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https://issues.apache.org/jira/browse/HBASE-18097?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16028663#comment-16028663
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Karan Mehta commented on HBASE-18097:
-------------------------------------
The first part for saving 1 RPC request is already implemented as a part of
HBASE-17508, where the scannerId is set to -1 whenever results are not left in
region.
For the second part related to ScanResponse proto, we can save some data in RPC
call.
[~Apache9] Do you feel it is reasonable to do so from the next version?
> Client can save 1 RPC call for CloseScannerRequest
> --------------------------------------------------
>
> Key: HBASE-18097
> URL: https://issues.apache.org/jira/browse/HBASE-18097
> Project: HBase
> Issue Type: Improvement
> Reporter: Karan Mehta
>
> Starting version 1.3, HBase automatically closes scanner on server side
> whenever the results are exhausted and corresponding bits are set in the
> {{ScanResponse}} proto returned to the client. We can use that info to
> eliminate the closeScanRequest RPC call, thereby saving 1 RPC per region per
> scan. This can be particularly useful for tables with more regions.
> Also, currently the {{ScanResponse}} proto sends out 1 bit per {{Result}}
> that it has embeds inside the {{CellScanner}} to indicate if it is partial or
> not.
> {code}
> // In every RPC response there should be at most a single partial result.
> Furthermore, if
> // there is a partial result, it is guaranteed to be in the last position
> of the array.
> {code}
> According to client, only the last result can be partial, thus this repeated
> bool can be converted to a bool, thus reducing overhead of serialization and
> deserialization of the array. This will break wire compatibility therefore
> this is something to look for in upcoming versions.
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