Multiple Joins LINQ Query performance - performance

Question

I'm new to LINQ and have very little knowledge.
I have the following complex query. it runs 3 or 4 times slower than the stored procedure which i translated to LINQ.
any tips for me to make it run faster?
var result = from a in db.A
join al in db.AL.Where(q => q.CurrentLocation == 1) on a.AID equals al.AID into tmp_al
from al in tmp_al.DefaultIfEmpty()
join l in db.Lon al.LID equals l.LID into tmp_l
from l in tmp_l.DefaultIfEmpty()
join r in db.R on l.RID equals r.RID into tmp_r
from r in tmp_r.DefaultIfEmpty()
join b in db.B on r.BID equals b.BID into tmp_b
from b in tmp_b.DefaultIfEmpty()
join ap in db.AP.Where(q => q.CurrentProtocol == 1) on a.AID equals ap.AID into tmp_ap
from ap in tmp_ap.DefaultIfEmpty()
join p in db.P on ap.PID equals p.PID into tmp_p
from p in tmp_p.DefaultIfEmpty()
join s in db.S on a.SID equals s.SID into tmp_s
from s in tmp_s.DefaultIfEmpty()
join ans in db.AS on a.ASID equals ans.ASID into tmp_ans
from ans in tmp_ans.DefaultIfEmpty()
join pr in db.P on p.PI equals pr.PID into tmp_pr
from pr in tmp_pr.DefaultIfEmpty()
where a.Active == 1
group a by new { a.Active, pr.LN, pr.FN, b.BN, r.RID, r.R1, p.PN, s.S1, ans.AS1 }
into grp
orderby grp.Key.BN, grp.Key.R1, grp.Key.PN, grp.Key.S1, grp.Key.AS1
select new
{
PIName = grp.Key.LN + " " + grp.Key.FN,
BN = grp.Key.BN,
RID = grp.Key.RID,
R = grp.Key.R1,
PN = grp.Key.PN,
S = grp.Key.S1,
AS = grp.Key.AS1,
NumberOA = grp.Count()
};
Thanks for your answers. #Albin Sunnanbo: i dont know how to check the execution plans. my LINQ runs correctly and produces the required output. it is just slow. I would like to speeden it up. #usr: the original sql is as follows:
sorry about the silly table names. the original code is confidential. so i'm not posting the complete table names.
CREATE PROCEDURE [dbo].[report_CBRP] --
AS
SELECT LN + ' ' + FN As PIN, BN, R.RID, R, PN,
S, AS, COUNT(*) As NOA
FROM A
LEFT JOIN AL
ON A.AID = AL.AID
AND AL.CL = 1
LEFT JOIN L
ON AL.LID = L.LID
LEFT JOIN R
ON L.RID = R.RID
LEFT JOIN B
ON R.BID = B.BID
LEFT JOIN AP
ON A.AID = AP.AID
AND AP.CPl = 1
LEFT JOIN P
ON AP.PID = P.PID
LEFT JOIN S
ON A.SID = S.SID
LEFT JOIN AS
ON A.ASID = AS.ASID
LEFT JOIN P
ON P.PI = P.PID
GROUP BY A.A, LN , FN , B.BN, R.RID, R.R, P.PN,
S.S, AS.AS
HAVING A.A = 1
ORDER BY B.BN, R.R, P.PN, S, AS
GO

Answer 1

It seems you're doing SQL hard life here.
In general, try to avoid so many joins, but rather break them into few small queries.
More than that, you're performing a group by which in itself is an expensive operation, let alone with so many columns
I've noticed that you're joining all the columns in each table. Try to select only the relevant columns.
Also noticed that few of the tables aren't used in the group by like al, ap and l. Do you need them at all??
Use AsNoTracking() for readonly data from EF. In that way you speed up things.
Use SQL Views