Stored and Inherited Relations with PKN Foreign Keys

Abstract

AbstractA stored and inherited relation (SIR) is 1NF stored relation enlarged with inherited attributes (IAs). The latter make SIRs as base tables the only known view-savers for logical navigation free (LNF) or calculated attribute free (CAF) queries, without any denormalization. Recall that LN means joins among base tables, while calculated attributes serve as the virtual ones do at some popular DBSs, but can be more general, e.g., with aggregate functions or sub-queries. The overall advantage of SIRs is substantially less procedural queries and DB schemes. We now show that usual schemes of stored relations with foreign keys implicitly define IAs forming so-called natural SIRs. The exclusive advantage of the latter is the LNF queries with zero procedurality to define the IAs. We then discuss SIRs with FKs and explicit IAs, the calculated ones especially. We show that generalizing a typical relational DBS to SIR-enabled one should be simple. Preexisting applications could remain not affected, while new ones could profit from LNF and CAF queries. We conclude that major relational DBS should evolve to SIR-enabled “better sooner than later”. To make LNF and CAF queries standard, at last, for the benefit of, likely, millions of SQL users.KeywordsRelational modelForeign keyInheritanceLogical navigationSQLStored and inherited relation