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java.lang.Objectorg.apache.derby.impl.sql.compile.VTIDeferModPolicy
class VTIDeferModPolicy
This class applies a VTI modification deferral policy to a statement to see whether it should be deferred.
Field Summary | |
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private java.util.Hashtable |
columns
|
private DeferModification |
deferralControl
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private boolean |
deferred
|
private int |
statementType
|
private int |
tableNumber
|
Constructor Summary | |
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private |
VTIDeferModPolicy(FromVTI targetVTI,
java.lang.String[] columnNames,
DeferModification deferralControl,
int statementType)
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Method Summary | |
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static boolean |
deferIt(int statementType,
FromVTI targetVTI,
java.lang.String[] updateColumnNames,
QueryTreeNode source)
See if a VTI modification statement should be deferred. |
boolean |
skipChildren(Visitable node)
Method that is called to indicate whether we should skip all nodes below this node for traversal. |
boolean |
stopTraversal()
Method that is called to see if query tree traversal should be stopped before visiting all nodes. |
Visitable |
visit(Visitable node)
This is the default visit operation on a QueryTreeNode. |
boolean |
visitChildrenFirst(Visitable node)
Method that is called to see if visit() should be called on
the children of node before it is called on node itself. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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private boolean deferred
private DeferModification deferralControl
private int statementType
private int tableNumber
private java.util.Hashtable columns
Constructor Detail |
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private VTIDeferModPolicy(FromVTI targetVTI, java.lang.String[] columnNames, DeferModification deferralControl, int statementType)
Method Detail |
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public static boolean deferIt(int statementType, FromVTI targetVTI, java.lang.String[] updateColumnNames, QueryTreeNode source) throws StandardException
statementType
- DeferModification.INSERT_STATEMENT, UPDATE_STATEMENT, or DELETE_STATEMENTtargetVTI
- The target VTIupdateColumnNames
- The list of columns being updated, null if this is not an update statementsource
-
StandardException
public Visitable visit(Visitable node) throws StandardException
Visitor
Visitors will overload this method by implementing a version with a signature that matches a specific type of node. For example, if I want to do something special with aggregate nodes, then that Visitor will implement a visit(AggregateNode node) method which does the aggregate specific processing.
visit
in interface Visitor
node
- the node to process
StandardException
- may be throw an error
as needed by the visitor (i.e. may be a normal error
if a particular node is found, e.g. if checking
a group by, we don't expect to find any ColumnReferences
that aren't under an AggregateNode -- the easiest
thing to do is just throw an error when we find the
questionable node).public boolean stopTraversal()
Visitor
stopTraversal
in interface Visitor
public boolean skipChildren(Visitable node)
Visitor
Differs from stopTraversal() in that it only affects subtrees, rather than the entire traversal.
skipChildren
in interface Visitor
node
- the node to process
public boolean visitChildrenFirst(Visitable node)
Visitor
visit()
should be called on
the children of node
before it is called on node
itself.
If this method always returns true
, the visitor will walk the
tree bottom-up. If it always returns false
, the tree is visited
top-down.
visitChildrenFirst
in interface Visitor
node
- the top node of a sub-tree about to be visited
true
if node
's children should be visited
before node
, false
otherwise
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