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From "Andrew Purtell (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HBASE-899) Support for specifying a timestamp and numVersions on a per-column basis
Date Thu, 25 Sep 2008 13:17:44 GMT

    [ https://issues.apache.org/jira/browse/HBASE-899?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12634477#action_12634477
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Andrew Purtell commented on HBASE-899:
--------------------------------------

Can this be handled with filters? For example, by making a FilterSet that ANDs its terms,
then by adding to the set a filter that selects col1 by modified ColumnValueFilter that has
comparison operators for timestamps, and then by adding a (new) VersionFilter that only allows
through a specified number of versions? 

Although in general what this request is asking for is to move some overhead of culling results
from client side to server side. In general is that a good idea? Region servers are quite
busy.

> Support for specifying a timestamp and numVersions on a per-column basis
> ------------------------------------------------------------------------
>
>                 Key: HBASE-899
>                 URL: https://issues.apache.org/jira/browse/HBASE-899
>             Project: Hadoop HBase
>          Issue Type: New Feature
>            Reporter: Doğacan Güney
>
> This is just an idea and it may be better to wait after the planned API changes. But
I think it would be useful to support fetching different timestamps and versions for different
columns.
> Example:
> If a row has 2 columns, "col1:" and "col2:" I want to be able to ask for (during scan
or read time, doesn't matter) 2 versions of "col1:" (maybe even between timestamps t1 and
t2) but only 1 version of "col2:". This would be especially handy if during an MR job you
have to read 2 versions of a small column, but do not want the overhead of reading 2 versions
of every other column too....
> (Also, the mechanism is already there. I mean, making the changes to support a per-column
timestamp/numVersions is  ridiculously easy :)

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