Hi, Christoffer, Thanks for your reply. I will try to fix the problem based on the information you provided.
Best regards, Wei HAO On 2017/2/22 16:58, Christoffer Bruun wrote:
Hi, This is because the Xalan XPATH engine creates some internal lookup tables/indexes *every time* you perform a xpath query. You notice this on large documents when creating the lookup tables consumes much more time than the actual query. You could look into https://xalan.apache.org/old/xalan-j/apidocs/org/apache/xpath/CachedXPathAPI.html br Christoffer Bruun Den 2/19/2017 kl. 1:54 AM skrev shath...@e-z.net:Dear all, I'm a Ph.D. student in Kochi University of Technology in Japan. I recently got started to use Xalan for some implementation work as a part of a project, and I encountered an efficiency problem. Here is the problematic function I designed for evaluating XPath queries. 1: public void process(org.w3c.dom.Document doc, String xquery){ 2: ... // skipped some irrelevant code 3: NodeList nodes = XPathAPI.selectSingleNode(doc, xquery); 4: ... // skipped some irrelevant code 5: } In Line 3, an XPath query is applied to an XML document. The processing was done on an document sized 596 MB generated by xmlgen from XMark project. The query is rather simple "/site/*". Since there are only six children of "site", it should take very short time. However, it took 3.6 seconds. Then I tried to evaluate it directly by the getChildNodes() function on the root of the document, and it took only 0.003 second for the same query. 1: Node root = doc.getChildNodes().item(0); 2: NodeList chs = root.getChildNodes(); Although this efficiency was pretty good, it is hard for me to evaluate complex queries. I spent a couple of days trying to solve this problem, but still I have no idea. So, could you please give me some help about how to improve the efficiency of Xalan? Thank you in advance. Best regards, Wei HAO.I am releasing this to the J-USERS group.
