Abstract: A method, computer program product and computing device for promoting reuse of previously generated access plans are disclosed. SQL statements containing literals are amended so as to substitute a parameter marker for each literal. Amended statements are provided to the DBMS along with parameters including the substituted literals and a substitution indicator indicating that the substitution has been performed. The DBMS assesses the soundness of the substitutions that are performed. Soundness may be measured in terms of the semantic correctness of the amended statement and the likelihood that the literal substitution will improve DBMS efficiency. If a substitution is unsound, the DBMS may obtain and optimize the original version of the amended SQL statement. Otherwise, the amended statement is optimized. Advantageously, SQL statements originally differing only in the value of one or more literals may become functionally equivalent, and the reuse of cached, previously generated access plans is thus promoted.

Abstract: A method, computer program product and computing device for promoting reuse of previously generated access plans in a relational DBMS are disclosed. SQL statements containing literals are amended so as to substitute a parameter marker for each literal. Amended statements are provided to the DBMS along with parameters comprising the substituted literals and a substitution indicator indicating that the substitution has been performed. The DBMS assesses the soundness of the substitutions that are performed. Soundness may be measured in terms of the semantic correctness of the amended statement and the likelihood that the literal substitution will improve DBMS efficiency. If a substitution is unsound, the DBMS may obtain and optimize (i.e. select an access plan for) the original version of the amended SQL statement. Otherwise, the amended statement is optimized.

Abstract: A method for externalizing database monitor information, and a database management system incorporating the method, which utilizes the database system's own data manipulation and retrieval system is disclosed. Monitor information is logically available in pseudotable form which may be accessed as any other data. However pseudotables do not actually exist; rather the result set is constructed when a request is made to select from a pseudotable. A predefined format for each pseudotables is stored in the database catalog tables and is used in constructing the tuples from existing internal data structures which are constantly updated with monitor data.

Abstract: A join optimizer and method for a relational database management system including a data processor, a stored database, and a plurality of database relations, wherein one or more of the relations are retrieved by the processor by means of query commands by performing a plurality of join operations on the relations, the system employing a general purpose heuristic algorithm which excludes or defers Cartesian products as late in the join sequence as possible, the method includes the steps of determining, in association with the execution of, or preferably prior to executing the general purpose algorithm, whether tables referenced in a query command includes a hub table and at least two encoding tables related to the hub table and, when the query command references a hub table and at least two encoding tables, determining the best access plan for the hub table, determining whether the best access plan utilizes an index used to access the hub table and, if so, constructing a plan to join the encoding tables as Car

Abstract: A method of index scanning involves scanning one or more selected indexes and determining the number of data transfers required to traverse all or a portion of a selected index for a selected number of buffer pool sizes. The number of page transfers to scan a whole table of interest versus the number of page transfers to scan each relevant index in accordance with the buffer pool size is determined for a query. The number of page transfers required in proportion to the selectivity of starting and stopping conditions is determined and scaled down in proportion to the selectivity of any starting and stopping conditions present in the search criteria in the query. A suitable correction factor is applied to the number of transfers to account for few rows remaining to be transferred after applying the search criteria, the buffer pool being large, or a low degree of clustering for an index,, as well as accounting for any remaining index sargable search criteria.

Abstract: The present invention provides a method for estimating cardinalities for query processing in a relational database management system. The present method is suitable for use with a query optimizer for estimating cardinalities for sets of columns or keys resulting from a grouping operation or a duplicate removal operation.

Abstract: Described herein is a system and method for operating a data processing system having a processing unit and physical storage in which data is stored. The storage is connected to the processing unit for transferring pages of data to the processing unit. The storage contains at least one database table stored on a plurality of pages. Each data base table has a plurality of rows of data, and one or more indexes composed of a sequence of entries which reference the rows. The processing unit has a memory associated with it. A portion of the memory comprises a buffer pool for caching data pages from the table. The method operates by scanning one or more selected indexes in determining the relationship of the number of data transfers required to traverse all or a portion of each selected index for a selected range of buffer pool sizes. Then, a description of this relationship is stored.

Abstract: A regulation and closure apparatus for a metallurgical vessel includes a stator to be disposed in a vessel wall and a rotor is rotatably supported in the stator for choking or blocking melt flow. A heating capability is provided in that the rotor is encompassed by an inductor to whose field melt in a through-passage channel in the rotor or the rotor can be coupled electromagnetically.

Abstract: A refractory assembly includes a refractory outer member having therein an opening defined by an inner surface and a refractory inner member having an outer surface. The dimension of the outer surface of the inner member is greater than the dimension of the inner surface of the outer member by an amount of from 0.05 to 0.15 mm. The outer member is heated to at least 1000.degree. C. to thereby increase the dimension of the inner surface. The inner member then is inserted into the opening in the outer member, and the outer member then is cooled to room temperature. As a result, the inner surface of the outer member shrinks against the outer surface of the inner member to thereby form an interference shrink fit joint between the members.

Abstract: A closure mechanism includes a conical discharge nozzle and a shielding tube fitted over the exterior of the discharge nozzle. A snug conical joint is formed by closely complementary conical surfaces of the discharge nozzle and the shielding tube. At least one ring-shaped seal is provided in such joint to prevent exterior air from entering between the discharge nozzle and the shielding tube into the interior of the shielding tube. The ring-shaped seal comprises an annular recess formed in one of the conical surfaces, thereby defining an annular chamber, and an inert gas filling such chamber.

Abstract: A closure mechanism includes a conical discharge nozzle and a shielding tube fitted over the exterior of the discharge nozzle. A snug conical joint is formed by closely complementary conical surfaces of the discharge nozzle and the shielding tube. At least one ring-shaped seal is provided in such joint to prevent exterior air from entering between the discharge nozzle and the shielding tube into the interior of the shielding tube. The ring-shaped seal comprises an annular recess formed in one of the conical surfaces, thereby defining an annular chamber, and an inert gas filling such chamber.