Login Redirection

SAP Sybase IQ 16.0 provides load balancing when a user tries to log into an overloaded node by redirecting the attempted login to a node that is less loaded in the same logical server.

Use the LOGIN_REDIRECTION logical server policy to enable redirection. You can now define your own logical server policies and assign them to one or more logical servers to specify server behavior. Connection parameters, logical server policies, login policies, and user privileges determine the nodes available to a particular user for processing.

For example, the following creates a logical server policy lsp1 where login redirection is enabled and associates the new policy with logical server ls1:

CREATE LS POLICY lsp1 LOGIN_REDIRECTION=ON
ALTER LOGICAL SERVER ls1 POLICY lsp1

To specify the target logical server, connect using the LOGICALSERVER parameter. To specify the target server role instead, connect with the NODETYPE parameter. For example, to connect an application executing INSERT or UPDATE statements to a member node with the writer role, use NODETYPE=WRITER.

You can specify the current coordinator without knowing the host name by using the built-in logical server, COORDINATOR.

If login redirection is enabled and a connection is allowed, SAP Sybase IQ redirects connections when:

The initial connection node is not a member of the target logical server.
The initial connection node is a member of the target logical server but has a role other than that requested.
The initial node is a member of the target logical server and has the requested role, but the user has reached the limit of maximum connections on the current logical server member node.

If the initial request fails, SAP Sybase IQ returns a list of available nodes to the user. If available member nodes of the requested role are unavailable, the connection fails.