Help Center/ DataArts Fabric/ Developer Guide/ Performance Tuning/ SQL Tuning/ Configuring Optimizer Parameters
Updated on 2025-09-18 GMT+08:00
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Configuring Optimizer Parameters

This section introduces the key CN parameters affecting the DataArts Fabric SQL tuning performance. For detailed methods, refer to Viewing and Setting GUC Parameters.

Table 1 CN parameters

Parameter/Reference Value

Description

enable_nestloop=on

Specifies how the optimizer uses Nest Loop Join. If this parameter is set to on, the optimizer preferentially uses Nest Loop Join. If it is set to off, the optimizer preferentially uses other methods, if any.

NOTE:

To temporarily change the value of this parameter in the current database connection (that is, the current session), run the following SQL statement:

1
 
SET enable_nestloop to off;

By default, this parameter is set to on. Change the value as required. Generally, nested loop join has the poorest performance among the three JOIN methods (nested loop join, merge join, and hash join). You are advised to set this parameter to off.

enable_hashagg=on

Specifies whether to enable the optimizer's use of Hash-aggregation plan types.

enable_hashjoin=on

Specifies whether to enable the optimizer's use of Hash-join plan types.

rewrite_rule

Specifies whether the optimizer enables a specific rewriting rule.
Parent topic: SQL Tuning