Backing off, NLP and Indexing Methods for String Matching in Query Execution
نویسندگان
چکیده
Steps involved in converting a query into its equivalent internal form include generation of logically equivalent expressions, using equivalence rules, secondly providing enough information for extracting alternate solutions and finally optimizing the query. Queries written in high level languages are transformed into lower level forms by making use of relational algebra.
منابع مشابه
Approximate String Matching ? Edgar
We present a radically new indexing approach for approximate string matching. The scheme uses the metric properties of the edit distance and can be applied to any other metric between strings. We build a metric space where the sites are the nodes of the suux tree of the text, and the approximate query is seen as a proximity query on that metric space. This permits us nding the R occurrences of ...
متن کاملTree Signatures for XML Querying and Navigation
In order to accelerate execution of various matching and navigation operations on collections of XML documents, new indexing structure, based on tree signatures, is proposed. We show that XML tree structures can be efficiently represented as ordered sequences of preorder and postorder ranks, on which extended string matching techniques can easily solve the tree matching problem. We also show ho...
متن کاملConceptual Search in Electronic Patient Record
Search by content in a large corpus of free texts in the medical domain is, today, only partially solved. The so-called GREP approach (Get Regular Expression and Print), based on highly efficient string matching techniques, is subject to inherent limitations, especially its inability to recognize domain specific knowledge. Such methods oblige the user to formulate his or her query in a logical ...
متن کاملA General Approach to Indexing and Retrieval of Images in Image Databases∗
In this paper we present a very general approach to indexing and retrieval of images in image database systems. We allow different ways of indexing and matching for objects in an image, and integrate them with our existing approach of the generalized extended pseudo-2D string and generalized combined 2D string representation of the image to formulate a more general framework for iconic indexing...
متن کاملProbabilistic Threshold Indexing for Uncertain Strings
Strings form a fundamental data type in computer systems. String searching has been extensively studied since the inception of computer science. Increasingly many applications have to deal with imprecise strings or strings with fuzzy information in them. String matching becomes a probabilistic event when a string contains uncertainty, i.e. each position of the string can have different probable...
متن کامل