Function key

nodedb/src/control/gateway/plan_cache.rs:272–278

(sql: &str, collection: &str, version: u64)

    }

    fn key(sql: &str, collection: &str, version: u64) -> PlanCacheKey {
        PlanCacheKey {
            sql_text_hash: hash_sql(sql),
            placeholder_types_hash: 0,
            version_set: GatewayVersionSet::from_pairs(vec![(collection.into(), version)]),
        }
    }

    #[test]
    fn cache_hit_and_miss() {