In a cluster affected by
WT-7995 and WT-8395, there two documents sharing the same _id value.
Our remediation process guide requires running reIndex to fix inconsistencies detected by validate. In master, when reIndex encounters duplicate _ids it invariants. The server ends up in a bad state because it tries to build the _id index during recovery but fails every time due to the duplicate values.
In 4.4 the behaviour is a bit different, reIndex adds the duplicate entries to the index and validate invariants when it encounters two duplicate values in a unique index.
- is related to
SERVER-65086 Deprecate the `collection.reIndex()` command
SERVER-65087 Audit the usage of foreground index builds through IndexBuildsCoordinator::createIndex()