For each primary database that is managed by an SAP Replication Server, the distributor (DIST) thread uses SQT to read from the inbound queue, and SQM threads to write transactions to the outbound queue.
By default, there is one distributor (DIST) thread for each primary database that is managed by an SAP Replication Server. If you have three primary databases for example, then there are three inbound queues, three DIST threads, and three SQT threads.
In determining the destination of each transaction row, the DIST thread makes calls to the Subscription Resolution Engine (SRE), Transaction Delivery, and Message Delivery modules. All DIST threads share these modules.