Abstract: Systems and methods process generalized-tree-pattern queries by processing a twig query with a bottom-up computation to generate a generalized tree pattern result; encoding the generalized tree pattern results using hierarchical stacks; enumerating the generalized tree pattern result with a top-down computation; a hybrid of top-down and bottom-up computation for early result enumeration before reaching the end of document; and a more succinct encoding scheme that replaces the hierarchical stacks to further improve the performance.

Abstract: Systems and methods to provide two bottom up path matching solutions and one post processing solution for evaluating value predicates and tree pattern queries. The first path matching method triggers the matching whenever a leaf query step is seen and stores the prefix sub-matches in a cache for reuse. The second path matching method is an NFA (non-deterministic finite state automata) based solution through a post-order traversal of the XML document tree. The post processing method relies on a compact encoding the path results, which avoids redundant value predicate, join evaluations and any duplicate elimination, sort and grouping operations.

Abstract: Systems and methods are disclosed to guarantee the safety of a continuous join query (CJQ) over one or more punctuated data streams by constructing a punctuation graph; checking whether the punctuation graph is strongly connected and if so, indicating that the CJQ is safe to execute. The system uses a generalized punctuation graph and its transformation to support arbitrary punctuation schemes. The system also provides an efficient shared purge algorithm for multi-way join operator.