Experimental Characterization of Metadata Synchronization in a Homogeneous MySQL Multidatabase Testbed Direct JSON-over-TCP/IP Fan-out, Serial JSON-over-SMB Relay, and Native Replication

Abstract Schema changes in autonomous database nodes can invalidate integrated catalog views unless metadata propagation is timely and correct. This study comparatively evaluates three operationally distinct Data Definition Language (DDL) propagation implementations in a three-node homogeneous MySQL environment: application-level direct TCP/IP fan-out, serial JSON-over-SMB relay, and native MySQL replication. Five latency observations per destination and technique yield 30 recorded measurements. The mean propagation latencies for Nodes 1 and 2 within same subnet is 1200.0 and Nodes 1 and 3 within two different subnets is 1383.0 ms for direct TCP/IP fan-out, Nodes 1 and 2 within same subnet is 3241.0 and Nodes 1 and 3 within two different subnets is 4664.6 ms for serial JSON-over-SMB relay, and Nodes 1 and 2 within same subnet is 171.6 and Nodes 1 and 3 within two different subnets is 146.4 ms for native MySQL replication. The comparatively higher serial-relay latency is consistent with cumulative processing and coordination overhead associated with sequential forwarding, JSON serialization, and SMB-based file handling. The study distinguishes metadata delivery, DDL application, acknowledgement, and catalog convergence as separate operational endpoints, examines descriptive latency variability and event-index comparisons, and establishes a catalog-consistency specification. The recorded observations show lower mean delays for direct TCP/IP fan-out than for serial relay, while native MySQL replication exhibits the lowest mean delays under the evaluated conditions. Nevertheless, architectural differences and measurement semantics limit direct causal attribution of performance differences to individual transport mechanisms. The findings provide empirical insights into the performance characteristics and architectural trade-offs of DDL propagation strategies, establishing a foundation for designing reliable metadata synchronization mechanisms in distributed database environments without claiming experimentally verified heterogeneous interoperability or global catalog convergence.