How can you avoid the fetch stage in a query?

Avoiding the fetch stage in a query is achieved by covering the query with an index. When a query is covered by an index, all the fields required to fulfill the query are included in that index. This allows the database to satisfy the query entirely with index data, eliminating the need to access the full documents stored in the collection. As a result, performance is improved since accessing index data is typically faster than retrieving full documents, and it reduces the overall workload on the database.

Covering indexes particularly benefit read-heavy applications where performance is critical. When a query can be satisfied directly from the index, it bypasses the fetch stage, leading to a more efficient and faster response. Additionally, this minimizes the amount of data that MongoDB needs to read from disk or memory, streamlining query execution.

Other strategies, while they can optimize queries or query performance, do not inherently avoid the fetch stage. For instance, optimizing query structure might help, but if the fields requested are not indexed, the fetch stage cannot be avoided. Similarly, the aggregate function can provide powerful data manipulations, but whether it bypasses the fetch stage depends on how the data is structured and indexed, rather than being a guaranteed method to avoid the fetch. Limiting the number