Cannot create index in mongodb, "key too large to index"

Question

I am creating index in mongodb having 10 million records but following error

db.logcollection.ensureIndex({"Module":1})
{
        "createdCollectionAutomatically" : false,
        "numIndexesBefore" : 3,
        "ok" : 0,
        "errmsg" : "Btree::insert: key too large to index, failing play.logcollection.$Module_1 1100 { : \"RezGainUISystem.Net.WebException: The request was aborted: The request was canceled.\r\n   at System.Net.ConnectStream.InternalWrite(Boolean async, Byte...\" }",
        "code" : 17282
}

Please help me how to createindex in mongodb,

Answer 1

MongoDB will not create an index on a collection if the index entry for an existing document exceeds the index key limit (1024 bytes). You can however create a hashed index or text index instead:

db.logcollection.createIndex({"Module":"hashed"})

or

db.logcollection.createIndex({"Module":"text"})