You can push down a custom query or an SQL override to Amazon Redshift.
Before you run a task that contains a custom query as the source object or you configure an SQL override, you must set the
Create Temporary View
session property in the mapping task properties.
If you do not set the
Create Temporary View
property, the mapping runs without pushdown optimization.
Perform the following task to set the property:
In the mapping task, navigate to the
Advanced Session Properties
on the
Schedule
tab.
From the
Session Property Name
list, select
Create Temporary View
and set the
Session Property Value
to
Yes
.
Click
Finish
.
Mappings enabled for pushdown optimization has the following restrictions for sources:
When you select an Amazon Redshift ODBC connection as source and select an external table as a source object, the data preview fails.
You must include all the unique column fields in the SQL query.
When you use a custom query or an SQL override in a Source transformation, you must have the permissions to access and perform operations in the Amazon Redshift source and target tables.
When you configure an SQL override, make sure that you include all the connected fields in the SQL query.