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From "Dylan Hutchison (JIRA)" <j...@apache.org>
Subject [jira] [Created] (ACCUMULO-3959) Confusing wording on BatchScanner javadoc
Date Tue, 11 Aug 2015 20:18:45 GMT
Dylan Hutchison created ACCUMULO-3959:
-----------------------------------------

             Summary: Confusing wording on BatchScanner javadoc
                 Key: ACCUMULO-3959
                 URL: https://issues.apache.org/jira/browse/ACCUMULO-3959
             Project: Accumulo
          Issue Type: Bug
          Components: docs
    Affects Versions: 1.7.0
            Reporter: Dylan Hutchison
            Priority: Minor


The following sentence in the [BatchScanner Javadoc|https://accumulo.apache.org/1.7/apidocs/org/apache/accumulo/core/client/BatchScanner.html]
has confused my colleagues into using Scanners and wondering why performance doesn't scale.

bq. If you want to lookup a few ranges and expect those ranges to contain a lot of data, then
use the Scanner instead.

Also regarding this next sentence, from what I see of the BatchScanner it will break up "large
Range objects" that span multiple extents (tablets) into multiple ranges, possibly one for
each tablet.

bq. Use this when looking up lots of ranges and you expect each range to contain a small amount
of data.

If the client is okay with unsorted order and it is okay with using multiple threads, then
isn't it always a better decision to use a BatchScanner than regular Scanner?  In the worst
case, one Range over a single row, the BatchScanner will perform the same as a regular Scanner,
ya?



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