[jira] Commented: (HBASE-1935) Scan in parallel

["Dan Washusen (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-1935?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12783985#action_12783985 ] 

Dan Washusen commented on HBASE-1935:
-------------------------------------

There is a minor bug in v2 of the patch.  The logic in the ParallelScannerManager to determine if a scan is interested in a region doesn't handle the case when there is only one region.  

The following fixes it:
{code}
Set<HRegionInfo> regions = table.getRegionsInfo().keySet();
for (HRegionInfo region : regions) {
  ...
  boolean isScanInterestedInRegion = (scan.getStartRow().length == 0 && scan.getStopRow().length == 0) || regions.size() == 1;
{code}

          

> Scan in parallel
> ----------------
>
>                 Key: HBASE-1935
>                 URL: https://issues.apache.org/jira/browse/HBASE-1935
>             Project: Hadoop HBase
>          Issue Type: New Feature
>            Reporter: stack
>         Attachments: pscanner-v2.patch, pscanner.patch
>
>
> A scanner that rather than scan in series, instead scanned multiple regions in parallell would be more involved but could complete much faster partiularly if results are sparse.

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