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From "Aman Sinha (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-1500) Partition filtering might lead to an unnecessary column in the result set.
Date Sun, 11 Jan 2015 03:47:34 GMT

    [ https://issues.apache.org/jira/browse/DRILL-1500?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14272794#comment-14272794
] 

Aman Sinha commented on DRILL-1500:
-----------------------------------

This is not related to partition filters.  I can repro the extra column even with the query
below which does not involve partition columns.  I believe this has to do with how we handle
the '*' column in the planning and/or execution phase.  In planning phase, if a Project above
Scan is producing both * and another column, we should remove that column since the * column
subsumes all columns. In execution phase, there's a known issue with duplicates (DRILL-1778)
which seems related to this. 

{sql}
// Wrong number of columns
 jdbc:drill:zk=local> select * from cp.`tpch/nation.parquet` where n_nationkey < 2 order
by n_regionkey;
+-------------+------------+-------------+------------+--------------+
| n_nationkey |   n_name   | n_regionkey | n_comment  | n_regionkey0 |
+-------------+------------+-------------+------------+--------------+
| 0           | ALGERIA    | 0           |  haggle. carefully final deposits detect slyly
agai | 0            |
| 1           | ARGENTINA  | 1           | al foxes promise slyly according to the regular
accounts. bold requests alon | 1            |
+-------------+------------+-------------+------------+--------------+
{sql}


> Partition filtering might lead to an unnecessary column in the result set. 
> ---------------------------------------------------------------------------
>
>                 Key: DRILL-1500
>                 URL: https://issues.apache.org/jira/browse/DRILL-1500
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Query Planning & Optimization
>            Reporter: Jinfeng Ni
>            Assignee: Aman Sinha
>            Priority: Critical
>             Fix For: 0.8.0
>
>
> When partition filtering is used together with select * query, Drill might return the
partitioning column duplicately. 
> Q1 : 
> {code}
> select * from dfs.`/Users/jni/work/incubator-drill/exec/java-exec/src/test/resources/multilevel/parquet`
where dir0=1994 and dir1='Q1' order by dir0 limit 1;
> +------------+------------+------------+------------+------------+------------+-------------+------------+-----------------+---------------+----------------+--------------+
> |   dir00    |    dir0    |    dir1    |  o_clerk   | o_comment  | o_custkey  | o_orderdate
| o_orderkey | o_orderpriority | o_orderstatus | o_shippriority | o_totalprice |
> +------------+------------+------------+------------+------------+------------+-------------+------------+-----------------+---------------+----------------+--------------+
> | 1994       | 1994       | Q1         | Clerk#000000743 | y pending requests integrate
| 1292       | 1994-01-20  | 66         | 5-LOW           | F             | 0            
 | 104190.66    |
> +------------+------------+------------+------------+------------+------------+-------------+------------+-----------------+---------------+----------------+--------------+
> 1 row selected (2.097 seconds)
> {code}
> We can see that column "dir0" appeared twice in the result set.  In comparison, here
is the query without partition filtering and the query result:
> Q2:
> {code}
> select * from dfs.`/Users/jni/work/incubator-drill/exec/java-exec/src/test/resources/multilevel/parquet`
order by dir0 limit 1;
> +------------+------------+------------+------------+------------+-------------+------------+-----------------+---------------+----------------+--------------+
> |    dir0    |    dir1    |  o_clerk   | o_comment  | o_custkey  | o_orderdate | o_orderkey
| o_orderpriority | o_orderstatus | o_shippriority | o_totalprice |
> +------------+------------+------------+------------+------------+-------------+------------+-----------------+---------------+----------------+--------------+
> | 1994       | Q1         | Clerk#000000743 | y pending requests integrate | 1292   
   | 1994-01-20  | 66         | 5-LOW           | F             | 0              | 104190.66
   |
> +------------+------------+------------+------------+------------+-------------+------------+-----------------+---------------+----------------+--------------+
> 1 row selected (0.761 seconds)
> {code}



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