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https://issues.apache.org/jira/browse/HBASE-2038?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13181069#comment-13181069
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Alex Baranau commented on HBASE-2038:
-------------------------------------
+1 for collaboration!
re HBASE-2037 (aka IHBase): it is the base for this effort. Yes, it doesn't
require ITHBase, it is alternative implementation. The refactored code I
pointed above (https://github.com/abaranau/ihbase) is also based on the IHBase
code.
In short (sorry, the description is not tied to classes, don't have them in
front of me currently):
As far as I remember (need to refresh my memory though) the point is that index
is being kept for each Region, it is loaded in RAM, not persistent. It is built
during Region initialization (after HBase restart or new region creation after
split and such). When scan is performed with indexed columns involved it uses
the index when finding the next record to navigate to and *fast forwards* to
this next record (usually by skipping some other records without even reading
them). This is where it wins the speed.
As this was developed before CPs were added the special API was developed which
is being used by client.
Hope this helps a bit. I will refresh my memory from the code and we'll discuss
that a bit deeper.
> Coprocessors: Region level indexing
> -----------------------------------
>
> Key: HBASE-2038
> URL: https://issues.apache.org/jira/browse/HBASE-2038
> Project: HBase
> Issue Type: New Feature
> Components: coprocessors
> Reporter: Andrew Purtell
> Priority: Minor
>
> HBASE-2037 is a good candidate to be done as coprocessor. It also serve as a
> good goalpost for coprocessor environment design -- there should be enough of
> it so region level indexing can be reimplemented as a coprocessor without any
> loss of functionality.
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