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https://issues.apache.org/jira/browse/HBASE-16649?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15501315#comment-15501315
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Matteo Bertozzi commented on HBASE-16649:
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current implementation we drop the fs dirs, and recreate them.
we can just regenerate the regionInfo, so they will get a new encodedName
> Truncate table with splits preserved can cause both data loss and truncated
> data appeared again
> -----------------------------------------------------------------------------------------------
>
> Key: HBASE-16649
> URL: https://issues.apache.org/jira/browse/HBASE-16649
> Project: HBase
> Issue Type: Bug
> Affects Versions: 1.1.3
> Reporter: Allan Yang
>
> Since truncate table with splits preserved will delete hfiles and use the
> previous regioninfo. It can cause odd behaviors
> - Case 1: *Data appeared after truncate*
> reproduce procedureļ¼
> 1. create a table, let's say 'test'
> 2. write data to 'test', make sure memstore of 'test' is not empty
> 3. truncate 'test' with splits preserved
> 4. kill the regionserver hosting the region(s) of 'test'
> 5. start the regionserver, now it is the time to witness the miracle! the
> truncated data appeared in table 'test'
> - Case 2: *Data loss*
> reproduce procedure:
> 1. create a table, let's say 'test'
> 2. write some data to 'test', no matter how many
> 3. truncate 'test' with splits preserved
> 4. restart the regionserver to reset the seqid
> 5. write some data, but less than 2 since we don't want the seqid to run over
> the one in 2
> 6. kill the regionserver hosting the region(s) of 'test'
> 7. restart the regionserver. Congratulations! the data writen in 4 is now all
> lost
> *Why?*
> for case 1
> Since preserve splits in truncate table procedure will not change the
> regioninfo, when log replay happens, the 'unflushed' data will restore back
> to the region
> for case 2
> since the flushedSequenceIdByRegion are stored in Master in a map with the
> region's encodedName. Although the table is truncated, the region's name is
> not changed since we chose to preserve the splits. So after truncate the
> table, the region's sequenceid is reset in the regionserver, but not reset in
> master. When flush comes and report to master, master will reject the update
> of sequenceid since the new one is smaller than the old one. The same happens
> in log replay, all the edits writen in 4 will be skipped since they have a
> smaller seqid
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