Abstract: Techniques are presented for tracking status within object chains. Global objects are associated with unique identifiers and each dependent local object created within the context of a particular global object receives that particular global object's identifier. A unique counter value is maintained for each status type of each global object. The local object facilitates communicating changes in its status using the received global identifier, and the counter values are updated accordingly for the affected global object.

Abstract: A system, method, and computer-readable medium for optimized processing of queries that feature maximum or minimum equality conditions are provided. A table on which the query is applied is scanned a single time. Rows of the table distributed to respective processing modules are scanned by the processing modules. Each processing module maintains identification of any rows distributed to the respective processing module that have attribute values that equal the maximum or minimum attribute value locally identified by the processing module. Subsequently, a global aggregation mechanism is invoked to compute the query result without requiring an additional rescan of the table. Further, the disclosed mechanisms may be extended to compute top N queries featuring maximum or minimum equality conditions.

Abstract: A system, method, and computer-readable medium for optimization of query processing in a parallel processing system are provided. Skewed values and non-skewed values are treated differently to improve upon conventional DISTINCT and aggregation query processing. Skewed attribute values on which a DISTINCT selection or group by aggregation is applied are allocated entries in a hash table. In this manner, a processing module may consult the hash table to determine if a skewed attribute value has been encountered during the query processing in a manner that precludes repetitive redistribution of rows with highly skewed attribute values on which a DISTINCT selection or group by aggregation is applied.

Abstract: A system, method, and computer-readable medium for optimizing execution of a join operation in a parallel processing system are provided. A plurality of processing nodes that have at least one row of one or more tables involved in a join operation are identified. For each of the processing nodes, respective counts of rows that would be redistributed to each of the processing nodes based on join attributes of the rows are determined. A redistribution matrix is calculated from the counts of rows of each of the processing nodes. An optimized redistribution matrix is generated from the redistribution matrix, wherein the optimized redistribution matrix provides a minimization of rows to be redistributed among the nodes to execute the join operation.

Abstract: A system, method, and computer-readable medium that facilitate in-database supervised discretisation mechanisms which improve data classification are provided. The disclosed mechanisms provide an efficient, automatic, and repeatable way to perform data discretisation without human intervention. Efficient processing of large and complex unknown data is provided that advantageously does not require the data being analyzed to be processed outside the database. The disclosed mechanisms may use an External Stored Procedure to avoid multiple joins of large tables and minimize the number of full table scans and, consequently, provide better performance than contemporary mechanisms. The disclosed system produces intermediate results in tables which may be conveyed to a visualization subsystem thereby providing users a better understanding of the data distribution in each category.

Abstract: A system, method, and computer-readable medium for optimizing the performance of outer joins in a parallel processing system are provided. Predicates involving only attributes of a left table of a left outer join are pushed down to the outer relation for left outer joins having join predicates involving left table attributes and/or predicates involving attributes of both the right and left table. In such an instance, the rows of the left table may be partitioned into two sub-relations according to the predicate involving only attributes of the left table. Rows of the left table are allocated to a first sub-relation if the rows satisfy the predicate involving only attributes of the left table and rows of the left table are allocated to a second sub-relation if the rows fail to satisfy the predicate involving only attributes of the left table. Accordingly, only rows of the first sub-relation are required to be left outer joined with the right table.

Abstract: A system, method, and computer-readable medium for optimizing join operations in a parallel processing system are provided. A respective set of rows of a first table and a second table involved in a join operation are distributed to each of a plurality of processing modules. The join operation comprises a join on a first column of the first table and a second column of the second table. Each of the plurality of processing modules redistributes at least a portion of the rows of the first table distributed thereto substantially equally among the other processing modules and duplicates at least a portion of the rows of the second table distributed thereto among the plurality of processing modules. The disclosed optimization mechanisms provide for reduced spool space requirements for execution of the parallel join operation.

Abstract: A system, method, and computer-readable medium that facilitate workload management in a computer system are provided. A workload's system resource consumption is adjusted against a target consumption level thereby facilitating maintenance of the consumption to the target consumption within an averaging interval by dynamically controlling workload concurrency levels. System resource consumption is compensated during periods of over or under-consumption by adjusting workload consumption to a larger averaging interval. Further, mechanisms for limiting, or banding, dynamic concurrency adjustments to disallow workload starvation or unconstrained usage at any time are provided.

Abstract: A system, method, and computer readable medium that facilitate operation of a file system capable of dividing an existing homogeneous file system into a series of regions, with each region accommodating storage devices having compatible characteristics are provided. The file system is divided into logical regions, with each region containing a particular class of storage devices possessing a particular set of common storage traits. The regionalization of the file system provides for all cylinders of storage devices sharing a common storage characteristic to be contained within a single region, and dedicated file system logic can be written to service that region. A master index configuration implemented in accordance with disclosed embodiments includes a region descriptor construct that enables cylinder index descriptors associated with cylinders of storage devices sharing a common storage characteristic to be grouped into regions.

Abstract: A system, method, and computer-readable medium for dynamic detection and management of data skew in parallel join operations are provided. Receipt of an excessive number of redistributed rows by a processing module is detected thereby identifying the processing module as a hot processing module. Other processing modules then terminate redistribution of rows to the hot processing module and maintain rows of a skewed table of the join operation that would be redistributed to the hot processing module in a local spool. Rows of a smaller table that would be redistributed to the hot processing module are duplicated to each processing module involved in the join operation. Rows of tables that are to be redistributed by a processing module to any processing module excluding the hot processing module are redistributed accordingly and maintained locally by the processing module. The join operation is completed by merging results of local join data sets of each processing module.

Abstract: An air-cooled electronic component cabinet has an air sampling conduit to enable smoke detection from air from different areas within the cabinet. An air sampling conduit has one or more orifices to sample air from the different areas within the cabinet, such as adjacent different electronic chassis assemblies or enclosures stacked in a rack within the cabinet. An axial fan or blower draws air samples into the conduit, or the air samples are drawn in by operation of convection or other airflow established within the cabinet. In the air sampling conduit, the air samples are mixed and conveyed for sampling by one or more smoke detection devices mounted, e.g., within the conduit, or within an attached expansion joint section to reduce the airflow velocity or accommodate multiple smoke detection devices. Orifices in the air sampling conduit varying in size or number at different conduit areas regulate associated sampled air proportions.

Abstract: The invention relates to a method and database system for rewriting a SQL query having at least one null sensitive expression (NSE) in a select list of the query, the query comprising at least one outer join command to be performed on at least two tables and involving a view or a Derived Table (DT). The method comprising the steps of: identifying at least one unmatching row belonging to the view or DT using non-nullable fields that belong to the outermost table in the view or DT; converting the NSE(s) from the at least one identified rows into a SQL case construct; and performing the at least one outer join. The database system comprising means for rewriting a SQL query having at least one null sensitive expression (NSE) in a select list of the query, the query comprising at least one outer join command to be performed on at least two tables and involving a view or a Derived Table (DT).