@Override
  public void setQueryType(ASTNode tree) {
    queryProperties.setQueryType(QueryProperties.QueryType.STATS);
  }
@param ast
         is the original analyze ast
@param context
         the column stats auto gather context
@return the rewritten AST
ql/src/java/org/apache/hadoop/hive/ql/parse/ColumnStatsSemanticAnalyzer.java