Abstract: In one general aspect, a computer-implemented method includes a computer-implemented method that includes executing, using at least one processor, instructions recorded on a non-transitory computer-readable storage medium. The method includes receiving a request to insert a data record within a database of a data collection system. The data record can be placed within a buffer in a main memory of the data collection system. A record data structure and a record index structure associated with the data record are defined. The record data structure and the record index structure are stored within a storage chunk in a storage medium of the database, and the storage medium is different than the main memory. The storage chunk has an associated index that can be used to retrieve the data record and the storage chunk can include other data records different than the data record associated with the received request.

Abstract: In one general aspect, a computer-implemented method includes a computer-implemented method that includes executing, using at least one processor, instructions recorded on a non-transitory computer-readable storage medium. The method includes receiving a request to insert a data record within a database of a data collection system. The data record can be placed within a buffer in a main memory of the data collection system. A record data structure and a record index structure associated with the data record are defined. The record data structure and the record index structure are stored within a storage chunk in a storage medium of the database, and the storage medium is different than the main memory. The storage chunk has an associated index that can be used to retrieve the data record and the storage chunk can include other data records different than the data record associated with the received request.

Abstract: A method of dynamically expanding or contracting a DB2 buffer pool, a set of control blocks emulating certain DB2 control blocks is constructed. If the size of the buffer pool is to be increased, the buffer pool expansion routine used by DB2 to accommodate abnormally high storage demand is repeatedly invoked to perform the expansion. However, the contractable-page flag that is set by DB2 for each 4K or 32K page that is added to the buffer pool in this way, indicating that the added page should be removed from the buffer pool as soon as the high storage demand condition has ended, is reset. If the size of the buffer pool is to be decreased, pages are removed from DB2's three queues or chains used to manage the buffer pool, i.e., the never-used chain, the previously-used chain, and the in-use chain, in that order; in the latter two cases the pages are "removed" by marking them as contractable pages so that DB2 itself will soon remove the pages from the appropriate chain as part of its own normal processing.

Abstract: A DB2 thread cancellation method permits operator intervention to terminate a DB2 thread. After the thread to be canceled has been located, a series of one or more SRBs is scheduled to cancel the thread. The basic approach is an iterative one, involving (1) making the thread nondispatchable, i.e., freezing execution of work associated with the thread to prevent such work from making undesirable environmental changes while the thread canceling operation is in progress, (2) testing to ensure that canceling the thread at that moment will not create certain undesirable side effects, primarily in the context of serialization of DB2 resource usage; (3) invoking the DB2 thread cancellation routine; (4) making the thread dispatchable again to permit the cancellation process to begin; (5) receiving a message whether the cancellation request was completed successfully, and (6) returning a status code indicating a successful or unsuccessful cancellation attempt.

Abstract: In a novel method of dynamically adding or removing active logs in a DB2 subsystem without the necessity of cycling DB2, a set of control blocks emulating certain DB2 control blocks is constructed. In adding an active log, a call to a DB2 module is made to allocate the new active log data set and create a new LDSD control block for the new active log data set. The NEW and REUSABLE status flags are set in the new LDSD control block, initialization of the new LDSD control block is completed, and the new LDSD control block is added to the LDSD chain off the LMB. The BSDS record(s) and the cached portions of the BSDS information are updated to reflect the addition of the new active log. In removing an active log, the LDSD of the active log is removed from the LDSD chain and an attempt is made to deallocate the active log data set via a call to a DB2 module.