The rise of global data-driven applications has made geo-distributed hybrid transactional and analytical processing (HTAP) databases increasingly desirable. Existing distributed HTAP systems provide users with good performance on both transactions and analytical queries, and this good performance is scalable across a large number of data nodes. Unfortunately, these systems either provide weak consistency or incur bad data freshness when deployed geographically. In this paper, we present P erseus , a scalable HTAP database that enforces strong consistency for both transactions and analytical queries. To handle consistency efficiently, P erseus augments the classical dependency graph in concurrency control protocols to explicitly record the versions of data and their complete dependencies, implying which data needs to be read together in a snapshot. To minimize data staleness on analytical queries (another important goal of HTAP), P erseus further introduces a new dynamic snapshot algorithm that chooses updates selectively. Extensive evaluation results show that, compared to the HTAP databases with even weaker consistency, P erseus achieves up to 90% lower visibility delay, a metric of data freshness, capturing the time interval during which transactional updates are committed to the database and can be visible to analytical queries. Besides, Perseus is scalable across many nodes and robust to network instability.

Training GNNs over large graphs faces a severe data processing bottleneck, involving both sampling and feature loading. To tackle this issue, we introduce F 2 CGT, a fast GNN training system incorporating feature compression. To avoid potential accuracy degradation, we propose a two-level, hybrid feature compression approach that applies different compression methods to various graph nodes. This differentiated choice strikes a balance between rounding errors, compression ratios, model accuracy loss, and preprocessing costs. Our theoretical analysis proves that this approach offers convergence and comparable model accuracy as the conventional training without feature compression. Additionally, we also co-design the on-GPU cache sub-system with compression-enabled training within F 2 CGT. The new cache sub-system, driven by a cost model, runs new cache policies to carefully choose graph nodes with high access frequencies, and well partitions the spare GPU memory for various types of graph data, for improving cache hit rates. Finally, extensive evaluation of F 2 CGT on two popular GNN models and four datasets, including three large public datasets, demonstrates that F 2 CGT achieves a compression ratio of up to 128 and provides GNN training speedups of 1.23-2.56× and 3.58--71.46× for single-machine and distributed training, respectively, with up to 32 GPUs and marginal accuracy loss.

Transaction performance in geo-replicated databases heavily relies on the request location: when not issued by the primary region, transactions are forced to involve costly wide-area communication. While existing systems distribute primary roles across regions, such assignment typically occurs at the shard level, making it difficult to align with geographically dispersed access to individual records. This paper introduces PolyBase, a pioneering architecture to address such misalignment, leveraging the widely adopted Paxos-based log replication mechanisms. It enables flexible row-level consensus group affiliation , which runs on an unchanged Paxos protocol , but dynamically re-assigns database rows between Paxos log replication groups, whose leaders become the primary region, enjoying faster writes and up-to-date versions for reads. With carefully designed data structures and protocols, PolyBase significantly reduces wide-area RTTs without compromising transaction or log replication consistency or reliability guarantees. We implemented PolyBase with optimized re-assignment policies and integrated it into two popular databases (RocksDB and MySQL). Our evaluation on AWS, using a production e-commerce workload and microbench-marks confirms that PolyBase offers significantly higher transaction throughput and lower average/tail latency compared to baselines.

Geo-replication is essential for providing low latency response and quality Internet services. However, designing fast and correct geo-replicated services is challenging due to the complex trade-off between performance and consistency semantics in optimizing the expensive cross-site coordination. State-of-the-art solutions rely on programmers to derive sufficient application-specific invariants and code specifications, which is both time-consuming and error-prone. In this paper, we propose an end-to-end geo-replication deployment framework AUTOGR (AUTOmated Geo-Replication) to free programmers from such label-intensive tasks. AutoGR enables the geo-replication features for non-replicated, serializable applications in an automated way with optimized performance and correct application semantics. Driven by a novel static analyzer RIGI, AUTOGR can extract application invariants by verifying whether their geo-replicated versions obey the serializable semantics of the non-replicated application. RIGI takes application codes as inputs and infers a set of side effects and path conditions possibly leading to consistency violations. RIGI employs the Z3 theorem prover to identify pairs of conflicting side effects and feed them to a geo-replication framework for automated across-site deployment. We evaluate AUTOGR by transforming four serializable and originally non-replicated DB-compliant applications to geo-replicated ones across 3 sites. Compared with state-of-the-art human-intervention-free automated approaches (e.g., strong consistency), AUTOGR reduces up to 61.8% latency and achieves up to 2.12X higher peak throughput. Compared with state-of-the-art approaches relying on a manual analysis (e.g., PoR), AUTOGR can quickly enable the geo-replication feature with zero human intervention while offering similarly low latency and high throughput.

It is challenging for cloud-native relational databases to meet the ever-increasing needs of scaling compute and memory resources independently and elastically. The recent emergence of memory disaggregation architecture, relying on high-speed RDMA network, offers opportunities to build cost-effective and elastic cloud-native databases. There exist proposals to let unmodified applications run transparently on disaggregated systems. However, running relational database kernel atop such proposals experiences notable performance degradation and time-consuming failure recovery, offsetting the benefits of disaggregation. To address these challenges, in this paper, we propose a novel database architecture called LegoBase, which explores the co-design of database kernel and memory disaggregation. It pushes the memory management back to the database layer for bypassing the Linux I/O stack and re-using or designing (remote) memory access optimizations with an understanding of data access patterns. LegoBase further splits the conventional ARIES fault tolerance protocol to independently handle the local and remote memory failures for fast recovery of compute instances. We implemented LegoBase atop MySQL. We compare LegoBase against MySQL running on a standalone machine and the state-of-the-art disaggregation proposal Infiniswap. Our evaluation shows that even with a large fraction of data placed on the remote memory, LegoBase's system performance in terms of throughput (up to 9.41% drop) and P99 latency (up to 11.58% increase) is comparable to the monolithic MySQL setup, and significantly outperforms (1.99x-2.33x, respectively) the deployment of MySQL over Infiniswap. Meanwhile, LegoBase introduces an up to 3.87x and 5.48x speedup of the recovery and warm-up time, respectively, over the monolithic MySQL and MySQL over Infiniswap, when handling failures or planned re-configurations.