net.sf.farrago.ddl
Class DdlAlterTableStructureStmt

java.lang.Object
  net.sf.farrago.ddl.DdlStmt
      net.sf.farrago.ddl.DdlReloadTableStmt
          net.sf.farrago.ddl.DdlAlterTableStructureStmt

All Implemented Interfaces:

DdlMultipleTransactionStmt, FarragoSessionDdlStmt

public class DdlAlterTableStructureStmt
extends DdlReloadTableStmt

DdlAlterTableStructureStmt represents an ALTER TABLE statement which adds/drops columns or changes their datatype, implying that stored tuples may need to be reshaped. Currently it can only handle addition of a new column at the end. It extends DdlRebuildTableStmt since the default implementation for the reshape is to rebuild the entire table by copying from the old structure to the new.

Version:

$Id: //open/dev/farrago/src/net/sf/farrago/ddl/DdlAlterTableStructureStmt.java#6 $

Author:

John Sichi

Field Summary

private CwmTable

origTable

Constructor Summary

DdlAlterTableStructureStmt(FarragoRepos repos, CwmTable table)

Method Summary

private RefObject	cloneRefObj(JmiModelGraph oldModelGraph, JmiModelGraph newModelGraph, RefObject oldObj) Clones an object from one repository to another, sort of.
void	completeAfterExecuteUnlocked(FarragoSessionDdlValidator ddlValidator, FarragoSession session, boolean success) Provides access to the repository after execution of the DDL.
private static void	deleteGrants(FarragoRepos repos, CwmModelElement element)
private static void	deleteModelElement(FarragoRepos repos, CwmModelElement element)
protected CwmTable	getOldTableStructureForIndexMap()
protected String	getReloadDml(SqlPrettyWriter writer) Generates the SQL to be used to reload the table.
void	prepForExecuteUnlocked(FarragoSessionDdlValidator ddlValidator, FarragoSession session) Provides access to the repository in preparation for the execution of DdlStmt.
void	preValidate(FarragoSessionDdlValidator ddlValidator) Called before generic validation.
static void	recover(FarragoRepos repos, CwmTable failedTable) Recovers after a problem (either execution failure or system crash) while a table was being altered.
protected void	recoverFromFailure(FarragoSessionDdlValidator ddlValidator, FarragoSession session) Called after an exception is thrown during the execution phase.
protected boolean	shouldRebuildIndexes(FarragoSessionDdlValidator ddlValidator) Determines whether statement execution should rebuild all indexes on the table.

Methods inherited from class net.sf.farrago.ddl.DdlReloadTableStmt

completeRequiresWriteTxn, executeUnlocked, getTable, setRecoveryRef, visit

Methods inherited from class net.sf.farrago.ddl.DdlStmt

getModelElement, isDropRestricted, postCommit, postExecute, preExecute, requiresCommit, runsAsDml

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.sf.farrago.session.FarragoSessionDdlStmt

getModelElement, isDropRestricted, postCommit, postExecute, preExecute, requiresCommit, runsAsDml

Field Detail

origTable

private CwmTable origTable

Constructor Detail

DdlAlterTableStructureStmt

public DdlAlterTableStructureStmt(FarragoRepos repos,
                                  CwmTable table)

Method Detail

cloneRefObj

private RefObject cloneRefObj(JmiModelGraph oldModelGraph,
                              JmiModelGraph newModelGraph,
                              RefObject oldObj)

Clones an object from one repository to another, sort of.

TODO jvs 4-Dec-2008: make this handle more cases generically and then promote it to JmiObjUtil.

Parameters:

oldModelGraph - model graph for the old repository

newModelGraph - model graph for the new repository

oldObj - object to be cloned

Returns:

result of cloning

prepForExecuteUnlocked

public void prepForExecuteUnlocked(FarragoSessionDdlValidator ddlValidator,
                                   FarragoSession session)

Description copied from interface: DdlMultipleTransactionStmt

Provides access to the repository in preparation for the execution of DdlStmt. This method is invoked within the context the original repository transaction for the DDL statement. Whether that transaction is a write transaction depends on the DDL statement being executed.

Specified by:

prepForExecuteUnlocked in interface DdlMultipleTransactionStmt

Overrides:

prepForExecuteUnlocked in class DdlReloadTableStmt

Parameters:

ddlValidator - DDL validator for this statement

See Also:

FarragoReposTxnContext

getOldTableStructureForIndexMap

protected CwmTable getOldTableStructureForIndexMap()

Overrides:

getOldTableStructureForIndexMap in class DdlReloadTableStmt

Returns:

the old table structure if the table structure is being altered, or null if no change is taking place

preValidate

public void preValidate(FarragoSessionDdlValidator ddlValidator)

Description copied from interface: FarragoSessionDdlStmt

Called before generic validation.

Specified by:

preValidate in interface FarragoSessionDdlStmt

Overrides:

preValidate in class DdlStmt

Parameters:

ddlValidator - the object validating this stmt

shouldRebuildIndexes

protected boolean shouldRebuildIndexes(FarragoSessionDdlValidator ddlValidator)

Description copied from class: DdlReloadTableStmt

Determines whether statement execution should rebuild all indexes on the table. Some ooptimzed reloads may be able to avoid this.

Overrides:

shouldRebuildIndexes in class DdlReloadTableStmt

Parameters:

ddlValidator - validator for this DDL statement

Returns:

whether to rebuild

recover

public static void recover(FarragoRepos repos,
                           CwmTable failedTable)

Recovers after a problem (either execution failure or system crash) while a table was being altered.

Parameters:

repos - repository containing table definition

failedTable - table to recover

deleteModelElement

private static void deleteModelElement(FarragoRepos repos,
                                       CwmModelElement element)

deleteGrants

private static void deleteGrants(FarragoRepos repos,
                                 CwmModelElement element)

recoverFromFailure

protected void recoverFromFailure(FarragoSessionDdlValidator ddlValidator,
                                  FarragoSession session)

Description copied from class: DdlReloadTableStmt

Called after an exception is thrown during the execution phase.

Overrides:

recoverFromFailure in class DdlReloadTableStmt

Parameters:

ddlValidator - DDL validator for this statement

session - reentrant Farrago session

completeAfterExecuteUnlocked

public void completeAfterExecuteUnlocked(FarragoSessionDdlValidator ddlValidator,
                                         FarragoSession session,
                                         boolean success)

Description copied from interface: DdlMultipleTransactionStmt

Provides access to the repository after execution of the DDL. Typically implementations of this method modify the repository to store the results of DdlMultipleTransactionStmt.executeUnlocked(FarragoSessionDdlValidator, FarragoSession). This method is invoked in a locked repository transaction. The method DdlMultipleTransactionStmt.completeRequiresWriteTxn() controls whether the transaction read-only or not. This method may not access and/or modify repository objects loaded in a previous transaction unless they are reloaded by MOF ID. Be aware that objects may have been modified by another session unless some external mechanism (for instance, the "table-in-use" collection) guarantees that they have not been modified by another statement.

Note that any repository modifications made during the execution of this method will not be post-processed by DdlValidator. For instance, DdlValidator.checkJmiConstraints(RefObject) is not called, and therefore any mandatory default primitives are not automatically set, which will cause errors later if the attributes have not been explicitly initialized. See JmiObjUtil.setMandatoryPrimitiveDefaults(javax.jmi.reflect.RefObject).

Specified by:

completeAfterExecuteUnlocked in interface DdlMultipleTransactionStmt

Overrides:

completeAfterExecuteUnlocked in class DdlReloadTableStmt

Parameters:

ddlValidator - DDL validator for this statement

session - reentrant Farrago session which may be used to execute DML statements

success - whether the execution succeeded; detection of failure can be used to recover

getReloadDml

protected String getReloadDml(SqlPrettyWriter writer)

Description copied from class: DdlReloadTableStmt

Generates the SQL to be used to reload the table. Note that this is called from prepForExecuteUnlocked, so it is allowed to call getTable().

Specified by:

getReloadDml in class DdlReloadTableStmt

Parameters:

writer - writer to uses for generating SQL

Returns:

DML statement which accomplishes reload