private String getModifiedAlias(QB qb, String alias) {
    return QB.getAppendedAliasFromId(qb.getId(), alias);
  }
Extract the filters from the join condition and push them on top of the
source operators. This procedure traverses the query tree recursively,
ql/src/java/org/apache/hadoop/hive/ql/parse/SemanticAnalyzer.java