The Missing Dimensions in Geo-Distributed Database Evaluation
For database researchers and practitioners, this work highlights critical gaps in evaluating geo-distributed systems, but the contribution is incremental as it primarily identifies overlooked factors rather than introducing a new paradigm.
Current evaluation practices for geo-distributed OLTP databases fail to account for network instability, data locality, and cross-region costs. The proposed Gaia framework reveals that most systems are sensitive to network issues, network costs dominate cloud expenses, and multi-region fault-tolerance adds critical-path overhead.
Geo-distributed OLTP databases are widely deployed across cloud regions, yet current evaluation practices do not cover the challenges of this aspect. Existing benchmarks assume stable network conditions; they lack explicit settings for data and client locality, and they largely ignore data transfer costs across regions. In addition, most evaluations rely on a limited set of geo-distribution patterns. In this paper, we propose Gaia, a comprehensive evaluation framework that addresses these gaps. We use Gaia to perform a comprehensive evaluation of existing geo-distributed OLTP systems. We deploy them across multiple cloud regions, using different geo-distribution patterns and variable cross-region network conditions. Among other interesting findings, our framework reveals that: i) most systems are sensitive to network instabilities, ii) network costs dominate cloud deployment expenses iii) multi-region fault-tolerance mechanisms incur measurable critical-path overhead that is often overlooked in prior evaluations. We argue that for the design of future geo-distributed databases, we must rethink the trade-offs between performance, fault-tolerance, and cost.