affinity is defined as the host (single cluster only) or dataservice (composite clusters) to prefer for reads when QOS RO_RELAXED is in use.

The affinity feature routes both reads and writes when using a Composite Active/Active topology.

This can be handled per user in user.map, globally via the tpm option connector-affinity, or via the connection string.

The affinity string is an ordered list of dataservice names, separated by commas, where the first dataservice entry will be the one used by default. If the first dataservice in the list is not available, the connector will use the next one listed, and so forth.

Dataservices not specified in the list, if any, will be used last and randomly.

It is also possible to exclude one or more dataservices by adding a hyphen ("-") in front of the dataservice name.

The deployment used in the examples below consists of a composite dataservice global, with four member dataservices (i.e. one cluster per site): east, west, north and south.

Just for reference, this is the user definition syntax in the user.map file:

{User} {Password} {DataServiceName-or-CompositeDataServiceName} [Affinity]

For example, to exclude site south from servicing read request in user.map:

sales secret global east,west,north,-south

To do the same globally via the tpm command, use the following configuration setting:

connector-affinity=east,west,north,-south

The above affinity string "east,west,north,-south" will try east, then west, then north. If none of the first three are available, a connection request would not succeed since south has been excluded by the negation ("-").

In the following user.map example, dataservices north and south would be available as random candidates if the first two (east and west) were unavailable:

sales secret global east,west

To do the same globally via the tpm command, use the following configuration setting:

connector-affinity=east,west