Parallel handling of integrity constraints on fragmented relations

Abstract

Integrity constraint handling is considered an important issue in relational database management systems. Many studies were already conducted in this area. Little attention has been paid however to the influence of relation fragmentation and parallelism on constraint handling. This paper shows how relation fragmentation complicates matters on the one hand, but how parallelism can help to get better efficiency in enforcing constraints on the other hand. The ideas as presented in this paper are used in the context of the PRISMA database machine; they have a more general applicability though.

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“…Most work addressing the problem of integrity constraint checking in multidatabase environments has considered tightly-coupled distributed databases in which global queries, global transactions, and global concurrency control are present, e.g., [13,24,28]. Since these approaches rely on global services that typically are unavailable in federated databases, they are inappropriate for the environment we consider.…”

“…See the earlier technical report version of this paper [19] for a complete definition of the class of constraints considered. The problem of incremental constraint checking has been studied extensively (see, e.g., [4,13,22,26,25,29]). The protocols we present can be extended in a straightforward way to constraints over more than two relations; the two-relation restriction is adopted for clarity and brevity only.…”

PRISMA/DB: a parallel, main memory relational DBMS

“…The effects of data distribution and parallel enforcement are described in detail in [20]. Here, attention is paid to the translation of constraints in a functional specification (first-order logic) to an operational specification in XRA, the removal of fragmentation transparency and the optimization of constraints in a parallel context, and to the mapping of constraints to the parallel query execution machinery of PRISMAIDB.…”