org.apache.derby.impl.sql.compile
Class DefaultVTIModDeferPolicy

java.lang.Object
  org.apache.derby.impl.sql.compile.DefaultVTIModDeferPolicy

All Implemented Interfaces:

DeferModification

 class DefaultVTIModDeferPolicy
extends java.lang.Object
implements DeferModification

This class implements the default policy for defering modifications to virtual tables.

Field Summary

private java.lang.String	targetVTIClassName
private boolean	VTIResultSetIsSensitive

Fields inherited from interface org.apache.derby.vti.DeferModification

DELETE_STATEMENT, INSERT_STATEMENT, UPDATE_STATEMENT

Constructor Summary

DefaultVTIModDeferPolicy(java.lang.String targetVTIClassName, boolean VTIResultSetIsSensitive)

Method Summary

boolean	alwaysDefer(int statementType) This method is called during preparation of an insert, update, or delete statement with this VTI as the target.
boolean	columnRequiresDefer(int statementType, java.lang.String columnName, boolean inWhereClause) This method is called during preparation of an update or delete statement on the virtual table if getResultSetType() returns ResultSet.TYPE_SCROLL_SENSITIVE or TYPE_SCROLL_SENSITIVE and alwaysDefer( statementType) returns false.
void	modificationNotify(int statementType, boolean deferred) This VTI method is called by Derby when a VTI modification (insert, update, or delete) is executed.
boolean	subselectRequiresDefer(int statementType, java.lang.String VTIClassName) This method is called during preparation of an insert, update, or delete statement that has this virtual table as its target and that has a sub-select.
boolean	subselectRequiresDefer(int statementType, java.lang.String schemaName, java.lang.String tableName) This method is called during preparation of an insert, update, or delete statement that has this virtual table as its target and that has a sub-select.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

targetVTIClassName

private final java.lang.String targetVTIClassName

VTIResultSetIsSensitive

private final boolean VTIResultSetIsSensitive

Constructor Detail

DefaultVTIModDeferPolicy

DefaultVTIModDeferPolicy(java.lang.String targetVTIClassName,
                         boolean VTIResultSetIsSensitive)

Method Detail

alwaysDefer

public boolean alwaysDefer(int statementType)

Description copied from interface: DeferModification

This method is called during preparation of an insert, update, or delete statement with this VTI as the target. It indicates whether the statement should be deferred irregardless of the other clauses in the statement. If alwaysDefer returns true then the other methods in this interface are not called. (At least not for this statement type).

Specified by:

alwaysDefer in interface DeferModification

Parameters:

statementType - One of INSERT_STATEMENT, UPDATE_STATEMENT, DELETE_STATEMENT.

Returns:

true if the statement type should always be deferred on this VTI, false other criteria (see below) should be examined to determine whether to defer the modification.

See Also:

DeferModification.alwaysDefer(int)

columnRequiresDefer

public boolean columnRequiresDefer(int statementType,
                                   java.lang.String columnName,
                                   boolean inWhereClause)

Description copied from interface: DeferModification

This method is called during preparation of an update or delete statement on the virtual table if getResultSetType() returns ResultSet.TYPE_SCROLL_SENSITIVE or TYPE_SCROLL_SENSITIVE and alwaysDefer( statementType) returns false. ColumnRequiresDefer is called once for each column that is being updated, or each column in a DELETE where clause until it returns true or until all the columns have been exhausted.

Specified by:

columnRequiresDefer in interface DeferModification

Parameters:

statementType - UPDATE_STATEMENT or DELETE_STATEMENT.

columnName - the name of one of the columns being updated

inWhereClause - indicates whether the column also appears in the where clause

Returns:

true if the update must be deferred false if this column does not require a deferred update

See Also:

DeferModification.columnRequiresDefer(int, java.lang.String, boolean)

subselectRequiresDefer

public boolean subselectRequiresDefer(int statementType,
                                      java.lang.String schemaName,
                                      java.lang.String tableName)

Description copied from interface: DeferModification

This method is called during preparation of an insert, update, or delete statement that has this virtual table as its target and that has a sub-select. It is invoked once for each regular table in a sub-select, if it has not already been determined that the statement should be deferred or that the VTI does not support deferral.

Specified by:

subselectRequiresDefer in interface DeferModification

Parameters:

statementType - the statement type: INSERT_STATEMENT, UPDATE_STATEMENT, or DELETE_STATEMENT.

schemaName - the schema of the table in the sub-select.

tableName - the name of the table in the sub-select.

Returns:

true if the modification must be deferred false if this source table does not necessitate a deferred modification

See Also:

DeferModification.subselectRequiresDefer(int,String,String)

subselectRequiresDefer

public boolean subselectRequiresDefer(int statementType,
                                      java.lang.String VTIClassName)

Description copied from interface: DeferModification

This method is called during preparation of an insert, update, or delete statement that has this virtual table as its target and that has a sub-select. It is invoked once for each virtual table in the sub-select, if it has not already been determined that the statement should be deferred or that the VTI does not support deferral.

Specified by:

subselectRequiresDefer in interface DeferModification

Parameters:

statementType - the statement type: INSERT_STATEMENT, UPDATE_STATEMENT, or DELETE_STATEMENT.

VTIClassName - the name of the class implementing the VTI in the sub-select.

Returns:

true if the modification must be deferred false if this source table does not necessitate a deferred modification

See Also:

DeferModification.subselectRequiresDefer(int, String)

modificationNotify

public void modificationNotify(int statementType,
                               boolean deferred)

Description copied from interface: DeferModification

This VTI method is called by Derby when a VTI modification (insert, update, or delete) is executed. It is called after the VTI has been instantiated but before any rows are read, inserted, updated, or deleted.

Specified by:

modificationNotify in interface DeferModification

Parameters:

statementType - one of INSERT_STATEMENT, UPDATE_STATEMENT, or DELETE_STATEMENT

deferred - true if the modification will be deferred, false if not.