SQL server 查詢效能的問題

use [spoofspam2]

go/****** object:  storedprocedure [dbo].[getmessagelist]    script date: 04/09/2013 18:00:34 ******/
set ansi_nulls on
goset quoted_identifier on
gocreate procedure [dbo].[getmessagelist]
@status_code varchar(20),
@kana_instance int = -1,
@message_type nvarchar(64),
@numrows int,
@datelimit int
as/* @@decommissioned due to performance issue on  
d.status_code in (select c1 from func_splitstring(@status_code, ','))
--set transaction isolation level read uncommitted
select top (@numrows) d.message_detail_id, d.message_id, d.subject, 
d.email_from, d.email_to, d.status_code, isnull(d.action_failed_times,0) action_failed_times,
d.score, c.body, c.headers, c.status, c.source, d.user_from_status,
d.site_id,t.action_id,ad.type,ad.value, ad.exclude_reply
from message_detail d with(readpast)
inner join message_clob c with(readpast) on d.message_detail_id= c.message_detail_id
left join message_tracking t with(readpast) on t.message_detail_id= c.message_detail_id
left join action_detail ad on t.action_id= ad.id
where
d.status_code in (select c1 from func_splitstring(@status_code, ','))
and (@kana_instance = -1 or d.kana_instance = @kana_instance )
and d.message_type = @message_type
and d.date_entered > dateadd(day,-@datelimit ,getdate())
and c.date_entered > dateadd(day,-@datelimit ,getdate())
--and d.email_to = 'pptest8@paypal.com' --test only, to be removed later; in kana104_dev is 'pptest8@paypal.com'; in stkana5_macro is 'spoof@paypal.com' 
order by d.message_detail_id asc
*/ declare @sql nvarchar(max)
set @sql='
select top (' + convert(varchar(10),@numrows) + ') d.message_detail_id, d.message_id, d.subject, 
d.email_from, d.email_to, d.status_code, isnull(d.action_failed_times,0) action_failed_times,
d.score, c.body, c.headers, c.status, c.source, d.user_from_status,
d.site_id,t.action_id,ad.type,ad.value, ad.exclude_reply
from message_detail d with(readpast)
inner join message_clob c with(readpast) on d.message_detail_id= c.message_detail_id
left join message_tracking t with(readpast) on t.message_detail_id= c.message_detail_id
left join action_detail  ad  on t.action_id= ad.id 
where
d.status_code in (' + @status_code + ')
and d.message_type = ''' + @message_type + '''
and (' + convert(varchar(10),@kana_instance) + ' = -1 or d.kana_instance = ' + convert(varchar(10),@kana_instance) + ' )
and d.date_entered > dateadd(day,-' + convert(varchar(10),@datelimit) + ' ,getdate())
and c.date_entered > dateadd(day,-' + convert(varchar(10),@datelimit) + ' ,getdate())
order by d.message_detail_id asc
' exec(@sql)
return
go

d.status_code in (select c1 from func_splitstring(@status_code, ','))

會影響執行效能。不知為何，d.status_code的索引不起作用，導致資料返回很慢！貌似用函式的條件，sql server不會應用索引，哪怕是建了索引。

於是，改了另一種做法：

d.status_code in (' + @status_code + ')

效能問題馬上解決！執行計畫馬上正確使用了d.status_code的索引。

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