摘要:
A system and method for translating source code, comprising high level source code with embedded SQL statements, to p-code or machine-language instructions by a one-pass parsing mechanism. The one-pass parsing mechanism generates executable code without the need to generate an intermediate file. Additionally, the p-code or machine-language instructions are annotated with references to the line numbers of the corresponding source code, thereby allowing a source level debugger to debug the source code with embedded SQL statements.
摘要:
A system and method for translating source code, comprising high level source code with embedded SQL statements, to p-code or machine-language instructions by a one-pass parsing mechanism. The one-pass parsing mechanism generates executable code without the need to generate an intermediate file. Additionally, the p-code or machine-language instructions are annotated with references to the line numbers of the corresponding source code, thereby allowing a source level debugger to debug the source code with embedded SQL statements.
摘要:
A system and method for passing arrays and structures as host variables to a stored procedure. An application program packs an array or structure into a binary large object (BLOB) and sends the BLOB to a database management system. An adapter called by the database management system, and coupled to the stored procedure, passes a reference to the data area in the BLOB to the stored procedure. After completion of the stored procedure, the BLOB is returned to the application program. Finally, upon the return from the stored procedure call, the application program unpacks the BLOB back into the array or structure.
摘要:
An optimization technique that reorders outerjoins and antijoins with inner joins in a bottom-up optimizer of a relational database management system (RDBMS). Each join predicate is associated with a normal eligibility list (NEL) that includes tables that are referenced in the join predicate and an extended eligibility list (EEL) that includes additional tables that are referenced in conflicting join predicates. An EEL includes all the tables needed by a predicate to preserve the semantics of the original query. During join enumeration, the optimizer determines whether a join predicate's EEL is a subset of all the tables in two subplans to be merged, i.e., whose EEL is covered. If so, the two subplans are combined using the join predicate. Otherwise, the two subplans cannot be joined. Two approaches are used to reordering: without compensation and with compensation. The “without compensation” approach only allows join reorderings that are valid under associative rules. Thus, the optimizer will not combine subplans using a join predicate whose EEL is not covered. The “with compensation” approach allows two subplans to be combined using the join predicate, when a join predicate's EEL is not covered, as long as the join predicate's NEL is covered. Compensation is performed through nullification and best match. Multiple compensations may be merged and performed at any time.
摘要:
A system, method, and article of manufacture for supporting summary tables in a distributed database environment is disclosed. The system generally comprises a central program and a plurality of remote database systems that may be heterogeneous. The central program is configured to communicate with the database systems and to support summary tables (also referred to as materialized views) within the central program or within one or more of the database systems. The summary tables may contain summary data from one or more of the database systems. The central program may initiate the generation of summary tables, which may be populated local to the central program or local to one or more of the database systems. The central program may also maintain or coordinate maintenance of the summary tables. In addition, the central program may be configured to receive user queries on one or more of the database systems and to generate optimized query plans based upon the user queries, considering in so doing, the summary tables.
摘要:
Query evaluation is optimized using parallel optimization techniques to make repartitioning more efficient. Efficiency is improved by recognizing the possible partitioning requirements for achieving parallelism for a query operation, and by recognizing when the partitioning property of data satisfies the partitioning requirements of a query operation. A data base management system in accordance with the invention uses parallel query processing techniques to optimize data repartitioning, or to avoid it altogether.
摘要:
An automated methodology, and an apparatus for practicing the methodology, which enables the power and flexibility inherent in shared nothing parallel database systems (MPP) to be utilized on complex queries which have, heretofore, contained query elements requiring local computation or local coordination of data computation performed across the nodes of the distributed system. The present invention provides these features and advantages by identifying and marking the subgraphs containing these types of query elements as "no TQ zones" in the preparation phase prior to optimization. When the optimizer sees the markings, it builds a plan that will force the computation of the marked subgraphs to be in the same section. This preparation phase also provides the partitioning information for all inputs to the "no TQ zones". This allows the bottom-up optimizer to correctly plan the partitioning for the "no TQ zones". These partitionings can force the operation to a single-node, the coordinator node, the catalog node, or to a particular partition class on multiple nodes, or nodegroups.
摘要:
Method for specifying SQL "full outer joins" which enables the use of arbitrary join conditions in specifying the query. This is enabled by equating a full outer join with a left outer join unioned with a right outer join less the matched tuples from the right outer join. A number of embodiments further present improvements in execution speed. One such improvement utilizes as a second operand of the union query a novel operator, the "ANTI-JOIN". The anti-join is implemented as a right outer join coupled with an ISNULL predicate.
摘要:
A system, method and computer program product for executing a query on linked data sources. Embodiments of the invention generate an instance graph expressing relationships between objects in the linked data sources and receive a query including at least first and second search terms. The first search term is then executed on the instance graph and a summary graph is generated using the results of the executing step. A second search term is then executed on the summary graph.
摘要:
According to one embodiment of the present invention, a method for processing join predicates in full-text indexes is provided. The method includes evaluating local predicates of an outer full text index to generate a first posting list of documents. For each document in the first posting list, the value of a join attribute is determined and an inner full text index is probed to obtain a second posting list of documents containing one of the join attributes determined for each document. Local predicates of an inner full text index are evaluated to generate a third posting list of documents, and the second posting list is merged with the third posting list to generate a merge list of documents. Documents in the first posting list may be paired up with documents in the merge list.