PPT Slide
Predicate Migration Algorithm
- Reordering of join nodes are not allowed
- Each stream remain semantically correct
1) Push all predicates down as far as possible.
2) Traverse stream from top to bottom finding modules.
S is a set of nodes. S’ Í S n Î S - S’ and n has a constraint relationshipwith all nodes in S’
3) For each module, order nodes optimally and define constraints.
4) Find ill-ordered adjacent groups and merge them.