| Value | Meaning |
|---|---|
| local"local" | This is the default read concern level. |
| available"available" | This is the default for reads against secondaries when afterClusterTime and "level" are unspecified. The query returns the the instance’s most recent data. |
| majority"majority" | Available for replica sets that use WiredTiger storage engine. |
| linearizable"linearizable" | Available for read operations on the primary only. |