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https://issues.apache.org/jira/browse/DRILL-683?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Aditya Kishore updated DRILL-683:
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Attachment: DRILL-683-Qualify-HBase-scan-with-specified-columns-.patch
> Qualify HBase scan with specified columns even if row_key is required.
> ----------------------------------------------------------------------
>
> Key: DRILL-683
> URL: https://issues.apache.org/jira/browse/DRILL-683
> Project: Apache Drill
> Issue Type: Task
> Reporter: Aditya Kishore
> Assignee: Aditya Kishore
> Labels: documentaion, hbase
> Attachments:
> DRILL-683-Qualify-HBase-scan-with-specified-columns-.patch,
> DRILL-683-Qualify-HBase-scan-with-specified-columns-.patch
>
>
> Currently (as of
> https://github.com/apache/incubator-drill/commit/612527bd22c27aa92363d2297a9c2b4a05475fd0),
> if row_key is specified as one of the projected column in a query, we do not
> qualify the HBase scan with the specified cf\[:column qualifier].
> This is done because if we qualify the scan with the columns and for some
> rows if ALL of these columns do not exist (but other columns do, which means
> the row and hence the row_key exists), HBase will not return even the row key.
> For example, for the sample query:
> {{SELECT row_key, f\['c1'], f\['c7'] from hbase.MyTable;}}
> if there exists a row with following row.
> {noformat}
> row_key f['c2'] f['c3'] f['c6']
> ---------------------------------------------
> row1 val1 val2 val3
> {noformat}
> if we qualify the HBase scan with {{f\['c1'], f\['c7']}}, then the row =>
> {{row1}} will get dropped from the scan result.
> However, not qualifying the scan would have severe impact on scan performance.
> Hence we propose the behavior that at if NONE of the specified columns in the
> query are present in a row, the entire row will be omitted from the scan
> result.
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