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Velox Design Philosophy


This page lists a set of directional principles and values meant to guide contributors and maintainers as they develop the Velox project. These are not meant to be hard-and-fast rules, but to inform decision making and help guide discussions that may come up during the development of Velox.

Velox Mission

The Velox project aspires to:

“Accelerate data management systems by providing a reliable and unified state-of-the-art open-source execution platform”

The Velox community is composed of a set of highly-skilled individuals with the shared purpose of achieving this mission through the development and maintenance of the Velox open-source library and its ecosystem. In order to support and inform community efforts as we progress towards achieving the mission, a few overarching principles and values are highlighted below.

Velox Principles

  • Reliable. To become the true execution underpinnings for data management systems across the industry, Velox strives for excellence in reliability. This means that as a community we heavily invest in enhancing our test infrastructure, and building sophisticated database testing and validation frameworks. During Velox development, we do not compromise on stability, reliability, or correctness.

  • Unified. We envision that by unifying execution across data management systems (hence reducing the existing fragmentation), we can be more efficient as an engineering community. Therefore, Velox aspires to provide components which are engine- and dialect-agnostic, containing extensibility APIs through which the behavior of the library can be extended to match a desired semantic.

  • State-of-the-art. As a unified platform, we believe in the opportunity of centralizing advanced optimizations and techniques previously only available in individual monolithic systems (many of which proprietary), making them easily available everywhere. Although there is a large set of optimizations that can be added (each adding a layer of complexity), we prioritize adding the features that provide the largest performance improvement to real workloads - as opposed to synthetic benchmarks.

  • Open-source. We take the old saying by heart: “if you want to go fast, go alone; if you want to go far, go together”. We believe that by developing Velox as a community, there is an opportunity to create a virtuous cycle between developers who would like to leverage state-of-the-art execution in their systems; and developers, researchers, and hardware vendors who would like their techniques and hardware platforms to be pervasively adopted in the industry.

Velox Values

  • High quality. The development process in Velox is optimized for ensuring (a) reliability and high-quality, and (b) ease of maintenance in the long term, not for the productivity of the developer adding the feature.

  • Test and verification. Every change in Velox should be accompanied by tests, and a summary describing how the correctness of the change can be verified. Oftentimes, extensions to Velox’s automated testing infrastructure (fuzzers) should also be added by the author to further validate correctness.

  • Readability. As a library, Velox coding is optimized for the reader, not the writer. We appropriately add comments to our code, document APIs, and produce documentation about the main library components. It might take longer to write, but eases maintenance and other enhancements in the long run.

  • Code consistency. The Velox codebase favors consistency over personal preference. When contributing code, first review and follow the guidelines, and strictly adhere to our document.

  • Data-driven. As an execution engine, there is a large number of optimizations that can be implemented to improve performance. We prioritize the ones that have clear data (in the form of benchmarks based on real-world use cases) supporting their efficacy.

  • Adaptivity. Exposing too many configuration knobs to users increases the API complexity, and makes it more error-prone. As much as possible, we try to make the library self-adapt to find optimal execution configurations.