[teiid-issues] [JBoss JIRA] (TEIID-3957) Impala translator - Add pushdown of offset in LIMIT clause to overcome difference in LIMIT clause

[Don Krapohl (JIRA)]

Don Krapohl created TEIID-3957:
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             Summary: Impala translator - Add pushdown of offset in LIMIT clause to overcome difference in LIMIT clause
                 Key: TEIID-3957
                 URL: https://issues.jboss.org/browse/TEIID-3957
             Project: Teiid
          Issue Type: Bug
          Components: JDBC Connector
    Affects Versions: 8.12.4
         Environment: Ubuntu Trusty
            Reporter: Don Krapohl
            Assignee: Steven Hawkins
            Priority: Minor


With the impala translator we issue this LIMIT to Teiid:
ORDER BY somecolumn DESC LIMIT 75, 25
this means give me 25 rows starting from *ROW* 76.

In Impala's SQL this should be translated to:
ORDER BY somecolumn DESC LIMIT 25 OFFSET 75
BUT this means give me 25 rows starting from *PAGE * 76 (with page size of 25 rows)

ref: http://www.cloudera.com/documentation/archive/impala/2-x/2-1-x/topics/impala_offset.html

The Teiid Impala translator doesn't push the offset but sums the limit and offset:
ORDER BY somecolumn DESC LIMIT 100

Request we add pushdown, which will be more efficient and overcome the difference in how offsets are handled between Impala and Teiid.



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