code: @Override
  	public long blocksAccessed() {
  		// block accesses to search for a join record in the index
  		long searchCost = Index.searchCost(ii.indexType(),
  				new SearchKeyType(schema(), ii.fieldNames()), tp2.recordsOutput(), 1);
  		return p1.blocksAccessed() + (p1.recordsOutput() * searchCost)
  				+ recordsOutput();
  	}
docs: Estimates the number of block accesses to compute the join. The formula
  is:
  
  <pre>
  B(indexjoin(p1,p2,idx)) = B(p1) + R(p1)*B(idx)
  + R(indexjoin(p1,p2,idx)
  </pre>
  
  @see Plan#blocksAccessed()