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Vassili Zarouba

Vassili Zarouba

Articles by Vassili Zarouba (2)

Query Optimization

How Readyset Rewrites Your SQL: Subqueries in HAVING, ORDER BY, JOIN ON

Readyset used to reject subqueries in HAVING, ORDER BY, and JOIN ON outright, sending the whole query back to the database, uncached. This post extends the rewrite pipeline to decorrelate all four positions, with the soundness argument for the tricky one: LEFT OUTER JOIN, where the obvious move silently returns wrong answers.

Vassili Zarouba
2026-08-2013 min read
Engineering

How Readyset Rewrites Your SQL: Inside the Query Transformation Pipeline

Why Query Rewriting Matters for Dataflow Most databases work the same way: a query arrives, the engine builds an execution plan, scans tables, joins rows, filters, aggregates, and returns the result. Every time the query runs, the work repeats from scratch. This pull-based model has served relational databases for decades, but it carries an inherent cost: read latency is proportional to the complexity of the query and the size of the data it touches. Readyset takes a fundamentally different ap

Vassili Zarouba
2026-04-2817 min read