Compatibility Changes in MongoDB 7.3

Equivalent Indexes

Starting in MongoDB 7.3, you cannot create equivalent indexes, which are partial indexes with the same index keys and the same partial expressions that use a collation.

For databases in MongoDB 7.3 with existing equivalent indexes, the indexes are retained but only the first equivalent index is used in queries. This is the same behavior as MongoDB versions earlier than 7.3.

For an example, see Equivalent Indexes Example.

Truncated Log Messages

Starting in version 7.3, MongoDB changes the format of truncated log messages to include nested truncated objects that correspond to each level of the final truncated object. MongoDB 7.3 also introduces a new omitted field, which counts the number of omitted elements at each level of the truncated JSON object. To see a truncated log message example, see Truncation.

Find Cursor Behavior on Views

Starting in MongoDB 7.3, when you use a find command on a view with the singleBatch: true and batchSize: 1 options, a cursor is no longer returned. In previous versions of MongoDB these find queries would return a cursor even when you set the single batch option to true.