In hash partitioning, Adaptive Server uses a hash function to specify the partition assignment for each row. You select the partitioning key columns, but Adaptive Server chooses the hash function that controls the partition assignment.
Hash partitioning is a good choice for:
Large tables with many partitions, particularly in decision-support environments
Efficient equality searches on hash key columns
Data with no particular order, for example, alphanumeric product code keys
If you choose an appropriate partition key, hash partitioning distributes data evenly across all partitions. However, if you choose an inappropriate key—for example, a key that has the same value for many rows—the result may be an unbalanced distribution of rows among the partitions.
