Simple Multiwrite Databases

Multi-write databases allow more than one user to write to the same database. Elements in multi-write databases must be claimed when they are modified so that no other user can change them at the same time. When the user creates a multi-write database, they must set its claim mode:

• If the claim mode is explicit, users must explicitly claim any element they want to change before the modification starts.

• If the claim mode is implicit, an element will automatically be claimed when it is modified.

  If a user tries to claim an element that has already been claimed, the second claim will fail. The disadvantage of implicit mode is that users may spend some time defining a change, for example, filling in a window, and then not be able to apply the window if the element has been claimed by someone else.

In a simple multi-write database, all claimed elements are released when the user changes modules. Elements can be released at any other time, providing they have not been modified since the last SAVEWORK.

The user can only claim primary elements. See the appropriate Reference Manual for each AVEVA base product module for information about primary elements, and what happens in special cases.

Note:
If using Status Control, Databases (DBs) must be set to the Implicit Claim mode as the hidden status links behind those elements being managed cannot be explicitly claimed.