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https://issues.apache.org/jira/browse/HBASE-1978?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Schubert Zhang updated HBASE-1978:
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Attachment: HBASE-1978-HFile-v1.patch
This patch (HBASE-1978-HFile-v1.patch) is only for HFile.java. The HBase does
not work with only this patch, it need other modules coordination.
If you use HFile to do something else, you can use this patch.
> Change the range/block index scheme from [start,end) to (start, end], and
> index range/block by endKey, specially in HFile
> -------------------------------------------------------------------------------------------------------------------------
>
> Key: HBASE-1978
> URL: https://issues.apache.org/jira/browse/HBASE-1978
> Project: Hadoop HBase
> Issue Type: New Feature
> Components: io, master, regionserver
> Reporter: Schubert Zhang
> Attachments: HBASE-1978-HFile-v1.patch
>
>
> From the code review of HFile (HBASE-1818), we found the HFile allows
> duplicated key. But the old implementation would lead to missing of
> duplicated key when seek and scan, when the duplicated key span multiple
> blocks.
> We provide a patch (HBASE-1841 is't step1) to resolve above issue. This patch
> modified HFile.Writer to avoid generating a problem hfile with above
> cross-block duplicated key. It only start a new block when current appending
> key is different from the last appended key. But it still has a rish when the
> user of HFile.Writer append many same duplicated key which lead to a very
> large block and need much memory or Out-of-memory.
> The current HFile's block-index use startKey to index a block, i.e. the
> range/block index scheme is [startKey,endKey).
> As refering to the section 5.1 of the Google Bigtable paper.
> "The METADATA table stores the location of a tablet under a row key that is
> an encoding of the tablet's table identifer and its end row."
> The theory of Bigtable's METADATA is same as the BlockIndex in a SSTable or
> HFile, so we should use EndKey in HFile's BlockIndex. In my experiences of
> Hypertable, the METADATA is also "tableID:endRow".
> We would change the index scheme in HFile, from [startKey,endKey) to
> (startKey,endKey]. And change the binary search method to meet this index
> scheme.
> This change can resolve above duplicated-key issue.
> Note:
> The totally fix need to modify many modules in HBase, seems include HFile,
> META schema, some internal code, etc.
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