from RFC2236:
With respect to
each of its attached networks, a multicast router may assume one of
two roles: Querier or Non-Querier. There is normally only one
Querier per physical network. All multicast routers start up as a
Querier on each attached network. If a multicast router hears a
Query message from a router with a lower IP address, it MUST become a
Non-Querier on that network. If a router has not heard a Query
message from another router for [Other Querier Present Interval], it
resumes the role of Querier. Routers periodically [Query Interval]
send a General Query on each attached network for which this router
is the Querier, to solicit membership information.
basically once you introduce second IGMP querier (for whatever reason), the only router remains in IGMP Querier role - the one with lowest IP address of subjected network.
This all means that your network should remain stable and non-affected.
> If it's set to auto is there any way to see which switch is the querier
sure, it should be determinable from some output. as because you are not mentioning device type/model on which you implementing IGMP querier role, I can't tell you command which reveals that information.
