Examples of org.apache.tajo.engine.planner.NamedExprsManager$UnevaluatedIterator

org.apache.tajo.engine.planner.NamedExprsManager

NamedExprsManager manages an expressions used in a query block. All expressions used in a query block must be added to NamedExprsManager. When an expression is added to NamedExprsManager, NamedExprsManager gives a reference to the expression. If the expression already has an alias name, it gives the alias name as the reference to the expression. If the expression does not have any alias, it gives a generated name as the reference to the expression. Usually, predicates in WHERE clause, expressions in GROUP-BY, ORDER-BY, LIMIT clauses are not given any alias name. Those reference names are used to identify an individual expression. NamedExprsManager only keeps unique expressions. Since expressions in a query block can be duplicated, one or more reference names can point one expressions. Due to this process, it naturally removes duplicated expression. As we mentioned above, one or more reference names can indicate one expression. Primary names are used for representing expressions. A primary name of an expression indicates the reference obtained when the expression is added firstly. All output schemas uses only primary names of expressions. Each expression that NamedExprsManager keeps has an boolean state to indicate whether the expression is evaluated or not. The evaluated state means that upper logical operators can access this expression like a column reference. For it, the reference name is used to access this expression like a column reference, The evaluated state is set with an EvalNode which is an annotated expression. {@link #getTarget(String)} returns EvalNodes by a reference name.

    Column rightExpr = EvalTreeUtil.findAllColumnRefs(joinCondition.getRightExpr()).get(0);


    // 0 - left table, 1 - right table
    String [] relationNames = new String[2];


    NamedExprsManager namedExprsMgr = block.getNamedExprsManager();
    if (leftExpr.hasQualifier()) {
      relationNames[0] = leftExpr.getQualifier();
    } else {
      if (namedExprsMgr.isAliasedName(leftExpr.getSimpleName())) {
        String columnName = namedExprsMgr.getOriginalName(leftExpr.getSimpleName());
        String qualifier = CatalogUtil.extractQualifier(columnName);
        relationNames[0] = qualifier;
      } else {
        throw new PlanningException("Cannot expect a referenced relation: " + leftExpr);
      }
    }


    if (rightExpr.hasQualifier()) {
      relationNames[1] = rightExpr.getQualifier();
    } else {
      if (namedExprsMgr.isAliasedName(rightExpr.getSimpleName())) {
        String columnName = namedExprsMgr.getOriginalName(rightExpr.getSimpleName());
        String qualifier = CatalogUtil.extractQualifier(columnName);
        relationNames[1] = qualifier;
      } else {
        throw new PlanningException("Cannot expect a referenced relation: " + rightExpr);
      }

Examples of org.apache.tajo.engine.planner.NamedExprsManager$UnevaluatedIterator

Related Classes of org.apache.tajo.engine.planner.NamedExprsManager$UnevaluatedIterator