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https://issues.apache.org/jira/browse/HIVE-22255?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16940995#comment-16940995
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Peter Vary commented on HIVE-22255:
-----------------------------------

[~dineshchitlangia]: {{insert overwrite}} should on full ACID tables should not 
delete the previous base directory immediately. There might be other queries 
already using the previous snapshot (previous base file). Until all running 
queries are finished the previous directory is kept. Also I think the previous 
base is removed not by compaction, but by the cleanup process.

Thanks,
Peter

> Hive don't trigger Major Compaction automatically if table contains only base 
> files 
> ------------------------------------------------------------------------------------
>
>                 Key: HIVE-22255
>                 URL: https://issues.apache.org/jira/browse/HIVE-22255
>             Project: Hive
>          Issue Type: Bug
>          Components: Hive, Transactions
>    Affects Versions: 3.1.2
>         Environment: Hive-3.1.1
>            Reporter: Rajkumar Singh
>            Assignee: Rajkumar Singh
>            Priority: Major
>
> user may run into the issue if the table consists of all base files but no 
> delta, then the following condition will yield false and automatic major 
> compaction will be skipped.
> [https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/txn/compactor/Initiator.java#L313]
>  
> Steps to Reproduce:
>  # create Acid table 
> {code:java}
> //  create table myacid(id int);
> {code}
>  # Run multiple insert table 
> {code:java}
> // insert overwrite table myacid values(1);insert overwrite table myacid 
> values(2),(3),(4){code}
>  # DFS ls output
> {code:java}
> // dfs -ls -R /warehouse/tablespace/managed/hive/myacid;
> +----------------------------------------------------+
> |                     DFS Output                     |
> +----------------------------------------------------+
> | drwxrwx---+  - hive hadoop          0 2019-09-27 16:42 
> /warehouse/tablespace/managed/hive/myacid/base_0000001 |
> | -rw-rw----+  3 hive hadoop          1 2019-09-27 16:42 
> /warehouse/tablespace/managed/hive/myacid/base_0000001/_orc_acid_version |
> | -rw-rw----+  3 hive hadoop        610 2019-09-27 16:42 
> /warehouse/tablespace/managed/hive/myacid/base_0000001/bucket_00000 |
> | drwxrwx---+  - hive hadoop          0 2019-09-27 16:43 
> /warehouse/tablespace/managed/hive/myacid/base_0000002 |
> | -rw-rw----+  3 hive hadoop          1 2019-09-27 16:43 
> /warehouse/tablespace/managed/hive/myacid/base_0000002/_orc_acid_version |
> | -rw-rw----+  3 hive hadoop        633 2019-09-27 16:43 
> /warehouse/tablespace/managed/hive/myacid/base_0000002/bucket_00000 |
> +----------------------------------------------------+{code}
>  
> you will see that Major compaction will not be trigger until you run alter 
> table compact MAJOR.



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