Field Detail

• rightOuterJoin

  private boolean rightOuterJoin

• transformed

  private boolean transformed

Constructor Detail

• HalfOuterJoinNode

  HalfOuterJoinNode​(ResultSetNode leftResult,
                    ResultSetNode rightResult,
                    ValueNode onClause,
                    ResultColumnList usingClause,
                    boolean rightOuterJoin,
                    java.util.Properties tableProperties,
                    ContextManager cm)
             throws StandardException

  Constructor for a HalfOuterJoinNode.

  Parameters:

  leftResult - The ResultSetNode on the left side of this join

  rightResult - The ResultSetNode on the right side of this join

  onClause - The ON clause

  usingClause - The USING clause

  rightOuterJoin - Whether or not this node represents a user specified right outer join

  tableProperties - Properties list associated with the table

  cm - The context manager

  Throws:

  StandardException - Thrown on error

Method Detail

• pushOptPredicate

  public boolean pushOptPredicate​(OptimizablePredicate optimizablePredicate)
                           throws StandardException

  Description copied from interface: Optimizable
  Push an OptimizablePredicate down, if this node accepts it.

  Specified by:

  pushOptPredicate in interface Optimizable

  Overrides:

  pushOptPredicate in class JoinNode

  Parameters:

  optimizablePredicate - OptimizablePredicate to push down.

  Returns:

  Whether or not the predicate was pushed down.

  Throws:

  StandardException - Thrown on error

  See Also:

  Optimizable.pushOptPredicate(org.apache.derby.iapi.sql.compile.OptimizablePredicate)

• toString

  public java.lang.String toString()

  Convert this object to a String. See comments in QueryTreeNode.java for how this should be done for tree printing.

  Overrides:

  toString in class TableOperatorNode

  Returns:

  This object as a String

• preprocess

  ResultSetNode preprocess​(int numTables,
                           GroupByList gbl,
                           FromList fromList)
                    throws StandardException

  Put a ProjectRestrictNode on top of each FromTable in the FromList. ColumnReferences must continue to point to the same ResultColumn, so that ResultColumn must percolate up to the new PRN. However, that ResultColumn will point to a new expression, a VirtualColumnNode, which points to the FromTable and the ResultColumn that is the source for the ColumnReference. (The new PRN will have the original of the ResultColumnList and the ResultColumns from that list. The FromTable will get shallow copies of the ResultColumnList and its ResultColumns. ResultColumn.expression will remain at the FromTable, with the PRN getting a new VirtualColumnNode for each ResultColumn.expression.) We then project out the non-referenced columns. If there are no referenced columns, then the PRN's ResultColumnList will consist of a single ResultColumn whose expression is 1.

  Overrides:

  preprocess in class JoinNode

  Parameters:

  numTables - Number of tables in the DML Statement

  gbl - The group by list, if any

  fromList - The from list, if any

  Returns:

  The generated ProjectRestrictNode atop the original FromTable.

  Throws:

  StandardException - Thrown on error

• pushExpressions

  void pushExpressions​(PredicateList outerPredicateList)
                throws StandardException

  Push expressions down to the first ResultSetNode which can do expression evaluation and has the same referenced table map. RESOLVE - This means only pushing down single table expressions to DistinctNodes today. Once we have a better understanding of how the optimizer will work, we can push down join clauses.

  Overrides:

  pushExpressions in class JoinNode

  Parameters:

  outerPredicateList - The PredicateList from the outer RS.

  Throws:

  StandardException - Thrown on error

• LOJ_reorderable

  boolean LOJ_reorderable​(int numTables)
                   throws StandardException

  This method recursively:

  • determines if this part of the query tree is a compound OJ of the shape required for reordering and if so,
  • does a reordering.

  
      OJ1  pT1T2                      OJ1  pT2T3
     /  \                             / \
    /    \                 can       /   t3
   t1    OJ2 pT2T3       reorder    /
         /  \              to      OJ2  pT1T2
        /    \                    /   \
       t2    t3                  /     \
                               t1     t2
  
   where pR1R2 is a null-rejecting predicate which references the schema
   of joinee R1 and R2, cf. terminology explanation in #isNullRejecting.
   
  
   OJ1 represents this before and after the reordering.
   

  The join predicates are assumed to be in CNF form.

  Note: Present implementation limitations

  • Only left outer joins are considered, i.e. both OJs in diagram above must be LOJ.
  • Top left side must be a base table (t1 above). The bottow right side (t3 above) may be another OJ, so reordering can happen recursively.

  Overrides:

  LOJ_reorderable in class JoinNode

  Parameters:

  numTables - number of tables involved (needed to right size the bitmaps)

  Returns:

  boolean true if any reordering took place at this level or deeper so caller can know whether rebinding may be necessary

  Throws:

  StandardException - standard error policy

• isNullRejecting

  private boolean isNullRejecting​(ValueNode joinClause,
                                  JBitSet leftTableMap,
                                  JBitSet rightTableMap)
                           throws StandardException

  Tests pRiRj in the sense of Galindo-Legaria et al: Outerjoin Simplification and Reordering for Query Optimization, ACM Transactions on Database Systems, Vol. 22, No. 1, March 1997, Pages 43-74: "The set of attributes referenced by a predicate p is called the schema of p, and denoted sch(p). As a notational convention, we annotate predicates to reflect their schema. If sch(p) includes attributes of both Ri, Rj and only those relations, we can write the predicate as pRiRj. If a null-valued column is compared in a predicate that contains no OR connectives, the predicate evaluates to undefined, and the tuple is rejected. The relops satisfy this criterion.

  To simplify analysis, we only accept predicates of the form:

   X relop Y [and .. and X-n relop Y-n]
   

  At least one of the relops should reference both leftTableMap and rightTableMap, so that we know that sch(p) includes attributes of both Ri, Rj. I.e.

  X should be a table in leftTableMap, and Y should be a table in rightTableMap.

  or X should be a table in rightTableMap, and Y should be a table in leftTableMap.

  Parameters:

  joinClause - The join clause (i.e. predicate) we want to check

  leftTableMap - a bit map representing the tables expected for the predicate (logical left)

  rightTableMap - a bit map representing the tables expected for the predicate (logical right)

  Returns:

  true if the joinClause has at least one relop that references both leftTableMap and rightTableMap

  Throws:

  StandardException - standard exception policy

• LOJ_bindResultColumns

  boolean LOJ_bindResultColumns​(boolean anyChange)
                         throws StandardException

  Throws:

  StandardException

• transformOuterJoins

  FromTable transformOuterJoins​(ValueNode predicateTree,
                                int numTables)
                         throws StandardException

  Transform any Outer Join into an Inner Join where applicable. (Based on the existence of a null intolerant predicate on the inner table.)

  Overrides:

  transformOuterJoins in class JoinNode

  Parameters:

  predicateTree - The predicate tree for the query block

  Returns:

  The new tree top (OuterJoin or InnerJoin).

  Throws:

  StandardException - Thrown on error

• adjustNumberOfRowsReturned

  protected void adjustNumberOfRowsReturned​(CostEstimate costEstimate)

  Description copied from class: JoinNode
  Some types of joins (e.g. outer joins) will return a different number of rows than is predicted by optimizeIt() in JoinNode. So, adjust this value now. This method does nothing for most join types.

  Overrides:

  adjustNumberOfRowsReturned in class JoinNode

  See Also:

  JoinNode.adjustNumberOfRowsReturned(org.apache.derby.iapi.sql.compile.CostEstimate)

• generate

  void generate​(ActivationClassBuilder acb,
                MethodBuilder mb)
         throws StandardException

  Generate the code for an inner join node.

  Overrides:

  generate in class JoinNode

  Parameters:

  acb - The ActivationClassBuilder for the class being built

  mb - The method for the generated code to go into

  Throws:

  StandardException - Thrown on error

• addOuterJoinArguments

  int addOuterJoinArguments​(ActivationClassBuilder acb,
                            MethodBuilder mb)
                     throws StandardException

  Generate and add any arguments specifict to outer joins. Generate the methods (and add them as parameters) for returning an empty row from 1 or more sides of an outer join, if required. Pass whether or not this was originally a right outer join.

  Overrides:

  addOuterJoinArguments in class JoinNode

  Parameters:

  acb - The ActivationClassBuilder

  mb - the method the generate code is to go into return The args that have been added

  Throws:

  StandardException - Thrown on error

• getNumJoinArguments

  protected int getNumJoinArguments()

  Return the number of arguments to the join result set.

  Overrides:

  getNumJoinArguments in class JoinNode

• oneRowRightSide

  void oneRowRightSide​(ActivationClassBuilder acb,
                       MethodBuilder mb)

  Overrides:

  oneRowRightSide in class JoinNode

• getLogicalLeftResultSet

  ResultSetNode getLogicalLeftResultSet()

  Return the logical left result set for this qualified join node. (For RIGHT OUTER JOIN, the left is the right and the right is the left and the JOIN is the NIOJ).

  Overrides:

  getLogicalLeftResultSet in class JoinNode

• getLogicalRightResultSet

  ResultSetNode getLogicalRightResultSet()

  Return the logical right result set for this qualified join node. (For RIGHT OUTER JOIN, the left is the right and the right is the left and the JOIN is the NIOJ).

  Overrides:

  getLogicalRightResultSet in class JoinNode

• isRightOuterJoin

  boolean isRightOuterJoin()

  Return true if right outer join or false if left outer join Used to set Nullability correctly in JoinNode

• isJoinColumnForRightOuterJoin

  void isJoinColumnForRightOuterJoin​(ResultColumn rc)

  If this is a right outer join node with USING/NATURAL clause, then check if the passed ResultColumn is a join column. If yes, then ResultColumn should be marked such. DERBY-4631

  Overrides:

  isJoinColumnForRightOuterJoin in class FromTable

  See Also:

  isJoinColumnForRightOuterJoin(org.apache.derby.impl.sql.compile.ResultColumn)

• LOJgetNPReferencedTables

  JBitSet LOJgetNPReferencedTables​(int numTables)
                            throws StandardException

  Throws:

  StandardException

• LOJgetRPReferencedTables

  public JBitSet LOJgetRPReferencedTables​(int numTables)
                                   throws StandardException

  Throws:

  StandardException