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We introduce the notion of XML Stream Attribute Grammars (XSAGs). XSAGs are the first scalable query language for XML streams (running strictly in linear time with bounded memory consumption independent of the size of the stream) that allows for actual data transformations rather than just document filtering. XSAGs are also relatively easy to use for(More)
NoSQL data stores are commonly schema-less, providing no means for globally defining or managing the schema. While this offers great flexibility in early stages of application development, developers soon can experience the heavy burden of dealing with increasingly heterogeneous data. This paper targets schema evolution for NoSQL data stores, the complex(More)
We introduce an extension of the XQuery language , FluX, that supports event-based query processing and the conscious handling of main memory buffers. Purely event-based queries of this language can be executed on streaming XML data in a very direct way. We then develop an algorithm that allows to efficiently rewrite XQueries into the event-based FluX(More)
NoSQL data stores are becoming increasingly popular in application development. These systems are attractive for developers due to their ability to handle large volumes of data, as well as data with ah igh degree of structural variety.T yp-ically,N oSQL data stores are accessed programmatically.D ue to the imminent lack of standardized query languages,(More)
Effective buffer management is crucial for efficient in-memory and streaming XQuery processing. We propose a buffer management scheme which combines static and dynamic analysis to keep main memory consumption low. Our approach relies on a technique that we call active garbage collection and which actively purges buffers at runtime based on the current(More)
In this demonstration, we present the main-memory based streaming XQuery engine GCX which implements novel buffer management strategies that combine static and dynamic analysis to keep main memory consumption low. Depending on the progress made in query evaluation, memory buffers are dynamically purged and minimized. In this demo, we show the various stages(More)
Schema-less NoSQL data stores offer great flexibility in application development , particularly in the early stages of software design. Yeto vert ime, software engineers struggle with the heavy burden of dealing with increasingly heterogeneous data. In this demo we present Cleager,aframework for eagerly managing schema evolution in schema-less NoSQL(More)
Although most NoSQL Data Stores are schema-less, information on the structural properties of the persisted data is nevertheless essential during application development. Otherwise, accessing the data becomes simply impractical. In this paper, we introduce an algorithm for schema extraction that is operating outside of the NoSQL data store. Our method is(More)
In der Entwicklung von interaktiven Web-Anwendungen sind NoSQL-Datenbanksysteme zunehmend beliebt, nicht zuletzt, weil sie flexible Datenmodelle erlauben. Das erleichtert insbesondere ein agiles Projektmanagement, das sich durch häufige Releases und entsprechend häufige Änderungen am Datenmodell auszeichnet. In diesem Artikel geben wir einen Überblick über(More)