A query tree is a tree structure that corresponds to a query by having zero input operators (e.g. GET) as leaf nodes of the tree (representing the access of a stored relation) and arity one or more operators as internal nodes. An evaluation of the query tree consists of evaluating an internal node operation whenever its operands are available and the replacing that internal node by the table that results from evaluating the operation. The evaluation terminates when the root node is evaluated and replaced by the table that is the result of the query.
|3. Fundamental Concepts:||
3.1: EQJOIN 3.2a: Query Tree 3.2b: Equiv. 3.3a: Init Memo 3.3b: Memo 3.3c: Key 3.4: Complexity 3.5: Phys Memo 3.6: Plan 3.7: Pred. 3.8: Op Types 3.9: Rule