I have this method that uses unstable_cache to fetch data from Vercel postgres db, and cache it for 10 seconds.

I expect every time the method is called, it should return a list of records of fixed length off 4 (either from cache, or fetching from database). However, I realized that sometimes the method doesn't return any data. It is inconsistent.

This is how I used unstable_cache, I wonder if I did something not right.

export async function fetchData(geoName: string, year: number, month: string) {
    try {
      const data = await unstable_cache(async () => fetchDataAction(geoName, year, month), [], { revalidate: 10 });

      // log to validate if data is returned properly for a given geoName.
      console.log("fetched data for " + geoName + ", size: " + data.length);

      return data;
    } catch (error) {
      console.error('Database Error:', error);
      throw new Error('Failed to fetch card data.');
    }
}

export async function fetchDataAction(geoName: string, year: number, month: string) {
    const data = await sql<MarketTrendData>`
    SELECT * 
    FROM my_vercel_postgres_table 
    WHERE geo_name=${geoName} 
    AND year=${year}
    AND month=${month}`;
    return data.rows;
}

I tested it locally, and seeing many times it returns no data:

- When it's good:
GET /map/New%20Hampshire?_rsc=bjq2a 200 in 17ms
fetched data for New%20Hampshire, size: 4

- When it returns no data:
GET /map/Michigan?_rsc=hc3wf 200 in 21ms
✓ Compiled in 1739ms (2077 modules)
fetched data for Michigan, size: 0