Collision :
An attempt by more than one user (typically on a networked, multiuser system) to update a database simultaneously, usually resulting in data corruption. Generally due to poor implementation of the code to support multiuser operations.
See Also: Deadly Embrace, LAN, Local Area Network
Deadly Embrace :
In a multiuser database management system, the result of an unforeseen flaw that has allowed a situation wherein two or more simultaneous operations cannot be completed because each has instigated locks on files or records that the other needs to complete its task.
Exclusive :
In a network, to assure that no other user will write data to a file, it may be opened in an Exclusive mode. Only the user opening the file exclusively may then access it until exclusive use of the file (by closing it, or opening it SHARED) is relinquished.
File Locking :
The process by which a user is guaranteed exclusive access to a database file. The file is only available to the user that applied the lock.
See Also: Record Locking
File Server :
A computer on a network dedicated to providing data storage to other computers (i.e., workstations) for the purpose of sharing information among multiple users. File servers tend to provide other services such as E-Mail service and shared printer support as well.
LAN :
An acronym for Local Area Network. Generally used to describe a system by which microcomputers are connected together to perform such functions as file and peripheral sharing, electronic mail, and centralized backup of data.
Local Area Network :
A system by which microcomputers are connected (via coaxial cable, optical fiber, twisted pair phone wire, or other media), relying on sophisticated operating software to perform such functions as file and peripheral sharing, electronic mail, and centralized backup of data.
See Also : LAN
Record Locking :
The process by which one user obtains exclusive access to a record in a database to prevent another user from attempting to write data to it concurrently. A record lock must be applied prior to writing to a database in use by more than one user.
Retry :
Upon failing to lock a record in a database that is opened in shared mode, retry refers to attempting the write again based upon certain programmatic parameters.
See Also: Error, Exception, Exclusive, Failure, Runtime Error
Shared :
A mode in which a file is opened that allows it to be accessed by more than one user at the same time. The inverse of Exclusive.
Spooler :
See : Print Spooler
Workstation :
A personal computer connected to a network used to run applications and front end processes.
See Also: File Server
