摘要:
A database system includes database software to receive a query specifying a join of plural base tables, and to determine whether a foreign key and primary key relationship exists between join columns specified by the query and a materialized view definition. Based on the existence of the foreign key and the primary key relationship between join columns specified by the query and the materialized view definition, the database software determines that a result for the received query is to be computed from the materialized view.
摘要:
A method and apparatus determines (1) if a materialized view can be used to respond to a query for data stored in one or more base tables of a database system; and/or (2) if the materialized view needs to be updated in response to an update query. A query expression tree represents the query, and a materialized view expression tree represents the materialized view. The components of the query expression tree are compared with components of the materialized view expression tree to determine if the materialized view covers the query that is, the tuples in the result of the query expression are a subset of the tuples in the result of the materialized view expression.
摘要:
A database system includes a storage to store a view containing results of a cube-based operation on at least one base table, with the view containing a first result set for a group-by on a first grouping set, and a second result set for a group-by on a second grouping set. In response to a change to the at least one base table, a controller updates the first result set by computing a change to the first result set based on a change in the at least one base table, and updates the second result set by computing a change to the second result set based on the change to the first result set.
摘要:
A non-blocking parallel spatial join algorithm generates the spatial join result tuples continuously even in the event of memory overflow. The algorithm employs duplicate avoidance techniques to avoid the blocking and time-consuming removal of duplicates. The algorithm also uses parallelism to improve performance.
摘要:
Auxiliary relations are used to maintain a materialized view. The materialized view comprises results of some operation performed between two or more base relations of a parallel database management system comprising a plurality of nodes. The two or more base relations are distributed to the nodes according to some partitioning strategy. Each auxiliary relation is partitioned according to the join attribute in the materialized view definition. During join or other operations involving the relations, the auxiliary relations, not the base relations, are used to construct join results and to maintain the materialized view.
摘要:
A database system receives a transaction that causes a tuple to be integrated into a join view. In response to receiving the transaction, a predefined first lock is placed on at least a portion of the join view, the predefined first lock conflicting with either a shared lock or an exclusive lock placed on the join view, but not conflicting with another predefined first lock placed on the join view. Also, a latch or semaphore associated with a value of a predetermined attribute of the tuple is obtained before integrating the tuple into the join view.
摘要:
A non-blocking parallel band join method and apparatus partitions tuples of two relations for localized processing. At each processing node, the tuples are further partitioned such that join operations may be performed efficiently, as tuples are received by the node during the partitioning.
摘要:
A database system is capable of processing a query and providing a progress indicator of the processing of the query based on at least a first cost factor. Initially, an estimate is set for the first cost factor. During processing of the query, the estimate of the first cost factor is updated to enable refinement of the progress indicator.
摘要:
Auxiliary relations are used to maintain a materialized view. The materialized view comprises results of some operation performed between two or more base relations of a parallel database management system comprising a plurality of nodes. The two or more base relations are distributed to the nodes according to some partitioning strategy. Each auxiliary relation is partitioned according to the join attribute in the materialized view definition. During join or other operations involving the relations, the auxiliary relations, not the base relations, are used to construct join results and to maintain the materialized view.
摘要:
A method or apparatus for use with a database system that stores a join view associated with plural base relations includes receiving modification operations to modify at least two of the base relations of the join view, and re-ordering the received modification operations to avoid concurrent execution of modification operations of more than one of at least two base relations.