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From "ASF GitHub Bot (JIRA)" <>
Subject [jira] [Commented] (ACCUMULO-3959) Confusing wording on BatchScanner javadoc
Date Mon, 24 Aug 2015 02:22:45 GMT


ASF GitHub Bot commented on ACCUMULO-3959:

GitHub user dhutchis opened a pull request:

    ACCUMULO-3959 More accurate BatchScanner javadoc

    This will help clear possible confusion on when to use BatchScanners vs Scanners.

You can merge this pull request into a Git repository by running:

    $ git pull ACCUMULO-3959

Alternatively you can review and apply these changes as the patch at:

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #45
commit 01dd7e32e864c7359f8b289f1434c9d9a5c154d4
Author: Dylan Hutchison <>
Date:   2015-08-24T02:19:47Z

    ACCUMULO-3959 More accurate BatchScanner javadoc


> Confusing wording on BatchScanner javadoc
> -----------------------------------------
>                 Key: ACCUMULO-3959
>                 URL:
>             Project: Accumulo
>          Issue Type: Bug
>          Components: docs
>    Affects Versions: 1.7.0
>            Reporter: Dylan Hutchison
>            Priority: Minor
>              Labels: docuentation
> The following sentence in the [BatchScanner Javadoc|]
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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