SQL存储过程超时

Question

I have a stored procedure which is timing out when called thru a .net windows service.

Error: Execution Timeout Expired.
The timeout period elapsed prior to completion of the operation or the server is not responding.

The wait operation timed out

@fetchbatchsize gets the value from ctp_config which is '2500' and uses that value to select top 2500 records from another table ctp_otran. approx records in ctp_otran is 23102025.

The same stored proc works good with '1000' records without giving any timeout issues.

Following is the stored proc.

ALTER PROCEDURE [dbo].[sp_ctp_get_otran]
@feed varchar(20)
AS
BEGIN
SET NOCOUNT ON;

DECLARE @fetchbatchsize char(25),
        @parameter varchar(50) = 'otran_default_batch_size_'
        ,@dync_exec nvarchar(MAX)

set @fetchbatchsize = (select value from [dbo].[ctp_config] where parameter = 
@parameter+@feed)

If(@fetchbatchsize is null)
set @fetchbatchsize = '1000'

select top (0) ctp_otran.otran_id, ctp_otran.unq_number as unq_number,  
   ctp_otran.entity, ctp_otran.field, 
   ctp_otran.str_value, ctp_otran.dec_value, ctp_otran.dtm_value, 
ctp_otran.proc_status 
into #otran
from ctp_otran with (nolock) 

select @dync_exec = 'INSERT INTO #otran (
otran_id,
unq_number,
entity,
field,
str_value,
dec_value,dtm_value,proc_status
)
select top (cast(' +@fetchbatchsize+ ' as int)) ctp_otran.otran_id, 
ctp_otran.unq_number as unq_number, 
ctp_otran.entity, ctp_otran.field, 
ctp_otran.str_value, ctp_otran.dec_value, ctp_otran.dtm_value, 
ctp_otran.proc_status 


from ctp_otran with (nolock) 
where ctp_otran.feed = '''+@feed + '''
and ctp_otran.proc_status = 0 
order by entity, unq_number, field;'


EXEC (@dync_exec)

update ctp_otran 
set proc_status = 3 -- in process 
where otran_id in (select otran_id from #otran);


select otran_id, unq_number, entity, field, str_value, dec_value, dtm_value, 
proc_status 
from #otran; 

drop table #otran;

END

Answer 1

Assuming you're on SQL 2005 or later (and you really should be), you can replace the dynamic SQL with this:

INSERT INTO #otran (
    otran_id,
    unq_number,
    entity,
    field,
    str_value,
    dec_value,dtm_value,proc_status
)
select top (@fetchbatchsize) 
    ctp_otran.otran_id, 
    ctp_otran.unq_number as unq_number, 
    ctp_otran.entity, ctp_otran.field, 
    ctp_otran.str_value, ctp_otran.dec_value, ctp_otran.dtm_value, 
    ctp_otran.proc_status 
from ctp_otran with (nolock) 
where ctp_otran.feed = @feed 
and ctp_otran.proc_status = 0 
order by entity, unq_number, field;

@fetchbatchsize will need to be stored as an Int rather than a Varchar, of course.

Finally, you don't need to explicitly drop your temp table(s). They vanish when the stored procedure ends.

Answer 2

I think you could replace the whole logic with this:

select @fetchbatchsize = value 
from dbo.ctp_config 
where parameter = @parameter+@feed

update o 
set proc_status = 3 -- in process 
from (
    select top @fetchbatchsize *
    from ctp_otran
    where ctp_otran.feed = @feed
    and ctp_otran.proc_status = 0 
    order by entity, unq_number, field
) o
output inserted.otran_id, inserted.unq_number, inserted.entity, inserted.field, inserted.str_value, inserted.dec_value, inserted.dtm_value, inserted.proc_status 

Didn't test this but don't see why it wouldn't work. If the derived table doesn't work CTE should at least.

If you have more than 1 process doing this same handling in the table at the same time, your code ends up in both race conditions where same ids are selected multiple times and to deadlocks in the database (which is probably why you added nolock)