pack-priv Class HalfOuterJoinNode

Overrides org.apache.derby.impl.sql.compile.JoinNode.addOuterJoinArguments.

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.

Parameters

acb:ActivationClassBuilder

The ActivationClassBuilder

mb:MethodBuilder

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

Annotations

@Override

Exceptions

StandardException:

Thrown on error

Overrides org.apache.derby.impl.sql.compile.JoinNode.generate.

Generate the code for an inner join node.

Parameters

acb:ActivationClassBuilder

Doc from org.apache.derby.impl.sql.compile.QueryTreeNode.generate.

The ActivationClassBuilder for the class being built

mb:MethodBuilder

Doc from org.apache.derby.impl.sql.compile.QueryTreeNode.generate.

The method for the generated code to go into

Annotations

@Override

Exceptions

StandardException:

Thrown on error

Overrides org.apache.derby.impl.sql.compile.JoinNode.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).

Annotations

@Override

Overrides org.apache.derby.impl.sql.compile.JoinNode.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).

Annotations

@Override

Overrides org.apache.derby.impl.sql.compile.FromTable.isJoinColumnForRightOuterJoin.

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

Annotations

@Override

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

Overrides org.apache.derby.impl.sql.compile.JoinNode.LOJ_reorderable.

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.

Parameters

numTables:int

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

Returns:boolean

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

Annotations

@Override

Exceptions

StandardException:

standard error policy

Overrides org.apache.derby.impl.sql.compile.JoinNode.oneRowRightSide.

Annotations

@Override

Overrides org.apache.derby.impl.sql.compile.JoinNode.preprocess.

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.

Parameters

numTables:int

Number of tables in the DML Statement

gbl:GroupByList

The group by list, if any

fromList:FromList

The from list, if any

Returns:ResultSetNode

The generated ProjectRestrictNode atop the original FromTable.

Annotations

@Override

Exceptions

StandardException:

Thrown on error

Overrides org.apache.derby.impl.sql.compile.JoinNode.pushExpressions.

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.

Parameters

outerPredicateList:PredicateList

The PredicateList from the outer RS.

Annotations

@Override

Exceptions

StandardException:

Thrown on error

Overrides org.apache.derby.impl.sql.compile.JoinNode.transformOuterJoins.

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

Parameters

predicateTree:ValueNode

The predicate tree for the query block

Returns:FromTable

The new tree top (OuterJoin or InnerJoin).

Annotations

@Override

Exceptions

StandardException:

Thrown on error