Package edu.caltech.nanodb.plannodes

Class RenameNode

  • All Implemented Interfaces:
    java.lang.Cloneable
    public class RenameNode
extends PlanNode
    This plan-node implements the Rename relational algebra operation, for either renaming a table in a query, or assigning a table-name to a derived relation. Note that at present, it is not possible to rename individual columns. That should be done with the ProjectNode instead.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private static org.apache.logging.log4j.Logger logger
      A logging object for reporting anything interesting that happens.
      private java.lang.String resultTableName
      The result table-name to use in the output schema of this plan-node.

    • Constructor Summary

      Constructors 
      Constructor Description
      RenameNode​(PlanNode subplan, java.lang.String resultTableName)  

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void cleanUp()
      Perform any necessary clean up tasks.
      boolean equals​(java.lang.Object obj)
      Checks if the argument is a plan node tree with the same structure, but not necesarily the same references.
      Tuple getNextTuple()
      Gets the next tuple that fulfills the conditions for this plan node.
      int hashCode()
      Computes the hash-code of a plan-node, including any sub-plans of this plan.
      void initialize()
      Does any initialization the node might need, including setting up the node's execution environment.
      void markCurrentPosition()
      Marks the current tuple in the tuple-stream produced by this node.
      void prepare()
      This method is responsible for computing critical details about the plan node, such as the schema of the results that are produced, the estimated cost of evaluating the plan node (and its children), and statistics describing the results produced by the plan node.
      boolean requiresLeftMarking()
      This method reports whether this plan node requires the left child to support marking for proper evaluation.
      boolean requiresRightMarking()
      This method reports whether this plan node requires the right child to support marking for proper evaluation.
      void resetToLastMark()
      Resets the node's tuple-stream to the most recently marked position.
      java.util.List<OrderByExpression> resultsOrderedBy()
      If the results are ordered in some way, this method returns a collection of expressions specifying what columns or expressions the results are ordered by.
      boolean supportsMarking()
      This method reports whether this plan node supports marking a certain point in the tuple-stream so that processing can return to that point as needed.
      java.lang.String toString()
      Reports this node and its vital parameters as a string.

      • Methods inherited from class java.lang.Object

        finalize, getClass, notify, notifyAll, wait, wait, wait

    • Field Detail

      • logger

        private static org.apache.logging.log4j.Logger logger
        A logging object for reporting anything interesting that happens.

      • resultTableName

        private java.lang.String resultTableName
        The result table-name to use in the output schema of this plan-node.

    • Constructor Detail

      • RenameNode

        public RenameNode​(PlanNode subplan,
                  java.lang.String resultTableName)

    • Method Detail

      • resultsOrderedBy

        public java.util.List<OrderByExpression> resultsOrderedBy()
        Description copied from class: PlanNode
        If the results are ordered in some way, this method returns a collection of expressions specifying what columns or expressions the results are ordered by. If the results are not ordered then this method may return either an empty list or a null value.

        When this method returns a list of ordering expressions, the order of the expressions themselves also matters. The entire set of results will be ordered by the first expression; rows with the same value for the first expression will be ordered by the second expression; etc.

        Specified by:
        resultsOrderedBy in class PlanNode
        Returns:
        If the plan node produces ordered results, this will be a list of objects specifying the ordering. If the node doesn't produce ordered results then the return-value will either be an empty list or it will be null.

      • supportsMarking

        public boolean supportsMarking()
        Description copied from class: PlanNode
        This method reports whether this plan node supports marking a certain point in the tuple-stream so that processing can return to that point as needed.
        Overrides:
        supportsMarking in class PlanNode
        Returns:
        true if the node supports position marking, false otherwise.

      • requiresLeftMarking

        public boolean requiresLeftMarking()
        Description copied from class: PlanNode
        This method reports whether this plan node requires the left child to support marking for proper evaluation.
        Overrides:
        requiresLeftMarking in class PlanNode
        Returns:
        true if the node requires that its left child supports marking, false otherwise.

      • requiresRightMarking

        public boolean requiresRightMarking()
        Description copied from class: PlanNode
        This method reports whether this plan node requires the right child to support marking for proper evaluation.
        Overrides:
        requiresRightMarking in class PlanNode
        Returns:
        true if the node requires that its right child supports marking, false otherwise.

      • prepare

        public void prepare()
        Description copied from class: PlanNode
        This method is responsible for computing critical details about the plan node, such as the schema of the results that are produced, the estimated cost of evaluating the plan node (and its children), and statistics describing the results produced by the plan node.
        Specified by:
        prepare in class PlanNode

      • initialize

        public void initialize()
        Description copied from class: PlanNode
        Does any initialization the node might need, including setting up the node's execution environment. Subclasses of PlanNode can extend this method to perform other kinds of initialization, but they must be sure to call their parent class' implementation as well.
        Overrides:
        initialize in class PlanNode

      • getNextTuple

        public Tuple getNextTuple()
        Description copied from class: PlanNode
        Gets the next tuple that fulfills the conditions for this plan node. If the node has a child, it should call getNextTuple() on the child. If the node is a leaf, the tuple comes from some external source such as a table file, the network, etc.
        Specified by:
        getNextTuple in class PlanNode
        Returns:
        the next tuple to be generated by this plan, or null if the plan has finished generating plan nodes.

      • markCurrentPosition

        public void markCurrentPosition()
                         throws java.lang.UnsupportedOperationException
        Description copied from class: PlanNode
        Marks the current tuple in the tuple-stream produced by this node. The PlanNode.resetToLastMark() method can be used to return to this tuple. Note that only one marker can be set in the tuple-stream at a time.
        Overrides:
        markCurrentPosition in class PlanNode
        Throws:
        java.lang.UnsupportedOperationException - if the node does not support marking.

      • resetToLastMark

        public void resetToLastMark()
        Description copied from class: PlanNode
        Resets the node's tuple-stream to the most recently marked position. Note that only one marker can be set in the tuple-stream at a time.
        Overrides:
        resetToLastMark in class PlanNode

      • cleanUp

        public void cleanUp()
        Description copied from class: PlanNode
        Perform any necessary clean up tasks. This should probably be called when we are done with this plan node.
        Specified by:
        cleanUp in class PlanNode

      • toString

        public java.lang.String toString()
        Description copied from class: PlanNode
        Reports this node and its vital parameters as a string.
        Specified by:
        toString in class PlanNode
        Returns:
        the node in string format.

      • equals

        public boolean equals​(java.lang.Object obj)
        Description copied from class: PlanNode
        Checks if the argument is a plan node tree with the same structure, but not necesarily the same references.
        Specified by:
        equals in class PlanNode
        Parameters:
        obj - the object to which we are comparing

      • hashCode

        public int hashCode()
        Description copied from class: PlanNode
        Computes the hash-code of a plan-node, including any sub-plans of this plan. This method is used to see if two plan nodes (or subtrees) might be equal.
        Specified by:
        hashCode in class PlanNode
        Returns:
        the hash code for the plan node and any subnodes it may contain.