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From "Vladimir Rodionov (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-11811) Use binary search for seeking into a block
Date Fri, 26 Jun 2015 18:13:04 GMT

    [ https://issues.apache.org/jira/browse/HBASE-11811?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14603342#comment-14603342
] 

Vladimir Rodionov commented on HBASE-11811:
-------------------------------------------

I think I know why the patch has been abandoned. PREFIX_TREE encoding solves the fast search
problem inside HFile block  - this is why the patch has not been supported. But, any block
encodings in HBase reduces (sometimes, significantly - read this discussion 
http://comments.gmane.org/gmane.comp.java.hadoop.hbase.devel/40477
) overall scan speed.

We need key encoding which is lightweight on scans and fast on search. Having block encoding
NONE and key index solves both, but does not reduce memory footprint. For applications, there
key overhead is not so large this might be a good feature.


> Use binary search for seeking into a block
> ------------------------------------------
>
>                 Key: HBASE-11811
>                 URL: https://issues.apache.org/jira/browse/HBASE-11811
>             Project: HBase
>          Issue Type: Brainstorming
>            Reporter: Lars Hofhansl
>         Attachments: 11811-wip-v2.txt, 11811-wip-v4.txt, block_index-v2.txt
>
>
> Currently upon every seek (including Gets) we need to linearly look through the block
from the beginning until we find the Cell we are looking for.
> It should be possible to build a simple cache of offsets of Cells for each block as it
is loaded and then use binary search to find the Cell in question.



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