and be reasonably memory efficient.
> This is a significant amount of work but worth doing.



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