There's more...

Here are some effects of skew PI:

• Running out of space on a database: Database space is equally distributed across all AMPs on a Teradata system. If your database runs out of space, it could be out of space on just one AMP because of a skewed table. 
• Running out of spool: At runtime, if data is skewed on a join, one of the AMPs can run out of space, causing the query to fail.
• High runtime: Skew queries tend to run more, as one of the AMPs works more than the other.