pack-priv Class UnionNode

Overrides org.apache.derby.impl.sql.compile.ResultSetNode.enhanceRCLForInsert.

Make the RCL of this node match the target node for the insert. If this node represents a table constructor (a VALUES clause), we replace the RCL with an enhanced one if necessary, and recursively enhance the RCL of each child node. For table constructors, we also need to check that we don't attempt to override auto-increment columns in each child node (checking the top-level RCL isn't sufficient since a table constructor may contain the DEFAULT keyword, which makes it possible to specify a column without overriding its value). If this node represents a regular UNION, put a ProjectRestrictNode on top of this node and enhance the RCL in that node.

Parameters

target:InsertNode

Doc from org.apache.derby.impl.sql.compile.ResultSetNode.enhanceRCLForInsert.

the target node for the insert

inOrder:boolean

Doc from org.apache.derby.impl.sql.compile.ResultSetNode.enhanceRCLForInsert.

are source cols in same order as target cols?

colMap:int[]

Doc from org.apache.derby.impl.sql.compile.ResultSetNode.enhanceRCLForInsert.

int array representation of correspondence between RCLs - colmap[i] = -1 -> missing in current RCL colmap[i] = j -> targetRCL(i) <-> thisRCL(j+1)

Returns:ResultSetNode

Doc from org.apache.derby.impl.sql.compile.ResultSetNode.enhanceRCLForInsert.

a node that replaces this node and whose RCL matches the target RCL. May return this node if no changes to the RCL are needed, or if the RCL is modified in-place.

Annotations

@Override

Exceptions

StandardException:

Doc from org.apache.derby.impl.sql.compile.ResultSetNode.enhanceRCLForInsert.

Thrown on error

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

Generate the code for this UnionNode.

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.FromTable.getFinalCostEstimate.

Doc from org.apache.derby.impl.sql.compile.FromTable.getFinalCostEstimate.

Get the final CostEstimate for this FromTable.

Returns:CostEstimate

The final CostEstimate for this UnionNode, which is the sum of the two child costs.

Annotations

@Override

See Also

Get the final CostEstimate for this UnionNode.

Implements abstract org.apache.derby.impl.sql.compile.SetOperatorNode.getOperatorName.

Returns:String

Doc from org.apache.derby.impl.sql.compile.SetOperatorNode.getOperatorName.

the operator name: "UNION", "INTERSECT", or "EXCEPT"

Mark this as the top node of a table constructor.

Overrides org.apache.derby.impl.sql.compile.TableOperatorNode.modifyAccessPaths.

Doc from org.apache.derby.impl.sql.compile.ResultSetNode.modifyAccessPaths.

Modify the access paths according to the decisions the optimizer made. This can include adding project/restrict nodes, index-to-base-row nodes, etc.

Returns:ResultSetNode

The modified query tree

Annotations

@Override

Exceptions

StandardException:

Thrown on error

See Also

ResultSetNode#modifyAccessPaths

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

DERBY-649: Handle pushing predicates into UnionNodes. It is possible to push single table predicates that are binaryOperations or inListOperations. Predicates of the form or IN are currently handled. Since these predicates would allow optimizer to pick available indices, pushing them provides maximum benifit. It should be possible to expand this logic to cover more cases. Even pushing expressions (like a+b = 10) into SELECTs would improve performance, even if they don't allow use of index. It would mean evaluating expressions closer to data and hence could avoid sorting or other overheads that UNION may require. Note that the predicates are not removed after pushing. This is to ensure if pushing is not possible or only partially feasible.

Parameters

predicateList:PredicateList

List of single table predicates to push

Annotations

@Override

Exceptions

StandardException:

Thrown on error

Overrides org.apache.derby.impl.sql.compile.TableOperatorNode.rejectParameters.

Check for (and reject) ? parameters directly under the ResultColumns. This is done for SELECT statements. Don't reject parameters that are in a table constructor - these are allowed, as long as the table constructor is in an INSERT statement or each column of the table constructor has at least one non-? column. The latter case is checked below, in bindExpressions().

Annotations

@Override

Exceptions

StandardException:

Thrown if a ? parameter found directly under a ResultColumn

Overrides org.apache.derby.impl.sql.compile.ResultSetNode.setTableConstructorTypes.

Set the type of column in the result column lists of each source of this union tree to the type in the given result column list (which represents the result columns for an insert). This is only for table constructors that appear in insert statements.

Parameters

typeColumns:ResultColumnList

The ResultColumnList containing the desired result types.

Annotations

@Override

Exceptions

StandardException:

Thrown on error

Tell whether this is a UNION for a table constructor.