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From "Jinfeng Ni (JIRA)" <j...@apache.org>
Subject [jira] [Created] (DRILL-3246) Query planning support for partition by clause in Drill's CTAS statement
Date Wed, 03 Jun 2015 00:41:50 GMT
Jinfeng Ni created DRILL-3246:
---------------------------------

             Summary: Query planning support for partition by clause in Drill's CTAS statement
                 Key: DRILL-3246
                 URL: https://issues.apache.org/jira/browse/DRILL-3246
             Project: Apache Drill
          Issue Type: New Feature
          Components: Query Planning & Optimization
    Affects Versions: 1.0.0
            Reporter: Jinfeng Ni
            Assignee: Jinfeng Ni
             Fix For: 1.1.0


We are going to add "PARTITION BY" clause in Drill's CTAS statement. The "PARTITION BY" clause
will specify the list of columns out of the result table's column list that will be used to
partition the data.  

CREATE TABLE  table_name  [ (col_name, .... ) ]
[PARTITION BY (col_name, ...)]
AS SELECT_STATEMENT;

Semantics restriction for the PARTITION BY clause:
 -  All the columns in the PARTITION BY clause have to be in the table's column list, or the
SELECT_STATEMENT has a * column, when the base table in the SELECT_STATEMENT is schema-less.
 Otherwise, an query validation error would be raised.

 - When the partition column is resolved to * column in a schema-less query, this * column
could not be a result of join operation. This restriction is added, since for * out of join
operation, query planner would not know which table might produce this partition column. 

Example :

{code}
create table mytable1  partition by (r_regionkey) as 
  select r_regionkey, r_name from cp.`tpch/region.parquet`
{code}

{code}
create table mytable2  partition by (r_regionkey) as 
  select * from cp.`tpch/region.parquet`
{code}

{code}
create table mytable3  partition by (r_regionkey) as
  select r.r_regionkey, r.r_name, n.n_nationkey, n.n_name 
  from cp.`tpch/nation.parquet` n, cp.`tpch/region.parquet` r
  where n.n_regionkey = r.r_regionkey
{code}

Invalid case 1: Partition column is not in table's column list. 

{code}
create table mytable4  partition by (r_regionkey2) as 
  select r_regionkey, r_name from cp.`tpch/region.parquet`
{code}

Invalid case 2: Partition column is resolved to * out of a join operator.
{code}
create table mytable5  partition by (r_regionkey) as
  select * 
  from cp.`tpch/nation.parquet` n, cp.`tpch/region.parquet` r
  where n.n_regionkey = r.r_regionkey
{code}




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