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From "mahesh kumar behera (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-21197) Hive Replication can add duplicate data during migration to a target with hive.strict.managed.tables enabled
Date Tue, 19 Feb 2019 11:59:02 GMT

     [ https://issues.apache.org/jira/browse/HIVE-21197?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

mahesh kumar behera updated HIVE-21197:
---------------------------------------
    Description: During bootstrap phase it may happen that the files copied to target are
created by events which are not part of the bootstrap. This is because of the fact that, bootstrap
first gets the last event id and then the file list. During this period if some event are
added, then bootstrap will include files created by these events also.The same files will
be copied again during the first incremental replication just after the bootstrap. In normal
scenario, the duplicate copy does not cause any issue as hive allows the use of target database
only after the first incremental. But in case of migration, the file at source and target
are copied to different location (based on the write id at target) and thus this may lead
to duplicate data at target. This can be avoided by having at check at load time for duplicate
file. This check can be done only for the first incremental and the search can be done in
the bootstrap directory (with write id 1). if the file is already present then just ignore
the copy.  (was: During bootstrap phase it may happen that the files copied to target are
created by events which are not part of the bootstrap. This is because of the fact that, bootstrap
first gets the last event id and then the file list. So during this period if some event happens,
then bootstrap will include files created by these events also. So the same files will be
copied again during the first incremental replication just after the bootstrap. In normal
scenario, the duplicate copy does not cause any issue as hive allows the use of target database
only after the first incremental. But in case of migration, the file at source and target
are copied to different location (based on the write id at target) and thus this may lead
to duplicate data at target. This can be avoided by having at check at load time for duplicate
file. This check can be done only for the first incremental and the search can be done in
the bootstrap directory (with write id 1). if the file is already present then just ignore
the copy.)

> Hive Replication can add duplicate data during migration to a target with hive.strict.managed.tables
enabled
> ------------------------------------------------------------------------------------------------------------
>
>                 Key: HIVE-21197
>                 URL: https://issues.apache.org/jira/browse/HIVE-21197
>             Project: Hive
>          Issue Type: Task
>          Components: repl
>            Reporter: mahesh kumar behera
>            Assignee: mahesh kumar behera
>            Priority: Major
>
> During bootstrap phase it may happen that the files copied to target are created by events
which are not part of the bootstrap. This is because of the fact that, bootstrap first gets
the last event id and then the file list. During this period if some event are added, then
bootstrap will include files created by these events also.The same files will be copied again
during the first incremental replication just after the bootstrap. In normal scenario, the
duplicate copy does not cause any issue as hive allows the use of target database only after
the first incremental. But in case of migration, the file at source and target are copied
to different location (based on the write id at target) and thus this may lead to duplicate
data at target. This can be avoided by having at check at load time for duplicate file. This
check can be done only for the first incremental and the search can be done in the bootstrap
directory (with write id 1). if the file is already present then just ignore the copy.



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