Recursive Query Processing in SBQL
Tomasz Pieciukiewicz, Kazimierz Subieta, Krzysztof Stencel · 2004
Abstract. Recursive queries are required for many database applications. Among them we can mention Bill-Of-Material (BOM), various kinds of networks (transportation, telecommunication, etc.), workflows, processing semi-structured data (XML, RDF), and others. The support for recursive queries in current query languages is limited. In particular, this concerns the corresponding extensions of SQL in Oracle and DB2. In this paper we present recursive query processing capabilities for the object-oriented Stack-Based Query Language (SBQL). SBQL offers very powerful and flexible recursive querying capabilities due to the fact that recursive processing operators are fully orthogonal to other capabilities of this language. Recursive queries formulated in SBQL turned out to be much simpler in comparison to equivalent queries which could be formulated in other languages. This paper discusses SBQL constructs, such as transitive closures, fixed point equations and recursive procedures/views. Their main advantage is that they are seamlessly integrated with object-oriented facilities, computer environment and databases. We also consider a semi-strong typing system for the abovementioned recursive facilities. 1.