Query optimization in language xml

ABSTRACT: Nowadays, XML is one of the most important models for storing and communicating data. The flexibility of XML leads to be used commonly. The size of XML documents is increasing day to day. In order to manage these documents, an expressive system is needed because traditional file systems can’t manage such a huge volume of data. So, a lot of efforts have been done in this regard. On the one hand, by prevalent use of XML databases, it is needed to promote queries, and that is why most of the researchers concern to improve this aspect of XML. On the other hand, since XML structure is completely different from traditional relational databases, most methods are not efficient and have not been accepted as a standard for XML users, so the researchers have motivated more than the past.On the other aspect, hence XML has flexible structure, it could attract web designers to develop their web pages as XML format, and nowadays, too many XML web pages can be seen, so users expect to receive their query indexs as they could in the past, but there is less coherence among web page information than a unit database. As a index, in addition to accelerating queries, the coherence among indexs must be regarded in this case. Unfortunately, there are a lot of deficiencies among proposed methods. Each method just concerns few aspects of the problems, and it is used for specific queries, therefore; it’s not efficient for all kinds of queries, and no method has ever been proposed as a standard like SQL in relational database, and it could be said that XML has not reached to its own maturity, and it is hoped that the thesis could open a path even for the future. In this article we search the method that be profit for a big nods of queries the method compared with the other similar methods placed on achieving the numbers of fewer nods and in less time to reach the answer. The method had been ability of modulate with similar methods index and be able to use it to accelerate the queries (Al-Khalifa et al., 2003). Were looking for a method that can jump from node tobe useless and less than in similar fashion to produce an intermediate data. The method using a pattern matching method. Directly and blindly not processing nods in the documents(Kim, L 2008).