Why Do My Aurora MySQL Views Time Out While Table Queries Work?

If the query uses window functions in addition to DISTINCT or complex joins, inspect those operations in the execution plan too. They may require sorting or processing a very large intermediate result even when the final output is small. A timeout usually means the server is doing more work than the view definition makes obvious.

The view probably isn’t the root problem by itself. Run EXPLAIN on the SELECT behind the view and check for full table scans, large temporary tables, poor join plans, and whether filters are being pushed down to the underlying tables. DISTINCT commonly requires a temporary result set, especially when the source is large. Make sure the columns used for joins and filtering are indexed, and compare the estimated plan with the actual workload if possible.

Look specifically for “Using temporary” and signs that predicates are not being applied until after the view is materialized. Depending on the query, rewriting the view without nesting it, adding indexes to the base tables, or precomputing the expensive result may help. Also check Aurora CPU, memory, connection, and timeout metrics before changing databases; moving the same expensive SELECT elsewhere will not necessarily solve it.

Try running the underlying SELECT directly and test the same schema and data on a local or non-Aurora MySQL instance. That can help separate a query-design problem from an Aurora resource or configuration issue. Nested views can make optimization harder, so expanding the definitions into one query may produce a better execution plan.