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https://issues.apache.org/jira/browse/HBASE-2001?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12792652#action_12792652
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Andrew Purtell commented on HBASE-2001:
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Nobody has to develop and deploy custom coprocessors if they don't want the
risk.
Maybe it's not highlighted enough but my current thinking and plan is to use
ASM to also impose some constraints. This is middle ground between arbitrary
function and a locked down language and will take only reasonable effort to
achieve (with part time one person contribution).
Beyond that, I'm not opposed if someone wants to contribute a restricted yet
somehow useful little language, I just have no plans to do that or I'll be
working on this indefinitely.
> Coprocessors: Colocate arbitrary code with regions
> --------------------------------------------------
>
> Key: HBASE-2001
> URL: https://issues.apache.org/jira/browse/HBASE-2001
> Project: Hadoop HBase
> Issue Type: Sub-task
> Reporter: Andrew Purtell
> Assignee: Andrew Purtell
> Attachments: asm-3.2-bin.zip, asm-transformations.pdf,
> org.apache.hadoop.hbase.coprocessor.Coprocessor.pdf
>
>
> "Support arbitrary code that runs run next to each region in table. As
> regions split and move, coprocessor code should automatically move also."
> Use classloader which looks on HDFS.
> Associate a list of classes to load with each table. Put this in HRI so it
> inherits from table but can be changed on a per region basis (so then those
> region specific changes can inherited by daughters).
> Not completely arbitrary code, should require implementation of an interface
> with callbacks for:
> * Open
> * Close
> * Split
> * Compact
> * (Multi)get and scanner next()
> * (Multi)put
> * (Multi)delete
> Add method to HRegionInterface for invoking coprocessor methods and
> retrieving results.
> Add methods in o.a.h.h.regionserver or subpackage which implement convenience
> functions for coprocessor methods and consistent/controlled access to
> internals: store access, threading, persistent and ephemeral state, scratch
> storage, etc.
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