[jira] [Created] (HBASE-18097) Client can save 1 RPC call for CloseScannerRequest

["Karan Mehta (JIRA)" <ji...@apache.org>]

Karan Mehta created HBASE-18097:
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             Summary: 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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