摘要:
A method for typed view hierarchies for an object-relational database management (OPDBMS). The views in the hierarchy are merged into a unified hierarchy view through case expressions for mapping and wrapping of overloaded columns. During the merge, the underlying logical tables are eliminated which results in a simplified query graph. The transformation is a non-loss operation which condenses the type information within the case expressions. This allows update, delete and insert operations to be resolved on the query graph on a local level. Using query rewrite rules, the case expressions may be simplified further.
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 method, apparatus, and article of manufacture for an intelligent compiler. A query is executed in a computer to retrieve data from a relational database stored on a data storage device. The query contains a procedural function. The query is compiled to generate an internal representation of the procedural function. Then, the execution of the procedural function is optimized using the generated internal representation.
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.
摘要:
Provided is a system, method, and program for specifying multidimensional calculations. Selection of a subset of a cube model metadata object that is generated from a facts metadata object and one or more dimension metadata objects is received. The facts metadata object references one or more measure metadata objects. A statement is generated for retrieving multidimensional information using metadata in the cube model metadata object and the measure metadata objects, wherein each of the measure metadata objects specifies one or more aggregations.
摘要:
A local database cache enabling persistent, adaptive caching of either full or partial content of a remote database is provided. Content of tables comprising a local cache database is defined on per-table basis. A table is either: defined declaratively and populated in advance of query execution, or is determined dynamically and asynchronously populated on-demand during query execution. Based on a user input query originally issued against a remote DBMS and referential cache constraints between tables in a local database cache, a Janus query plan, comprising local, remote, and probe query portions is determined. A probe query portion of a Janus query plan is executed to determine whether up-to-date results can be delivered by the execution of a local query portion against a local database cache, or whether it is necessary to retrieve results from a remote database by executing a remote query portion of Janus query plan.
摘要:
A set of algebraic rules applicable to a query are identified, wherein each of the algebraic rules represents a relationship between two columns in a relational database table. A source column is identified by searching the query for a source predicate, wherein the source predicate is a range predicate. One or more candidate target columns are identified by searching the set of algebraic rules, wherein each of the candidate target columns occurs on one side of a binding expression and the source column occurs on the other side of the binding expression. For each of the one or more candidate target columns, a bounds subquery that provides a lower bound and an upper bound for a new range predicate is derived and he new range predicate is introduced into the query, wherein the query is executed to retrieve data from one or more data stores.
摘要:
A method for using pre-computed information stored in auxiliary structures to speed up processing of expensive queries on hierarchical documents such as XML documents being queried using XPath. The invention defines a taxonomy of such structures such as indexes and materialized views for storing pre-computed XPath results (PXRs), determines what portion of the query can be evaluated by the structures, and computes the compensation for the results generated by the structures. The invention detects all structures applicable to the query and rewrites the query to use such structures, speeding up the performance of the queries. The invention identifies the matching structures by detecting containment mappings between XPath expressions in the query and the structure. The invention also includes a new representation for XPath expressions that is rich enough to express all features of XPath.
摘要:
A system and method transform queries with subqueries, using window aggregation. An optimizer in a relational database management system transforms queries to optimize their efficiency and speed. The method transforms queries that have a subquery, replacing the subquery with a window aggregation function. In the case of a correlated subquery, the window aggregation function is partitioned by a correlated column of a correlated table. All data in the main select clause, or outer block, of the query that was obtained through references to the correlated table is instead obtained through the new window aggregation subquery. By using window aggregation, the aggregation is performed at the same time as the selection of relevant data from the correlated table, thereby compiling all needed data in a single pass through the table or view. Reducing the number of times that tables or views are accessed reduces the computational demands of a query.
摘要:
A reverse routing system optimizes execution of a query that accesses data stored in one or more materialized query tables in a database of a computer system. The system receives a query directly referencing the materialized query table. The system identifies the referenced materialized query tables in a catalogue of materialized query tables and a defining query associated with the referenced materialized query table. The system substitutes the defining query for the referenced materialized query table in the received query. The system adds the referenced materialized query table to the set of eligible materialized query tables that are selected using query matching algorithms so that they can be considered for routing by the query optimizer.