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From "Eugene Koifman (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-9995) ACID compaction tries to compact a single file
Date Thu, 09 Jun 2016 23:18:24 GMT

     [ https://issues.apache.org/jira/browse/HIVE-9995?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Eugene Koifman updated HIVE-9995:
---------------------------------
    Description: 
Consider TestWorker.minorWithOpenInMiddle()

since there is an open txnId=23, this doesn't have any meaningful minor compaction work to
do.  The system still tries to compact a single delta file for 21-22 id range, and effectively
copies the file onto itself.

This is 1. inefficient and 2. can potentially affect a reader.

(from a real cluster)
Suppose we start with 
{noformat}
drwxr-xr-x   - ekoifman staff          0 2016-06-09 16:03 /user/hive/warehouse/t/base_0000016
-rw-r--r--   1 ekoifman staff        602 2016-06-09 16:03 /user/hive/warehouse/t/base_0000016/bucket_00000
drwxr-xr-x   - ekoifman staff          0 2016-06-09 16:07 /user/hive/warehouse/t/base_0000017
-rw-r--r--   1 ekoifman staff        588 2016-06-09 16:07 /user/hive/warehouse/t/base_0000017/bucket_00000
drwxr-xr-x   - ekoifman staff          0 2016-06-09 16:07 /user/hive/warehouse/t/delta_0000017_0000017_0000
-rw-r--r--   1 ekoifman staff        514 2016-06-09 16:06 /user/hive/warehouse/t/delta_0000017_0000017_0000/bucket_00000
drwxr-xr-x   - ekoifman staff          0 2016-06-09 16:07 /user/hive/warehouse/t/delta_0000018_0000018_0000
-rw-r--r--   1 ekoifman staff        612 2016-06-09 16:07 /user/hive/warehouse/t/delta_0000018_0000018_0000/bucket_00000
{noformat}
then do _alter table T compact 'minor';_

then we end up with 
{noformat}
drwxr-xr-x   - ekoifman staff          0 2016-06-09 16:07 /user/hive/warehouse/t/base_0000017
-rw-r--r--   1 ekoifman staff        588 2016-06-09 16:07 /user/hive/warehouse/t/base_0000017/bucket_00000
drwxr-xr-x   - ekoifman staff          0 2016-06-09 16:11 /user/hive/warehouse/t/delta_0000018_0000018
-rw-r--r--   1 ekoifman staff        500 2016-06-09 16:11 /user/hive/warehouse/t/delta_0000018_0000018/bucket_00000
drwxr-xr-x   - ekoifman staff          0 2016-06-09 16:07 /user/hive/warehouse/t/delta_0000018_0000018_0000
-rw-r--r--   1 ekoifman staff        612 2016-06-09 16:07 /user/hive/warehouse/t/delta_0000018_0000018_0000/bucket_00000
{noformat}

So compaction created a new dir _/user/hive/warehouse/t/delta_0000018_0000018_

  was:
Consider TestWorker.minorWithOpenInMiddle()

since there is an open txnId=23, this doesn't have any meaningful minor compaction work to
do.  The system still tries to compact a single delta file for 21-22 id range, and effectively
copies the file onto itself.

This is 1. inefficient and 2. can potentially affect a reader.


> ACID compaction tries to compact a single file
> ----------------------------------------------
>
>                 Key: HIVE-9995
>                 URL: https://issues.apache.org/jira/browse/HIVE-9995
>             Project: Hive
>          Issue Type: Bug
>          Components: Transactions
>    Affects Versions: 1.0.0
>            Reporter: Eugene Koifman
>            Assignee: Eugene Koifman
>
> Consider TestWorker.minorWithOpenInMiddle()
> since there is an open txnId=23, this doesn't have any meaningful minor compaction work
to do.  The system still tries to compact a single delta file for 21-22 id range, and effectively
copies the file onto itself.
> This is 1. inefficient and 2. can potentially affect a reader.
> (from a real cluster)
> Suppose we start with 
> {noformat}
> drwxr-xr-x   - ekoifman staff          0 2016-06-09 16:03 /user/hive/warehouse/t/base_0000016
> -rw-r--r--   1 ekoifman staff        602 2016-06-09 16:03 /user/hive/warehouse/t/base_0000016/bucket_00000
> drwxr-xr-x   - ekoifman staff          0 2016-06-09 16:07 /user/hive/warehouse/t/base_0000017
> -rw-r--r--   1 ekoifman staff        588 2016-06-09 16:07 /user/hive/warehouse/t/base_0000017/bucket_00000
> drwxr-xr-x   - ekoifman staff          0 2016-06-09 16:07 /user/hive/warehouse/t/delta_0000017_0000017_0000
> -rw-r--r--   1 ekoifman staff        514 2016-06-09 16:06 /user/hive/warehouse/t/delta_0000017_0000017_0000/bucket_00000
> drwxr-xr-x   - ekoifman staff          0 2016-06-09 16:07 /user/hive/warehouse/t/delta_0000018_0000018_0000
> -rw-r--r--   1 ekoifman staff        612 2016-06-09 16:07 /user/hive/warehouse/t/delta_0000018_0000018_0000/bucket_00000
> {noformat}
> then do _alter table T compact 'minor';_
> then we end up with 
> {noformat}
> drwxr-xr-x   - ekoifman staff          0 2016-06-09 16:07 /user/hive/warehouse/t/base_0000017
> -rw-r--r--   1 ekoifman staff        588 2016-06-09 16:07 /user/hive/warehouse/t/base_0000017/bucket_00000
> drwxr-xr-x   - ekoifman staff          0 2016-06-09 16:11 /user/hive/warehouse/t/delta_0000018_0000018
> -rw-r--r--   1 ekoifman staff        500 2016-06-09 16:11 /user/hive/warehouse/t/delta_0000018_0000018/bucket_00000
> drwxr-xr-x   - ekoifman staff          0 2016-06-09 16:07 /user/hive/warehouse/t/delta_0000018_0000018_0000
> -rw-r--r--   1 ekoifman staff        612 2016-06-09 16:07 /user/hive/warehouse/t/delta_0000018_0000018_0000/bucket_00000
> {noformat}
> So compaction created a new dir _/user/hive/warehouse/t/delta_0000018_0000018_



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