When implementing efficient CouchDB queries from chaincode in Hyperledger Fabric, it is important to use indexes effectively and focus on crafting simple queries that avoid full index scans. Operators such as $or, $in, and $regex can lead to performance issues because they often result in full scans of the database or index.
Instead, it is recommended to structure queries that make optimal use of indexes, targeting specific key-value pairs or ranges to minimize the amount of data scanned during query execution. This approach helps in maintaining high query performance and reducing the load on the CouchDB database, which is crucial for achieving efficient data retrieval in a blockchain environment.