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Oracle® Database Workspace Manager Developer's Guide
11g Release 1 (11.1)

B28396-03
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1 Introduction to Workspace Manager

Oracle Workspace Manager, often referred to as Workspace Manager, provides an infrastructure that enables applications to create workspaces and group different versions of table row values in different workspaces. Users are permitted to create new versions of data to update, while maintaining a copy of the old data. The ongoing results of the activity are stored persistently, assuring concurrency and consistency.

Applications that can benefit from Workspace Manager typically do one or more of the following operations:

Workspace Manager is also useful in managing long-transaction scenarios, where complex, long-duration database transactions can take days to complete, and multiple users must access the same database.

This chapter explains concepts and operations that you must understand to use Workspace Manager. It contains the following major sections:

For complete examples of Workspace Manager, see Section 1.17. However, you may want to read the rest of this chapter first, to understand the concepts that the examples illustrate.

Note:

Workspace Manager is installed by default in the Oracle seed database and any database created using the Database Configuration Assistant (DBCA). To use Workspace Manager in any other Oracle database, you must first perform the installation procedure described in Appendix A, "Installing Workspace Manager with Custom Databases".

1.1 Workspace Manager Overview

Workspace Manager enables you to version-enable one or more user tables in the database. When a table is version-enabled, all rows in the table can support multiple versions of the data. The versioning infrastructure is not visible to the users of the database, and application SQL statements for selecting, inserting, modifying, and deleting data continue to work in the usual way with version-enabled tables, although you cannot update a primary key column value in a version-enabled table. (Workspace Manager implements these capabilities by maintaining system views and creating INSTEAD OF triggers, as explained in Section 1.1.11; however, application developers and users do not need to see or interact with the views and triggers.)

After a table is version-enabled, users in a workspace automatically see the correct version of the record in which they are interested. If you no longer need a table to be version-enabled, you can disable versioning for the table.

A workspace is a virtual environment that one or more users can share to make changes to the data in the database. A workspace logically groups collections of new row versions from one or more version-enabled tables, and isolates these versions until they are explicitly merged with production data or discarded, thus providing maximum concurrency. Users can perform a variety of operations involving workspaces: go to, create, refresh, merge, roll back, remove, compress, alter, and other operations.

Users in a workspace always see a transactionally consistent view of the entire database; that is, they see changes made in their current workspace plus the rest of the data in the database as it existed either when the workspace was created or when the workspace was most recently refreshed with changes from the parent workspace. (Workspace hierarchy and parent and child workspaces are explained in Section 1.1.1.)

Workspace Manager automatically detects conflicts, which are differences in data values resulting from changes to the same row in a workspace and its parent workspace. You must resolve conflicts before merging changes from a workspace into its parent workspace. You can use workspace locks to avoid conflicts.

Savepoints are points in the workspace to which row changes in version-enabled tables can be rolled back, and to which users can go to see the database as it existed at that point. Savepoints are usually created in response to a business-related milestone, such as the completion of a design phase or the end of a billing period. (For more information about savepoints, see Section 1.1.2.)

The history option enables you to timestamp changes made to all rows in a version-enabled table and to save a copy of either all changes or only the most recent changes to each row. If you keep all changes (specifying the "without overwrite" history option) when version-enabling a table, you keep a persistent history of all changes made to all row versions, and enable users to go to any point in time to view the database as it existed from the perspective of that workspace.

Workspace Manager provides a comprehensive PL/SQL API that you can add to new and existing applications to manage workspaces, savepoints, history information, privileges, access modes, and Workspace Manager locks, and to detect and resolve conflicts. You can also perform many of these operations using the Oracle Enterprise Manager graphical user interface.

Another database object created by Workspace Manager is a database-wide system table that maps row versions to workspaces. This table is not visible to users.

1.1.1 Workspace Hierarchy

There can be a hierarchy of workspaces in the database. For example, a workspace can be a parent to one or more workspaces (child workspaces). By default, when a workspace is created, it is created from the topmost, or LIVE, database workspace. (Workspace names are case-sensitive, and the workspace name of the live database is spelled LIVE. The length of a workspace name must not exceed 30 characters, and the depth of the workspace hierarchy must not exceed 30 levels.) Users are included in a workspace by a GotoWorkspace operation.

Figure 1-1 shows a hierarchy of workspaces. Workspace1 and Workspace4 were formed off the LIVE database workspace; Workspace2 and Workspace3 were formed off Workspace1, and Workspace5 was formed off Workspace4. After Workspace1 was created, a user executed a GotoWorkspace operation specifying Workspace1, and then executed CreateWorkspace operations to create Workspace2 and Workspace3. A comparable sequence was followed with Workspace4 and Workspace5.

Figure 1-1 Workspace Tree

Description of Figure 1-1 follows
Description of "Figure 1-1 Workspace Tree"

See also Section 1.1.2.1 for a discussion of design issues in deciding whether to create a child workspace or a savepoint for certain needs

1.1.2 Using Savepoints

A savepoint is a point in the workspace to which data changes can be rolled back. Workspace Manager accomplishes the rollback by deleting the row versions that contain the unwanted changes.

An explicit savepoint is a savepoint that you create and name. You can later roll back changes in version-enabled tables to the savepoint, or you can go to the savepoint to view the state of the entire database (including versioned rows) at the time the savepoint was created. In Figure 1-2, SP1, SP2, SP3, and SP4 are explicit savepoints that were created in the workspaces indicated. (Savepoints are indicated by dashed lines in Figure 1-2.)

In addition, implicit savepoints are created automatically whenever a new workspace is created. An implicit savepoint is needed so that the users in the child workspace get a view of the database that is frozen at the time of the workspace creation. Thus, in Figure 1-2 two implicit savepoints (SPa and SPd) are created in the LIVE workspace corresponding to Workspace1 and Workspace4 creation; two implicit savepoints (SPb and SPc) are created in Workspace1 corresponding to Workspace2 and Workspace3 creation; and one implicit savepoint (SPe) is created in Workspace4 corresponding to Workspace5 creation.

Workspace Manager uses the name LATEST to designate a logical savepoint that refers to the latest version in the workspace. LATEST is often the default when a savepoint is an optional parameter for a DBMS_WM subprogram (procedure or function).

A removable savepoint is a savepoint that can be deleted by the CompressWorkspace, CompressWorkspaceTree, and DeleteSavepoint procedures. A savepoint is removable if either of the following applies:

  • It is an explicit savepoint.

  • It is an implicit savepoint that does not have any child dependencies.

1.1.2.1 Design Issue: Savepoint or Child Workspace?

A Workspace Manager design issue that you may face is whether to create a savepoint or a child workspace to "save" a project at a given point. Both a savepoint and a child workspace allow you to group a set of changes, compare changes in different row versions, and roll back a set of changes. However, creating a savepoint enables you to continue to make changes in the same workspace, and it allows other users in the workspace immediate access to the changes. (Changes in another workspace are not visible to users until the current workspace is refreshed or merged.) Creating a savepoint also makes it convenient to archive a set of changes, to which you can later roll back.

On the other hand, creating a child workspace is convenient for providing an isolated environment in which a complex set of changes can be made, completely removed from the parent workspace (for example, the production data). If you want to set up an independent environment for a scenario, and if regular users in the parent workspace do not need access to this scenario's data, you probably want to create a child workspace instead of simply creating a savepoint in the parent workspace.

1.1.3 Merging and Rolling Back Workspace Changes

Workspaces can be merged or rolled back.

Merging a workspace involves applying changes made in a child workspace to its parent workspace, after which the child workspace is removed. To merge a workspace, use the MergeWorkspace procedure.

Rolling back a workspace involves deleting either all data changes (row versions) made in the workspace or all changes made after an explicit savepoint.

  • To roll back all changes made in the workspace, use the RollbackWorkspace procedure.

  • To roll back changes made in the workspace after a savepoint, use the RollbackToSP procedure.

    Note:

    You cannot roll back to a savepoint if any implicit savepoints were created since the specified savepoint, unless you first merge or remove the descendent workspaces that caused the implicit savepoints to be created. For example, referring to Figure 1-2 in Section 1.1.2, the user in Workspace1 cannot roll back to savepoint SP1 until Workspace3 (which caused implicit savepoint SPc to be created) is merged or removed.

A workspace cannot be rolled back when it has open database transactions. Rollback of a workspace leaves behind the workspace structure for future use; only the data in the workspace is deleted. (To completely remove a workspace, use the RemoveWorkspace procedure, as described in Section 1.1.6.)

1.1.4 Resolving Conflicts Before a Merge or Refresh Operation

When a child workspace is merged, the row changes in the child workspace are incorporated in its parent workspace; and when a child workspace is refreshed, row changes in the parent workspace are incorporated in the child workspace. When a row is changed in both the child and parent workspace, a data conflict is created. Conflicts are automatically detected when a merge or refresh operation is requested, and they are presented to the user in conflict (xxx_CONF) views. There is one conflict view for each table, as described in Section 5.45. This view lists the column values of the rows in the two workspaces involved in the conflict.

You must resolve conflicts manually by setting the workspace conflict context for the session and then using the ResolveConflicts procedure. For each conflict you can choose to keep the row from the child workspace, the row from the parent workspace, or the common base row (that is, no change: keep the original data values for the row). You must resolve the conflicts before you can perform a merge (MergeWorkspace) or refresh (RefreshWorkspace) operation.

The base row is the currently visible row at the time of the first update or delete operation in the child workspace. In the case of an insert operation, the base row does not exist, except if the inserted row was previously deleted in an ancestor version of a parent workspace, the base row is that deleted row. The parent row is the currently visible row in the parent workspace at the time of the conflict resolution, and the child row is the currently visible row in the child workspace at the time of the conflict resolution.

Absence of data is not a conflict. In these cases, you can use the xxx_DIFF view (described in Section 5.46) to detect a change in one workspace when there is no row or no change to the row in the other workspace.

The general process for resolving conflicts is as follows:

  1. Use the GotoWorkspace or SetConflictWorkspace procedure to set the workspace conflict context for the session.

  2. Examine the xxx_CONF views (described in Section 5.45) to see what conflicts exist.

  3. Execute the BeginResolve procedure.

  4. Execute the ResolveConflicts procedure as often as needed: once for each affected combination of table and workspace.

  5. After resolving all conflicts, execute one of the following procedures:

    • CommitResolve if you want to make permanent all changes from the preceding step. (However, the changes are not made permanent in the database until you perform a standard database commit operation and execute the MergeWorkspace or RefreshWorkspace procedure, as described in the next step.)

    • RollbackResolve to discard all changes from the preceding step. (If you discard all changes, do not perform the next step.)

  6. Perform a standard database commit operation and execute the MergeWorkspace or RefreshWorkspace procedure.

1.1.5 Freezing and Unfreezing Workspaces

You can control read and write access to a workspace by freezing and unfreezing the workspace. If a workspace is frozen, the ability of users to access the workspace and to make changes to rows in version-enabled tables is restricted. You can freeze a workspace in any of the following modes: no access, read-only, and one writer only (1WRITER).

To make a workspace frozen, use the FreezeWorkspace procedure. To make a frozen workspace not frozen, use the UnfreezeWorkspace procedure.

In addition, some procedures automatically freeze one or more workspaces. Table 1-1 lists these procedures, the workspaces affected, and the mode in which the workspaces are frozen. (For explanations of the mode values, see the FreezeWorkspace procedure description in Chapter 4.)

Table 1-1 Freeze Results of Procedures

Procedure Workspace and Mode

BeginResolve

Specified workspace: 1WRITER

MergeWorkspace

Specified workspace: NO_ACCESS

Parent workspace: READ_ONLY

CompressWorkspace

Specified workspace: NO_ACCESS (Also, checks to ensure that there are no sessions on savepoints other than LATEST.)

CompressWorkspaceTree

Specified workspace: NO_ACCESS (Also, checks to ensure that there are no sessions on savepoints other than LATEST.)

CreateSavepoint

Specified workspace: READ_ONLY

DeleteSavepoint

Specified workspace: NO_ACCESS

CreateWorkspace

Specified workspace: READ_ONLY

RemoveWorkspace

Specified workspace: NO_ACCESS

RefreshWorkspace

Specified workspace: READ_ONLY

Parent workspace: READ_ONLY

RollbackResolve

Specified workspace: 1WRITER

RollbackWorkspace

Specified workspace: NO_ACCESS


1.1.6 Removing Workspaces

A workspace can be removed with the RemoveWorkspace procedure. RemoveWorkspace rolls back the data in a workspace and then deletes the workspace structure. An entire tree of workspaces can be removed with the RemoveWorkspaceTree procedure. This will remove the workspace and all its descendant workspaces. A workspace cannot be removed when it has users in it.

1.1.7 Using Workspace Manager Events

Several types of Workspace Manager operations can be captured as events, and can be communicated to applications through the Oracle Advanced Queuing (AQ) framework. Messaging features provided by AQ, such as asynchronous notification, persistence, propagation, access control, history, and rule-based subscription, can be used for Workspace Manager events.

Support for Workspace Manager events includes the ALLOW_CAPTURE_EVENTS Workspace Manager system parameter, the SetCaptureEvent procedure, and the WM_EVENTS_INFO metadata view.

Chapter 2 describes Workspace Manager events and explains how to use them in applications.

1.1.8 Autocommitting of Workspace Manager Operations

Many Workspace Manager operations are by default executed as autonomous database transactions that will be committed when they finish. That is, each such transaction is an independent transaction that is called from within the current database transaction, leaves the context of the calling transaction, performs the Workspace Manager operation and then automatically commits it, and then returns to the calling transaction's context and continues with that transaction. Workspace Manager (DBMS_WM) subprograms that operate in this way have an optional auto_commit parameter, which has a default value of TRUE.

For example, the CompressWorkspace procedure by default starts an autonomous transaction, compresses the workspace, commits the compression operation, and returns to the calling transaction's context, where the current database transaction continues.

However, if you want such subprograms not to start an autonomous transaction, but instead to execute in the context of the calling transaction, you can specify the auto_commit parameter with a value of FALSE. In this case, the Workspace Manager operation is executed as part of the current database transaction; and if there is no current open transaction, the Workspace Manager operation starts a new transaction. In either case, the Workspace Manager operation does not take effect until that transaction ends with a commit operation. For example, if you call the CompressWorkspace procedure with the auto_commit parameter specified as FALSE, the workspace is not compressed until the transaction is committed; and if the transaction is rolled back, the workspace is not compressed.

Note that if you specify FALSE for the auto_commit parameter, you must remember to commit or roll back the transaction explicitly.

If the auto_commit parameter value is TRUE and any open transactions exist, the following considerations apply:

  • For the CompressWorkspace and CompressWorkspaceTree procedures, an exception is raised if there is any open transaction.

  • For all other Workspace Manager procedures, an exception is raised if there is an open transaction in a parent or child workspace of any table that needs to be modified.

1.1.9 Continually Refreshed Workspaces

A continually refreshed workspace is a workspace that is automatically refreshed from its parent workspace whenever data changes are committed in the parent workspace or are merged into the parent workspace from another child workspace. You do not need to call the RefreshWorkspace procedure for a continually refreshed workspace.

Any workspace in a branch of the workspace tree can be continually refreshed. A child workspace can be a continually refreshed workspace, regardless of whether its parent workspace is continually refreshed. However, if a parent workspace is a continually refreshed workspace, its child workspaces must also be continually refreshed.

To create a continually refreshed workspace, specify TRUE for the isrefreshed parameter in the call to the CreateWorkspace procedure. See the Usage Notes for the CreateWorkspace procedure for rules that apply to the creation of a continually refreshed workspace.

To change a workspace that is not continually refreshed to be continually refreshed, use the ChangeWorkspaceType procedure.

If a workspace is not continually refreshed, you must call the RefreshWorkspace procedure whenever you want to ensure that data changes in its parent workspace are visible in the workspace.

1.1.10 Multiparent Workspaces

A multiparent workspace is a child workspace that has two or more parent workspaces. A workspace is initially created with a single parent workspace. However, if the need arises, you can add other workspaces as parent workspaces to an existing workspace, thus making it a multiparent workspace. The multiparent workspace can see data from all of its parent workspaces and their ancestor workspaces, and it can be merged with and refreshed from its parent workspaces.

Figure 1-3 shows the same hierarchy of workspaces in Figure 1-1, except that Workspace3 is now a multiparent workspace with two parent workspaces: Workspace1 and Workspace4.

Figure 1-3 Multiparent Workspace in a Workspace Hierarchy

Description of Figure 1-3 follows
Description of "Figure 1-3 Multiparent Workspace in a Workspace Hierarchy"

A multiparent workspace is also called a multiparent leaf workspace. Thus, in Figure 1-3, Workspace3 is a multiparent leaf workspace. The nearest common ancestor of all parent workspaces of a multiparent lead workspace is called the multiparent root workspace. In Figure 1-3, the LIVE workspace is the multiparent root workspace of Workspace3. All of the workspaces in the directed acyclic graph (DAG) formed as a result of adding parent workspaces as parents of a leaf workspace are called multiparent graph workspaces. In Figure 1-3, Workspace1, Workspace4, and Workspace3 are the multiparent graph workspaces.

Multiparent workspaces are allowed only if the ALLOW_MULTI_PARENT_WORKSPACE Workspace Manager system parameter is set to ON. In addition, for a continually refreshed workspace to be a multiparent workspace, the CR_WORKSPACE_MODE Workspace Manager system parameter must be set to PESSIMISTIC_LOCKING; and for a workspace that is not continually refreshed to be a multiparent workspace, the NONCR_WORKSPACE_MODE Workspace Manager system parameter must be set to PESSIMISTIC_LOCKING. For information about Workspace Manager system parameters, see Section 1.5.

To create a multiparent workspace, use the AddAsParentWorkspace procedure. To remove a workspace as a parent of a multiparent workspace, use the RemoveAsParentWorkspace procedure. To grant and revoke privileges on multiparent graph workspaces, use the GrantGraphPriv and RevokeGraphPriv procedures, respectively. These procedures are described in Chapter 4.

Workspace Manager provides the following static data dictionary views (described in Chapter 5) to store information about multiparent workspaces:

1.1.11 Infrastructure for Version-Enabling of Tables

When you version-enable a table using the EnableVersioning procedure, Workspace Manager automatically performs operations and creates data structures that are invisible to non-DBA users, but that permit Workspace Manager to function. Some of the information maintained by Workspace Manager is stored in the static data dictionary views described in Chapter 5, and some is stored in system data structures not accessible by users.

When a table is version-enabled, Workspace Manager renames the table to <table-name>_LT, and it adds several columns to this table to store versioning metadata. Note that users and applications should not specify the <table-name>_LT table in SQL statements; they should continue to specify the original table name (<table-name>). (If you ever need to find the name of the <table_name>_LT table associated with a version-enabled table, or if you want to find out if a table is version-enabled by checking for the existence of a <table_name>_LT table, use the GetPhysicalTableName function.)

Workspace Manager also creates a view on the original table (<table-name>), as well as INSTEAD OF triggers on the view for insert, update, and delete operations. When an application executes a statement to insert, update, or delete data in a version-enabled table, the appropriate INSTEAD OF trigger performs the actual operation. When the view is accessed, it uses the workspace metadata to show only the row versions relevant to the current workspace of the user.

Because Workspace Manager uses the original object name when it creates infrastructure objects, the effective maximum length of the name for some kinds of objects is shorter than the maximum permitted by Oracle Database. Table 1-2 provides guidelines for the maximum name length for version-enabled tables and related objects. (See also the information in Section 1.15 about reserved words and characters for certain names.)

Table 1-2 Name Length Guidelines for Workspace Manager

Type of Object Maximum Name Length in Characters

Table

25

Column

28

Index

30 (26 if the index is created or altered between calls to the BeginDDL and CommitDDL procedures)

Trigger

27

Constraint

30 (26 if the constraint is created or altered between calls to the BeginDDL and CommitDDL procedures)


Workspace Manager does not support the RETURNING clause with INSERT, MERGE, or UPDATE statements on version-enabled tables. This restriction is caused by the fact that Workspace Manager creates views with INSTEAD OF triggers on version-enabled tables, and Oracle Database does not support the RETURNING clause on views that have INSTEAD OF triggers defined on them.

1.1.12 Creation of Row Versions and Historical Copies

This section describes the process by which Workspace Manager creates new row versions and maintains historical copies of old versions.

A new row version is created in a version-enabled table when you do either of the following:

  • Create an explicit savepoint in the current workspace, and update the row.

  • Create a child workspace (using the CreateWorkspace procedure) under the current workspace, thus creating an implicit savepoint in the current workspace; execute the GotoWorkspace procedure to go to the child workspace; and update the row.

Any subsequent update of the current row overwrites the current row version, unless history is enabled on the table or another savepoint is created.

  • If history is enabled without overwrite (VIEW_WO_OVERWRITE), each update of the current row version creates a full copy of the current row version with the changes and with a timestamp based on the transaction time. This copy becomes the new current row version.

  • If history is enabled with overwrite (VIEW_W_OVERWRITE), each update of the current row version overwrites the current row version and updates the transaction timestamp.

  • If a savepoint is created in the workspace, the next change to the row creates a new version, and the history cycle begins again.

Row versions created in a workspace are not visible from that workspace until you execute the MergeWorkspace or MergeTable procedure.

When you execute the MergeWorkspace procedure for a child workspace, only the current row version in the child workspace is merged into the parent workspace. If you specify the remove_workspace parameter as TRUE, any intermediate row versions in the child workspace are deleted when the child workspace is removed. To retain all intermediate versions created in the child workspace, the remove_workspace parameter value must be FALSE (the default).

When you execute the CompressWorkspace procedure on a child workspace to eliminate intermediate savepoints, you can also remove the associated historical copies of that row version. If you do not remove these copies, they are associated with the next version.

Intermediate row versions can only be selected for read-only access. To select an intermediate row version for read-only access, go to the workspace (GotoWorkspace procedure) if you are not already in it, and execute either the GotoDate procedure to set the session context to a historical time or the GotoSavepoint procedure to set the session context to a specific savepoint. Subsequent SELECT statements will select, for read-only access, the latest row version as of the specified date or savepoint.

1.1.13 Workspace Manager Schema, Metadata, and Package

Workspace Manager creates a user named WMSYS. The WMSYS schema is used to store all the metadata information for Workspace Manager. A PL/SQL package with the public synonym DBMS_WM contains the Workspace Manager subprograms (procedures and functions).

The following privileges are granted to the PUBLIC user group:

  • SELECT privilege on Workspace Manager static data dictionary views (described in Chapter 5)

  • EXECUTE privilege on the DBMS_WM package (described in Chapter 4)

1.2 Session Context Information for Workspace Manager

Users perform Workspace Manager operations within a standard Oracle session. (A session is a specific connection of a user to an Oracle instance through a user process; a session lasts from the time the user connects until the time the user disconnects or exits the database application.) When you perform Workspace Manager operations, information relating to the session context is automatically recorded.

The session context information includes the workspace name and a context value, and it determines what data the session can see in the workspace and what workspaces the session can enter. The context value is one of the following:

You can retrieve information about the session context by using the GetSessionInfo procedure. Retrieving this information can be useful if you need to know where a session is (workspace and context) -- for example, after you performed a combination of GotoWorkspace, GotoSavepoint, and GotoDate operations.

1.3 Lock Management with Workspace Manager

In addition to locks provided by regular Oracle database transactions, Workspace Manager provides two types of version locks. These locks are primarily intended to eliminate row conflicts between a parent workspace and a child workspace. You can enable locking for the workspace, the session, or specified rows, or some combination:

Workspace or session locks persist for the duration of the workspace or session, respectively, or until the workspace is merged or rolled back.

Like database locks, Workspace Manager locks can be exclusive or shared:

Workspace-exclusive locks and version-exclusive locks are forms of exclusive locking that control which users can and cannot change data values, but (unlike exclusive locking) they do not prevent conflicts from occurring. Workspace-exclusive locks lock rows such that only the user that set the lock can change the values in the current workspace; however, other users in other workspaces can change the values. Version-exclusive locks lock rows such that only the user that set the lock can change the values (and that user can be in any workspace); no other users (in any workspace) can change the values.

Table 1-3 indicates, for a row locked by a specific user in a specific workspace, which users in which workspaces can and cannot modify the row. For example, the first two entries in Table 1-3 mean that when a shared (S) lock is placed on a row, any user in the workspace in which the row was locked can modify the row, but any user in a workspace different from the workspace in which the row was locked cannot modify the row.

Table 1-3 Workspace Manager Lock Modes and Data Modification Ability

Lock Mode User Workspace of User Can Modify?

Shared (S)

Any user

Workspace in which row was locked

Yes

Shared (S)

Any user

Different from workspace in which row was locked

No

Exclusive (E)

User that locked the row

Workspace in which row was locked

Yes

Exclusive (E)

User that locked the row

Different from workspace in which row was locked

No

Exclusive (E)

Different user from the one that locked the row

Any workspace

No

Workspace Exclusive (WE)

User that locked the row

Any workspace

Yes

Workspace Exclusive (WE)

Different user from the one that locked the row

Different from workspace in which row was locked

Yes

Workspace Exclusive (WE)

Different user from the one that locked the row

Workspace in which row was locked

No

Version Exclusive (VE)

User that locked the row

Any workspace

Yes

Version Exclusive (VE)

Different user from the one that locked the row

Any workspace

No


Locking a row does not affect workspace merge, refresh, and rollback operations, but it affects what can be done with the row after these operations. You can control these workspace operations by using workspace privileges, calling the FreezeWorkspace procedure, and checking the workspace xxx_LOCK view or views (described in Section 5.48) before performing the operations.

The xxx_LOCK static data dictionary views (described in Section 5.48) contain information about locks in each version-enabled table.

For information about Workspace Manager locking with DML operations on tables with referential integrity constraints, see Section 1.9.1.1.

1.3.1 Exclusive Locking and Row Versions

The timing of an exclusive lock with respect to an update operation in a child workspace can affect which version, if any, of the row can be updated in a parent workspace. For example, when a table is version-enabled in the LIVE workspace, each original row is assigned version 0. Assume that a workspace named W1 is created as a child of the LIVE workspace. When workspace W1 is created, the following things happen:

  • Version 1 is assigned to the LIVE workspace (but no additional row is created).

  • Version 2 is assigned to workspace W1 (but no additional row is created). Queries in workspace W1 still return version 0 of the row that is in the LIVE workspace.

Using this example, if a user in workspace W1 places an exclusive lock on a row before it updates the row, only that user in workspace W1 can update the row. Specifically:

  • Version 0 of the row is locked, preventing any update of the row from any workspace until the row is unlocked.

  • The lock can be placed from workspace W1 (or a descendent workspace of W1) because version 0 is the current physical row for the workspace.

  • When a user in workspace W1 updates the row, a new row (version 2) is created that is visible only from workspace W1 and any of its child workspaces.

However, if the row is not locked in the LIVE workspace and if a user in workspace W1 updates the row and then places an exclusive lock on the row, a user in the LIVE workspace can update the row. Specifically:

  • A new row (version 2) is created that is visible only from workspace W1 and any of its child workspaces.

  • Version 2 of the row is locked. No user in workspace W1 other than the user that placed the lock, or no user in any child workspace of W1, can update the row or create a new version of the row.

  • Version 0 of the row in the LIVE workspace is not locked. If a user in the LIVE workspace or a sibling workspace of W1 updates the row, a new version (version 1) of the row is created. (Version 0 is not locked because it is no longer the current version of the row for users in workspace W1; rather, version 2 is the current version of the row in that workspace.)

In other words, an exclusive lock after an update does not lock previous versions of the row in workspaces above the locking workspace in the workspace tree or in other branches of the workspace tree.

1.4 Privilege Management with Workspace Manager

Workspace Manager provides a set of privileges that are separate from standard Oracle database privileges. Workspace Manager workspace-level privileges (with names in the form xxx_WORKSPACE) allow the user to affect a specified workspace, and system-level privileges (with names in the form xxx_ANY_WORKSPACE) allow the user to affect any workspace.

Table 1-4 lists the Workspace Manager privileges.

Table 1-4 Workspace Manager Privileges

Privilege Description

ACCESS_WORKSPACE

Allows the user to go to a specified workspace. ACCESS_WORKSPACE or ACCESS_ANY_WORKSPACE privilege is needed for all other privileges.

ACCESS_ANY_WORKSPACE

Allows the user to go to any workspace. ACCESS_WORKSPACE or ACCESS_ANY_WORKSPACE privilege is needed for all other privileges.

CREATE_WORKSPACE

Allows the user to create a child workspace in a specified workspace.

CREATE_ANY_WORKSPACE

Allows the user to create a child workspace in any workspace.

REMOVE_WORKSPACE

Allows the user to remove a specified workspace.

REMOVE_ANY_WORKSPACE

Allows the user to remove any workspace.

MERGE_WORKSPACE

Allows the user to merge the changes in a specified workspace to its parent workspace.

MERGE_ANY_WORKSPACE

Allows the user to merge the changes in any workspace to its parent workspace.

ROLLBACK_WORKSPACE

Allows the user to roll back the changes in a specified workspace.

ROLLBACK_ANY_WORKSPACE

Allows the user to roll back the changes in any workspace.

FREEZE_WORKSPACE

Allows the user to freeze and unfreeze a specified workspace.

FREEZE_ANY_WORKSPACE

Allows the user to freeze and unfreeze any workspace.


Each privilege can be granted with or without the grant option. The grant option allows the user to which the privilege is granted to grant the privilege to other users.

The WM_ADMIN_ROLE role has all Workspace Manager privileges with the grant option. By default, the database administrator (DBA role) is granted the WM_ADMIN_ROLE role. Thus, after you decide which users should be granted which privileges, either have the DBA grant the privileges, or have the DBA grant the WM_ADMIN_ROLE role to one or more selected users and have these users grant the privileges.

The GrantWorkspacePriv and GrantSystemPriv procedures are used to grant workspace-level privileges and system-level privileges, respectively.

The RevokeWorkspacePriv and RevokeSystemPriv procedures are used to revoke workspace-level privileges and system-level privileges, respectively. These procedures require that the user have sufficient privilege to revoke the specified privilege from the specified user. The user that granted a privilege can revoke it.

1.5 System Parameters for Workspace Manager

Workspace Manager provides a set of system parameters that allow a user with the WM_ADMIN_ROLE role (described in Section 1.4) to enforce global Workspace Manager-specific settings for the database. (These Workspace Manager system parameters are not Oracle initialization parameters. The only way to set Workspace Manager system parameters is to use the SetSystemParameter procedure, described in Chapter 4).

To set a system parameter, use the SetSystemParameter procedure. To get the current setting for a system parameter, use the GetSystemParameter procedure. Both procedures are described in Chapter 4.

Table 1-5 lists the Workspace Manager system parameters.

Table 1-5 Workspace Manager System Parameters

Parameter Name Values

ADD_UNIQUE_COLUMN_TO_HISTORY_VIEW

ON adds columns to the xxx_HIST views (described in Section 5.47) of version-enabled tables. When a table is version-enabled with valid time support (described in Chapter 3), WM_ROWID (rowid) and WM_FLAG (integer) are added. When a table is version-enabled without valid time support, only the WM_ROWID column is added. These columns can be used to uniquely identify each row in the xxx_HIST views. For a table with valid time support, you must use the WM_ROWID column and the WM_FLAG column in any WHERE clauses.

OFF (the default) does not add any columns to the xxx_HIST views.

ALLOW_CAPTURE_EVENTS

ON allows Workspace Manager events (described in Chapter 2) to be captured. Setting this parameter to ON causes some additional internal Workspace Manager processing operations; therefore, for performance reasons you should not set the value to ON unless you plan to capture events.

OFF (the default) does not allow Workspace Manager events to be captured.

ALLOW_MULTI_PARENT_WORKSPACES

ON allows multiparent workspaces (described in Section 1.1.10) to be created. Setting this parameter to ON causes some additional internal Workspace Manager processing operations; therefore, for performance reasons you should not set the value to ON unless you plan to use multiparent workspaces.

OFF (the default) does not allow multiparent workspaces to be created.

ALLOW_NESTED_TABLE_COLUMNS

ON allows tables containing a nested table column to be version-enabled. Setting this parameter to ON causes some additional internal Workspace Manager processing operations; therefore, for performance reasons you should not set the value to ON unless you plan to version-enable any tables with nested table columns.

OFF (the default) does not allow tables containing a nested table column to be version-enabled.

COMPRESS_PARENT_AFTER_REMOVE

ON (the default) implicitly calls the CompressWorkspace procedure to compress the parent workspace after a RemoveWorkspace operation, or after a MergeWorkspace operation in which the remove_workspace parameter was set to true.

OFF does not compress the parent workspace in these cases.

CR_WORKSPACE_MODE

OPTIMISTIC_LOCKING allows a record to be edited in two or more continually refreshed workspaces. If differences occur between parent and child workspaces, the record is considered to be in conflict, and the conflict must be resolved before the child workspace can be merged or refreshed.

PESSIMISTIC_LOCKING does not allow a record to be edited in two or more continually refreshed workspaces. This setting ensures that there are no conflicts between parent and child workspaces.

OPTIMISTIC_LOCKING is the default for new installations, but PESSIMISTIC_LOCKING is the default for upgrades from a version before release 9.2.0.2.

FIRE_TRIGGERS_FOR_NONDML_EVENTS

ON (the default) causes user-defined triggers on version-enabled tables to be fired when a workspace non-DML operation (such as MergeWorkspace or MergeTable) is executed, unless later overridden for specific triggers by the SetTriggerEvents procedure.

OFF causes user-defined triggers on version-enabled tables not to be fired when a workspace non-DML operation (such as MergeWorkspace or MergeTable) is executed, unless later overridden for specific triggers by the SetTriggerEvents procedure.

KEEP_REMOVED_WORKSPACE_INFO

ON keeps information about any workspaces that are removed. This information will be available in the DBA_REMOVED_WORKSPACES, ALL_REMOVED_WORKSPACES, and USER_REMOVED_WORKSPACES views. ON also adds two new columns to xxx_HIST views (described in Section 5.47): WM_CREATEWORKSPACEID and WM_RETIREWORKSPACEID can be used to determine the workspace from which a row was merged and the workspace that merged a row that caused the workspace to be retired.

OFF (the default) does not keep this information about any workspaces that are removed.

NONCR_WORKSPACE_MODE

OPTIMISTIC_LOCKING (the default for both new installations and upgrades) allows a record to be edited in two or more workspaces that are not continually refreshed. If differences occur between parent and child workspaces, the record is considered to be in conflict, and the conflict must be resolved before the child workspace can be merged or refreshed.

PESSIMISTIC_LOCKING does not allow a record to be edited in two or more workspaces that are not continually refreshed. This setting ensures that there are no conflicts between parent and child workspaces.

NUMBER_OF_COMPRESS_BATCHES

A number from 1 to 1000, identifying the number of batches to be used when the batch_size parameter value is PRIMARY_KEY_RANGE and general statistics, but not histogram statistics, are available for a primary key column of type NUMBER, INTEGER, DATE, or TIMESTAMP. (See the reference information for any DBMS_WM subprogram that has a batch_size parameter.)

ROW_LEVEL_LOCKING

ON takes row-level locks on any rows that need to be merged or refreshed during MergeTable, MergeWorkspace, or RefreshWorkspace operations. This allows these procedures to run in parallel for workspaces that share the same parent. It allows multiple workspaces or session threads to issue merge or refresh requests concurrently against the same table; it does not parallelize a single merge or refresh operation that includes a list of tables. (However, parallel merge and refresh operations are supported only for tables without valid time support, and only for workspaces that are not continually refreshed.) The ON setting does not take effect for continually refreshed workspaces or if any of the tables that need to be merged or refreshed have valid time support enabled.

OFF (the default) takes workspace-level locks for all workspace operations. This setting prevents MergeTable, MergeWorkspace, and RefreshWorkspace operations from running in parallel while operating on the same parent workspace.

TARGET_PGA_MEMORY

A number representing the maximum amount of memory, specified in bytes, that should be used for selecting rows into memory during any MergeTable, MergeWorkspace, or RefreshWorkspace operation. The default is 8388608 (8 megabytes). Workspace Manager uses this value to determine the optimal number of rows to fetch at any one time. This value does not affect the amount of memory used by other database processes, but only internal workspace operations.

UNDO_SPACE

A string containing UNLIMITED (for no specified limit) or a number representing the maximum number of bytes for undo space available for Workspace Manager operations. Example: '1048576' for 1 megabyte. Workspace manager tries to minimize the amount of undo space used in a single transaction so as not to exceed the UNDO_SPACE value.

You can override the value of the UNDO_SPACE system parameter by specifying the undo_space parameter in the call to the EnableVersioning procedure.

USE_SCALAR_TYPES_FOR_VALIDTIME

ON causes Workspace Manager to use two columns, named WM_VALIDFROM and WM_VALIDTILL, of type TIMESTAMP WITH TIME ZONE, instead of a single column named WM_VALID (of type WM_PERIOD) to indicate the valid time range in views created on a version-enabled table that has valid time support. (The WM_PERIOD type is described in Section 3.2.)

OFF (the default) causes Workspace Manager to a single column named WM_VALID (of type WM_PERIOD) to indicate the valid time range in views created on a version-enabled table that has valid time support.

This parameter affects only tables that are subsequently version-enabled; it does not affect the views on existing version-enabled tables. To change the views on an existing version-enabled table, use the AlterVersionedTable procedure and specify the alter_option parameter value USE_SCALAR_TYPES_FOR_VALIDTIME or USE_WM_PERIOD_FOR_VALIDTIME.

USE_TIMESTAMP_TYPE_FOR_HISTORY

ON (the default) causes Workspace Manager, if the Oracle database release is 9.0.1 or later, to use the TIMESTAMP WITH TIME ZONE type for CREATETIME and RETIRETIME columns. (See Section B.3 for information about using this type.)

OFF causes Workspace Manager to use the DATE type for CREATETIME and RETIRETIME columns.


1.6 Import and Export Considerations

Workspace Manager supports the import and export of version-enabled tables in one of the following two ways: a full database import and export, and a workspace-level import and export through Workspace Manager procedures. No other export modes, such as schema, table, or partition level, are currently supported.

Full database import and export operations can be performed on version-enabled databases using the Oracle utilities; however, the following considerations and restrictions apply:

For workspace-level export operations, each version-enabled table can be exported at the workspace level. Follow these steps to export a version-enabled table from one database into another database:

  1. Call the Export procedure to store all of the data that needs to be exported into a staging table (for example, t1). The data that is exported can either be all of the data as seen from a particular workspace, savepoint, or instant, or only the data that was modified in the particular workspace. See the information about the Export procedure in Chapter 4 for more details.

    To export multiple workspaces for a version-enabled table, call the Export procedure again, specifying the new workspace that needs to be exported as well as the original staging table. If you intend to import the data into a non-versioned table, specify the versioned_db parameter as FALSE.

  2. Export the staging table (for example, t1), using the Oracle Export utility.

  3. Import the staging table (for example, t1), using the Oracle Import utility, into the destination database.

  4. If you are importing into a version-enabled table, call the Import procedure to move the data from the staging table to the version-enabled table, specifying the workspace where the data resided on the source database and the workspace into which the data should be stored.

    The structure of the staging table must match that of the version-enabled table. By default, all enabled constraints must be validated before the import procedure successfully completes.

1.7 Bulk Loading into Version-Enabled Tables

You can use SQL*Loader to perform bulk loading into version-enabled tables, but you must also call some special Workspace Manager procedures, and some restrictions apply. You can perform both direct-path and conventional-path bulk loading of data into either the latest version of any workspace or into the root version (version number 0, which is in the LIVE workspace). The root version is the ancestor of all other versions, so data in the root version is visible from all other workspaces (unless non-LIVE workspaces have updated the data).

Follow these general steps for bulk loading into a version-enabled table:

  1. Call the GetBulkLoadVersion function to fetch the reserved version number with which the bulk loaded data needs to be tagged. All data bulk loaded into the versioned table needs to be tagged with a version number that depends upon the final destination of the data, namely, the latest version of a workspace or the root version. Use the version number returned by the GetBulkLoadVersion function in the SQL*Loader control file, as explained in step 3.

  2. Call the BeginBulkLoading procedure to prepare the table for bulk loading. When data is being bulk loaded into a version-enabled table, DML and workspace operations on the table are not allowed, although workspace operations that do not involve this table are allowed. The BeginBulkLoading procedure prevents invalid operations from being performed on this table.

  3. Use SQL*Loader to perform the bulk loading. Only one line needs to be changed in the control file, to specify the <table_name>_LT name and to include the version number fetched in step 1. For example, assume that the existing control file has the following line:

    Load data  into table departments (name, loc)
    

    If the version number fetched in step 1 is 5, the line in the control file for bulk loading into the version-enabled table should be changed to:

    Load data into table departments_LT (name, loc, version constant '5')
    

    This ensures that all the bulk-loaded rows will be tagged with version 5, and that the other Workspace Manager-specific columns for these rows will have null values. If the table was version-enabled with the history option, create and retire times can be bulk loaded into the createtime and retiretime columns of <table_name>_LT.

  4. Complete the bulk loading process by calling either the CommitBulkLoading procedure to commit the bulk loading changes or the RollbackBulkLoading procedure to roll back the bulk loading changes.

If you commit the bulk loading changes, Workspace Manager ensures that the data is updated in the required workspace and version. By default, the bulk-loaded data is checked for each unique or referential constraint defined on the table, and any bulk-loaded rows that are in violation of any constraints are moved to a discards table specified as a parameter to the CommitBulkLoading procedure. If you specified to check for duplicates (that is, records in the data to be bulk loaded that have the same values in the primary key columns), for any duplicate records only the record with the lowest ROWID value is loaded into the table, and the rest are moved to the discards table.

The following restrictions apply to bulk loading with version-enabled tables in the current release:

1.8 DDL Operations Related to Version-Enabled Tables

To perform DDL (data definition language) operations on a version-enabled table, you must use special Workspace Manager procedures before and after the DDL operations, and you must specify the name of a special table created by Workspace Manager. You cannot perform DDL operations in the usual manner on the table or any index or trigger that refers to the table. For example, to add a column to a table named EMPLOYEES that has been version-enabled, you cannot simply enter a statement in the form ALTER TABLE EMPLOYEES ADD (column-name data-type).

The reason for these requirements is to ensure that Workspace Manager versioning metadata is updated to reflect the DDL changes. Therefore, DDL operations affecting a version-enabled table must be preceded by a call to the BeginDDL procedure, and must be concluded by a call to either the CommitDDL or RollbackDDL procedure. The BeginDDL procedure creates an empty temporary table with a name in the form <table-name>_LTS (the S standing for skeleton). The actual DDL statement must specify the name of the temporary <table-name>_LTS table, and must not specify the <table-name> or <table-name>_LT name. The CommitDDL and RollbackDDL procedures delete the temporary <table-name>_LTS table.

Note:

An exception to this procedure is adding valid time support to an existing version-enabled table. To add valid time support, use the AlterVersionedTable procedure, as explained in Section 3.11.

The following DDL operations related to version-enabled tables are supported:

You can create the following types of indexes on version-enabled tables: normal, bitmap, function-based normal, function-based bitmap, and domain. You cannot create or drop a partitioned, reverse, or join index on a version-enabled table. (You can, however, version-enable a table that has a partitioned, reverse, or join index.)

If you try to perform an unsupported DDL operation, the change will not be made, and an exception might be raised by the CommitDDL procedure.

If the DDL operation involving a version-enabled table is on a domain index (for example, creating an R-tree index on the table), you must have the CREATE TABLE privilege.

If you need to perform DDL operations on a version-enabled table in an Oracle replication environment, see Section C.3 for additional guidelines.

If you need to perform DDL operations on a version-enabled table in an Oracle Label Security (OLS) environment, you can use the apply_table_policy, remove_table_policy, enable_table_policy, and disable_table_policy procedures of the SA_POLICY_ADMIN package on the skeleton (_LTS) table, and the changes will be transferred to the version-enabled table.

Example 1-1 shows the statements needed to add a column named COMMENTS to the COLA_MARKETING_BUDGET table by using the special table named COLA_MARKETING_BUDGET_LTS. It also includes a DESCRIBE statement to show the addition of the column.

Example 1-1 DDL Operation on a Version-Enabled Table

EXECUTE DBMS_WM.BeginDDL('COLA_MARKETING_BUDGET');
ALTER TABLE cola_marketing_budget_lts ADD (comments VARCHAR2(100));
DESCRIBE cola_marketing_budget_lts;

 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 PRODUCT_ID                                NOT NULL NUMBER
 PRODUCT_NAME                                       VARCHAR2(32)
 MANAGER                                            VARCHAR2(32)
 BUDGET                                             NUMBER
 COMMENTS                                           VARCHAR2(100)

EXECUTE DBMS_WM.CommitDDL('COLA_MARKETING_BUDGET');

In Example 1-1, the ALTER TABLE statement specifies the COLA_MARKETING_BUDGET_LTS table, which is created by the BeginDDL procedure. The CommitDDL procedure applies the change to the COLA_MARKETING_BUDGET table and deletes the COLA_MARKETING_BUDGET_LTS table.

1.9 Constraint Support with Workspace Manager

This section describes Workspace Manager considerations relating to the use of database constraints.

1.9.1 Referential Integrity Support

Version-enabled tables can have referential integrity constraints, including constraints with the CASCADE and RESTRICT options; however, the following considerations and restrictions apply:

  • If the parent table in a referential integrity relationship is version-enabled, the child table must be version-enabled also. (The child table is the one on which the constraint is defined.) For example, consider the following EMPLOYEE and DEPARTMENT table definitions, with a foreign key constraint added after the creation (that is, the dept_id value in each EMPLOYEE row must match an existing dept_id value in a DEPARTMENT row).

    CREATE TABLE employee (
      employee_id NUMBER,
      last_name VARCHAR2(32),
      first_name VARCHAR2(32),
      dept_id NUMBER);
    CREATE TABLE department (
      dept_id NUMBER,
      name VARCHAR2(32);
    ALTER TABLE employee ADD CONSTRAINT emp_forkey_deptid
      FOREIGN KEY (dept_id) REFERENCES department (dept_id)
      ON DELETE CASCADE;
    

    In this example, DEPARTMENT is considered the parent and EMPLOYEE is considered the child in the referential integrity relationship; and if DEPARTMENT is version-enabled, EMPLOYEE must be version-enabled also. In this relationship definition, when a DEPARTMENT row is deleted, all its child rows in the EMPLOYEE table are deleted (cascading delete operation).

  • A child table in a referential integrity relationship is allowed to be version-enabled without the parent table being version-enabled.

  • The foreign key in a child table must refer to the primary key in the parent table.

  • Primary key values in the parent table cannot be updated. For example, if DEPARTMENT is the parent table and EMPLOYEE is the child table, you cannot change the department ID of a department.

  • Multilevel referential integrity constraints are permitted on version-enabled tables. For example, the table EMPLOYEE(emp_id, dept_id) could have the constraint that the department ID must exist in the table DEPARTMENT(dept_id, dept_name, loc_id); and the table DEPARTMENT(dept_id, dept_name, loc_id) could have the constraint that the location ID must exist in the table LOCATION(loc_id, loc_name). However, all tables that are involved in multilevel referential integrity constraints must be version-enabled and version-disabled together, unless all the referential integrity constraints involved have the Restrict rule. If all the constraints involved have the Restrict rule, you can version-enable the tables either all together or one at a time with child tables preceding their parent tables. The table names must be passed as a comma-delimited list to the EnableVersioning and DisableVersioning procedures.

Workspace Manager uses the static data dictionary views ALL_WM_RIC_INFO and USER_WM_RIC_INFO (described in Chapter 5) to hold information pertinent to referential integrity support.

If you need to add, drop, enable, or disable a referential integrity constraint that involves two tables, it is more convenient if you perform the operation before version-enabling the tables. However, you can add, drop, enable, or disable a referential integrity constraint that involves two version-enabled tables if you follow these steps:

  1. Begin a DDL session specifying the parent table.

  2. Begin a DDL session specifying the child table.

  3. Alter the <table-name>_LTS table for the child table to add the foreign key constraint. (See Section 1.8 for information about <table-name>_LTS tables and performing DDL operations on version-enabled tables.)

  4. Commit the DDL changes specifying the child table.

  5. Commit the DDL changes specifying the parent table.

Example 1-2 adds a foreign key constraint. Assume that the EMPLOYEE and DEPARTMENT tables are version-enabled and are defined as follows:

EMPLOYEE(emp_id number  primary key, dept_id number)
DEPARTMENT(dept_id number  primary key, dept_name varchar2(30))

Example 1-2 Adding a Referential Integrity Constraint

-- Begin a DDL session on the parent table.
DBMS_WM.BeginDDL('DEPARTMENT'); 

-- Begin a DDL session on the child table.
DBMS_WM.BeginDDL('EMPLOYEE'); 

-- Add the constraint between EMPLOYEE_LTS and DAPATMENT_LTS.
ALTER TABLE employee_lts ADD CONSTRAINT employee_fk FOREIGN KEY (dept_id)
   REFERENCES department_lts(dept_id);

-- Commit DDL on the child table (transfers the constraint on employee_lts
-- to employee and drops employee_lts). 
EXECUTE DBMS_WM.CommitDDL('EMPLOYEE'); 

-- Commit DDL on the parent table (drops the department_lts table). 
EXECUTE DBMS_WM.CommitDDL('DEPARTMENT'); 

If you are in a DDL session (that is, if you have called the BeginDDL procedure), you cannot add, drop, enable, or disable a referential integrity constraint that involves two tables if one table is version-enabled and the other is not version-enabled. Both tables must be version-enabled.

1.9.1.1 Locking with DML Operations on Tables with Referential Integrity Constraints

When data manipulation language (DML) operations are performed on version-enabled tables that have referential integrity constraints, Workspace Manager acquired shared locks so that the following conditions are enforced:

  • During an insert operation or an update operation affecting the foreign key column on the child table, delete operations cannot be performed on the parent table. For example, if DEPARTMENT is the parent table and EMPLOYEE is the child table, during the time that a new employee is being added or an existing employee is being assigned to a different department, no departments can be deleted.

  • During a delete operation on the parent table, insert operations or updates operation affecting the foreign key column cannot be performed on the child table. For example, during the time that a department is being deleted, new employees cannot be added and existing employees cannot be assigned to different departments.

See also:

For general information about locking performed by Workspace Manager, including explanations of shared and exclusive locks, see Section 1.3.

Multiple sessions can simultaneously perform either of the following, but not both of the following, DML operations simultaneously:

  • Insert operations or update operations affecting the foreign key column on the child table

  • Delete operations on the parent table

Multiple sessions can simultaneously perform any of the following Workspace Manager operations simultaneously:

  • Use the MergeTable procedure to apply changes to a child table or parent table in different workspaces.

  • Use the MergeTable procedure to apply changes to a child table in one workspace, and insert or update the child table in another workspace.

  • Use the MergeTable procedure to apply changes to a parent table in one workspace, and delete from the parent table in another workspace.

One session will be blocked until the other session finishes in the following situations:

  • A session tries to merge changes to a child table in one workspace, and another session tries to merge changes to the parent table in another workspace.

  • A session tries to merge changes to a child table in one workspace, and another session tries to delete from the parent table.

  • A session tries to merge changes to a parent table in one workspace, and another session tries to insert into a child table or change a value in the foreign key of a child table.

1.9.2 Unique Constraints

Tables with unique constraints defined on them can be version-enabled. The following are supported:

  • UNIQUE constraint on a single column or multiple columns

  • Unique index on a single column or multiple columns

  • Functional unique index on the table

The treatment of null values is the same for version-enabled tables as for tables that are not version-enabled.

Workspace Manager uses the following static data dictionary views (described in Chapter 5) to hold information pertinent to support for unique constraints:

1.9.3 SET NULL Constraints

SET NULL constraints are not supported by Workspace Manager. If a table has any SET NULL constraints, they are converted to the RESTRICT option when the table is version-enabled.

For example, the constraint ON DELETE SET NULL is converted to ON DELETE RESTRICT.

1.10 Triggers on Version-Enabled Tables

Version-enabled tables can have triggers defined; however, the following considerations and restrictions apply:

Any triggers that are not supported for version-enabled tables are deactivated when versioning is enabled, and are activated when versioning is disabled.

You can selectively enable specific user-defined triggers for certain kinds of events by using the SetTriggerEvents procedure.

1.11 Virtual Private Database Considerations

You can use Workspace Manager in conjunction with the Oracle Virtual Private Database (VPD) technology. (Virtual private databases are described in Oracle Database Security Guide.) However, the following considerations apply Workspace Manager in a VPD:

1.12 Support for Table Synonyms

For any Workspace Manager procedure or function input parameter that calls for a table name, you can instead specify a synonym. When Workspace Manager looks for a table, it searches in the following sequence and uses the first match for the specified name:

  1. A table in the specified schema (or local schema if no schema is specified)

  2. A private synonym in the specified schema (or local schema if no schema is specified)

  3. A public synonym

1.13 Materialized View Support

This section describes considerations for using Workspace Manager with materialized views.

You can create a materialized view on a version-enabled table only if you specify the complete refresh method (REFRESH COMPLETE) when you create the materialized view. You cannot specify any of the following clauses in the CREATE MATERIALIZED VIEW statement:

You cannot version-enable a materialized view or the base table of a materialized view.

When the materialized view is created, its content is based on the workspace in which the session is at that time. When the materialized view is refreshed, its content is based on the workspace in which the session is when the DBMS_MVIEW.REFRESH operation is performed. When the materialized view is created or refreshed, it shows the same data in all workspaces.

1.14 Spatial Topology Support

This section describes special considerations and techniques for using Workspace Manager with tables in Oracle Spatial topologies, which are documented in Oracle Spatial Topology and Network Data Models Developer's Guide.

A topology consists of feature tables, as well as tables with names in the form <topology-name>_NODE$, <topology-name>_EDGE$, <topology-name>_FACE$, <topology-name>_RELATION$, and <topology-name>_HISTORY$. If you want to version-enable any topology tables, you must version-enable all tables associated with the topology. To do so, you must specify the topology name as the table_name parameter to the EnableVersioning procedure, and you must specify the isTopology parameter as TRUE. For example:

EXECUTE DBMS_WM.EnableVersioning(table_name => 'xyz_topo', isTopology => TRUE);

The preceding example version-enables the xyz_topo topology; that is, it version-enables all feature tables associated with the xyz_topo topology, as well as the XYZ_TOPO_NODE$, XYZ_TOPO_FACE$, XYZ_TOPO_EDGE$, XYZ_TOPO_RELATION$, and XYZ_TOPO_HISTORY$ tables.

A version-enabled topology must have at least one feature table.

To disable versioning on any topology tables, you must disable versioning on all tables associated with the topology by specifying the topology name as the table_name parameter to the DisableVersioning procedure and the isTopology parameter as TRUE.

However, exceptions apply to the preceding guidelines about version-enabling and version-disabling topology tables in the following cases:

In these cases, you must version-enable or version-disable the feature table separately. That is, first call the EnableVersioning or DisableVersioning procedure on the feature table (along with any tables required by the referential integrity constraint), and then invoke the EnableVersioning or DisableVersioning procedure specifying the topology name.

1.14.1 Locking Considerations with Topologies

To lock or unlock rows in tables associated with a topology, you must specify the topology name as the table_name parameter to the LockRows or UnlockRows procedure, and you must identify the window containing the rows by using the Xmin, Ymin, Xmax, and Ymax parameters. You must also not specify the where_clause parameter. For example:

EXECUTE DBMS_WM.LockRows (workspace => 'ws1', table_name => 'xyz_topo', Xmin => 0.1, Ymin => 0.1,  Xmax => 0.5, Ymax => 0.5 );

The preceding example puts version locks on all the rows of the specified topology contained in the specified window. To edit the elements of a topology in a workspace (including the LIVE workspace), follow these steps:

  1. Invoke the LockRows procedure to put version locks on all the elements of the topology contained in a window of interest.

  2. Invoke the Oracle Spatial Topology Java client loadWindow method for the same window of interest.

1.14.2 Additional Considerations with Topologies

The following additional considerations apply to using Workspace Manager with Spatial topologies:

  • You must invoke the SDO_TOPO.INITIALIZE_METADATA procedure at least once on a topology before you version-enable the tables associated with the topology. (You can also invoke the SDO_TOPO.INITIALIZE_METADATA procedure as needed after version-enabling a topology.)

  • Do not use the MergeTable, RefreshTable, or RollbackTable procedure on a version-enabled table associated with a topology. Instead, use the MergeWorkspace, RefreshWorkspace, or RollbackWorkspace procedure to merge, refresh, or roll back tables associated with a topology.

1.15 Reserved Words and Characters

Because Workspace Manager creates internal objects using its own naming conventions, you must avoid some words and characters in the names for certain kinds objects. Table 1-6 lists kinds of objects and restrictions that apply to their names. (See also the name length guidelines in Table 1-2 in Section 1.1.11.)

Table 1-6 Workspace Manager Reserved Words and Characters

Object Name Cannot Be Any of the Following

Workspace

BASE, LIVE, or a string containing any of the following characters: / (slash), * (asterisk), , (comma), $ (dollar sign), # (pound sign)

Version-enabled table

A string ending with _G

Column in a version-enabled table

VERSION, NEXTVER, DELSTATUS, LTLOCK, CREATETIME, RETIRETIME, or a string starting with WM$ or WM_

In addition, if the table includes valid time support (explained in Chapter 3), RID cannot be used as a column name.

Index on a version-enabled table

A string starting with _PKI$ or _TI$


1.16 DBMS_WM Subprogram Categories

The Workspace Manager application programming interface (API) consists of PL/SQL subprograms (procedures and functions) in a single PL/SQL package named DBMS_WM. The subprograms can be logically grouped into the categories described in this section.

Note:

Most Workspace Manager subprograms are procedures, but a few are functions. (A function returns a value; a procedure does not return a value.)

Most functions have names starting with Get (such as GetConflictWorkspace and CreateSavepoint).

Reference information for all subprograms is in Chapter 4.

1.16.1 Table Management Subprograms

Table management subprograms enable and disable workspace management on a table, and perform other table-related operations.

Table 1-7 shows the subprograms available for table management.

Table 1-7 Table Management Subprograms

Procedure Description

EnableVersioning

Version-enables a table, creating the necessary structures to enable the table to support multiple versions of rows.

DisableVersioning

Deletes all support structures that were created to enable the table to support versioned rows.

SetWoOverwriteOFF

Disables the VIEW_WO_OVERWRITE history option that was enabled by the EnableVersioning or SetWoOverwriteON procedure, changing the option to VIEW_W_OVERWRITE (with overwrite).

SetWoOverwriteON

Enables the VIEW_WO_OVERWRITE history option that was disabled by the SetWoOverwriteOFF procedure.

BeginDDL

Starts a DDL (data definition language) session for a specified table.

CommitDDL

Commits DDL changes made during a DDL session for a specified table, and ends the DDL session.

RollbackDDL

Rolls back (cancels) DDL changes made during a DDL session for a specified table, and ends the DDL session.

RecoverAllMigratingTables

Attempts to complete the migration process on a table that was left in an inconsistent state after the Workspace Manager migration procedure failed.

RecoverAllMigratingTables

Attempts to complete the migration process on all tables that were left in an inconsistent state after the Workspace Manager migration procedure failed.

CopyForUpdate

Allows LOB columns (BLOB, CLOB, or NCLOB) in version-enabled tables to be modified.

Export

Exports data from a version-enabled table (all rows, or as limited by any combination of several parameters) to a staging table.

Import

Imports data from a staging table (all rows, or as limited by any combination of several parameters) into a version-enabled table in a specified workspace.


1.16.2 Workspace Management Subprograms

Workspace management subprograms perform operations on workspaces.

Table 1-8 shows the subprograms available for workspace management.

Table 1-8 Workspace Management Subprograms

Procedure Description

CreateWorkspace

Creates a new workspace in the database.

GotoWorkspace

Moves the current session to the specified workspace.

SetDiffVersions

Finds differences in values in version-enabled tables for two savepoints and their common ancestor (base). It creates rows in the differences views describing these differences.

GetDiffVersions

Returns the names of the (workspace, savepoint) pairs on which the session has performed the SetDiffVersions operation.

MergeTable

Applies changes to a table (all rows or as specified in the WHERE clause) in a workspace to its parent workspace.

MergeWorkspace

Applies all changes in a workspace to its parent workspace, and optionally removes the workspace.

RollbackWorkspace

Discards all data changes made in the workspace to version-enabled tables.

RollbackTable

Discards all changes made in the workspace to a specified table (all rows or as specified in the WHERE clause).

RollbackToSP

Discards all data changes made in the workspace to version-enabled tables since the specified savepoint.

RefreshTable

Applies to a workspace all changes made to a table (all rows or as specified in the WHERE clause) in its parent workspace.

RefreshWorkspace

Applies to a workspace all changes made in its parent workspace.

AlterWorkspace

Modifies the description of a workspace.

ChangeWorkspaceType

Changes a workspace that is not continually refreshed to be continually refreshed.

RemoveWorkspace

Discards all row versions associated with a workspace and deletes the workspace.

RemoveWorkspaceTree

Discards all row versions associated with a workspace and its descendant workspaces, and deletes the affected workspaces.

FreezeWorkspace

Restricts access to a workspace and the ability of users to make changes in the workspace.

UnfreezeWorkspace

Enables access and changes to a workspace, reversing the effect of the FreezeWorkspace procedure.

CompressWorkspace

Deletes removable savepoints in a workspace, and minimizes the Workspace Manager metadata structures for the workspace.

CompressWorkspaceTree

Deletes removable savepoints in a workspace and all its descendant workspaces. It also minimizes the Workspace Manager metadata structures for the affected workspaces, and eliminates any redundant data that might arise from the deletion of the savepoints.

IsWorkspaceOccupied

Checks whether or not a workspace has any active sessions.

CreateSavepoint

Returns the current workspace for the session.

SetMultiWorkspaces

Makes the specified workspace or workspaces visible in the multiworkspace views for version-enabled tables.

GetMultiWorkspaces

Returns the names of workspaces visible in the multiworkspace views for version-enabled tables.

GetOpContext

Returns the context of the current operation for the current session.

AddAsParentWorkspace

Adds a workspace as a parent workspace to a child workspace in a multiparent workspace environment.

RemoveAsParentWorkspace

Removes a workspace as a parent workspace in a multiparent workspace environment.


1.16.3 Savepoint Management Subprograms

Savepoint management subprograms perform operations related to savepoints.

Table 1-9 shows the subprograms available for savepoint management.

Table 1-9 Savepoint Management Subprograms

Procedure Description

CreateSavepoint

Creates a savepoint for the current version.

GotoDate

Goes to the specified savepoint in the current workspace.

GotoDate

Goes to a point at or near the specified date and time in the current workspace.

GetSessionInfo

Retrieves information about the current workspace and session context; useful for finding the session's current savepoint or instant in time.

AlterSavepoint

Modifies the description of a savepoint.

DeleteSavepoint

Deletes a savepoint and associated rows in version-enabled tables.


1.16.4 Privilege Management Subprograms

Privilege management subprograms grant and revoke Workspace Manager privileges.

Table 1-10 shows the subprograms available for privilege management.

Table 1-10 Privilege Management Subprograms

Procedure Description

GrantWorkspacePriv

Grants workspace-level privileges to users, roles, or PUBLIC.

RevokeWorkspacePriv

Revokes workspace-level privileges from users and roles.

GrantSystemPriv

Grants privileges on all workspaces to users, roles, or PUBLIC.

RevokeSystemPriv

Revokes system-level privileges from users and roles.

GetPrivs

Returns a comma-delimited list of all privileges that the current user has for the specified workspace.


1.16.5 Lock Management Subprograms

Lock management subprograms control Workspace Manager locking.

Table 1-11 shows the subprograms available for lock management.

Table 1-11 Lock Management Subprograms

Procedure Description

SetLockingON

Enables Workspace Manager locking for the current session.

SetLockingOFF

Disables Workspace Manager locking for the current session.

SetWorkspaceLockModeON

Enables Workspace Manager locking for the specified workspace.

SetWorkspaceLockModeOFF

Disables Workspace Manager locking for the specified workspace.

GetLockMode

Returns the locking mode for the current session, which determines whether or not access is enabled to versioned rows and corresponding rows in the previous version.

LockRows

Controls access to versioned rows in a specified table and to corresponding rows in the parent workspace.

UnlockRows

Enables access to versioned rows in a specified table and to corresponding rows in the parent workspace.


1.16.6 Conflict Management Subprograms

Conflict management subprograms detect and resolve conflicts between workspaces.

Table 1-12 shows the subprograms available for conflict management.

Table 1-12 Conflict Management Subprograms

Procedure Description

SetConflictWorkspace

Determines whether or not conflicts exist between a workspace and its parent workspace.

GetConflictWorkspace

Returns the name of the workspace on which the session has performed the SetConflictWorkspace procedure.

BeginResolve

Starts a conflict resolution session.

ResolveConflicts

Resolves conflicts between workspaces.

CommitResolve

Ends a conflict resolution session and saves (makes permanent) any changes in the workspace since the BeginResolve procedure was executed.

RollbackResolve

Quits a conflict resolution session and discards all changes in the workspace since the BeginResolve procedure was executed.


1.16.7 Replication Support Subprograms

Replication support subprograms provide support for Oracle replication in a Workspace Manager environment. For information about using replication, see Appendix C.

Table 1-13 shows the subprograms available for replication support.

Table 1-13 Replication Support Subprograms

Procedure Description

GenerateReplicationSupport

Creates necessary structures for multimaster replication of Workspace Manager objects, and starts the master activity for the newly created master group.

DropReplicationSupport

Deletes replication support objects that were created by the GenerateReplicationSupport procedure.

RelocateWriterSite

Makes one of the nonwriter sites the new writer site in a Workspace Manager replication environment. (The old writer site becomes one of the nonwriter sites.)

SynchronizeSite

Brings the local site (the old writer site) up to date in the Workspace Manager replication environment after the writer site was moved using the RelocateWriterSite procedure.


1.16.8 Bulk Load Support Subprograms

Bulk load support subprograms enable SQL*Loader to be used for bulk loading data into version-enabled tables, as explained in Section 1.7.

Table 1-14 shows the subprograms available for bulk loading support.

Table 1-14 Bulk Loading Support Subprograms

Procedure Description

GetBulkLoadVersion

Returns a version number to be specified when you call the BeginBulkLoading procedure.

BeginBulkLoading

Starts the bulk loading process for a version-enabled table.

CommitBulkLoading

Ends the bulk loading process for a version-enabled table by committing the bulk load changes.

RollbackBulkLoading

Rolls back changes made to a version-enabled table during a bulk load operation.


1.17 Simplified Examples Using Workspace Manager

This section presents two simplified examples of using Workspace Manager to try out some scenarios and select one of them. Each example uses workspaces and one or more savepoints. One example (in Section 1.17.2) uses the OE.WAREHOUSES table in the Oracle sample schemas.

The examples refer to concepts that were explained in this chapter, and they use procedures documented in Chapter 4.

1.17.1 Example: Marketing Budget Options

In Example 1-3, a soft drink (cola) manufacturer has four products, each with a marketing manager and a marketing budget. Because of an exceptional opportunity for growth in the market for one product (cola_b), the company wants to do what-if analyses involving different managers and budget amounts.

Example 1-3 Marketing Budget Options

-------------------------------------------------------------------
-- INITIAL SET-UP
-------------------------------------------------------------------
-- Create the user for schema objects.
CREATE USER wm_developer IDENTIFIED BY password;

-- Grant regular privileges.
GRANT connect, resource to wm_developer;
GRANT create table to wm_developer;

-- Grant WM-specific privileges (with grant_option = YES).
EXECUTE DBMS_WM.GrantSystemPriv ('ACCESS_ANY_WORKSPACE, MERGE_ANY_WORKSPACE,
 CREATE_ANY_WORKSPACE, REMOVE_ANY_WORKSPACE, ROLLBACK_ANY_WORKSPACE',
 'wm_developer', 'YES');

---------------------------------------------------------------------------
-- CREATE AND POPULATE DATA TABLE --
---------------------------------------------------------------------------
CONNECT wm_developer
-- Enter password when prompted.

-- Cleanup: remove B_focus_2 workspace if it exists from previous run.
EXECUTE DBMS_WM.RemoveWorkspace ('B_focus_2');

-- Create a table for the annual marketing budget for
-- several cola (soft drink) products.
-- Each row will contain budget data for a specific
-- product. Note: This table does not reflect recommended
-- database design. (For example, a manager ID should
-- be used, not a name.) It is deliberately oversimplified
-- for purposes of illustration.

CREATE TABLE cola_marketing_budget (
  product_id NUMBER PRIMARY KEY,
  product_name VARCHAR2(32),
  manager VARCHAR2(32),  -- Here a name, just for simplicity
  budget NUMBER  -- Budget in millions of dollars. Example: 3 = $3,000,000.
);

-- Version-enable the table. Specify hist option of VIEW_WO_OVERWRITE so that
-- the COLA_MARKETING_BUDGET_HIST view contains complete history information
-- about data changes.
EXECUTE DBMS_WM.EnableVersioning ('cola_marketing_budget', 'VIEW_WO_OVERWRITE');

INSERT INTO cola_marketing_budget VALUES(
  1,
  'cola_a',
  'Alvarez',
  2.0
);
INSERT INTO cola_marketing_budget VALUES(
  2,
  'cola_b',
  'Baker',
  1.5
);
INSERT INTO cola_marketing_budget VALUES(
  3,
  'cola_c',
  'Chen',
  1.5
);
INSERT INTO cola_marketing_budget VALUES(
  4,
  'cola_d',
  'Davis',
  3.5
);
COMMIT;

-- Relevant data values now in LIVE workspace:
-- 1, cola_a, Alvarez, 2.0
-- 2, cola_b, Baker, 1.5
-- 3, cola_c, Chen, 1.5
-- 4, cola_d, Davis, 3.5

---------------------------------------------------------------------------
-- CREATE WORKSPACES --
---------------------------------------------------------------------------
-- Create workspaces for the following scenario: a major marketing focus
-- for the cola_b product. Managers and budget amounts for each
-- product can change, but the total marketing budget cannot grow.
--
-- One scenario (B_focus_1) features a manager with more expensive 
-- plans (which means more money taken from other products' budgets).
-- The other scenario (B_focus_2) features a manager with less expensive 
-- plans (which means less money taken from other products' budgets).
--
-- Two workspaces (B_focus_1 and B_focus_2) are created as child workspaces 
-- of the LIVE database workspace.

EXECUTE DBMS_WM.CreateWorkspace ('B_focus_1');
EXECUTE DBMS_WM.CreateWorkspace ('B_focus_2');

---------------------------------------------------------------------------
-- WORK IN FIRST WORKSPACE --
---------------------------------------------------------------------------
-- Enter the B_focus_1 workspace and change the cola_b manager to Beasley and 
-- raise the cola_b budget amount by 1.5 to bring it to 3.0. Reduce all other 
-- products' budget amounts by 0.5 to stay within the overall budget.

EXECUTE DBMS_WM.GotoWorkspace ('B_focus_1');
UPDATE cola_marketing_budget
  SET manager = 'Beasley' WHERE product_name = 'cola_b';
UPDATE cola_marketing_budget
  SET budget = 3 WHERE product_name = 'cola_b';
UPDATE cola_marketing_budget
  SET budget = 1.5 WHERE product_name = 'cola_a';
UPDATE cola_marketing_budget
  SET budget = 1 WHERE product_name = 'cola_c';
UPDATE cola_marketing_budget
  SET budget = 3 WHERE product_name = 'cola_d';
COMMIT;

-- Relevant data values now in B_focus_1 workspace::
-- 1, cola_a, Alvarez, 1.5
-- 2, cola_b, Beasley, 3.0
-- 3, cola_c, Chen, 1.0
-- 4, cola_d, Davis, 3.0

-- Freeze this workspace to prevent any changes until workspace is unfrozen.
-- However, first go to the LIVE workspace, because a workspace cannot be frozen
-- if any users (including you) are in it.
EXECUTE DBMS_WM.GotoWorkspace ('LIVE');
EXECUTE DBMS_WM.FreezeWorkspace ('B_focus_1');

---------------------------------------------------------------------------
-- CREATE ANOTHER SCENARIO IN SECOND WORKSPACE --
---------------------------------------------------------------------------
-- Enter the B_focus_2 workspace and change the cola_b manager to Burton and 
-- raise the cola_b budget amount by 0.5 to bring it to 2.0. Reduce only the 
-- cola_d amount by 0.5 to stay within the overall budget.

EXECUTE DBMS_WM.GotoWorkspace ('B_focus_2');
UPDATE cola_marketing_budget
  SET manager = 'Burton' WHERE product_name = 'cola_b';
UPDATE cola_marketing_budget
  SET budget = 2 WHERE product_name = 'cola_b';
UPDATE cola_marketing_budget
  SET budget = 3 WHERE product_name = 'cola_d';
COMMIT;

-- Relevant data values now in B_focus_2 workspace::
-- 1, cola_a, Alvarez, 2.0 (no change from LIVE)
-- 2, cola_b, Burton, 2.0
-- 3, cola_c, Chen, 1.5 (no change from LIVE)
-- 4, cola_d, Davis, 3.0 (same manager, new budget)

-- Create a savepoint (B_focus_2_SP1), then change scenario to 
-- raise cola_b budget and reduce cola_d budget by 0.5 each.

EXECUTE DBMS_WM.CreateSavepoint ('B_focus_2', 'B_focus_2_SP1');
UPDATE cola_marketing_budget
  SET budget = 2.5 WHERE product_name = 'cola_b';
UPDATE cola_marketing_budget
  SET budget = 2.5 WHERE product_name = 'cola_d';
COMMIT;

-- Relevant data values now in B_focus_2 workspace:
-- 1, cola_a, Alvarez, 2.0 (no change from LIVE)
-- 2, cola_b, Burton, 2.5 
-- 3, cola_c, Chen, 1.5 (no change from LIVE)
-- 4, cola_d, Davis, 2.5 (same manager, new budget)

-- Discard this scenario; roll back to row values at the time savepoint 
-- B_focus_2_SP1 was created. First, though, get out of the workspace
-- so it can be rolled back (no users in it).

EXECUTE DBMS_WM.GotoWorkspace ('LIVE');
EXECUTE DBMS_WM.RollbackToSP ('B_focus_2', 'B_focus_2_SP1');

-- Go back to the B_focus_2 workspace and display current values 
-- (should include budget of 2 for cola_b and 3 for cola_d).
EXECUTE DBMS_WM.GotoWorkspace ('B_focus_2');
SELECT * FROM cola_marketing_budget;

---------------------------------------------------------------------------
-- SELECT SCENARIO AND UPDATE DATABASE --
---------------------------------------------------------------------------
-- Assume that you have decided to adopt the scenario of the second 
-- workspace (B_focus_2) using that workspace's current values.

-- First go to the LIVE workspace, because a workspace cannot be removed
-- or merged if any users (including you) are in it.
EXECUTE DBMS_WM.GotoWorkspace ('LIVE');

-- Unfreeze the first workspace and remove it to discard any changes there.
EXECUTE DBMS_WM.UnfreezeWorkspace ('B_focus_1');
EXECUTE DBMS_WM.RemoveWorkspace ('B_focus_1');

-- Apply changes in the second workspace to the LIVE database workspace.
-- Note that the workspace is not removed by default after MergeWorkspace.
EXECUTE DBMS_WM.MergeWorkspace ('B_focus_2');

-- Display the current data values (which are in the LIVE database 
-- workspace, which is the only workspace currently existing).
SELECT * FROM cola_marketing_budget;

---------------------------------------------------------------------------
-- DISABLE VERSIONING --
---------------------------------------------------------------------------
-- Disable versioning on the table because you are finished testing scenarios.
-- Set force parameter to TRUE if you want to force the disabling even
-- if changes were made in a non-LIVE workspace.

EXECUTE DBMS_WM.DisableVersioning ('cola_marketing_budget', TRUE);

1.17.2 Example: Warehouse Expansion Options

In Example 1-4, a company that uses the Oracle sample schemas decided that it needs additional warehouse space. It wants to consider two scenarios: a single large warehouse in Town A, and two smaller warehouses in Town B and Town C that together offer more total storage capacity. There are potential advantages and disadvantages to each scenario, and financial and legal issues to be resolved with each. Later, the company decides that it might need even more warehouse space under each scenario, so it wants to consider the same additional warehouse in each scenario.

Example 1-4 creates a workspace for each scenario; and within each workspace it creates a savepoint before adding an extra new warehouse to the table, because the company might decide not to use the extra warehouse. The warehouse rows are stored on the OE.WAREHOUSES table, which is part of the Oracle sample schemas.

Example 1-4 Warehouse Expansion Options

-------------------------------------------------------------------
-- INITIAL SET-UP
-------------------------------------------------------------------
-- Clean up from any previous running of this procedure.
DROP USER wm_developer CASCADE;

-- Create the user for schema objects.
CREATE USER wm_developer IDENTIFIED BY password;

-- Grant regular privileges.
GRANT connect, resource TO wm_developer;
GRANT create table TO wm_developer;

-- Grant privileges on tables to be modified.
GRANT select, insert, delete, update ON oe.warehouses TO wm_developer; 
GRANT select, insert, delete, update ON hr.locations TO wm_developer; 

-- Grant WM-specific privileges (with grant_option = YES).
EXECUTE DBMS_WM.GrantSystemPriv ('ACCESS_ANY_WORKSPACE, MERGE_ANY_WORKSPACE,
 CREATE_ANY_WORKSPACE, REMOVE_ANY_WORKSPACE, ROLLBACK_ANY_WORKSPACE',  
 'wm_developer', 'YES');

-- WM_ADMIN_ROLE required to version-enable a table in another schema.
GRANT wm_admin_role TO wm_developer;

-- Create rows for new locations, since a valid location ID is needed for each
-- proposed new warehouse.
INSERT INTO hr.locations VALUES 
   (4000, '123 Any Street', '01234', 'Town A', 'MA', 'US');
INSERT INTO hr.locations VALUES 
   (4100, '456 Some Street', '01235', 'Town B', 'MA', 'US');
INSERT INTO hr.locations VALUES 
   (4200, '789 Other Street', '01236', 'Town C', 'MA', 'US');
INSERT INTO hr.locations VALUES 
   (4300, '1 Yetanother Street', '01237', 'Town D', 'MA', 'US');

---------------------------------------------------------------------------
-- CREATE AND VERSION-ENABLE THE DATA TABLE --
---------------------------------------------------------------------------
CONNECT wm_developer
-- Enter password when prompted.
set echo on
set serveroutput on

-- Version-enable the OE.WAREHOUSES table. Specify hist option of 
-- VIEW_WO_OVERWRITE so that the WAREHOUSES_HIST view contains 
-- complete history information about data changes. However, because 
-- OE.WAREHOUSES is the parent table in a referential integrity constraint
-- with OE.INVENTORIES, you must also version-enable that table.

EXECUTE DBMS_WM.EnableVersioning ('OE.WAREHOUSES, OE.INVENTORIES', hist => 'VIEW_WO_OVERWRITE');

------------------------------------------------------------------------
-- CREATE AND USE WORKSPACES --
------------------------------------------------------------------------
-- The company has decided that it needs additional warehouse space. 
-- It wants to consider two scenarios: a single large warehouse in Town A,
-- and two smaller warehouses in Town B and Town C that together offer more
-- total storage capacity. There are potential advantages and disadvantages 
-- to each scenario, and financial and legal issues to be resolved with each.
--
-- Later, the company decides that it might need even more warehouse
-- space under each scenario, so it wants to consider the same additional 
-- warehouse in each scenario.

-- Create a workspace for each scenario, with both created as child 
-- workspaces of the LIVE database workspace.
-- In workspace large_warehouse, add one row for the single large warehouse.
-- In workspace smaller_warehouses, add two rows, one for each warehouse.
--
-- Also, within each workspace create a savepoint before adding the
-- extra warehouse, because the company might decide it does not
-- need the warehouse.

EXECUTE DBMS_WM.CreateWorkspace (workspace => 'large_warehouse');
EXECUTE DBMS_WM.CreateWorkspace (workspace => 'smaller_warehouses');

-- Set up the first scenario: Go to the large_warehouse workspace and first add
-- one row for a warehouse.

EXECUTE DBMS_WM.GotoWorkspace (workspace => 'large_warehouse');

INSERT INTO oe.warehouses VALUES (10, NULL, 'Town A', 4000,
        MDSYS.SDO_GEOMETRY(2001, 8307, 
        MDSYS.SDO_POINT_TYPE(-71.00703, 42.27099, NULL), NULL, NULL)); 

UPDATE oe.warehouses SET warehouse_spec = sys.xmltype.createxml( 
'<?xml version="1.0"?> 
<Warehouse> 
<Building>Owned</Building> 
<Area>100000</Area> 
<Docks>2</Docks> 
<DockType>Side load</DockType> 
<WaterAccess>Y</WaterAccess> 
<RailAccess>Y</RailAccess> 
<Parking>Lot</Parking> 
<VClearance>15 ft</VClearance> 
</Warehouse>' 
) WHERE warehouse_id = 10; 

COMMIT;

-- Create a savepoint so that you can, if necessary, roll back to the point
-- before the extra warehouse was added.
EXECUTE DBMS_WM.CreateSavepoint ('large_warehouse', 'large_warehouse_add_wh');

-- Add another warehouse for this scenario.
INSERT INTO oe.warehouses VALUES (11, NULL, 'Town D', 4300,
        MDSYS.SDO_GEOMETRY(2001, 8307, 
        MDSYS.SDO_POINT_TYPE(-71.00707, 42.35226, NULL), NULL, NULL)); 

UPDATE oe.warehouses SET warehouse_spec = sys.xmltype.createxml( 
'<?xml version="1.0"?> 
<Warehouse> 
<Building>Leased</Building> 
<Area>55000</Area> 
<Docks>1</Docks> 
<DockType>Rear load</DockType> 
<WaterAccess>N</WaterAccess> 
<RailAccess>N</RailAccess> 
<Parking>Street</Parking> 
<VClearance>10 ft</VClearance> 
</Warehouse>' 
) WHERE warehouse_id = 11; 

COMMIT;

-- Freeze this workspace to prevent any changes until the workspace is unfrozen.
-- However, first go to the LIVE workspace, because a workspace cannot be frozen
-- if any users (including you) are in it.
EXECUTE DBMS_WM.GotoWorkspace ('LIVE');
EXECUTE DBMS_WM.FreezeWorkspace ('large_warehouse');

-- Set up the second scenario: Go to the smaller_warehouses workspace and first 
-- add two rows for the smaller warehouses.

EXECUTE DBMS_WM.GotoWorkspace ('smaller_warehouses');

INSERT INTO oe.warehouses VALUES (10, NULL, 'Town B', 4100,
        MDSYS.SDO_GEOMETRY(2001, 8307, 
        MDSYS.SDO_POINT_TYPE(-71.02439, 42.28628, NULL), NULL, NULL)); 

INSERT INTO oe.warehouses VALUES (11, NULL, 'Town C', 4200,
        MDSYS.SDO_GEOMETRY(2001, 8307, 
        MDSYS.SDO_POINT_TYPE(-70.97980, 42.37961, NULL), NULL, NULL)); 

UPDATE oe.warehouses SET warehouse_spec = sys.xmltype.createxml( 
'<?xml version="1.0"?> 
<Warehouse> 
<Building>Owned</Building> 
<Area>60000</Area> 
<Docks>1</Docks> 
<DockType>Side load</DockType> 
<WaterAccess>Y</WaterAccess> 
<RailAccess>Y</RailAccess> 
<Parking>Lot</Parking> 
<VClearance>15 ft</VClearance> 
</Warehouse>' 
) WHERE warehouse_id = 10; 

UPDATE oe.warehouses SET warehouse_spec = sys.xmltype.createxml( 
'<?xml version="1.0"?> 
<Warehouse> 
<Building>Leased</Building> 
<Area>550000</Area> 
<Docks>1</Docks> 
<DockType>Rear load</DockType> 
<WaterAccess>N</WaterAccess> 
<RailAccess>Y</RailAccess> 
<Parking>Street</Parking> 
<VClearance>12 ft</VClearance> 
</Warehouse>' 
) WHERE warehouse_id = 11; 

COMMIT;

-- Create a savepoint so that you can, if necessary, roll back to the point
-- before the extra warehouse was added.
EXECUTE DBMS_WM.CreateSavepoint ('smaller_warehouses', 'smaller_warehouses_add_wh');

-- Add the extra warehouse for this scenario.
INSERT INTO oe.warehouses VALUES (12, NULL, 'Town D', 4300,
        MDSYS.SDO_GEOMETRY(2001, 8307, 
        MDSYS.SDO_POINT_TYPE(-71.00707, 42.35226, NULL), NULL, NULL)); 

UPDATE oe.warehouses SET warehouse_spec = sys.xmltype.createxml( 
'<?xml version="1.0"?> 
<Warehouse> 
<Building>Leased</Building> 
<Area>55000</Area> 
<Docks>1</Docks> 
<DockType>Rear load</DockType> 
<WaterAccess>N</WaterAccess> 
<RailAccess>N</RailAccess> 
<Parking>Street</Parking> 
<VClearance>10 ft</VClearance> 
</Warehouse>' 
) WHERE warehouse_id = 12; 

COMMIT;

---------------------------------------------------------------------------
-- SELECT A SCENARIO, AND APPLY IT --
---------------------------------------------------------------------------
-- Later, the company makes its decisions:
-- 1. Add two smaller warehouses.
-- 2. Do not add the extra warehouse (that is, no third new warehouse).
-- Consequently, you need to discard the first scenario (large_warehouse
-- workspace) completely, discard the warehouse addition in the second
-- scenario (roll back to smaller_warehouses_add_wh savepoint), and 
-- apply the second scenario.

-- First go to the LIVE workspace, because a workspace cannot be removed
-- or merged if any users (including you) are in it.
EXECUTE DBMS_WM.GotoWorkspace ('LIVE');

-- Unfreeze the first workspace and remove it to discard any changes there.
EXECUTE DBMS_WM.UnfreezeWorkspace ('large_warehouse');
EXECUTE DBMS_WM.RemoveWorkspace ('large_warehouse');

-- Rollback the workspace for the second scenario to the savepoint created
-- before the extra warehouse was added.
EXECUTE DBMS_WM.RollbackToSP ('smaller_warehouses', 'smaller_warehouses_add_wh');

-- Apply changes in the smaller_warehouses workspace to the LIVE database 
-- workspace; use the remove_workspace parameter to remove the 
-- smaller_warehouses workspace after the merge.
EXECUTE DBMS_WM.MergeWorkspace ('smaller_warehouses', remove_workspace => TRUE);

-- The OE.WAREHOUSES table now has the desired data (two additional warehouses
-- from the smaller_warehouses scenario). Display the IDs and names just to be
-- sure.
SELECT warehouse_id, warehouse_name FROM oe.warehouses 
   ORDER BY warehouse_id;

-- Disable versioning on the table because you are finished testing scenarios.
-- Set the force parameter to TRUE to force disabling even though changes 
-- were made in a non-LIVE workspace. You must also version-disable
-- the other tables previously version-enabled (along with OE.WAREHOUSES).

EXECUTE DBMS_WM.DisableVersioning ('OE.WAREHOUSES, OE.INVENTORIES', force => TRUE);

-- Clean up by deleting the rows that were added to the OE.WAREHOUSES table.
DELETE FROM oe.warehouses WHERE warehouse_id >= 10;

-- Clean up by deleting the locations that were added.
DELETE FROM hr.locations WHERE location_id >= 4000;

The SELECT statement near the end of Example 1-4 displays the IDs and names of warehouses in the OE.WAREHOUSES table, including the newly added warehouses in Town B and Town C, as shown in the following example:

SELECT warehouse_id, warehouse_name FROM oe.warehouses 
   ORDER BY warehouse_id;

WAREHOUSE_ID WAREHOUSE_NAME                                                     
------------ -----------------------------------                                
           1 Southlake, Texas                                                   
           2 San Francisco                                                      
           3 New Jersey                                                         
           4 Seattle, Washington                                                
           5 Toronto                                                            
           6 Sydney                                                             
           7 Mexico City                                                        
           8 Beijing                                                            
           9 Bombay                                                             
          10 Town B                                                             
          11 Town C