下面这个查询可以返回产生多个执行计划的sql(仅对sql server 2008有效,引自Troubleshooting Performance Problems in SQL Server 2008)
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select q.query_hash,
q.number_of_entries,
t.text as sample_query,
p.query_plan as sample_plan
from (select top 20 query_hash,
count(*) as number_of_entries,
min(sql_handle) as sample_sql_handle,
min(plan_handle) as sample_plan_handle
from sys.dm_exec_query_stats
group by query_hash
having count(*) > 1
order by count(*) desc) as q
cross apply sys.dm_exec_sql_text(q.sample_sql_handle) as t
cross apply sys.dm_exec_query_plan(q.sample_plan_handle) as p
q.number_of_entries,
t.text as sample_query,
p.query_plan as sample_plan
from (select top 20 query_hash,
count(*) as number_of_entries,
min(sql_handle) as sample_sql_handle,
min(plan_handle) as sample_plan_handle
from sys.dm_exec_query_stats
group by query_hash
having count(*) > 1
order by count(*) desc) as q
cross apply sys.dm_exec_sql_text(q.sample_sql_handle) as t
cross apply sys.dm_exec_query_plan(q.sample_plan_handle) as p