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From "Elliott Clark (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-8521) Cells cannot be overwritten with bulk loaded HFiles
Date Fri, 10 May 2013 04:11:16 GMT

    [ https://issues.apache.org/jira/browse/HBASE-8521?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13653522#comment-13653522
] 

Elliott Clark commented on HBASE-8521:
--------------------------------------

@Ted he opened this because of me.  It's a pretty tough thing to repro.

Bulk load files (on trunk) are sorted by [see StoreFile#Comparator]:

SeqID
Size (reversed)
TimeStamp
filename


So bulkoad files that are larger than the bulkloaded files that come before them can overwrite
key values with the same timestamp.  We should adopt what 0.89-fb does.  Assign seqid to bulk
loaded files at bulk load time, by renaming the files.

This should mean that bulk load files are treated in much the same way as flushed/compacted
files.
                
> Cells cannot be overwritten with bulk loaded HFiles
> ---------------------------------------------------
>
>                 Key: HBASE-8521
>                 URL: https://issues.apache.org/jira/browse/HBASE-8521
>             Project: HBase
>          Issue Type: Bug
>    Affects Versions: 0.92.1
>            Reporter: Jonathan Natkins
>
> Let's say you have a pre-built HFile that contains a cell:
> ('rowkey1', 'family1', 'qual1', 1234L, 'value1')
> We bulk load this first HFile. Now, let's create a second HFile that contains a cell
that overwrites the first:
> ('rowkey1', 'family1', 'qual1', 1234L, 'value2')
> That gets bulk loaded into the table, but the value that HBase bubbles up is still 'value1'.
> It seems that there's no way to overwrite a cell for a particular timestamp without an
explicit put operation. This seems to be the case even after minor and major compactions happen.
> My guess is that this is pretty closely related to the sequence number work being done
on the compaction algorithm via HBASE-7842, but I'm not sure if one of would fix the other.

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