Federation variables

You use federation variables to control the default behavior of federation nicknames.

DB2_FEDERATION_OVERRIDES

Operating system: All
Default: NULL. Values: Keywords=ON|OFF
Controls how the federation optimizer manages pushdown analysis. The variable supports the following keywords:
- CSE_PUSHDOWN: When set to ON, the pushdown of a common table expression (CTE) clause to a remote data source is enabled. The default value is ON.
- CSE_PUSHDOWN_DRDA: When set to ON, the pushdown of a common table expression (CTE) clause to a remote Distributed Relational Database Architecture (DRDA) data source is enabled. The default value is ON.
- CSE_PUSHDOWN_ORACLE: When set to ON, the pushdown of a common table expression (CTE) clause to an Oracle remote data source is enabled. The default value is ON.
- HSJN_PUSHDOWN: When set to ON, the pushdown of a hash join to a remote data source is enabled. The default value is ON.
- EN_MAX_SEL_SIZE: When set to ON, the server option db2_max_sel_size is checked and the assigned value validated. The default value is OFF.
  Example
  The following example shows the command syntax used by a customer who does not want to pushdown both the CSE clause and hash join to a remote data source.
```
db2set DB2_FEDERATION_OVERRIDES="CSE_PUSHDOWN_DRDA=OFF,HSJN_PUSHDOWN=OFF" 
```