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Posted to issues@drill.apache.org by "salim achouche (JIRA)" <ji...@apache.org> on 2018/01/22 19:14:00 UTC

[jira] [Created] (DRILL-6101) Optimize Implicit Columns Processing

salim achouche created DRILL-6101:
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             Summary: Optimize Implicit Columns Processing
                 Key: DRILL-6101
                 URL: https://issues.apache.org/jira/browse/DRILL-6101
             Project: Apache Drill
          Issue Type: Improvement
          Components: Execution - Relational Operators
            Reporter: salim achouche
            Assignee: salim achouche


Problem Description -
 * Apache Drill allows users to specify columns even for SELECT STAR queries
 * From my discussion with [~paul-rogers], Apache Calcite has a limitation where the, extra columns are not provided
 * The workaround has been to always include all implicit columns for SELECT STAR queries
 * Unfortunately, the current implementation is very inefficient as implicit column values get duplicated; this leads to substantial performance degradation when the number of rows are large

Suggested Optimization -
 * The NullableVarChar vector should be enhanced to efficiently store duplicate values
 * This will not only address the current Calcite limitations (for SELECT STAR queries) but also optimize all queries with implicit columns

 



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