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https://issues.apache.org/jira/browse/HIVE-22336?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16953271#comment-16953271
 ] 

Hive QA commented on HIVE-22336:
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|| Vote || Subsystem || Runtime || Comment ||
|| || || || {color:brown} Prechecks {color} ||
| {color:green}+1{color} | {color:green} @author {color} | {color:green}  0m  
0s{color} | {color:green} The patch does not contain any @author tags. {color} |
|| || || || {color:brown} master Compile Tests {color} ||
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green}  9m 
26s{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green}  0m 
29s{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green}  0m 
23s{color} | {color:green} master passed {color} |
| {color:blue}0{color} | {color:blue} findbugs {color} | {color:blue}  1m 
18s{color} | {color:blue} standalone-metastore/metastore-server in master has 
170 extant Findbugs warnings. {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green}  0m 
24s{color} | {color:green} master passed {color} |
|| || || || {color:brown} Patch Compile Tests {color} ||
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green}  0m 
34s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green}  0m 
29s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javac {color} | {color:green}  0m 
29s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green}  0m 
23s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} whitespace {color} | {color:green}  0m 
 0s{color} | {color:green} The patch has no whitespace issues. {color} |
| {color:green}+1{color} | {color:green} findbugs {color} | {color:green}  1m 
25s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green}  0m 
22s{color} | {color:green} the patch passed {color} |
|| || || || {color:brown} Other Tests {color} ||
| {color:red}-1{color} | {color:red} asflicense {color} | {color:red}  0m 
15s{color} | {color:red} The patch generated 3 ASF License warnings. {color} |
| {color:black}{color} | {color:black} {color} | {color:black} 16m  0s{color} | 
{color:black} {color} |
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|| Subsystem || Report/Notes ||
| Optional Tests |  asflicense  javac  javadoc  findbugs  checkstyle  compile  |
| uname | Linux hiveptest-server-upstream 3.16.0-4-amd64 #1 SMP Debian 
3.16.43-2+deb8u5 (2017-09-19) x86_64 GNU/Linux |
| Build tool | maven |
| Personality | 
/data/hiveptest/working/yetus_PreCommit-HIVE-Build-19025/dev-support/hive-personality.sh
 |
| git revision | master / 5ce0b40 |
| Default Java | 1.8.0_111 |
| findbugs | v3.0.0 |
| asflicense | 
http://104.198.109.242/logs//PreCommit-HIVE-Build-19025/yetus/patch-asflicense-problems.txt
 |
| modules | C: standalone-metastore/metastore-server U: 
standalone-metastore/metastore-server |
| Console output | 
http://104.198.109.242/logs//PreCommit-HIVE-Build-19025/yetus.txt |
| Powered by | Apache Yetus    http://yetus.apache.org |


This message was automatically generated.



> The updates should be pushed to the Metastore backend DB before creating the 
> notification event
> -----------------------------------------------------------------------------------------------
>
>                 Key: HIVE-22336
>                 URL: https://issues.apache.org/jira/browse/HIVE-22336
>             Project: Hive
>          Issue Type: Bug
>          Components: Metastore
>    Affects Versions: 4.0.0
>            Reporter: Marta Kuczora
>            Assignee: Marta Kuczora
>            Priority: Major
>         Attachments: HIVE-22336.1.patch
>
>
> There was an issue on HDP-3.1 where a table couldn't be deleted, because some 
> related objects (like storage descriptor) were missing from the metastore. 
> There was a previous delete attempt on that table which went wrong, but no 
> rollback happened, that's why the SD were missing. In that previous delete, 
> the notification creation swallowed the error which came from the backend DB, 
> that's why no rollback happened. Here are the steps which happened in the 
> first delete attempt:
>  
> # Open a transaction (transaction_1) - this step was successful
> # Delete all the objects which are related to the table - this step was 
> successful too, so the SD and other objects were deleted
> # Delete the table - this step failed in the backend DB, but according to the 
> log the delete happens in a batch statement, so it won't necessarily be 
> executed right at this moment, so we won't see an error here
> # Create a notification about the table delete:
> ## Open an other transaction for the notification creation (transaction_2) - 
> call the ObjectStore.openTransaction method which increases a counter for 
> open transactions and then checks if there is already an active transaction. 
> If there is, then just returns true and doesn't really create a new 
> transaction.
> ## Lock the notification id in the metastore backend db for update - here is 
> where the exception from the backend DB (let's call it "MySQL Exception") 
> manifests
> ## If an exception occurs during acquiring the log, retry - The "MySQL 
> Exception" was caught and since there is no check on the exception, the retry 
> mechanism thinks that it happened because couldn't acquire the log for the 
> notification id, so retries and "forgot" about the "MySQL Exception".
> ## If the lock was acquired successfully, create the notification - Second 
> time, the lock was acquired successfully, so the notification creation was 
> successful.
> ## Commit transaction_2 - Just decrease the transaction counter, but doesn't 
> actually commits anything.
> # Commit transaction_1 - This commits the transaction, but since the error 
> already got manifested and kind of "handled", here we won't see any error, 
> just that the commit was successful, so no rollback happens and leaves the 
> table object in an invalid state.
> # If the commit was not successful then rollback
> In the customer setup, this issue could be fixed by adding a flush call 
> before creating the notification event, so all the updates would be pushed to 
> the backend db and the error would manifest at this point. With this, the 
> error would go back to the HiveMetastore class which would do the rollback 
> and the delete table operation would fail as it should be, since the table 
> couldn't be deleted. But then the Hivemetastore retry mechanism could try the 
> table deletion again.



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