feat: 🎉 postgresql broker first commit of forked prototype from my original code

pkg/broker/install/sql/procedures/04_broker_register_instance.sql

@@ -0,0 +1,82 @@
+-- broker_register_instance function
+-- Registers a new broker instance in the database
+-- Returns: p_retval (0=success, >0=error), p_errmsg (error message), p_instance_id (new instance ID)
+
+CREATE OR REPLACE FUNCTION broker_register_instance(
+    p_name TEXT,
+    p_hostname TEXT,
+    p_pid INTEGER,
+    p_version TEXT,
+    p_queue_count INTEGER,
+    OUT p_retval INTEGER,
+    OUT p_errmsg TEXT,
+    OUT p_instance_id BIGINT
+)
+RETURNS RECORD
+LANGUAGE plpgsql
+AS $$
+DECLARE
+    v_active_count INTEGER;
+BEGIN
+    p_retval := 0;
+    p_errmsg := '';
+    p_instance_id := NULL;
+
+    -- Validate inputs
+    IF p_name IS NULL OR p_name = '' THEN
+        p_retval := 1;
+        p_errmsg := 'Instance name is required';
+        RETURN;
+    END IF;
+
+    IF p_hostname IS NULL OR p_hostname = '' THEN
+        p_retval := 2;
+        p_errmsg := 'Hostname is required';
+        RETURN;
+    END IF;
+
+    -- Check for existing active instances
+    -- Only one broker instance should be active per database
+    SELECT COUNT(*)
+    INTO v_active_count
+    FROM broker_queueinstance
+    WHERE status = 'active';
+
+    IF v_active_count > 0 THEN
+        p_retval := 3;
+        p_errmsg := 'Another broker instance is already active in this database. Only one broker instance per database is allowed.';
+        RETURN;
+    END IF;
+
+    -- Insert new instance
+    INSERT INTO broker_queueinstance (
+        name,
+        hostname,
+        pid,
+        version,
+        status,
+        queue_count,
+        started_at,
+        last_ping_at
+    ) VALUES (
+        p_name,
+        p_hostname,
+        p_pid,
+        p_version,
+        'active',
+        p_queue_count,
+        NOW(),
+        NOW()
+    )
+    RETURNING id_broker_queueinstance INTO p_instance_id;
+
+EXCEPTION
+    WHEN OTHERS THEN
+        p_retval := 99;
+        p_errmsg := SQLERRM;
+        RAISE WARNING 'broker_register_instance error: %', SQLERRM;
+END;
+$$;
+
+-- Comments
+COMMENT ON FUNCTION broker_register_instance IS 'Registers a new broker instance';