Parametric Search without Main Text Query

If a Parametric Search field is to be searched without any main text search at all (e.g. the query infield:Price<24 alone), then a separate index should be created via the Extra Indexes setting. The index should be created on the html table; the type of index depends on the operator being used. For text searches (infield: ~ operator or Parametric Search Query LIKE operator), the index should be Metamorph Inverted. For relational operators (equals, less-than, greater-than etc.) and geographic searches, the index type should be Regular.