Oracle Partition Pruning: Mechanics, Gotchas, and VLDB Design Patterns
Partition pruning is the optimizer’s ability to eliminate partitions from a query’s access path based on predicate analysis. When it works, a query against a 10 TB table might access only 50 GB of relevant partitions. When it fails, you get a full table scan across every partition — often with no visible indication in the execution plan that pruning is not occurring. How Partition Pruning Works The optimizer evaluates predicates in the WHERE clause against the partition key definition during the parse phase. If a predicate can be resolved to a specific partition range, those partitions are excluded from the access path. ...