3 ms·

exactly. Using an IN statement with a subquery is textbook "how to make a query slow" - it forces a sequential scan. No-one who understands SQL would write a qu

exactly. Using an IN statement with a subquery is textbook "how to make a query slow" - it forces a sequential scan. No-one who understands SQL would write a query like that.

encoderer 16y ago
It's certainly a cardinal sin on MySQL but commercial platforms have optimizations that make these correlated subqueries performant.
Lozzer 16y ago
It's not inherent in SQL, it's down to the optimizer