Within composite clusters, both Composite Active/Passive and Composite Active/Active, the selection of datasources can be made to be deterministic by specifying the list of datasources within the user.map configuration. The configuration is based on an ordered, comma-separated list of services to use which are then selected in order.

The format of the speecification is as follows:

user pass compositeDS dataservice_by_order_of_priority* [-dataservice_to_exclude]*

The specification operates on the following rules:

For example, in a setup made of three data service, usa, asia and europe using the following configuration:

app_user secret usa,asia,-europe

Will select data sources in data service usa. If usa is not available, in asia. If asia is not availble, then connection will not succeed since europe has been negated.