ClickHouse Joins No Longer Suck: Why the "Denormalize Everything" Advice is Outdated Hi SQL folks, If you evaluated ClickHouse a few years ago, you were likely told to avoid JOINs at all costs. The standard industry advice was to denormalize everything into massive, flat tables. In 2020, that criticism was fair. ClickHouse had a single hash join algorithm; if your right-side table exceeded memory, the query simply crashed. **That advice is now officially outdated.** I recently dug into the commit history, and between 2022 and 2026, the engineering team merged over 50 pull requests that dismantled almost every limitation of the join engine. ClickHouse now has the planning sophistication of a mature RDBMS operating inside a columnar vectorized model. # 5 Impactful Changes Shipping by Default Today: * **Grace Hash Join:** Inactive buckets now spill to disk. OOM (Out of Memory) crashes for memory-bound joins are completely solved.…