XQueC: A Query-Conscious Compressed XML Database (to appear

XML compression has gained prominence recently because it counters the disadvantage of the “verbose ” representation XML gives to data. In many applications, such as data exchange and data archiving, entirely compressing and decompressing a document is acceptable. In other applications, where queries must be run over compressed documents, compression may not be beneficial since the performance penalty in running the query processor over compressed data outweights the data compression benefits. While balancing the interests of compression and query processing has received significant attention in the domain of relational databases, these results do not immediately translate to XML data. In this paper, we address the problem of embedding compression into XML databases without degrading query performance. Since the setting is rather different from relational databases, the choice of compression granularity and compression algorithms must be revisited. Query execution in the compressed domain must also be rethought in the framework of XML query processing, due to the richer structure of XML data. Indeed, a proper storage design for the compressed data plays a crucial role here. The XQueC system (standing for XQuery Processor and C ompressor) covers a wide set o