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https://issues.apache.org/jira/browse/HBASE-4811?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13675487#comment-13675487
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Lars Hofhansl commented on HBASE-4811:
--------------------------------------
Added a bunch of comments to RB.
Generally I think the implementation leaks too many details up the scanner
stack. Instead of exposing the special backwardSeek, etc, methods everywhere we
should be able to set up the scanner tree with reverse scanners, that just
seek/next in the right direction. Only StoreFileScanner and MemstoreScanner
need to the special it seems.
> Support reverse Scan
> --------------------
>
> Key: HBASE-4811
> URL: https://issues.apache.org/jira/browse/HBASE-4811
> Project: HBase
> Issue Type: Improvement
> Components: Client
> Affects Versions: 0.20.6, 0.94.7
> Reporter: John Carrino
> Assignee: Liang Xie
> Attachments: 4811-trunk-v5.patch, HBase-4811-0.94.3modified.txt,
> HBase-4811-0.94-v2.txt, hbase-4811-trunkv1.patch, hbase-4811-trunkv4.patch,
> hbase-4811-trunkv6.patch
>
>
> All the documentation I find about HBase says that if you want forward and
> reverse scans you should just build 2 tables and one be ascending and one
> descending. Is there a fundamental reason that HBase only supports forward
> Scan? It seems like a lot of extra space overhead and coding overhead (to
> keep them in sync) to support 2 tables.
> I am assuming this has been discussed before, but I can't find the
> discussions anywhere about it or why it would be infeasible.
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