mongodb fulltext searching strategy

I do not see any reason to use ElasticSearch in conjunction with MongoDb, just use ElasticSearch as separate document storage for documents, that have to be searched. And yes, you can even as whole db. Of course it depends on your domain model and other factors.

If you don't need stemming, fuzzy search, complicated wildcard search, you can do search with mongoDb. When new document inserted, split it to words in lower case, and add to the array "words" for example. Later you can perform search request against this array with regex. Not you can' use I (ignore case) option in this regex, and you can search only LIKE% wildcard (or without wildcard), otherwise search would not use mongoDb index.

One more option - you can try to find river for mongoDb

Another option - is to use Lucene if you are using Java. Probably you will be able to extend Directory class, in such a way, that Lucene will store index in MongoDb instead of file system or RAM. I have not made any research in this area, but I think it is possible

I experimented with full text search in MongoDB by splitting the words in the string like @Umar suggested. Honestly though, its a database and not a search engine so I would use Mongo for persistant storage and ElasticSearch for the search engine part of it. As a matter of fact, I would stick with something like Postgresql for persistant storage and then push the data you want to search out to the search engine. http://gdal.org/ogr/drv_elasticsearch.html is a driver that will allow you to quickly export your data from one RDBMS to ElasticSearch. THe data does not have to be geospatial in order to use it GDAL as long as their is a way to connect to the input source.

Adam