select * from R where a between 10 and 30;

Give a detailed algorithm for solving such range queries

• assume table is indexed on attribute a
• assume file is not sorted on a
• assume existence of Set data type:
  s=empty(); insert(s, n); foreach elems(s)
• assume "the usual" operations on relations:
  r = openRelation(name,mode); b=nPages(r); file(r)
• assume "the usual" operations on pages:
  buf=getPage(f,pid); foreach tuples(buf); pid = next(buf)