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From "Mike Drob (JIRA)" <j...@apache.org>
Subject [jira] [Created] (ACCUMULO-1801) Create a SelectColumnsIterator
Date Tue, 22 Oct 2013 15:35:42 GMT
Mike Drob created ACCUMULO-1801:
-----------------------------------

             Summary: Create a SelectColumnsIterator
                 Key: ACCUMULO-1801
                 URL: https://issues.apache.org/jira/browse/ACCUMULO-1801
             Project: Accumulo
          Issue Type: Improvement
          Components: client
            Reporter: Mike Drob
            Priority: Minor
             Fix For: 1.5.1, 1.6.0


A user can already limit columns on a scanner, however there is not an easy way to limit the
columns propagated in the middle of an iterator stack. For example, if a user has data like
the following:
{noformat}
user-1 age:25
user-1 occupation:Student
user-2 age:45
user-2 occupation:Engineer
{noformat}
and wants to get only the users that are younger than 30, it is easy to write a custom {{RowFilter}}
to do that.

However, to get only the occupation of users under 30, there would need to be additional filtering
done on the client side. If the rows get large or particularly numerous, then this becomes
undesirable. And setting the fetch columns is not an option since that would hide the age
column from the {{RowFilter}}.



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