Consider the following factors about global space accounting:
- Teradata recommends global space accounting for a database or user when space use is expected to be nonuniform. For example, when large data sets that may be skewed are loaded into the underlying tables or when the database or user has stored procedures or UDFs that record rows with object-specific data.
- AMP-level space accounting does not have the overhead of dynamic, need-based space allocation and is recommended when the database is uniformly distributed across all AMPs in the system or when the global limit is high enough to allow for variability in data distribution due to skew .
- An unlimited skew limit for spool space may not be a good option, because design issues or a lack of statistics may cause a request to use excessive spool on AMPs. A lower spool limit causes requests using excessive spool space to abort.
- To reduce the chance of space shortages causing aborted transactions, consider setting a higher value for the global soft limit if the system has long-running transactions that consume significant space.
- Skew limits cannot solve space problems, especially when actual use is close to the limits. If there is not enough space, increase the space limits instead of allowing more skew.