Checking Whether the Shard Key Can Be Obtained from the Source Database

MongoDB Migration

**Table 1** Checking whether the shard keys can be obtained from the source database
Check Item	Whether the shard keys can be obtained from the source database
Description	Check whether the destination database user permissions meet the migration requirements. If the permissions are insufficient, the migration will fail.
Failure Cause and Handling Suggestion	Item to be confirmed: The source database is a replica set but the shard keys have not been configured in the destination database. Handling suggestion: If the destination database cannot obtain the shard keys of the source database, the data in the source database will be migrated to the primary shard node of the sharded cluster in the destination database. To fully utilize the read/write performance, storage capability, and high availability of the cluster, see FAQs.
	Item to be confirmed: The source database type is unknown, and the shard keys have not been configured in the destination database. Handling suggestion: If the destination database cannot obtain the shard keys of the source database, the data in the source database will be migrated to the primary shard node of the sharded cluster in the destination database. To fully utilize the read/write performance, storage capability, and high availability of the cluster, see FAQs.
	Item to be confirmed: The source database contains collections that do not have shard keys configured. Handling suggestion: If the destination database cannot obtain the shard keys of the source database, the data in the source database will be migrated to the primary shard node of the sharded cluster in the destination database. To fully utilize the read/write performance, storage capability, and high availability of the cluster, see FAQs.