最近收到一SQL Server数据库服务器的告警邮件，告警内容具体如下所示：
DATE/TIME: 10/23/2018 4:30:26 PM
DESCRIPTION: The query processor ran out of internal resources and could not produce a query plan. This is a rare event and only expected for extremely complex queries or queries that reference a very large number of tables or partitions. Please simplify the query. If you believe you have received this message in error, contact Customer Support Services for more information.
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关于“8623 The query processor ran out of internal resources and could not produce a query plan”这个错误，这篇文章不分析错误产生的原因以及解决方案。这里仅仅介绍如何捕获产生这个错误的SQL语句。因为出现这个错误，具体对应的SQL语句不会写入到错误日志。不能定位到具体SQL语句，很难解决这错误。所以解决问题的前提是先定位SQL语句。我们可以通过扩展事件或服务器端跟踪两种方式来定位SQL语句。
扩展事件（Extended Events）捕获
如下所示，脚本只需根据实际情况修改filename、metadatafile参数对应的值。就会创建扩展事件（Extented Events)overly_complex_queries
CREATE EVENT SESSION
overly_complex_queries
ON SERVER
ADD EVENT sqlserver.error_reported
(
ACTION (sqlserver.sql_text, sqlserver.tsql_stack, sqlserver.database_id, sqlserver.username)
WHERE ([severity] = 16
AND [error_number] = 8623)
)
ADD TARGET package0.asynchronous_file_target
(set filename = 'D:\DB_BACKUP\overly_complex_queries.xel' ,
metadatafile = 'D:\DB_BACKUP\overly_complex_queries.xem',
max_file_size = 10,
max_rollover_files = 5)
WITH (MAX_DISPATCH_LATENCY = 5SECONDS)
GO
-- Start the session
ALTER EVENT SESSION overly_complex_queries
ON SERVER STATE = START
GO
然后我们测试，使用网上一个脚本测试验证，如下所示，执行这个脚本就会报“8623 The query processor ran out of internal resources and could not produce a query plan”错误，如下所示：
选中扩展事件（Extented Events)overly_complex_queries，单击右键“Watch Live Data"就能查看是那个SQL语句出现这个错误（sql_text），当然，也可以通过选项“View Target Data”查看所有捕获的数据。
注意：这个扩展事件只能运行在SQL Server 2012及后续版本，如果是SQL Server 2008的相关版本部署，就会报下面错误：
Msg 25706, Level 16, State 8, Line 1
The event attribute or predicate source, "error_number", could not be found.
Msg 15151, Level 16, State 1, Line 18
Cannot alter the event session 'overly_complex_queries', because it does not exist or you do not have permission.
服务器端跟踪（Server Side Trace）捕获
如上所示，刚好我们这台数据库服务器的版本为SQL Server 2008 R2，我们只能采取Server Side Trace来捕获这个错误的SQL语句。设置Server Side Trace脚本如下（相关参数需根据实际情况等设定）：
-- 定义参数
declare @rc int
declare @TraceID int
declare @maxfilesize bigint
set @maxfilesize = 1024
-- 初始化跟踪
exec @rc = sp_trace_create @TraceID output, 0, N'D:\SQLScript\trace_error_8623', @maxfilesize, NULL
--此处的D:\SQLScript\trace_error_8623是文件名（可自行修改），SQL会自动在后面加上.trc的扩展名
if (@rc != 0) goto error
-- 设置跟踪事件
declare @on bit
set @on = 1
--trace_event_id=13 SQL:BatchStarting trace_event_id=22 ErrorLog
exec sp_trace_setevent @TraceID, 13, 1, @on
exec sp_trace_setevent @TraceID, 13, 3, @on
exec sp_trace_setevent @TraceID, 13, 6, @on
exec sp_trace_setevent @TraceID, 13, 7, @on
exec sp_trace_setevent @TraceID, 13, 8, @on
exec sp_trace_setevent @TraceID, 13, 11, @on
exec sp_trace_setevent @TraceID, 13, 12, @on
exec sp_trace_setevent @TraceID, 13, 14, @on
exec sp_trace_setevent @TraceID, 13, 15, @on
exec sp_trace_setevent @TraceID, 13, 35, @on
exec sp_trace_setevent @TraceID, 13, 63, @on
exec sp_trace_setevent @TraceID, 22, 1, @on
exec sp_trace_setevent @TraceID, 22, 3, @on
exec sp_trace_setevent @TraceID, 22, 6, @on
exec sp_trace_setevent @TraceID, 22, 7, @on
exec sp_trace_setevent @TraceID, 22, 8, @on
exec sp_trace_setevent @TraceID, 22, 12, @on
exec sp_trace_setevent @TraceID, 22, 11, @on
exec sp_trace_setevent @TraceID, 22, 14, @on
exec sp_trace_setevent @TraceID, 22, 14, @on
exec sp_trace_setevent @TraceID, 22, 35, @on
exec sp_trace_setevent @TraceID, 22, 63, @on
-- 启动跟踪
exec sp_trace_setstatus @TraceID, 1
-- 记录下跟踪ID，以备后面使用
select TraceID = @TraceID
goto finish
error:
select ErrorCode=@rc
finish:
GO
上面SQL会生成一个服务器端跟踪事件，并返回对应的id，如下查看所示：
注意：上面捕获SQL:BatchStarting事件（trace_event_id=13），是因为捕获ErrorLog（trace_event_id=22)等事件时，都
无法捕获到对应的SQL(对应的trace column没有捕获SQL语句，暂时还没有找到一个好的解决方法）。这里也有个弊端，就是会捕获大量无关的SQL语句。
测试过后，你可以使用SQL Profile工具打开D:\SQLScript\trace_error_8623.trc找到错误信息，对应的SQL语句（在这个时间点附近的SQL语句，一般为是错误信息后面的第一个SQL语句，需要做判断），如下截图所示:
也可以使用脚本查询，如下所示，也是需要自己判断定位SQL语句，一般都是“8623 The query processor ran out of internal resources and could not produce a query plan”出现后紧接着的SQL。
SELECT StartTime,EndTime,
TextData, ApplicationName,SPID,Duration,LoginName
FROM ::fn_trace_gettable(N'D:\SQLScript\trace_error_8623.trc',DEFAULT)
WHERE spid=64
ORDER BY StartTime
参考资料：