[jira] [Commented] (PHOENIX-4278) Implement pure client side transactional index maintenance

["James Taylor (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/PHOENIX-4278?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16192184#comment-16192184 ] 

James Taylor commented on PHOENIX-4278:
---------------------------------------

FYI, [~apurtell].

> Implement pure client side transactional index maintenance
> ----------------------------------------------------------
>
>                 Key: PHOENIX-4278
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-4278
>             Project: Phoenix
>          Issue Type: Improvement
>            Reporter: James Taylor
>
> The index maintenance for transactions follows the same model as non transactional tables - coprocessor based on data table updates that looks up previous row value to perform maintenance. This is necessary for non transactional tables to ensure the rows are locked so that a consistent view may be obtained. However, for transactional tables, the time stamp oracle ensures uniqueness of time stamps (via transaction IDs) and the filtering handles a scan seeing the "true" last committed value for a row. Thus, there's no hard dependency to perform this on the server side.
> Moving the index maintenance to the client side would prevent any RS->RS RPC calls (which have proved to be troublesome for HBase). It would require returning more data to the client (i.e. the prior row value), but this seems like a reasonable tradeoff.



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