Pipelined XPath Query Based on Cost Optimization

Table 5

Experimental cases.

Case	XPath expression	Number of results
T1	//S//NP/PP/NN	15
T2	//S[./VBP][.//NP/VP]//PP[.//IN]///VBN	174
T3	//EMPTY[.//VP/PP//NNP][.//S[.//PP//JJ]//VBN]//PP/NP//_NONE_	1589
X1	//open_auctions/open_auction//time	42915
X2	//regions/asia/item[./payment]//name	1440
X3	//categories[./category[./name]/@id]//description	720