Package org.apache.calcite.examples

Class RelBuilderExample

  • public class RelBuilderExample
extends java.lang.Object
    Example that uses RelBuilder to create various relational expressions.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private boolean verbose  

    • Constructor Summary

      Constructors 
      Constructor Description
      RelBuilderExample​(boolean verbose)  

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      private org.apache.calcite.tools.RelBuilder doExample​(org.apache.calcite.tools.RelBuilder builder, int i)  
      private org.apache.calcite.tools.RelBuilder example0​(org.apache.calcite.tools.RelBuilder builder)
      Creates a relational expression for a table scan.
      private org.apache.calcite.tools.RelBuilder example1​(org.apache.calcite.tools.RelBuilder builder)
      Creates a relational expression for a table scan.
      private org.apache.calcite.tools.RelBuilder example2​(org.apache.calcite.tools.RelBuilder builder)
      Creates a relational expression for a table scan and project.
      private org.apache.calcite.tools.RelBuilder example3​(org.apache.calcite.tools.RelBuilder builder)
      Creates a relational expression for a table scan, aggregate, filter.
      private org.apache.calcite.tools.RelBuilder example4​(org.apache.calcite.tools.RelBuilder builder)
      Sometimes the stack becomes so deeply nested it gets confusing.
      static void main​(java.lang.String[] args)  
      void runAllExamples()  

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Field Detail

      • verbose

        private final boolean verbose

    • Constructor Detail

      • RelBuilderExample

        public RelBuilderExample​(boolean verbose)

    • Method Detail

      • main

        public static void main​(java.lang.String[] args)

      • runAllExamples

        public void runAllExamples()

      • doExample

        private org.apache.calcite.tools.RelBuilder doExample​(org.apache.calcite.tools.RelBuilder builder,
                                                      int i)

      • example0

        private org.apache.calcite.tools.RelBuilder example0​(org.apache.calcite.tools.RelBuilder builder)
        Creates a relational expression for a table scan. It is equivalent to 
        SELECT *
 FROM emp

      • example1

        private org.apache.calcite.tools.RelBuilder example1​(org.apache.calcite.tools.RelBuilder builder)
        Creates a relational expression for a table scan. It is equivalent to 
        SELECT *
 FROM emp

      • example2

        private org.apache.calcite.tools.RelBuilder example2​(org.apache.calcite.tools.RelBuilder builder)
        Creates a relational expression for a table scan and project. It is equivalent to 
        SELECT deptno, ename
 FROM emp

      • example3

        private org.apache.calcite.tools.RelBuilder example3​(org.apache.calcite.tools.RelBuilder builder)
        Creates a relational expression for a table scan, aggregate, filter. It is equivalent to 
        SELECT deptno, count(*) AS c, sum(sal) AS s
 FROM emp
 GROUP BY deptno
 HAVING count(*) > 10

      • example4

        private org.apache.calcite.tools.RelBuilder example4​(org.apache.calcite.tools.RelBuilder builder)
        Sometimes the stack becomes so deeply nested it gets confusing. To keep things straight, you can remove expressions from the stack. For example, here we are building a bushy join: 
                        join
              /      \
         join          join
       /      \      /      \
 CUSTOMERS ORDERS LINE_ITEMS PRODUCTS

        We build it in three stages. Store the intermediate results in variables `left` and `right`, and use `push()` to put them back on the stack when it is time to create the final `Join`.