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From "Arina Ielchiieva (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-5538) Exclude ProjectRemoveRule during PHYSICAL phase if it comes from storage plugins
Date Wed, 31 May 2017 09:51:04 GMT

    [ https://issues.apache.org/jira/browse/DRILL-5538?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16030914#comment-16030914
] 

Arina Ielchiieva commented on DRILL-5538:
-----------------------------------------

Sure, I am contacting Calcite team to find out details about ProjectRemoveRule possible bug.
I'll write back once I get more information.

> 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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