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The Sort/Merge utility is a mainframe program to sort records in a file into a specified order, merge pre-sorted files into a sorted file, or copy selected records. Internally, these utilities use one or more of the standard sorting algorithms , often with proprietary fine-tuned code.
The operation of SORT is directed by control statements, which are largely compatible among various IBM and third-party sort programs. The SORT or MERGE statement defines the sort keys— the fields on which the data is to be sorted or merged. This statement identifies the position, length, and data type of each key.
In order to serialize accesses between data records on a loosely coupled system, a practice known as record locking must be used. This means that when one mainframe processor obtains a hold on a record, the mechanism must prevent all other processors from obtaining the same hold and communicate to the requesting processors that they are waiting.
As it is an assembly language, BAL uses the native instruction set of the IBM mainframe architecture on which it runs, System/360, just as the successors to BAL use the native instruction sets of the IBM mainframe architectures on which they run, including System/360, System/370, System/370-XA, ESA/370, ESA/390, and z/Architecture.
The sort-merge join (also known as merge join) is a join algorithm and is used in the implementation of a relational database management system. The basic problem of a join algorithm is to find, for each distinct value of the join attribute, the set of tuples in each relation which display that value.
In IBM mainframe operating systems, such as OS/360, MVS, z/OS, a Data Control Block (DCB) is a description of a dataset in a program. A DCB is coded in Assembler programs using the DCB macro instruction (which expands into a large number of "define constant" instructions). High level language programmers use library routines containing DCBs.
The S/360-67 was intended to satisfy the needs of key time-sharing customers, notably MIT (where Project MAC had become a notorious IBM sales failure), the University of Michigan, General Motors, Bell Labs, Princeton University, the Carnegie Institute of Technology (later Carnegie Mellon University), [2] and the Naval Postgraduate School.
external sorting algorithm. External sorting is a class of sorting algorithms that can handle massive amounts of data.External sorting is required when the data being sorted do not fit into the main memory of a computing device (usually RAM) and instead they must reside in the slower external memory, usually a disk drive.