how will it handle indexing if I have an array and in that array I have another array which have my desired key:value……that means I have to index the value which lies inside a nested array……?????

A fulltext index can be created on a single attribute. However, if the given attribute value is an array or object, the fulltext index will index the direct subvalues, e.g.

{ “text” : “some value” } => will index “some value”
{ “text” : [ “some value”, “foobar” ] } => will index “some value” and “foobar”
{ “text” : { “what” : “some value”, “else” : “foobar” } } => will index “some value” and “foobar”