In a                    the system makes repeated requests for tuples from the operation at the top of the pipeline.

Related MCQs

• Which one of the following provides the ability to query information from the database and to insert tuples into, delete tuples from, and modify tuples in the database?
• In a                            operations do not wait for requests to produce tuples, but instead generate the tuples eagerly.
• A                  on an attribute of a relation is a data structure that allows the database system to find those tuples in the relation that have a specified value for that attribute efficiently, without scanning through all the tuples of the relation.
• Suppose now that R(A,B:) and S(A,B:) are two relations with r and s tuples, respectively (again, not necessarily distinct). If m is the number of (not necessarily distinct) tuples in the result of the SQL query: R intersect S; Then which of the following is the most restrictive, correct condition on the value of m?
• The iterator maintains the                      of its execution in between calls so that successive next() requests receive successive result tuples.
• The           operation allows the combining of two relations by merging pairs of tuples, one from each relation, into a single tuple.
• The result which operation contains all pairs of tuples from the two relations, regardless of whether their attribute values match.
• The                        operation, denoted by −, allows us to find tuples that are in one relation but are not in another.
• The ___________ operation, denoted by −, allows us to find tuples that are in one relation but are not in another.
• Each operation in a demand-driven pipeline can be implemented as an          that provides the following functions: open(), next(), and close().