Indexes on multi-value fields
Example:
{ "name" : "Arnhem", "alternatenames" : [ "Arnem", "Arnheim", "Arnhem", ... ] }
Create as a normal index:
db.cities.createIndex( { alternatenames: 1 } );
The %isMultiKey% field is set to %true%:
db.cities.find( { alternatenames: 'Arnheim' } ).explain();
{
"cursor" : "BtreeCursor alternatenames_1",
"nscanned" : 1,
"nscannedObjects" : 1,
"n" : 1,
"millis" : 0,
"nYields" : 0,
"nChunkSkips" : 0,
*"isMultiKey" : true,*
...