When you select full or source pushdown optimization for a mapping that reads from or writes to Amazon Redshift, Data Integration analyzes the mapping from the source to the target or until it reaches a downstream transformation to determine whether to push down only partial or the entire mapping logic for processing to the database.
If all the transformations in the mapping are supported for pushdown optimization, the task pushes down the entire mapping logic to the database.
When a transformation is not supported in the mapping, the task partially pushes down the mapping logic to the point where the transformation is supported for pushdown optimization. Data Integration generates and executes a SELECT statement for the transformation logic that needs to be pushed down. Then, it reads the results of this SQL query and processes the remaining transformations in the mapping.