hive参数hive.mapred.mode分析

hive参数hive.mapred.mode分析

    // Use only 1 reducer in case of cartesian product
    if (reduceKeys.size() == 0) {
      numReds = 1;

      // Cartesian product is not supported in strict mode
      if (conf.getVar(HiveConf.ConfVars.HIVEMAPREDMODE).equalsIgnoreCase(
          "strict")) {
        throw new SemanticException(ErrorMsg.NO_CARTESIAN_PRODUCT.getMsg());
      }
    }

    if (sortExprs == null) {
      sortExprs = qb.getParseInfo().getOrderByForClause(dest);
      if (sortExprs != null) {
        assert numReducers == 1;
        // in strict mode, in the presence of order by, limit must be specified
        Integer limit = qb.getParseInfo().getDestLimit(dest);
        if (conf.getVar(HiveConf.ConfVars.HIVEMAPREDMODE).equalsIgnoreCase(
            "strict")
            && limit == null) {
          throw new SemanticException(generateErrorMessage(sortExprs,
                ErrorMsg.NO_LIMIT_WITH_ORDERBY.getMsg()));
        }
      }
    }

        // If the "strict" mode is on, we have to provide partition pruner for
        // each table.
        if ("strict".equalsIgnoreCase(HiveConf.getVar(conf,
            HiveConf.ConfVars.HIVEMAPREDMODE))) {
          if (!hasColumnExpr(prunerExpr)) {
            throw new SemanticException(ErrorMsg.NO_PARTITION_PREDICATE
                .getMsg("for Alias \"" + alias + "\" Table \""
                    + tab.getTableName() + "\""));
          }
        }