Your user applications should be scalable.
For example, assume that table BigT is a very large table but its rows are hash distributed based on only 16 unique values. Applications using BigT perform well and with high parallelism on a system with 1 or 2 nodes and 8 to 16 AMPs.
If you then expand the system to 128 AMPs, the rows of BigT still hash to only 16 unique values, and so are still distributed among only 16 AMPs. Thus, applications do not perform any better, and perhaps not as well.
To ensure scalability of your applications, try to make your PI a unique or nearly unique index. If a single column does not provide uniqueness, combine two or more columns to make up the index. You can define up to 64 columns per PI.
The result is many more unique hash combinations, and your applications should continue to perform well as your system expands.