Too many order by, max, subqueries for my intellect - sql

Question

I can not seem to work out this query. I'm sure it needs subqueries, but I am out of options. My brain can not handle this or something. I need help :)
Little intro
I have a betting odds website. Every 15 minutes I import the latest odds (win/draw/lose -- or 1/X/2) for particular events from various bookmakers.
Every row of the odds table has the odds_type ('1', 'X' or '2'), the odds_index which is the actual odds, the bookmaker_id and the event_id.
But equally important: created_at, because I need to work with the odds from the latest import. It is very important for obvious reasons.
Scenario
In the table below we are working with imported odds for event_id #1.
Needed query
Isolate the latest set of imported odds for event_id = 1 from all bookmakers (in this example 9 records)
On that set, return the highest odds_index record for odds_type '1', 'X', '2'.
Now I prefer to do this with Rails scoping, so I can use #event.best_odds1 and #event.best_odds2, but I'll take any approach if it works. Been busting my brain on this for 5 days. Need to solve it.
Result
After the query I end up with 3 records so I can display "The best odds for event #1".
The tables
Bookmakers
ID | NAME
----------------------
1 | Unibet
2 | 888
3 | Ladbrokes
Events
ID | NAME
--------------------------
1 | Holland vs Denmark
2 | England vs Germany
3 | France vs Spain
Odds
ID | OT | OI | BI | EI | CREATED_AT
---------------------------------------------------
(first import from the bookies)
1 | '1' | 2.4 | 1 | 1 | 2010-06-10 15:00
2 | 'X' | 1.5 | 1 | 1 | 2010-06-10 15:00
3 | '2' | 6.2 | 1 | 1 | 2010-06-10 15:00
4 | '1' | 2.2 | 2 | 1 | 2010-06-10 15:58
5 | 'X' | 1.8 | 2 | 1 | 2010-06-10 15:58
6 | '2' | 5.2 | 2 | 1 | 2010-06-10 15:58
7 | '1' | 2.8 | 3 | 1 | 2010-06-10 16:56
8 | 'X' | 1.3 | 3 | 1 | 2010-06-10 16:56
9 | '2' | 7.1 | 3 | 1 | 2010-06-10 16:56
(last import from the bookies)
10 | '1' | 2.5 | 1 | 1 | 2010-06-11 17:10
11 | 'X' | 1.3 | 1 | 1 | 2010-06-11 17:10
12 | '2' | 6.4 | 1 | 1 | 2010-06-11 17:10
13 | '1' | 2.1 | 2 | 1 | 2010-06-11 18.12
14 | 'X' | 1.2 | 2 | 1 | 2010-06-11 18:58
15 | '2' | 6.2 | 2 | 1 | 2010-06-11 18:58
16 | '1' | 1.8 | 3 | 1 | 2010-06-12 14:56
17 | 'X' | 2.3 | 3 | 1 | 2010-06-12 14:56
18 | '2' | 5.1 | 3 | 1 | 2010-06-12 14:56
Abbreviated column names to fit on screen
OT = odds_type
OI = odds_index
BI = bookmaker_id
EI = event_id

Answer 1

You could use row_number() twice:
select *
from (
select *
, row_number() over (partition by OT order by OI desc) as rn2
from (
select *
, row_number() over (partition by EI, BI, OT
order by created_at desc) as rn1
from Odds
where EI = 1 -- for event 1
) sub1
where rn1 = 1 -- Latest row per EI, BI, OT
) sub2
where rn2 = 1 -- Highest OI per OT
But if the table keeps growing, this will perform badly. You could add a history table like OddsHistory, and move outdated Odds there. When only the latest Odds are in the Odds table, your query becomes much simpler.
Live example at SQL Fiddle.