In this paper we propose an approach for performing data transformations near- or in-storage. The currently prevailing approach of extracting the data and then transforming it to a target format suffers data movement and causes degraded system performance. To mitigate these challenges we propose an approach offloading data transformations as near-data processing operations. The results show robust performance of foreground workloads and lower resource contention. We present opportunities in multi-engine and multi-system settings, for ML pipelines and for reuse.

The performance and scalability of modern data-intensive systems processing large datasets are limited by unnecessary data movement. Even though near-data processing (NDP) can provably reduce data transfers and increase performance, at present, NDP is utilized primarily in read-only settings. Near-data execution of data-intensive modification operations is currently infeasible due to the lack of transactional consistency and the absence of practicable low-latency synchronization mechanisms between the host database engine and the NDP-engine on smart storage. In this article, we introduce update NDP as an approach to offloading modifications to computational storage with transactional guarantees in an NDP database system called neoDBMS . To ensure consistency, we introduce a low-latency shared lock table between the host and computational storage, based on novel cache-coherent interconnects . We also introduce a novel locking protocol that seamlessly integrates the shared lock table within the lock manager of the host NDP-engine. To handle failure recovery, while preserving high and robust performance, we introduce novel extended locking and logging mechanisms that allow the host and computational storage to perform useful work during log-movement. Our evaluation indicates that in-storage modifications in neoDBMS in mixed workload settings are ≥ 6.52× faster than host-only executions and exhibit robust performance due to lower data movement and better resource utilization.

Near-Data Processing (NDP) has been proven useful to accelerate Database Management Systems (DBMS) that handle infrequently accessed data stored in slow persistent storage. A key challenge for such an architecture is the synchronization of host-based and NDP operations, which require fine-grained interactions especially when the NDP device can also update (modify) the DBMS data autonomously.This paper introduces CINDA, the first full-stack computational storage capable of acceleratingbothread and update (write) database transactions using NDP. The proposed system relies on a hybrid host-device interface to enable the DBMS accessing persisted data, offloading computation to the storage device, and coordinating concurrent device-update operations with the host-update ones. A hybrid interface utilizes a cache-coherent inter-connect such as CCIX or CXL for low-latency synchronization using a shared-lock table, and PCIe DMA for high-throughput bulk I/O. We evaluated the effectiveness of the proposed approach in a CCIX-based system by realizing an FPGA-based NDP-capable computational storage device and customizing an NDP-capable DBMS based on PostgreSQL to support update NDP operations. Our full-stack evaluation using the YCSB benchmark demonstrates that CINDA can deliver ≈4.2× end-to-end speedup when executing long-running update transactions directly on the storage device, while the host DBMS performs frequent short updates.

This article introduces DANSEN , the hardware accelerator component for neoDBMS, a full-stack computational storage system designed to manage on-device execution of database queries/transactions as a Near-Data Processing (NDP)-operation. The proposed system enables Database Management Systems (DBMS) to offload NDP-operations to the storage while maintaining control over data through a native storage interface . DANSEN provides an NDP-engine that enables DBMS to perform both low-level database tasks, such as performing database administration, as well as high-level tasks like executing SQL, on the smart storage device while observing the DBMS concurrency control. Furthermore, DANSEN enables the incorporation of custom accelerators as an NDP-operation (e.g., to perform hardware-accelerated ML inference directly on the stored data). We built the DANSEN storage prototype and interface on an UltraScale+HBM FPGA and fully integrated it with PostgreSQL 12. Experimental results demonstrate that the proposed NDP approach outperforms software-only PostgreSQL using a fast off-the-shelf NVMe drive and significantly improves the end-to-end execution time of an aggregation operation (similar to Q6 from CH-benCHmark, 150 million records) by ≈ 10.6×. The versatility of the proposed approach is also validated by integrating a compute-intensive data analytics application with multi-row results, outperforming PostgreSQL by ≈ 1.5×.

The performance and scalability of modern data-intensive systems are limited by massive data movement of growing datasets across the whole memory hierarchy to the CPUs. Such traditional processor-centric DBMS architectures are bandwidth- and latency-bound. Processing-in-Memory (PIM) designs seek to overcome these limitations by integrating memory and processing functionality on the same chip. PIM targets near- or in-memory data processing, leveraging the greater in-situ parallelism and bandwidth.

Current data-intensive systems suffer from scalability as they transfer massive amounts of data to the host DBMS to process it there. Novel near-data processing (NDP) DBMS architectures and smart storage can provably reduce the impact of raw data movement. However, transferring the result-set of an NDP operation may increase the data movement, and thus, the performance overhead. In this paper, we introduce a set of in-situ NDP result-set management techniques, such as spilling, materialization, and reuse. Our evaluation indicates a performance improvement of 1.13 × to 400 ×.

For a long time, most discrete accelerators have been attached to host systems using various generations of the PCI Express interface. However, with its lack of support for coherency between accelerator and host caches, fine-grained interactions require frequent cache-flushes, or even the use of inefficient uncached memory regions. The Cache Coherent Interconnect for Accelerators (CCIX) was the first multi-vendor standard for enabling cache-coherent host-accelerator attachments, and already is indicative of the capabilities of upcoming standards such as Compute Express Link (CXL). In our work, we compare-and-contrast the use of CCIX with PCIe when interfacing an ARM-based host with two generations of CCIX-enabled FPGAs. We provide both low-level throughput and latency measurements for accesses and address translation, as well as examine an application-level use-case of using CCIX for fine-grained synchronization in an FPGA-accelerated database system. We can show that especially smaller reads from the FPGA to the host can benefit from CCIX by having roughly 33% shorter latency than PCIe. Small writes to the host have a latency roughly 32% higher than PCIe, though, since they carry a higher coherency overhead. For the database use-case, the use of CCIX allowed to maintain a constant synchronization latency even with heavy host-FPGA parallelism.

Multi-versioning and MVCC are the foundations of many modern DBMSs. Under mixed workloads and large datasets, the creation of the transactional snapshot can become very expensive, as long-running analytical transactions may request old versions, residing on cold storage, for reasons of transactional consistency. Furthermore, analytical queries operate on cold data, stored on slow persistent storage. Due to the poor data locality, snapshot creation may cause massive data transfers and thus lower performance. Given the current trend towards computational storage and near-data processing, it has become viable to perform such operations in-storage to reduce data transfers and improve scalability. neoDBMS is a DBMS designed for near-data processing and computational storage. In this paper, we demonstrate how neoDBMS performs snapshot computation in-situ. We showcase different interactive scenarios, where neoDBMS outperforms PostgreSQL 12 by up to 5×.

Abstract Massive data transfers in modern data-intensive systems resulting from low data-locality and data-to-code system design hurt their performance and scalability. Near-Data processing (NDP) and a shift to code-to-data designs may represent a viable solution as packaging combinations of storage and compute elements on the same device has become feasible. The shift towards NDP system architectures calls for revision of established principles. Abstractions such as data formats and layouts typically spread multiple layers in traditional DBMS, the way they are processed is encapsulated within these layers of abstraction. The NDP-style processing requires an explicit definition of cross-layer data formats and accessors to ensure in-situ executions optimally utilizing the properties of the underlying NDP storage and compute elements. In this paper, we make the case for such data format definitions and investigate the performance benefits under RocksDB and the COSMOS hardware platform.

Today's Hybrid Transactional and Analytical Processing (HTAP) systems, tackle the ever-growing data in combination with a mixture of transactional and analytical workloads. While optimizing for aspects such as data freshness and performance isolation, they build on the traditional data-to-code principle and may trigger massive cold data transfers that impair the overall performance and scalability. Firstly, in this paper we show that Near-Data Processing (NDP) naturally fits in the HTAP design space. Secondly, we propose an NDP database architecture, allowing transactionally consistent in-situ executions of analytical operations in HTAP settings. We evaluate the proposed architecture in state-of-the-art key/value-stores and multi-versioned DBMS. In contrast to traditional setups, our approach yields robust, resource- and cost-efficient performance.

Many modern DBMS architectures require transferring data from storage to process it afterwards. Given the continuously increasing amounts of data, data transfers quickly become a scalability limiting factor. Near-Data Processing and smart/computational storage emerge as promising trends allowing for decoupled in-situ operation execution, data transfer reduction and better bandwidth utilization. However, not every operation is suitable for an in-situ execution and a careful placement and optimization is needed.

Massive data transfers in modern key/value stores resulting from low data-locality and data-to-code system design hurt their performance and scalability. Near-data processing (NDP) designs represent a feasible solution, which although not new, have yet to see widespread use.

Massive data transfers in modern data-intensive systems resulting from low data-locality and data-to-code system design hurt their performance and scalability. Near-data processing (NDP) designs represent a feasible solution, which although not new, has yet to see widespread use. In this paper we demonstrate various NDP alternatives in nKV, which is a key/value store utilizing native computational storage and near-data processing. We showcase the execution of classical operations ( GET, SCAN ) and complex graph-processing algorithms ( Betweenness Centrality ) in-situ, with 1.4x-2.7x better performance due to NDP. nKV runs on real hardware - the COSMOS+ platform.