Deferred Transactions vs Physical Transactions (Magic xpa 4.x)

The following sections provide information about the differences between the two types of transactions:

Transaction Begin

In deferred transactions, a logical transaction is opened, but the physical transaction is only opened before a Commit.

In Deferred mode, it is not recommended to begin the transaction before the Task Prefix logic unit since these operations are stored in Cache memory, and memory is limited.

Locking Strategy

Deferred transactions can have the following lock set values:

• On-Modify - Selecting the On-Modify locking strategy in a deferred transaction task does not issue locks to the database. These locks are handled through the locking mechanism. Lock settings should be used as required.

• No Lock

SQL Range Statement

When using a DB SQL Where clause in a deferred transaction task, any update done in another task on the queried data source will not be seen.

Direct SQL

Direct SQL tasks can be included within a physical transaction mode task. Deferred transactions can be defined for tasks that are set by a Direct SQL statement.

Note: Table-based tasks in a deferred transaction reflect modifications of the tables that were entered by another task within the same transaction. However, a Direct SQL-based task does not reflect such modifications.