Explanation:sh._adminCommand() runs a database command against the admin database, like db.runCommand(), but can confirm that it is issued against a mongos. 2. Point out the correct statement:
A. The unique constraint on indexes ensures that only one document can have a value for a field in a collection
B. MongoDB support creating new unique indexes in sharded collections
C. If you use a compound shard key, you cannot enforce uniqueness on the combination of component keys in the shard key
D. All of the mentioned
Answer:A
Explanation:sh._adminCommand() runs a database command against the admin database, like db.runCommand(), but can confirm that it is issued against a mongos. 2. Point out the correct statement:
A. The unique constraint on indexes ensures that only one document can have a value for a field in a collection B. MongoDB support creating new unique indexes in sharded collections C. If you use a compound shard key, you cannot enforce uniqueness on the combination of component keys in the shard key D. All of the mentioned
Explanation:For sharded collections these unique indexes cannot enforce uniqueness because insert and indexing operations are local to each shard. 3. ________ tests to see if the mongo shell is connected to a mongos instance.