We address the problem of expressing and evaluating computations on hierarchies represented as database tables. Engine support for such computations is very limited today, and so they are usually outsourced into stored procedures or client code. Recently, data model and SQL language extensions were proposed to conveniently represent and work with hierarchies. On that basis we introduce a concep...

The potential for substantial performance improvement in a main memory database system (MMDB) is promising, since I/O activity is kept at minimum. On the other hand, due to the volatility of main memory, the issue of failure recovery becomes more complex than in traditional disk resident database systems. In this paper, we present four checkpointing schemes for the MMDB. The proposed schemes ar...

Hierarchical data is prevalent in a number of business use cases. However, most business data is stored in a relational database and hierarchical data is somehow encoded relationally. Since most queries on hierarchies also feature relational data, companies must continue maintaining their hierarchical data in a relational database system. There are many challenges when storing and querying hier...

Optimization of queries with conjunctive predicates for main memory databases remains a challenging task. The traditional way of optimizing this class of queries relies on predicate ordering based on selectivities or ranks. However, the optimization of queries with conjunctive predicates is a much more challenging task, requiring a holistic approach in view of (1) an accurate cost model that is...

PRISMA/DB is a full-fledged parallel, main memory relational database management system the design of which is characterized by two main ideas. In the first place, high performance is obtained by the use of parallelism for query processing and main memory storage of the entire database. In the second place, a flexible architecture for experimenting with functionality and performance is obtained...

Emerging communication and sensor technologies enable new applications of database technology that require database systems to efficiently support very high rates of spatial-index updates. Previous works in this area require the availability of large amounts of main memory, do not exploit all the main memory that is indeed available, or do not support some of the standard index operations. Assu...

Disk-based database systems are widely used, offering a great set of functionalities perfectly suited for most kinds of applications. However, when high performance is the priority, such databases are unable to produce satisfactory results. Telecom applications demand high performance especially for their real-time applications. Location management is one of many telecom applications that fall ...

We evaluate and compare performance of signature nested loops, set partitioning, and inverted lists algorithms for set containment joins. We study running time and required storage space for the algorithms depending on such characteristics of input data sets as number of records, average cardinality of the set-valued attribute, and cardinality of the set elements domain. We outline implementati...

With the ubiquity of main memory databases which are increasingly replacing the old disk-oriented databases, relations are being stored in denormalized form in order to increase the query throughput, thus, the dominance of join operators in terms of costs is being replaced by the costs of evaluating selection predicates. Boolean expressions containing selection predicates connected both conjunc...