2.3.9 Using Views

HeatWave supports querying views. The table or tables upon which a view is created must be loaded in HeatWave. Queries executed on views are subject to the same offload prerequisites and limitations as queries executed on tables.

In the following example, a view is created on the orders table, described in Section 2.6, “Table Load and Query Example”. The example assumes the orders table is loaded in HeatWave.

mysql> CREATE VIEW v1 AS SELECT O_ORDERPRIORITY, O_ORDERDATE
          FROM orders;

To determine if a query executed on a view can be offloaded to HeatWave for execution, use EXPLAIN. If offload is supported, the Extra column of EXPLAIN output shows “Using secondary engine RAPID”, as in the following example:

mysql> EXPLAIN SELECT O_ORDERPRIORITY, COUNT(*) AS ORDER_COUNT
          FROM v1
          WHERE O_ORDERDATE >= DATE '1994-03-01'
          GROUP BY O_ORDERPRIORITY
          ORDER BY O_ORDERPRIORITY;
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: ORDERS
   partitions: NULL
         type: ALL
possible_keys: NULL
          key: NULL
      key_len: NULL
          ref: NULL
         rows: 1488248
     filtered: 33.32999801635742
        Extra: Using where; Using temporary; Using filesort; Using secondary engine RAPID