Help Center/ Data Replication Service/ Troubleshooting/ Troubleshooting/ Solutions to Failed Check Items/ Database Objects/ Checking Whether the _Id Fields in the Collection of the Source Database Have Indexes
Updated on 2025-07-21 GMT+08:00
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Checking Whether the _Id Fields in the Collection of the Source Database Have Indexes

MongoDB Migration

Table 1 Checking whether the _id fields in the collections of the source database have indexes

Check Item

Whether the _id fields in the collections of the source database have indexes

Description

Check whether the _id fields in the collections of the source database have indexes. If not, the migration fails.

Item to Be Confirmed and Handling Suggestion

Failure cause: The _id fields in the collections of the source database must have indexes.

Handling suggestion: Run the db.Collection name.ensureIndex({_id: 1}) command to add an index. If the index fails to be added and the system displays a message indicating that the _id value already exists, the collection cannot be migrated.
Parent topic: Database Objects