TransposeDbUsageExample

Diff: https://github.com/vir/yate/commit/254ea98839d366c475e4b0a77cd22112a9cb8a6b

register.conf:

[call.route]
query=SELECT * FROM forking_route('${called}');
result=location
priority=90
namevaluepairs=yes

Routing function example (requires HSTORE postgresql extension):

CREATE OR REPLACE FUNCTION forking_route(called_arg TEXT) RETURNS TABLE(key TEXT, value TEXT) AS $$
DECLARE
    res HSTORE;
    cntr INTEGER;
BEGIN

    .......

    res := 'location => fork';
    cntr := 0;

    FOR t IN SELECT * FROM .......... LOOP
        cntr := cntr + 1;
        res := res || hstore('callto.' || cntr, t.location);
        FOR kvp IN SELECT * FROM EACH(t.route_params) LOOP
            res := res || hstore('callto.' || cntr || '.' || kvp.key, kvp.value);
        END LOOP;
    END LOOP;

    ...

    RETURN QUERY SELECT * FROM each(res);
END;
$$ LANGUAGE PlPgSQL;