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https://issues.apache.org/jira/browse/HBASE-605?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12598902#action_12598902
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stack commented on HBASE-605:
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In TestOrderedScanner, do you want to remove commented out code? Do you want
to add a class comment that says this test depends/uses a 'special' version of
HRegionServer. Would suggest that all classes that depend on this custom
HRegionServer also get marked appropriately in their class comment (@see?):
e.g. OrderedScanner won't work unless its going against the ordered HRS -- same
for OrderedHRegion.
Some classes are missing licenses.
I suppose package protection prevents you putting all these new classes into a
new orderedregionserver package or into a subpackage named regionserver.ordered
and client.ordered or some such?
You need to explain somewhere in javadoc what this OrderedRegionServer is, how
it works, and how to enable it. Would suggest that the class comment in the
OrderedRegionServer or in the Ordered Interface as good places (otherwise,
should I put in place a package.html to which you can add?). What would be
great is that the next time someone shows up asking how they can customize
regionserver behavior, we can just point them to your OrderedRegionServer
javadoc as an example.
Thanks for adding accessors rather than making data members protected in
RegionServer and for making HStore, etc., subclassable.
Otherwise, the patch looks great.
> 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
> Attachments: hbase-605-v2.patch, hbase-605.patch
>
>
> 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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