Meaning of PDD term "RDBMS - Relational Database Management System"

RDBMS - Relational DataBase Management System

• A Relational Database Management System or RDBMS is a software program for storing and retreiving data objects or entities by specifying particular relationships between some of the entities.

• The RDBMS used with the PDD project is a system designed and built by the Image Processing Section in the LMMB of the NCI/FCRDC.

• The query and data manipulation language used in the RDBMS system is a subset of SQL query language with some DBaseIV constructs.

• The RDBMS program used with the PDD is memory based (rather than disk file based). This gives a major performance advantage when the database is small enough to fit in memory.

• The RDBMS program uses "threads" type light weight processes and currently runs on SUN computers under SUNOS-4.1.X and SOLARIS-2.3.

• Startup of the RDBMS server daemon consists of first loading the PDD tables into memory. This is fast and takes just a few seconds. Then it listens for client SQL command requests.

• RDBMS server access is restricted through security features where different access groups have different corresponding sets of command capabilities.

• Entry of new data to the PDD is a maintenance operation with access restricted accordingly. When a change is made to the database residing it memory, the affected tables are saved back out to disk in an atomic operations as table files. Older versions of the RDBMS table files are renamed with timestamp so recovery is possible if necessary.