SQL Server Native Delayed Delivery

The SQL Server transport can take advantage of native delayed delivery without the need to run the timeout manager. Instead, the transport creates infrastructure which can delay messages using native SQL Server transport features.

The native delayed delivery of SQL Server transport is available only in endpoints that are not configured as send-only.


The default values for the settings described in this section are used in snippets. The settings can be fine-tuned to fit a particular system's characteristic, e.g. in case the expired timeout messages need to be picked up more frequently to result in a more precise approximation of expiry time.

For upgrade guidance refer to the dedicated upgrade guide.

The transport creates an additional table that stores delayed messages. The table name has the format endpoint-name.suffix, using the suffix specified in the configuration:


SQL Server transport polls for expired messages every second by default. Polling interval can be configured:


then it picks and dispatches messages in batches of the specified size:


When the delay time lapses, SQL Server transport moves a batch of messages to the destination queue, i.e. the endpoint's input queue. Note that this means the exact time of delivering delayed message is always approximate.

Backwards compatibility

When upgrading to a version of the transport that supports native delayed delivery, it is safe to operate a combination of endpoints using native delayed delivery and endpoints using timeout manager at the same time:

  • Endpoints with native delayed delivery can send delayed messages to endpoints using timeout manager.
  • Endpoints with native delayed delivery can continue to receive delayed messages from endpoints using timeout manager.

Enable the timeout manager

To assist with the upgrade process when upgrading from an older version of the transport that doesn't support native-delayed delivery, the timeout manager can be enabled. Any delayed messages stored in the endpoint's persistence database before the upgrade are sent when their timeouts expire. Any delayed messages sent after the upgrade are sent through the native delayed delivery infrastructure, even though the timeout manager is enabled. The timeout manager migration mode can be enabled with:


Once an endpoint has no more delayed messages in its persistence database, there is no need for the timeout manager. It can be disabled by removing the above enable call.

At this point, all .Timeouts and .TimeoutsDispatcher tables for the endpoint can be deleted from the database. In addition, the endpoint no longer requires timeout persistence, so those storage entities can be removed from the persistence database as well.

Timeout Manager should also be disabled for newly created endpoints, i.e. endpoints that use the native delayed delivery implementation and haven't been deployed yet.

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