Choosing an appropriate primary key in a SQL database, particularly in a distributed system like CockroachDB, is critical for efficient querying and record distribution. Primary keys must be unique and non-null, with traditional best practices suggesting they should be immutable and fixed-size, though CockroachDB's scalability allows for some flexibility. The debate between using natural keys—derived from existing data—and surrogate keys, which are synthesized identifiers, hinges on the unique identification of records and their efficient distribution across a database cluster. Natural keys, like addresses, are advantageous for requiring no extra storage but can pose security concerns and create hotspots in high-traffic areas. Surrogate keys, such as Universally Unique Identifiers (UUIDs), offer a viable alternative, particularly in distributed databases, as they ensure even data distribution and are not bound by sequence, thus preventing bottlenecks. The choice of a primary key can significantly impact a database's health and performance, with UUIDs often recommended in scenarios requiring surrogate keys to maintain efficient data distribution and avoid hotspots.