[jira] [Commented] (HBASE-7495) parallel seek in StoreScanner

["Liang Xie (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-7495?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13568371#comment-13568371 ] 

Liang Xie commented on HBASE-7495:
----------------------------------

Hi [~yuzhihong@gmail.com], i ran the TestCoprocessorScanPolicy case, it costs 22+s in my box, if we have two cases w/ and w/o StoreScanner.STORESCANNER_PARALLEL_SEEK_ENABLE being true, it means the whole daily QA running time will add 22+s.
Is it ok that add "conf.setBoolean(StoreScanner.STORESCANNER_PARALLEL_SEEK_ENABLE, true);" into setUpBeforeClass(). It'll always enable this feature in TestCoprocessorScanPolicy case, without making QA time longger ?
                
> parallel seek in StoreScanner
> -----------------------------
>
>                 Key: HBASE-7495
>                 URL: https://issues.apache.org/jira/browse/HBASE-7495
>             Project: HBase
>          Issue Type: Bug
>          Components: Scanners
>    Affects Versions: 0.94.3, 0.96.0
>            Reporter: Liang Xie
>            Assignee: Liang Xie
>         Attachments: HBASE-7495.txt, HBASE-7495.txt, HBASE-7495.txt, HBASE-7495-v2.txt, HBASE-7495-v3.txt, HBASE-7495-v4.txt, HBASE-7495-v4.txt, HBASE-7495-v5.txt, HBASE-7495-v6.txt, HBASE-7495-v7.txt
>
>
> seems there's a potential improvable space before doing scanner.next:
> {code:title=StoreScanner.java|borderStyle=solid}
>     if (explicitColumnQuery && lazySeekEnabledGlobally) {
>       for (KeyValueScanner scanner : scanners) {
>         scanner.requestSeek(matcher.getStartKey(), false, true);
>       }
>     } else {
>       for (KeyValueScanner scanner : scanners) {
>         scanner.seek(matcher.getStartKey());
>       }
>     }
> {code} 
> we can do scanner.requestSeek or scanner.seek in parallel, instead of current serialization, to reduce latency for special case.
> Any ideas on it ?  I'll have a try if the comments/suggestions are positive：）

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