Abstract: A relational data base management system includes a query processor that permits consideration of alternative query plans by the query optimizer so one table can be sent to a selected network location for subquery evaluation in consideration of maximum processing efficiency. Subqueries are converted from "predicate push-down" form to scalar subqueries, enabling upper tables to be sent to nodes of lower tables and vice versa, thereby permitting selection of the node direction depending on the least cost alternative. The optimizer of the query processor is presented with rewritten query code that permits more than one alternative for sending tables for evaluation. The optimizer evaluates the alternatives permitted by the rewritten code, determines the optimal plan for each alternative, and selects the least-cost plan from among the plans evaluated.

Abstract: 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.

Abstract: A relational database management system (RDBMS) efficiently evaluates correlated subqueries by decorrelating them and taking care of the so-called SQL count bug and yet avoid using the expensive outer join operation. When there is no tuple match from a correlated subquery, the RDBMS query processor returns a tuple of null(s) from a scalar derived table, and then uses COALESCE function to generate a proper count value of zero from the null. The correlation level remains one. The query processor also performs a pass-through optimization to eliminate a join operation for floating SELECT operation by removing a join operation involving the magic operation, so that the correlation bindings are received from the correlation source table rather than the magic operation.

Abstract: A method of performing a parallel join operation on a pair of relations R1 and R2 in a system containing P processors organized into Q clusters of P/Q processors each. The system contains disk storage for each cluster, shared by the processors of that cluster, together with a shared intermediate memory (SIM) accessible by all processors. The relations R1 and R2 to be joined are first sorted on the join column. The underlying domain of the join column is then partitioned into P ranges of equal size. Each range is further divided into M subranges of progressively decreasing size to create MP tasks T.sub.m,p, the subranges of a given range being so sized relative to one another that the estimated completion time for task T.sub.m,p is a predetermined fraction that of task T.sub.m-1,p. Tasks T.sub.

Abstract: 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.

Abstract: In a relational database management system (RDMS), a method and system for constraint checking of bulk data after storage in a base table. This invention generates a "dummy" INSERT inquiry to cause the compiler constraint rule engine to generate code for checking for constraint violations. After construction of a Query Graph Model by the compiler, a logic module replaces the INSERT inquiry with a SELECT inquiry to create code that when executed will select records from the bulk data table. Constraint violations are handled in several ways by this invention, including merely reporting that a constraint error exists or listing those records that violate constraint conditions. The logic also enforces referential integrity constraints by applying the SQL CASCADE command to the violating records to expand the violation list to include children records that would be orphaned when their parent records are later removed.