When you read data from Amazon Redshift, you can configure partitioning to optimize the mapping performance at run time. The partition type controls how the agent distributes data among partitions at partition points.
You can define the partition type as key range partitioning. Configure key range partitioning to partition Amazon Redshift data based on the value of a fields or set of fields. With key range partitioning, the Secure Agent distributes rows of source data based the fields that you define as partition keys. The Secure Agent compares the field value to the range values for each partition and sends rows to the appropriate partition.
Use key range partitioning for columns that have an even distribution of data values. Otherwise, the partitions might have unequal size. For example, a column might have 10 rows between key values 1 and 1000 and the column might have 999 rows between key values 1001 and 2000.
With key range partitioning, a query for one partition might return rows sooner than another partition. Or, one partition can return rows while the other partitions are not returning rows. This situation occurs when the rows in the table are in a similar order as the key range. One query might be reading and returning rows while the other queries are reading and filtering the same rows.
The recommended maximum number of partitions is 32. If you configure more than 32 partitions, the mapping task might fail with a memory buffer error.