MySQL tip: composite index order matters — (customer_id, created_at) is not interchangeable
_jaydeepkarale · x · 2026-10-12
A production MySQL tip: a composite index on (customerid, createdat) is not interchangeable with one on (createdat, customerid) — column order matters. Indexes should be designed around your actual filters, joins, and sorting rather than just the columns appearing in the query.
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