VSAM is a file management method used on mainframes and PCs that speeds up file data access using a reverse index called a B+ tree. It is a record-oriented file system with three types of datasets: ESDS, KSDS, and RRDS. VSAM databases like FileMaker and Microsoft Access allow users to configure data into various presentations and search parameters. ESDS is the least suitable for research, while data with related keys or records is easier to present in an orderly fashion.
VSAM stands for Virtual Storage Access Method. It is a file management method that is mostly used on mainframes but also on PCs. In particular, VSAM can speed up file data access by using a reverse index of records added to files. This index is called a B+ tree.
VSAM is a type of record oriented file system. In this type of dataset, information is stored as a collection of records. VSAM records can be of any length; they don’t have to be of a fixed length. They are, however, organized into blocks called Control Intervals, which are measured in bytes. These control ranges are further organized into control areas, measured in much larger units.
VSAM can be organized into three types of datasets: Entry Sequenced Data Sets (ESDS), Key Sequenced Data Sets (KSDS), and Relative Record Data Sets (RRDS). ESDS items are listed in the order they were entered, regardless of any other considerations. Each item in a KSDS is assigned a unique numeric key, by which the data set is indexed. RRDS items are organized by related record numbers, which can be set by users.
A perfect example of a VSAM that millions of people use every day is a FileMaker or Microsoft Access database. Accelerated spreadsheets, these databases contain a variable amount of columns, all containing alphanumeric information. Financial institutions have databases containing personal information about customers and this is the type of database we are talking about. For example, Henry Gale lives at 815 Wayland Avenue in Wayzata, Minnesota. Each item of information would be stored in its own column, for easy comparison.
These VSAM database applications allow users to configure data into a variety of presentations and search parameters. The least suitable for research, at least initially, is ESDS, since its only method of organization is the potentially random order in which the data was entered. VSAM data that has related keys or records is much easier to present in an orderly fashion. You can do individual searches by names or numbers, but more sophisticated search possibilities need to have data organized differently to be most effective.
Protect your devices with Threat Protection by NordVPN
