Need to explain error messages that can occur when upgrading to 2.4 with invalid index types. See: SERVER-8751, et al.

• Indexes with invalid types created <2.4 will warn on startup (including {foo:"1"}

  instead of

  {foo:1}

  and

  {foo:"text"}

  ).

• When creating indexes of type "text" or "2dsphere" in 2.4, mongodb checks that there are no other indexes with types that were not valid in 2.2, including {foo:"1"}

  . In order to create new index type, user will have to drop offending indexes.

• Going forward, indexes of invalid types will not be allowed to be created.
• If you have invalid indexes and you try to reIndex(), it will drop all indexes and fail upon discovery of first invalid index.
• Invalid indexes are treated as ascending eg., {foo:"-1"}

  will be treated like,

  {foo:1}

  . This behavior is meant as a bridge for users who accidentally created indexes with invalid types, but is not guaranteed to be true forever.

Need to create two new dochub entries:

• http://dochub.mongodb.org/core/index-type-changes
• http://dochub.mongodb.org/core/upgrade-2.4
  • this page should point to the previous dochub page, but will be more general as this information will be valid going forward