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From "Arina Ielchiieva (JIRA)" <j...@apache.org>
Subject [jira] [Created] (DRILL-5538) Exclude ProjectRemoveRule during PHYSICAL phase if it comes from storage plugins
Date Thu, 25 May 2017 11:31:04 GMT
Arina Ielchiieva created DRILL-5538:
---------------------------------------

             Summary: Exclude ProjectRemoveRule during PHYSICAL phase if it comes from storage
plugins
                 Key: DRILL-5538
                 URL: https://issues.apache.org/jira/browse/DRILL-5538
             Project: Apache Drill
          Issue Type: Bug
          Components: Query Planning & Optimization
    Affects Versions: 1.10.0
            Reporter: Arina Ielchiieva
            Assignee: Arina Ielchiieva


When [RDBMS storage plugin|https://drill.apache.org/docs/rdbms-storage-plugin/]  is enabled,
during query execution certain JDBC rules are added.
One of the rules is [ProjectRemoveRule|https://github.com/apache/drill/blob/master/contrib/storage-jdbc/src/main/java/org/apache/drill/exec/store/jdbc/JdbcStoragePlugin.java#L140].
Drill also uses this rule but during phases when it considers it useful, for example, during
LOGICAL and JOIN_PLANNING. On the contrary, storage plugin rules are added to any phase of
query planning. Thus it results to project stage to be removed when actually it is needed.

Sometimes when ProjectRemoveRule decides that project is trivial and removes it, during this
stage Drill added column alias or removed implicit columns.

For example, with RDBMS plugin enabled, alias is not displayed for simple query:
{noformat}
0: jdbc:drill:zk=local> create temporary table t as select * from sys.version;
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
+-----------+----------------------------+
| Fragment  | Number of records written  |
+-----------+----------------------------+
| 0_0       | 1                          |
+-----------+----------------------------+
1 row selected (0.623 seconds)
0: jdbc:drill:zk=local> select version as current_version from t;
+------------------+
|     version      |
+------------------+
| 1.11.0-SNAPSHOT  |
+------------------+
1 row selected (0.28 seconds)
{noformat}

Proposed fix is to exclude ProjectRemoveRule during PHYSICAL phase if it comes from storage
plugins to prevent Drill losing column alias or displaying implicit columns.



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