The Help seems to imply that DEDICATED_TASK can (or should) only be set to On for one single connection.

It also says that "a request handling task is dedicated exclusively to handling requests for the connection".

However, testing with 16.0.0.2052 indicates that something far less dramatic may be the actual case.

First of all, it is possible to set DEDICATED_TASK to On for many connections, not just one; for example:

SELECT COUNT(*) AS "Connections with DEDICATED_TASK = ON"
  FROM sa_connection_properties()
 WHERE PropName = 'dedicated_task'
   AND Value = 'On';
Connections with DEDICATED_TASK = ON 
------------------------------------ 
                                 100 

Second, when those connections are used in an "overclocking" benchmark that pounds the server with an unrelenting series of UPDATE statements with no "think time" at all, the test runs faster with DEDICATED_TASK = On (582 seconds) than with DEDICATED_TASK = Off (679 seconds).

PLEASE NOTE: This posting DOES NOT IMPLY that setting DEDICATED_TASK = On for many connections is a good idea; the benchmark shown here is designed for DESTRUCTIVE TESTING, not evaluating performance improvements.

For the record, setting DEDICATED_TASK = On does seem to dramatically affect the dynamic tuning of the multiprogramming level. In particular, with DEDICATED_TASK set to Off for all 100 connections, the multiprogramming level (Max Req in the Foxhound screenshots below) did not rise above the default 20 very often, and stayed BELOW 20 most of the time.

With DEDICATED_TASK set to On for all 100 connections, however, the multiprogramming level rapidly rose far above 20, peaking at 80 for long periods of time. The resulting much-lower-level for Unscheduled Requests probably accounts for the higher throughput and shorter test run.

So... what exactly does DEDICATED_TASK = On do, anyway?

And, is it OK to set it to On for, say, three connections? (e.g., a DBA connection for administrator use, a SQL Anywhere Monitor connection, and a Foxhound Database Monitor connection... yes, some folks have all three).

Fast - Foxhound screenshot with DEDICATED_TASK = ON for 100 connections

Slow - Foxhound screenshot with DEDICATED_TASK = OFF for 100 connections