Using SQL to Build New Aggregates and Extenders for Object- Relational Systems
Haixun Wang, Carlo Zaniolo · 2000
User-defined Aggregates (UDAs) provide a versatile mechanism for extending the power and applicability of Object-Relational Databases (O-R DBs). In this paper, we describe the AXL system that supports an SQLbased language for introducing new UDAs. AXL is easy to learn and use for database programmers because it preserves the constructs, programming paradigm and data types of SQL (whereas there is an `impedance mismatch' between SQL and the procedural languages of user-defined functions currently used in O-R DBs). AXL will also inherit the benefits of database query languages, such as scalability, data independence and parallelizability. In this paper, we show that, while adding only minimal extensions to SQL, AXL is very powerful and capable of expressing complex algorithms e#ciently. We demonstrate this by coding data mining functions and other advanced applications that, previously, had been a major problem for SQL databases. Due to its flexibility, SQL-compati...