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From "Clint Morgan (JIRA)" <j...@apache.org>
Subject [jira] Created: (HBASE-605) allow scanners which return results ordred by a column value
Date Tue, 29 Apr 2008 21:49:55 GMT
allow scanners which return results ordred by a column value
------------------------------------------------------------

                 Key: HBASE-605
                 URL: https://issues.apache.org/jira/browse/HBASE-605
             Project: Hadoop HBase
          Issue Type: New Feature
          Components: client, regionserver
    Affects Versions: 0.2.0
            Reporter: Clint Morgan
            Priority: Minor


We would like to be able to scan though tables with results ordered by (deserialized) column
values. This approach maintains an in-memory sorted set for each ordered-by column in each
HStore. This allows us to iterate through the keys in column order, and to random reads on
the key to get the full row.

Without the index, then we have to scan through all the rows to get the first result ordered
by a column. Thus, when R is the number of rows in a table,  N is the number of ordered-by
rows we want, and R >> N we can save a lot of work by not doing the full table scan.



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