Velox Execution Engine

⬢ TIER 3Tech

High

Salary impact

6 months

Time to learn

Hard

Difficulty

—

Careers

At a glance

Specialist skill for working with Velox, Meta's high-performance vectorized SQL execution engine used in Presto, Spark, and Trino. Used by database engineers and performance optimization specialists. Salaries range $130k–$220k USD. Requires 5–6 months with C++ and OLAP database fundamentals. Sits between general SQL optimization and custom query engine design.

What is Velox Execution Engine

Velox is Meta's open-source, high-performance vectorized SQL execution engine designed to power OLAP systems. It separates query planning (handled by Presto, Spark, Trino) from runtime execution, providing a pluggable backend that operates on columnar batches (vectors) rather than individual rows. Velox implements vectorized evaluation, SIMD operations, and adaptive algorithms to make SQL queries 10–100x faster than traditional row-based executors. Velox is production-grade: Meta uses it internally at massive scale; Presto, Spark, and Trino all integrate with Velox to accelerate queries. Organizations running petabyte-scale data warehouses rely on engineers who can tune Velox for specific query patterns and implement custom execution strategies.

🔧 TOOLS & ECOSYSTEM

VeloxPrestoTrinoSparkDuckDBC++SIMDArrow

💰 Salary by region

Region	Junior	Mid	Senior
USA	$110k	$165k	$220k
UK	$65k	$100k	$135k
EU	$70k	$105k	$150k
CANADA	$100k	$150k	$210k

🎓 Certifications

Velox Contributor Program Meta Database Engineering Course

❓ FAQ

What is vectorization in Velox?

Vectorization processes batches of rows (1000+) in a single instruction, rather than one row at a time. Velox's columnar vectorized execution is 10–100x faster than row-based systems by improving CPU cache locality and enabling SIMD parallelism.

How does Velox improve on traditional SQL engines?

Velox separates execution planning from runtime, allowing Presto/Spark/Trino to use Velox as a pluggable execution backend. This improves performance through vectorized operations, better memory management, and expression optimization without reimplementing core SQL logic.

What role does C++ play in Velox work?

Velox is implemented in C++ for performance. Optimizing Velox requires understanding C++ memory management, SIMD intrinsics, and CPU cache behavior. Most tuning work involves custom function implementation or expression compilation.

How do I write custom Velox functions?

Use Velox's function registration API (RegisterFunction<T>) to define scalar or aggregate functions. Functions operate on VectorBatch objects; you optimize by implementing SIMD-friendly logic and leveraging Velox's type system and null handling.

What's the performance impact of expression compilation in Velox?

Velox can compile SQL expressions to machine code via LLVM, bypassing interpreter overhead. Compilation adds 1–10ms latency per query; payoff is immediate if the expression runs millions of times (10% speedup typical for complex aggregations).