The MTS/XA Transaction Manager, which operates only on Windows, supports the tightly-coupled mode. MTS tightly-coupled transaction support on the database server includes:

• Support for application programs with two tiers (a business-logic layer and a data-access layer).
• Connection pooling and session pooling.

MTS tightly-coupled transaction support does not affect existing loosely-coupled-transaction support. The same database server can use both loosely-coupled and tightly-coupled transaction support at the same time.

MTS tightly-coupled transaction support has the following restrictions:

• Temporary tables are limited to one transaction branch. Different transaction branches within one global transaction cannot share a temporary table.
• Different transaction branches within one global transaction cannot share cursors.
• Different transaction branches within one global transaction cannot share an isolation level or lock-wait mode. The isolation level and lock-wait mode of each transaction branch must be set individually or set to the default level. If you want the same isolation level for all transaction branches, you must use SQL to specify this information for each transaction branch.