Class VTIDeferModPolicy

  • All Implemented Interfaces:
    Visitor

    class VTIDeferModPolicy
    extends java.lang.Object
    implements Visitor
    This class applies a VTI modification deferral policy to a statement to see whether it should be deferred.
    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      private VTIDeferModPolicy​(FromVTI targetVTI, java.lang.String[] columnNames, DeferModification deferralControl, int statementType)  
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      static boolean deferIt​(int statementType, FromVTI targetVTI, java.lang.String[] updateColumnNames, QueryTreeNode source)
      See if a VTI modification statement should be deferred.
      boolean skipChildren​(Visitable node)
      Method that is called to indicate whether we should skip all nodes below this node for traversal.
      boolean stopTraversal()
      Method that is called to see if query tree traversal should be stopped before visiting all nodes.
      Visitable visit​(Visitable node)
      This is the default visit operation on a QueryTreeNode.
      boolean visitChildrenFirst​(Visitable node)
      Method that is called to see if visit() should be called on the children of node before it is called on node itself.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Field Detail

      • deferred

        private boolean deferred
      • statementType

        private int statementType
      • tableNumber

        private int tableNumber
      • columns

        private final java.util.HashSet<java.lang.String> columns
    • Constructor Detail

      • VTIDeferModPolicy

        private VTIDeferModPolicy​(FromVTI targetVTI,
                                  java.lang.String[] columnNames,
                                  DeferModification deferralControl,
                                  int statementType)
    • Method Detail

      • deferIt

        public static boolean deferIt​(int statementType,
                                      FromVTI targetVTI,
                                      java.lang.String[] updateColumnNames,
                                      QueryTreeNode source)
                               throws StandardException
        See if a VTI modification statement should be deferred.
        Parameters:
        statementType - DeferModification.INSERT_STATEMENT, UPDATE_STATEMENT, or DELETE_STATEMENT
        targetVTI - The target VTI
        updateColumnNames - The list of columns being updated, null if this is not an update statement
        source -
        Throws:
        StandardException
      • visit

        public Visitable visit​(Visitable node)
                        throws StandardException
        Description copied from interface: Visitor
        This is the default visit operation on a QueryTreeNode. It just returns the node. This will typically suffice as the default visit operation for most visitors unless the visitor needs to count the number of nodes visited or something like that.

        Visitors will overload this method by implementing a version with a signature that matches a specific type of node. For example, if I want to do something special with aggregate nodes, then that Visitor will implement a visit(AggregateNode node) method which does the aggregate specific processing.

        Specified by:
        visit in interface Visitor
        Parameters:
        node - the node to process
        Returns:
        a query tree node. Often times this is the same node that was passed in, but Visitors that replace nodes with other nodes will use this to return the new replacement node.
        Throws:
        StandardException - may be throw an error as needed by the visitor (i.e. may be a normal error if a particular node is found, e.g. if checking a group by, we don't expect to find any ColumnReferences that aren't under an AggregateNode -- the easiest thing to do is just throw an error when we find the questionable node).
      • stopTraversal

        public boolean stopTraversal()
        Description copied from interface: Visitor
        Method that is called to see if query tree traversal should be stopped before visiting all nodes. Useful for short circuiting traversal if we already know we are done.
        Specified by:
        stopTraversal in interface Visitor
        Returns:
        true/false
      • skipChildren

        public boolean skipChildren​(Visitable node)
        Description copied from interface: Visitor
        Method that is called to indicate whether we should skip all nodes below this node for traversal. Useful if we want to effectively ignore/prune all branches under a particular node.

        Differs from stopTraversal() in that it only affects subtrees, rather than the entire traversal.

        Specified by:
        skipChildren in interface Visitor
        Parameters:
        node - the node to process
        Returns:
        true/false
      • visitChildrenFirst

        public boolean visitChildrenFirst​(Visitable node)
        Description copied from interface: Visitor
        Method that is called to see if visit() should be called on the children of node before it is called on node itself. If this method always returns true, the visitor will walk the tree bottom-up. If it always returns false, the tree is visited top-down.
        Specified by:
        visitChildrenFirst in interface Visitor
        Parameters:
        node - the top node of a sub-tree about to be visited
        Returns:
        true if node's children should be visited before node, false otherwise