cdelmonte.dev

I write about data systems, distributed execution, and infrastructure boundaries.

This blog focuses on how modern platforms actually behave under load: Spark and Delta Lake internals, execution models, control planes, trust boundaries, and the architectural trade-offs hidden behind clean APIs.

The Disaggregation of the Lakehouse Stack

The Disaggregation of the Lakehouse Stack

How Delta Kernel, Arrow, and pluggable execution are disaggregating the lakehouse stack. The lakehouse stack is not converging on a new dominant engine — it is converging on a layered architecture in which protocol, data representation, and query execution are increasingly isolated behind stable interfaces.

March 8, 2026 · 15 min
Where Data System Abstractions Break: A Semiotic Reading

Where Data System Abstractions Break: A Semiotic Reading

Many of the most surprising performance pathologies in modern data systems are semiotic failures — structural divergences between what an interface signifies and what the underlying system does.

March 4, 2026 · 13 min
Delta Lake MERGE Is Not a Simple Upsert. What Actually Happens at Scale.

Delta Lake MERGE Is Not a Simple Upsert. What Actually Happens at Scale.

At 10 TB, updating 200k rows can mean rewriting thousands of files. Here’s why, and what to do about it.

March 2, 2026 · 15 min
Spark Is Not Lazy. Spark Compiles Dataflow.

Spark Is Not Just Lazy. Spark Compiles Dataflow.

Why calling Spark ’lazy’ is technically reductive, and how thinking of it as a dataflow compiler changes the way you design pipelines.

November 3, 2025 · 12 min
A Shared Kernel Is a Shared Trust Domain

A Shared Kernel Is a Shared Trust Domain

Containers isolate processes, not trust boundaries. When your platform runs untrusted code, the architectural question is where you place the kernel boundary, and what that costs in memory, latency, and operational complexity.

February 2, 2026 · 18 min
Fixing Skewed Nested Joins in Spark with Asymmetric Salting

Fixing Skewed Nested Joins in Spark with Asymmetric Salting

In large-scale Spark pipelines, skew can occur when a single key carries a disproportionately large nested payload. Asymmetric salting offers a targeted solution: explode, salt, join in parallel, and optionally re-aggregate.

December 1, 2025 · 17 min