Check query execution

You can determine if query vectorization occurred during execution by running the EXPLAIN VECTORIZATION query statement.

1. Start Hive from Beeline.

   $ hive

2. Set hive.explain.user to false to see vector values.

   SET hive.explain.user=false;

3. Run the EXPLAIN VECTORIZATION statement on the query you want CDP to process using vectorization.

   EXPLAIN VECTORIZATION SELECT COUNT(*) FROM employees where emp_no>10;

   The following output confirms that vectorization occurs:

   +----------------------------------------------------+
   |                      Explain                       |
   +----------------------------------------------------+
   | Plan optimized by CBO.                             |
   |                                                    |
   | Vertex dependency in root stage                    |
   | Reducer 2 <-Map 1 [CUSTOM_SIMPLE_EDGE] *vectorized*|
   |       File Output Operator [FS_14]                 |
   |         Group By Operator [GBY_13] (rows=1 width=12) |
   |           Output:["_col0"],aggregations:["count(VALUE._col0)"] |
   |         <-Map 1 [CUSTOM_SIMPLE_EDGE] vectorized    | 
   |           PARTITION_ONLY_SHUFFLE [RS_12]           |
   |             Group By Operator [GBY_11] (rows=1 width=12) |
   |               Output:["_col0"],aggregations:["count()"] |
   |               Select Operator [SEL_10] (rows=1 width=4) |
   |                 Filter Operator [FIL_9] (rows=1 width=4) |
   |                   predicate:(emp_no > 10)          |
   |                   TableScan [TS_0] (rows=1 width=4) |
   |                     default@employees,employees,Tbl:COMPLETE,Col:NONE,Output:["emp_no"] |
   |                                                    |
   +----------------------------------------------------+
   23 rows selected (1.542 seconds)