3.2.1 Partitioning
Postgres/MySQL can partition a table: orders_2026_01, orders_2026_02. Queries that filter on the partition key skip the rest.
Why it matters
Huge tables make vacuums, indexes, and deletes painful. Dropping an old partition is instant compared to DELETE.
How it is used
Partition time-series and logs by month. Always include the partition key in WHERE. This is not the same as sharding across machines.