[jira] [Commented] (HBASE-5313) Restructure hfiles layout for better compression

["He Yongqiang (Commented) (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-5313?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13222512#comment-13222512 ] 

He Yongqiang commented on HBASE-5313:
-------------------------------------

As part of working on HBASE-5313, we first tried to write a HFileWriter/HFileReader to do it. After finishing some work, it seems this requires a lot of code refactoring in order to reuse existing code as much as possible.

Then we find seems adding a new columnar encoder/decoder would be easy to do. opened https://issues.apache.org/jira/browse/HBASE-5521 to do encoder/decoder specific compression work.
                
> Restructure hfiles layout for better compression
> ------------------------------------------------
>
>                 Key: HBASE-5313
>                 URL: https://issues.apache.org/jira/browse/HBASE-5313
>             Project: HBase
>          Issue Type: Improvement
>          Components: io
>            Reporter: dhruba borthakur
>            Assignee: dhruba borthakur
>
> A HFile block contain a stream of key-values. Can we can organize these kvs on the disk in a better way so that we get much greater compression ratios?
> One option (thanks Prakash) is to store all the keys in the beginning of the block (let's call this the key-section) and then store all their corresponding values towards the end of the block. This will allow us to not-even decompress the values when we are scanning and skipping over rows in the block.
> Any other ideas? 

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