Extending a Graphical Query Language to Support Updates, Foreign Systems, and Transactions

In [STON93] we proposed a new user interface paradigm called Tioga for interacting with database management systems. Tioga simplifies the task of building database applications and is geared especially towards the needs of scientific users. We borrow the "boxes and arrows" visual programming notation of scientific visualization systems and allow users to graphically construct applications by using database procedures as building blocks. This paper extends the Tioga paradigm to a general database programming environment. In particular, we address three shortcomings of graphical query languages. First, we define a mechanism for allowing general programs---not just database procedures---as building blocks. This extension allows better handling of general data entry and data visualization needs and provides an interface to foreign systems. Second, we permit database updates. Third, we define a transaction semantics for graphical query languages. Unlike traditional transactions, Tioga transactions contain a directed graph of queries instead of a linear sequence of queries. We explore concurrency control techniques to promote both intra-transaction and inter-transaction parallelism. Finally, we present query processing strategies for graphical queries with general building blocks, updates, and transactions. We show how to efficiently execute a Tioga application by decomposing the application into components that are individually optimized.