Class IndexToBaseRowNode

All Implemented Interfaces:
Optimizable, Visitable

class IndexToBaseRowNode extends FromTable
This node type translates an index row to a base row. It takes a FromBaseTable as its source ResultSetNode, and generates an IndexRowToBaseRowResultSet that takes a TableScanResultSet on an index conglomerate as its source.
  • Field Details

  • Constructor Details

  • Method Details

    • forUpdate

      public boolean forUpdate()
      Description copied from interface: Optimizable
      Return true if this is the target table of an update
      Specified by:
      forUpdate in interface Optimizable
      Overrides:
      forUpdate in class FromTable
      See Also:
    • getTrulyTheBestAccessPath

      public AccessPath getTrulyTheBestAccessPath()
      Description copied from interface: Optimizable
      Get the best access path overall for this Optimizable.
      Specified by:
      getTrulyTheBestAccessPath in interface Optimizable
      Overrides:
      getTrulyTheBestAccessPath in class FromTable
      See Also:
    • getCostEstimate

      CostEstimate getCostEstimate()
      Description copied from class: ResultSetNode
      Get the CostEstimate for this ResultSetNode.
      Overrides:
      getCostEstimate in class ResultSetNode
      Returns:
      The CostEstimate for this ResultSetNode.
    • getFinalCostEstimate

      CostEstimate getFinalCostEstimate()
      Description copied from class: FromTable
      Get the final CostEstimate for this FromTable.
      Overrides:
      getFinalCostEstimate in class FromTable
      Returns:
      The final CostEstimate for this FromTable, which is the costEstimate of trulyTheBestAccessPath if there is one. If there's no trulyTheBestAccessPath for this node, then we just return the value stored in costEstimate as a default.
    • isOrderedOn

      boolean isOrderedOn(ColumnReference[] crs, boolean permuteOrdering, List<FromBaseTable> fbtHolder) throws StandardException
      Return whether or not the underlying ResultSet tree is ordered on the specified columns. RESOLVE - This method currently only considers the outermost table of the query block.
      Overrides:
      isOrderedOn in class ResultSetNode
      Parameters:
      crs - The specified ColumnReference[]
      permuteOrdering - Whether or not the order of the CRs in the array can be permuted
      fbtHolder - List that is to be filled with the FromBaseTable
      Returns:
      Whether the underlying ResultSet tree is ordered on the specified column.
      Throws:
      StandardException - Thrown on error
    • generate

      void generate(ActivationClassBuilder acb, MethodBuilder mb) throws StandardException
      Generation of an IndexToBaseRowNode creates an IndexRowToBaseRowResultSet, which uses the RowLocation in the last column of an index row to get the row from the base conglomerate (heap).
      Overrides:
      generate in class QueryTreeNode
      Parameters:
      acb - The ActivationClassBuilder for the class being built
      mb - the method for the method to be built
      Throws:
      StandardException - Thrown on error
    • isOneRowResultSet

      boolean isOneRowResultSet() throws StandardException
      Return whether or not the underlying ResultSet tree will return a single row, at most. This is important for join nodes where we can save the extra next on the right side if we know that it will return at most 1 row.
      Overrides:
      isOneRowResultSet in class ResultSetNode
      Returns:
      Whether or not the underlying ResultSet tree will return a single row.
      Throws:
      StandardException - Thrown on error
    • isNotExists

      boolean isNotExists()
      Return whether or not the underlying FBT is for NOT EXISTS.
      Overrides:
      isNotExists in class ResultSetNode
      Returns:
      Whether or not the underlying FBT is for NOT EXISTS.
    • decrementLevel

      void decrementLevel(int decrement)
      Decrement (query block) level (0-based) for this FromTable. This is useful when flattening a subquery.
      Overrides:
      decrementLevel in class FromTable
      Parameters:
      decrement - The amount to decrement by.
    • updateTargetLockMode

      int updateTargetLockMode()
      Get the lock mode for the target of an update statement (a delete or update). The update mode will always be row for CurrentOfNodes. It will be table if there is no where clause.
      Overrides:
      updateTargetLockMode in class ResultSetNode
      Returns:
      The lock mode
      See Also:
    • adjustForSortElimination

      void adjustForSortElimination()
      Description copied from class: ResultSetNode
      Notify the underlying result set tree that the optimizer has chosen to "eliminate" a sort. Sort elimination can happen as part of preprocessing (see esp. SelectNode.preprocess(...)) or it can happen if the optimizer chooses an access path that inherently returns the rows in the correct order (also known as a "sort avoidance" plan). In either case we drop the sort and rely on the underlying result set tree to return its rows in the correct order. For most types of ResultSetNodes we automatically get the rows in the correct order if the sort was eliminated. One exception to this rule, though, is the case of an IndexRowToBaseRowNode, for which we have to disable bulk fetching on the underlying base table. Otherwise the index scan could return rows out of order if the base table is updated while the scan is "in progress" (i.e. while the result set is open). In order to account for this (and potentially other, similar issues in the future) this method exists to notify the result set node that it is expected to return rows in the correct order. The result set can then take necessary action to satsify this requirement--such as disabling bulk fetch in the case of IndexRowToBaseRowNode. All of that said, any ResultSetNodes for which we could potentially eliminate sorts should override this method accordingly. So we don't ever expect to get here.
      Overrides:
      adjustForSortElimination in class ResultSetNode
      See Also:
    • adjustForSortElimination

      void adjustForSortElimination(RequiredRowOrdering rowOrdering) throws StandardException
      Description copied from class: ResultSetNode
      Same goal as adjustForSortElimination above, but this version takes a RequiredRowOrdering to allow nodes to adjust based on the ORDER BY clause, if needed.
      Overrides:
      adjustForSortElimination in class ResultSetNode
      Throws:
      StandardException
      See Also:
    • getIndexColMapping

      private int[] getIndexColMapping()
      Fill in the column mapping for those columns coming from the index.
      Returns:
      The int[] with the mapping.
    • acceptChildren

      void acceptChildren(Visitor v) throws StandardException
      Accept the visitor for all visitable children of this node.
      Overrides:
      acceptChildren in class FromTable
      Parameters:
      v - the visitor
      Throws:
      StandardException - on error