Warning
MongoDB 8.3 Not Yet Available
MongoDB 8.3 release candidates are not yet available. This version of the manual is for an upcoming release and is currently a work in progress.
Indexes
Stricter Wildcard Index Validation
Starting in MongoDB 8.3 (and 8.2.4, 8.0.18, 7.0.29), stricter validation
rules apply to wildcardProjection specifications in compound
wildcard indexes. Existing indexes that do not meet the new validation
requirements continue to function, but you cannot create new indexes
that don't meet these requirements.
For complete details on the validation rules, see Wildcard Index Restrictions.
General Changes
2dsphereIndexVersion
Starting in MongoDB 8.3, 2dsphereIndexVersion
is set to version 4 by default.
If you need to downgrade the FCV to anything below 8.3, you
must first drop the 2dsphere version 4 indexes.
$facet Memory-Limit Error Code
Starting in MongoDB 8.3, when a $facet stage constructs a
document larger than the 100 megabyte limit, MongoDB returns the
ExceededMemoryLimit error.
In earlier versions, stages that exceed the memory limit return the
error code 4031700. If you have applications, drivers, or tools
that explicitly check for 4031700, you can adjust your code to
recognize ExceededMemoryLimit instead.