Ncr Corporation

Oracle International Corporation

Chi Kim Hoang

Chih-Ping Wang

John William Miller

Nagender Bandi

James J Chen

Mark Anthony Hodgens

Grace Kwan On Au

Tirthankar Lahiri

Paul Laurence Sinclair

Ahmad Said Ghazal

Marie-Anne Neimat

Frederick Stuart Kaufmann

Fred S Kaufmann

Rolf G&uuml;nter Erich Stegelmann

Dilys Thomas

Susan Cheng

Rolf G E Stegelmann

Techniques are described for performing dependency locking to enable parallel execution of database server processes modifying the same object. In an embodiment, a DBMS receives a request to execute an operation on its managed database. The request may include an object identifier and a version identifier for a version of a database object, which is required for the successful execution of the operation on the database. The required version of the database object may not exist and may be generated only after the execution of another, second, operation on the database. The first database server process initiates execution of the earlier received operation on the database. The first database server process queries the first database for the version of the particular database object and determines that the version of the database object does not exist yet, in one embodiment. Based on such a determination, a dependency lock is generated for the version of the object, and the first database server process is suspended, preventing the completion of execution of the earlier received operation on the database. Another, second database server process executes another operation on the database and causes the generation of the version of the object on the database. The dependency lock is thereby released for the version of the object, and the first database server process completes the execution of the first operation on the first database.

Dependency locking

A plurality of mid-tier databases form a single, consistent cache grid for data in a one or more backend data sources, such as a database system. The mid-tier databases may be standard relational databases. Cache agents at each mid-tier database swap in data from the backend database as needed. Consistency in the cache grid is maintained by ownership locks. Cache agents prevent database operations that will modify cached data in a mid-tier database unless and until ownership of the cached data can be acquired for the mid-tier database. Cache groups define what backend data may be cached, as well as a general structure in which the backend data is to be cached. Metadata for cache groups is shared to ensure that data is cached in the same form throughout the entire grid. Ownership of cached data can then be tracked through a mapping of cached instances of data to particular mid-tier databases.

Distributed consistent grid of in-memory database caches

The retrieval of data from a database in a computerized database management system is optimized through the use of a plurality of join indexed. The join indexes are defined for a table stored in the database. The join indexes are updated to reflect any updated records stored in the table, wherein one or more common joins are identified among the join indexes, each of the common joins are materialized only once in a common spool file, and the common spool file is used to materialize one or more rows for updating the join indexes.

Common spool files for maintaining join indexes

The retrieval of data from a database in a computerized database management system is optimized through the use of an aggregate join index. The aggregate join index combines one or more commonly-used columns of the base tables with the results from one or more aggregation expressions pre-computed from one or more columns of the tables.

Aggregate join index for relational databases

The retrieval of data from a database in a computerized database management system is optimized through the use of a virtual join index and associated covering non-unique secondary indexes. The virtual join index is created by combining one or more commonly-used columns of one or more tables. The covering non-unique secondary indexes are generating by combining one or more commonly-used columns of the virtual join index. Data is not stored in the virtual join index after the covering non-unique secondary indexes are generated. Thereafter, some queries or portions thereof may be resolved solely by accessing one or more of the covering non-unique secondary indexes.

Virtual join index for relational databases

A method, apparatus, and article of manufacture for accessing a subject table in a computer system. The subject table is partitioned across a plurality of processing units of the computer system. A user query or other request to access the subject table is split into a plurality of step messages, wherein each of the step messages is assigned to one of the processing units managing one or more of the partitions of the subject table. A plurality of actions are identified for each of the step messages, and one or more necessary records for these actions are retrieved from the partition of the subject table and stored into a corresponding partition of a spool table. The necessary records are selected in such a manner that none of the actions involved in the request need to access the partition of the subject table. The actions from the step message are then performed against the partitions of the spool table rather than the partitions of the subject table. An optimizer function uses information from the spool table to generate more efficient execution plans for the step message and its associated actions.

Very large table reduction in parallel processing database systems

A method, apparatus, and article of manufacture for accessing a subject table in a computer system. The subject table is partitioned across a plurality of processing units of the computer system. A trigger is defined for the subject table, such that when a triggering event occurs on the subject table, a triggered action is performed. Both the triggering event and triggered action can be performed in parallel by the computer system. A spool table is generated for each partition of the subject table, wherein the spool table stores one or more necessary records accessed from the subject table by the triggering event. In this manner, triggered actions that refer to these necessary rows need not access the subject table again.

Parallel optimized triggers in parallel processing database systems

The retrieval of data from a computerized database is optimized through the use of a join index. A denormalized base table is converted into a plurality of normalized tables and the join index for the normalized tables is created by combining one or more commonly-used columns of the normalized tables. Outer joins are used to generate the join index, instead of inner joins, so that the join index satisfies queries with fewer join conditions than the ones used to generate the join index. Each row of the join index comprises a fixed part and a repeated part. The fixed part is stored only once in each row, but the repeated part is comprised of recursive levels within each row, so that each row may contain as many repeated parts as needed. In addition, each of the repeated parts comprises a fixed part and a repeated part.

Join index for relational databases

A method of optimizing a query and its subqueries together in a global manner regardless of the nesting levels. All joins in different nesting levels are effectively converted into joins in the same level by assigning a nesting level attribute to relations, assigning properties to the predicate, and assigning nesting level attributes and minimum relation set attributes to join predicate operands. The joins and their predicates are then considered as if they were contained in only the main query according to a set of rules based on the attributes of the relations and the join predicates.

Growing community of inventors

Palo Alto, CA, United States of America

Chi Kim Hoang