The preferred way is to place a tags array in the post document, and also create an index across this array (allowing efficient lookup by tag). There's actually

The preferred way is to place a tags array in the post document, and also create an index across this array (allowing efficient lookup by tag). There's actually a specific documentation page for this usage: http://www.mongodb.org/display/DOCS/Full+Text+Search+in+Mongo http://www.mongodb.org/display/DOCS/Full+Text+Search+in+Mong...