Search results for "query language"
showing 10 items of 39 documents
Reactome graph database: Efficient access to complex pathway data
2018
Reactome is a free, open-source, open-data, curated and peer-reviewed knowledgebase of biomolecular pathways. One of its main priorities is to provide easy and efficient access to its high quality curated data. At present, biological pathway databases typically store their contents in relational databases. This limits access efficiency because there are performance issues associated with queries traversing highly interconnected data. The same data in a graph database can be queried more efficiently. Here we present the rationale behind the adoption of a graph database (Neo4j) as well as the new ContentService (REST API) that provides access to these data. The Neo4j graph database and its qu…
Grammars++ for modelling information in text
1999
Abstract Grammars provide a convenient means to describe the set of valid instances in a text database. Flexibility in choosing a grammar can be exploited to provide information modelling capability by designing productions in the grammar to represent entities and relationships of interest to database applications. Additional constraints can be specified by attaching predicates to selected nonterminals in the grammar. When used for database definition, grammars can provide the functionality that users have come to expect of database schemas. Extended grammars can also be used to specify database manipulation, including query, update, view definition, and index specification.
On the Power of Tree-Walking Automata
2000
Tree-walking automata (TWAs) recently received new attention in the fields of formal languages and databases. Towards a better understanding of their expressiveness, we characterize them in terms of transitive closure logic formulas in normal form. It is conjectured by Engelfriet and Hoogeboom that TWAs cannot define all regular tree languages, or equivalently, all of monadic second-order logic. We prove this conjecture for a restricted, but powerful, class of TWAs. In particular, we show that 1-bounded TWAs, that is TWAs that are only allowed to traverse every edge of the input tree at most once in every direction, cannot define all regular languages. We then extend this result to a class …
Patient documentation for the ultrasound laboratory
1991
The development of a PC based system for the storage of patient data in the echocardiography laboratory is described. Special design objectives were low cost and user friendliness, including an integrated special query language. After 3 years of use, the system stores 80000 diagnoses from 12000 patients without any relevant slowdown of response. Future developments concerning the communication between the database system and an echocardiographic sector scanner are discussed.
Automated source code transformations on fourth generation languages
2004
To control the operation of large application suites or to tailor a special purpose application to particular need, developers frequently use application specific languages, such as batch, scripting, and query languages. These languages which are also referred to as fourth generation languages (4GLs) therefore play an important role in today's economy. Incompatibilities between different versions of 4GLs and changing requirements may make massive changes on a company's library of 4GL programs necessary. Here, we explore possibilities for performing mass changes on 4GLs and show how the transformation of programs written in 4GLs compares to the transformation of mainstream programming langua…
Tree Based Domain-Specific Mapping Languages
2012
Model transformation languages have been mainly used by researchers --- the software engineering industry has not yet widely accepted the model driven software development (MDSD). One of the main reasons is the complexity of metamodelling principles the developers are required to know to actually use model transformations in the way the OMG has stated. We offer the basic principles how to create domain-specific model transformation languages which can be used by developers relying only on familiar modelling concepts. We propose to use simple graphical mappings to specify the correspondence between source and target models which are represented using trees based on the concrete syntax of und…
Discovering temporal relationships in databases of newspapers
1998
This paper is mainly dedicated to analyse the problem of discovering frequent temporal patterns in event sequences extracted from a large repository of newspapers. The proposed formalism and algorithms rely on Toodor, which is a document retrieval system that allows users to specify conditions over the structure, contents and temporal features of the stored documents. We develop in this work several algorithms for recognising frequent temporal patterns in terms of arc-consistency, which consist of discarding temporal occurrences that do not satisfy a temporal structure.
A Graph Database Approach to Wireless IIoT Workcell Performance Evaluation
2020
The workcell is considered a main building block of various industrial settings. Hence, it is examined as a primary testing environment for studying wireless communication techniques in factory automation processes. A new testbed was recently designed and developed to facilitate such studies in workcells by replicating various data flows in an emulated production environment. In this paper, an approach to storing and analyzing network performance data from a manufacturing factory workcell is introduced. A robotic testbed was constructed using two collaborative grade robot arms, machine emulators, and wireless communication devices. A graph database approach was implemented to capture networ…
The visual query language CQL for transitive and relational computation
2000
Abstract Classification query language (CQL) is a high-level visual query language with a great expressive power. In CQL the processing of ordinary relations and classifications based on transitive relationships is integrated seamlessly. Relations and classifications are represented in the visual interface in a uniform way through relation and classification skeletons. All query formulation in CQL is QBE-like – based on the intuitive way of filling constants and sample values into the skeletons. In order to guarantee great expressive power, relational and classification expressions can be nested freely with each other at unlimited nesting levels. Recursive definition of transitive processin…
Errors and Complications in SQL Query Formulation
2018
SQL is taught in almost all university level database courses, yet SQL has received relatively little attention in educational research. In this study, we present a database management system independent categorization of SQL query errors that students make in an introductory database course. We base the categorization on previous literature, present a class of logical errors that has not been studied in detail, and review and complement these findings by analyzing over 33,000 SQL queries submitted by students. Our analysis verifies error findings presented in previous literature and reveals new types of errors, namely logical errors recurring in similar manners among different students. We…