Suppose our stream consists of baskets of items, as in the market-basket model of Section 22.1.1. Since we assume elements of streams are tuples, the contents of a basket must be represented by several consecutive tuples with the schema B askets (b ask et, item ). Write the following queries:
a) Find those items that have appeared in at least 1% of the baskets that arrived over the past hour.3
b) Find those pairs of items that have appeared in at least twice as many baskets in the previous half hour as in the half hour before that.
c) Find the most frequent pair(s) of items over the past hour.