1. A computer-implemented method comprising: receiving a normalized query tree; dividing the normalized query tree into regions of multiple join backbones that refer to multi-way joins between two or more relational expressions; analyzing the regions of the normalized query tree to collect information about: join operators and their children, and tables in an associated query; and making said information available to a rule based optimizer that produces, from the normalized query tree, an execution plan that visits only parts of a search space rather than using a pruning technique to reduce the search space.