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From "Anil Gupta (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-7474) Endpoint Implementation to support Scans with Sorting of Rows based on column values(similar to "order by" clause of RDBMS)
Date Fri, 04 Jan 2013 07:40:12 GMT

    [ https://issues.apache.org/jira/browse/HBASE-7474?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13543677#comment-13543677

Anil Gupta commented on HBASE-7474:

Yes, goal of my implementation is to fetch the top N rows of a table sorted by one column
value when the startIndex is 0.

Anoop:How you handle the start index? I guess you have some UI which shows the results in
pages with page size as say 100. So how you are showing page 2,3 etc.
Anil: Yes, that is right. The sorting feature is pretty handy when HBase is used as Data Source
for a web service. We can achieve pagination based on non-rowkey attribute sorting with the
help of this.
In this implementation pageSize is per request basis. So, startIndex tells how many Top N
records to skip. 
For example if the request has startIndex as 31 and pageSize as 20. Then Top 30(startIndex-1)
records will be ignored and Top 31-50 records will be the output of the request.

Do you want me to add in the description that Top N query can be done by this? The jira alreadt
says "(similar to "order by" clause of RDBMS)". Is it ambiguous?

> Endpoint Implementation to support Scans with Sorting of Rows based on column values(similar
to "order by" clause of RDBMS)
> ---------------------------------------------------------------------------------------------------------------------------
>                 Key: HBASE-7474
>                 URL: https://issues.apache.org/jira/browse/HBASE-7474
>             Project: HBase
>          Issue Type: New Feature
>          Components: Coprocessors, Scanners
>    Affects Versions: 0.94.3
>            Reporter: Anil Gupta
>            Priority: Minor
>              Labels: coprocessors, scan, sort
>             Fix For: 0.94.5
>         Attachments: hbase-7474.patch, SortingEndpoint_high_level_flowchart.pdf
> Recently, i have developed an Endpoint which can sort the Results(rows) on the basis
of column values. This functionality is similar to "order by" clause of RDBMS. I will be submitting
this Patch for HBase0.94.3
> I am almost done with the initial development and testing of feature. But, i need to
write the JUnits for this. I will also try to make design doc.
> Thanks,
> Anil Gupta
> Software Engineer II, Intuit, inc

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