Is there a way to improve this query further?

I've got a query that over time I've been improving. Originally it simply selected * from the records table, and the data was formatted on the webapp side. But that was slow and I wanted to make things faster. I found that I could format the output into the correct json in postgres very quickly but the query was UGLY as sin. Then postgres 9.4 came out and brought json_object_agg which made the query nice and simple, and even faster than before, and all I had to do was change the data type of the data column to be json (it had been storing json-formatted data anyway).

The current version of the query is: select json_object_agg(day,data) as jsobj from records

The records table is:

\d records
                         Table "public.records"
 Column |  Type   |                      Modifiers                       
--------+---------+------------------------------------------------------
 id     | integer | not null default nextval('records_id_seq'::regclass)
 day    | date    | 
 data   | json    | 
Indexes:
    "records_pkey" PRIMARY KEY, btree (id)
    "records_day_key" UNIQUE CONSTRAINT, btree (day)

What I'm wondering is this: is there a way to improve the query further? Either making it more readable or more performant?