CHANGE (Project Definition)

Function:

• Changes the Database (DB) access type (UPDATE or MULTIWRITE), and the claim mode for multiwrite DBs.

• It also changes the file number and control mode, and brings foreign DBs up to date.

• Optionally sets PROTECTION to limit copying and extraction of data between Users and Projects.

In a Global Project, this command can only be given at the Hub. It can also be used to change the Primary Location of a DB.

Description:

By default, DBs are created with UPDATE access type, which means that they can be opened with one writer and n readers.

Model, Draft (PADD), Catalogue and Isodraft DBs can be multiwrite DBs, which allows more than one User to write to the same DB. Multiwrite DBs can have their claim mode set to IMPLICIT, in which case any element which is modified will be claimed automatically. Alternatively, the claim mode can be set to EXPLICIT, in which case Users must claim elements before they can modify them, using the CLAIM command in the constructor modules. For more information, refer to the Reference Manual for the module.

The CHANGE command can be used to change the access mode from UPDATE to MULTIWRITE, and from MULTIWRITE to UPDATE. It can also be used to change the claim mode of multiwrite DBs from IMPLICIT to EXPLICIT, and from EXPLICIT to IMPLICIT.

Note:
The administrator cannot set the CONTROLLED attribute, which means that access is controlled by an external system, using this command.
If the DB has an extract DB created from it, the access mode must stay as MULTIWRITE.
If the access mode of a DB used as a foreign DB is changed, the administrator should use the CHANGE FOREIGN command in the Project which has included the foreign DB to update the Project.

Both update and multiwrite DBs can also have their CONTROLLED attribute set.

Setting the PROTECTION parameter will disallow copying extraction of data between Projects or Users which are not members of the protected DB. An optional expiry date may be specified.

CHANGE dbname PROTection [ ON | OFF ] [EXPires future-date ]

In a Global Project, the CHANGE command can be used at the Hub to change the Primary Location of a DB. The CHANGE PRIMARY command cannot complete while there are Users in the AVEVA base product with write access to the DB. The command will eventually complete once all such Users have left the AVEVA base product. The administrator may need to use the EXPUNGE command to remove phantom Users.

After the CHANGE PRIMARY command has been issued, Users in the AVEVA base product with write access to the DB can continue to modify the DB, even if GETWORK is used. Once they have made a module switch, the DB will become read-only.

If a CHANGE PRIMARY command fails, the previous Primary Location will normally be recovered automatically. If the recovery fails (for example, the daemon is not running), the administrator can recover the previous Primary Location using the command PREVOWN dbname.

Note:
Use of the PREVOWN command should be avoided if possible.

Offline Locations

Before issuing a CHANGE PRIMARY command to or from an offline Location, all users should have left the AVEVA base product at the old Primary Location. The TRANSFER command should first be used to bring the DB at the new Primary Location up-to-date. Any modifications to the DB at the old Primary Location subsequent to this transfer will be lost. Only after this transfer is it safe to issue the CHANGE PRIMARY command.

Examples:

Note:
On the following change: Primary commands
The new Primary Location will receive all outstanding updates of the DB from the current Primary Location.

Note:
Offline Locations
The Primary Location of a DB cannot be changed directly between an off-line satellite and an online Satellite. The Primary Location of the DB must first be changed to the Hub. The <date> option is not allowed for off-line Locations.

Command Syntax:

Note:
The CLAIM OFF option is only applicable to controlled DBs.

The CLAIM IMPLICIT and CLAIM EXPLICIT options are only applicable to multiwrite and controlled DBs.

The following option is only available at the Hub of a Global Project:

Querying:

Related Commands:

PREVOWNER (Global Project Administration - Hub only)