3.1.1 CELL_OFFLOAD_PROCESSING

The CELL_OFFLOAD_PROCESSING initialization parameter enables SQL processing offload to Oracle Exadata Storage Server.

When the value of the parameter is set to TRUE, predicate evaluation can be offloaded to cells. The default value of the parameter is TRUE. If the parameter is set to FALSE at the session or system level, then the database performs all the predicate evaluation with cells serving blocks. You can set CELL_OFFLOAD_PROCESSING dynamically with the SQL ALTER SYSTEM or ALTER SESSION commands, for example:

SQL> ALTER SESSION SET CELL_OFFLOAD_PROCESSING = TRUE;

The CELL_OFFLOAD_PROCESSING parameter can also be set with the OPT_PARAM optimizer hint to enable or disable predicate filtering for a specific SQL command.

• To disable CELL_OFFLOAD_PROCESSING for a SQL command:

  SELECT /*+ OPT_PARAM('cell_offload_processing' 'false') */ COUNT(*) FROM EMPLOYEES;
  

• To enable CELL_OFFLOAD_PROCESSING for a SQL command:

  SELECT /*+ OPT_PARAM('cell_offload_processing' 'true') */ COUNT(*) FROM EMPLOYEES;
  

Note:

The CELL_OFFLOAD_PROCESSING initialization parameter cannot be used to compare the performance of Oracle Exadata Storage Server with conventional storage. Even when CELL_OFFLOAD_PROCESSING is set to FALSE, Oracle Exadata Storage Server has many advantages over conventional storage. Oracle Exadata Storage Server is highly optimized for fast processing of large queries. It has no bottlenecks at the controller or other levels inside the cell. Oracle Exadata uses a modern scale-out architecture and state-of-the-art RDMA Network Fabric that has much higher throughput than conventional storage networks. Oracle Exadata is tightly integrated with the Oracle Database, and has unique capabilities for setup, execution, monitoring, diagnostics, resource management, and corruption prevention.