Mailing-List: contact issues-help@hbase.apache.org; run by ezmlm
Precedence: bulk
Date: Mon, 25 Aug 2014 04:46:58 +0000 (UTC)
From: "Enis Soztutar (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
Message-ID: <JIRA.12735981.1408681694363.1027.1408942018567@arcas>
In-Reply-To: <JIRA.12735981.1408681694363@arcas>
References: <JIRA.12735981.1408681694363@arcas>
Subject: [jira] [Commented] (HBASE-11803) Programming model for reverse scan
 is confusing
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit


    [ https://issues.apache.org/jira/browse/HBASE-11803?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14108728#comment-14108728 ] 

Enis Soztutar commented on HBASE-11803:
---------------------------------------

bq. If done such that we have new getters and setters for Scan for KeyRange while keeping current Scan methods in a backwards compatible way (with some deprecation), I don't see why that change couldn't go in on branch-1 - although that's Enis Soztutar's call - or even 0.98.
Sounds like a good idea. A range with explicit inclusion for boundaries will make client API cleaner. 

> Programming model for reverse scan is confusing
> -----------------------------------------------
>
>                 Key: HBASE-11803
>                 URL: https://issues.apache.org/jira/browse/HBASE-11803
>             Project: HBase
>          Issue Type: Bug
>          Components: Client
>    Affects Versions: 0.98.1
>            Reporter: James Taylor
>            Assignee: Ted Yu
>         Attachments: 11803-v1.txt
>
>
> The reverse scan is a very nice feature in HBase. We leverage it in Apache Phoenix 4.1 when possible and see a huge boost in performance over re-ordering the result set ourselves.
> However, the way in which you have to adjust the start/stop key is confusing. Our use case is that we have a scan that needs to be done and we've calculated an inclusive start row and an exclusive stop row. This is the way region boundaries are which is convenient as they can easily be intersected against the scan stop/start row. When we use a reverse scan, we are forced to switch the start and stop row values of the scan *and* adjust the byte values from inclusive to exclusive and from exclusive to inclusive. The former is not too bad, as you can just add a zero byte, but the latter is problematic. You can decrease the last byte by one, but you need to add an indeterminate 0xFF bytes to ensure you're not including a row unintentionally.
> IMHO, it would be much cleaner to just keep the start/stop row as is and just set  call the Scan.setReversed(true) method.


--
This message was sent by Atlassian JIRA
(v6.2#6252)