code: public String calculateCacheKey(String sql, int[] columnIndexes) {
  		StringBuilder tmp = new StringBuilder(sql.length()+4);
  		tmp.append(sql);
  		for (int i=0; i < columnIndexes.length; i++){
  			tmp.append(columnIndexes[i]);
  			tmp.append("CI,");
  		}
  		return tmp.toString();
  	}
docs: Calculate a cache key.
  @param sql to use
  @param columnIndexes to use
  @return cache key to use.