Abstract: A method for performing disjunctive single-index access on a database is disclosed. The method includes a query engine determining whether a first OR predicate and a second OR predicate map to a shared index. Responsive to the query engine determining that the first OR predicate and the second OR predicate map to the shared index, the first OR predicate and the second OR predicate are ordered in an ascending sequence. A first range of the first OR predicate is queued. A first row of the shared index is probed for the first range of the first OR predicate. Whether the first row is disqualified by the first OR predicate is determined. Responsive to determining that the first row is not disqualified by the first OR predicate, the row is reported in a result reporting structure.

Abstract: An apparatus, system, and method are disclosed for ensuring query execution plan stability in a database management system. The present invention binds a static database query to a new query execution plan (QEP) that produces the same result set as an original QEP bound to the static database query. Next, the present invention identifies one of the original QEP and the new QEP as a primary QEP and automatically collects execution statistics for the original QEP and the new QEP. Finally, the present invention automatically selects one of the original QEP and the new QEP as the primary QEP in response to completion of the automatic collection of execution statistics, the primary QEP selected such that the automatically selected QEP provides optimal execution performance based on performance criteria in comparison to the automatically unselected QEP, the primary QEP selected based on the execution statistics.

Abstract: A method and system for Extensible Markup Language (XML) schema validation, includes: loading an XML document into a runtime validation engine, where the runtime validation engine includes an XML schema validation parser; loading an annotated automaton encoding (AAE) for an XML schema definition into the XML schema validation parser; and validating the XML document against the XML schema definition by the XML schema validation parser utilizing the annotated automaton encoding. Each XML schema definition is compiled once into the AAE format, rather than being compiled each time an XML document is validated, and thus significant time is saved. The code for the runtime validation engine is fixed and does not vary depending on the XML schema definition, rather than varying for each XML schema definition, and thus space overhead is minimized. Flexibility in the validation process is provided without compromising performance.

Abstract: A method for executing a query to access data stored in a database, wherein the query includes a plurality of DISTINCT keys, is disclosed. The method of the present invention includes providing a first DISTINCT operation on a first DISTINCT key, storing data fetched from the first DISTINCT operation in a master workfile if more than one sort process is needed to execute the query, and utilizing the master workfile to perform subsequent DISTINCT operations for the other DISTINCT keys.

Abstract: Disclosed is a technique for maintaining statistics. A query is received. Column group generation is performed to form one or more column groups. Column group refinement is performed based on statistics data generated for a previously received query. A statistics check is automatically performed. A statistics collection command is generated to obtain statistics.

Abstract: Techniques are provided for processing a query using an index. It is determined whether a number of consecutive keys that evaluate to a false-positive when applying a screening predicate in the query exceeds a false-positive predefined value. One or more keys in the index are skipped in response to determining that the number of consecutive keys exceeds the false-positive predefined value.

Abstract: A system and computer readable medium for executing a query to access data stored in a database, wherein the query includes a plurality of DISTINCT keys, is disclosed. The system and computer readable medium includes a capture module for identifying each of the plurality of DISTINCT keys in the query and a sort module coupled to the capture module for determining if more than one sort is needed to execute the query, performing a first DISTINCT operation on a first DISTINCT key of the plurality of DISTINCT keys, storing data fetched from the first DISTINCT operation in a master workfile only if more than one sort process is needed to execute the query, and utilizing the master workfile to perform subsequent DISTINCT operations on the other of the plurality of DISTINCT keys.

Abstract: Disclosed is a technique for maintaining statistics. A query is received. Column group generation is performed to form one or more column groups. Column group refinement is performed based on statistics data generated for a previously received query. A statistics check is automatically performed. A statistics collection command is generated to obtain statistics.

Abstract: A method and system for managing a computer system are described. The method and system include defining and storing a policy using a policy manager. In one aspect, the policy manager also activates and resolves conflicts between policies. The policy is a declarative statement of a directive to be carried out by the computer system. The method and system also include using a policy executor to determine whether a request to the computer system is covered by the policy. The method and system further include utilizing the computer system to carry out the directive for the policy if the request is covered by the policy through a policy enforcer.

Abstract: The present invention provides a method and an apparatus for aggregating database runtime information and analyzing application performance. According to one aspect of the present invention, there is provided a method for aggregating database runtime information, comprising: aggregating said database runtime information based on queries; and aggregating, based on objects, said database runtime information that is aggregated based on queries.

Abstract: The application relates to a tool and a method for customizing hint. According to the invention, provided is at least one hint service adapter configured to collect relevant information of different database platforms, validate customized hint on real database platforms and provide feedback, and deploy the customized hint on database platform. Also provided is hint defining means configured to customize hint independently of database platforms, and providing customized hint to the at least one hint service adapter.

Abstract: A method, computer program product, and system for managing row identifier (RID) list processing on an index are provided. The method, computer program product, and system provide for accessing one or more key values in the index based on one or more keys specified in a query, retrieving a plurality of row identifiers corresponding to the one or more key values from the index, and predicting an actual number of row identifiers to be retrieved from the index based on the one or more key values accessed and the plurality of row identifiers retrieved.

Abstract: In various embodiments, a method, apparatus, and article of manufacture collect statistics in a database management system. A workload comprising a plurality of database queries is received. Query statistics for the database queries are identified. The query statistics for the database queries are consolidated to provide consolidated statistics. One or more statistics collection requests are generated based on the consolidated statistics.

Abstract: In various embodiments, a method, apparatus, and article of manufacture collect statistics in a database management system. A workload comprising a plurality of database queries is received. Query statistics for the database queries are identified. The query statistics for the database queries are consolidated to provide consolidated statistics. One or more statistics collection requests are generated based on the consolidated statistics.

Abstract: A partial index availability system places, in a restricted state, all pages in the index associated with a structure modification, when an error occurs in processing a log of the said structure modification. This maintains traversability of the rest of the index that is not in restricted state. The system locates and marks a left sentinel and a right sentinel associated with a non-leaf page that is in a restricted state preventing an undo of a transaction. The sentinels prevent a transaction from accessing an uncommitted change associated with the non-leaf page. After a recovery procedure is run the entire index is made available. During the period between the placement of the index pages in LPL or rebuild pending to the time of final removal of these pages from their restrictive states as a result of a recovery procedure being run, the users are given access to the non-restricted portion of the index.

Abstract: A method, computer program product, and system for processing dynamic statements in a database system are provided. The method, computer program product, and system provide for calculating a first set of characteristics associated with a dynamic statement when the dynamic statement matches one of a plurality of dynamic statements previously processed by the system, comparing the first set of characteristics associated with the dynamic statement to a second set of characteristics associated with one of one or more access paths generated for the one previously processed dynamic statement, and utilizing the one access path to execute the dynamic statement when the comparison of the first set of characteristics to the second set of characteristics satisfies one or more predetermined criteria.

Abstract: Techniques are provided for tuning work. In response to identifying a trigger for a work, automatic tuning is invoked. The trigger indicates that a performance goal for the work has been missed. The work is analyzed. A tuning operation is selected for the work based on a tuning history. The selected tuning operation is implemented for the work.

Abstract: Various embodiments of a computer-implemented method, system and article of manufacture maintain a logical page having a predetermined size. Data is added to an uncompressed area of the logical page. The uncompressed area of the logical page is associated with an uncompressed area of a physical page. The logical page also has a compressed area associated with a compressed area of a physical page. In response to exhausting the uncompressed area, data in the uncompressed area is included in the compressed area. The uncompressed area is adjusted.

Abstract: Provided are a techniques for processing a query including semi-joins. At execution time, a next semi-join is selected from the semi-joins for execution in a current round of semi-join executions. A reporting threshold is determined that indicates a number of record-identifiers to be retrieved for the determined semi-join. The selected semi-join is executed until the determined number of record identifiers are retrieved.

Abstract: Techniques are provided for processing a query using an index. It is determined whether a number of consecutive keys that evaluate to a false-positive when applying a screening predicate in the query exceeds a false-positive predefined value. One or more keys in the index are skipped in response to determining that the number of consecutive keys exceeds the false-positive predefined value.