Q:

How to postgres search with two search text parameter, Search FIlter text 1 && search filter text 2

How to Postgres search with two search text parameter ,  pg-search + Search FIlter 1 + search filter 2 . 
How to search in pg_Search  output I want union of  "filter 1" && "filter 1"
 @output = PgSearch.multisearch("filter 1") +  PgSearch.multisearch("filter 2")

A:

I'm the author and maintainer of pg_search. 
Search terms are joined by AND by default in PostgreSQL full text search.  Thus, you could simply do this:
 @output = PgSearch.multisearch("filter 1 filter 2")

Assuming you have the query terms in string variables, it would look something like one of these:
 @output = PgSearch.multisearch("#{query1} #{query2}") # if query1 and query2 are strings
 @output = PgSearch.multisearch(queries.join(" "))     # if queries is an array of strings

Joining by OR is a lot more complicated.  I don't yet have an easy solution for it, although it should be possible.