[jira] [Commented] (HBASE-6805) Extend co-processor framework to provide observers for filter operations

["Raymond Liu (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-6805?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13497735#comment-13497735 ] 

Raymond Liu commented on HBASE-6805:
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Gary Helmling and Andrew Purtell : I have try to redesign the code with the approaching of both Option A and Option B, It turn out that with Option B, to replace the standard StoreScanner is much more efficient then Option A to replace the filter. Since in the scanner version, I can decrypt the kv before send to matcher. thus save the effort needed in pre/postFilterxxx to do raw kv and real kvs mapping etc. While, just like Gary mentioned, to replace StoreScanner with say DocStoreScanner, I need to duplicate most part of the code in it. And actually, I only add a few extra members and modify the next() method. Also it seems pretty hard to add common enough hooks to perform the task I need in DocStoreScanner. However, if some of the private member of StoreScanner could be changed to protected, then I think can subclass StoreScanner and only override the method I need to tweak into. What's your opinion on this, do you think to change the private member to protected member is a feasible approaching? I think if anyone who want to replace the standard StoreScanner, they will probably encounter the same problem here.
                
> Extend co-processor framework to provide observers for filter operations
> ------------------------------------------------------------------------
>
>                 Key: HBASE-6805
>                 URL: https://issues.apache.org/jira/browse/HBASE-6805
>             Project: HBase
>          Issue Type: Sub-task
>          Components: Coprocessors
>    Affects Versions: 0.96.0
>            Reporter: Jason Dai
>         Attachments: extend_coprocessor.patch
>
>
> There are several filter operations (e.g., filterKeyValue, filterRow, transform, etc.) at the region server side that either exclude KVs from the returned results, or transform the returned KV. We need to provide observers (e.g., preFilterKeyValue and postFilterKeyValue) for these operations in the same way as the observers for other data access operations (e.g., preGet and postGet). This extension is needed to support DOT (e.g., extracting individual fields from the document in the observers before passing them to the related filter operations) 

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