join - Multiple queries are executed during fetch of an associated class - ruby on rails -

i want optimize code performance in such way instead of multiple queries; in single query can information database.

my code this:

i have class (called class:a) have sti (let type a1 , type a2).

and 2 more class(let class b , class c) associated class a.

something this...

class < activerecord::base     has_many :b     has_many :c     blahblah end  class b < activerecord::base     belongs_to :a      blahblah end  class c < activerecord::base     belongs_to :a      blahblah end   class a1 <      blahblah end  class a2 <      blahblah end 

now, when trying load a1 total 9 times queries executed... can optimize in a single query??

i trying excute this:

@datas = a1.where("id" < 5 ) 

console output:

  a1 columns (1.0ms)   show fields `a`   a1 load (2.2ms)   select * `a` (id < 5) , ( (`promotions`.`type` = 'a1' ) )     c load (0.4ms)   select * `c` (`c`.a_id = 1)    c columns (0.7ms)   show fields `c`   sql (0.1ms)   set names 'utf8'   sql (0.1ms)   set sql_auto_is_null=0   b load (0.4ms)   select * `b` (`b`.a_id = 1)    b columns (0.7ms)   show fields `b` rendered blahblah (42.1ms)   c load (3.5ms)   select * `c` (`c`.a_id = 2)    b load (5.3ms)   select * `b` (`b`.a_id = 2)  rendered blahblah (13.1ms)   c load (3.5ms)   select * `c` (`c`.a_id = 3)    b load (5.3ms)   select * `b` (`b`.a_id = 3)  rendered blahblah (13.1ms)   c load (3.5ms)   select * `c` (`c`.a_id = 4)    b load (5.3ms)   select * `b` (`b`.a_id = 4)  rendered blahblah (13.1ms) 

can information 3 tables in single query?

my try

@datas = a.join(:b).join(:c).where("id" < 5) 

but got same... multiple queries executed instead of single query....

can me in this????

thanks in advance.

edit

second try: @datas= a.find(:all, :joins=>[:b, :c], :conditions=>"id<5")

in end, rails executes this:

select `a`.* `a` inner join `b` on b.a_id = a.id inner join `c` on c.a_id = a.id ( id < 5 ) , ( (`a`.`type` = 'a1' ) ) 

which seems ok.

but again when try load b (like: <%= a.b.name %> ). excutes query.

so problem still exist.... :(

all need replace joins includes

@datas = a.includes(:b, :c).where("id < 5") 

note generate 1 query each association included. can reduce 1 single query forcing join using joins

@datas = a.joins(:b).includes(:b, :c).where("id < 5") 

or can specify condition on 1 of associated models e.g.

@datas = a.includes(:b, :c).where(:b => {:column => value})