SQL SERVER 内存分配及常见内存问题(2)——DMV查询
内存动态管理视图(DMV):
SELECT [type] , SUM(virtual_memory_reserved_kb) AS [VM Reserved] , SUM(virtual_memory_committed_kb) AS [VM Committed] , SUM(awe_allocated_kb) AS [AWE Allocated] , SUM(shared_memory_reserved_kb) AS [SM Reserved] , SUM(shared_memory_committed_kb) AS [SM Committed] , SUM(multi_pages_kb) AS [Multipage Allocator] , SUM(single_pages_kb) AS [SinlgePage Allocator], SUM(virtual_memory_reserved_kb)/(CASE WHEN SUM(virtual_memory_committed_kb)=0 THEN 1 ELSE SUM(virtual_memory_committed_kb) END ) AS [Reserved/Commit], SUM(single_pages_kb)+SUM(multi_pages_kb) AS Stolen, SUM(virtual_memory_committed_kb)+SUM(single_pages_kb) AS [SinlgePage Allocator] FROM sys.dm_os_memory_clerks GROUP BY [type] ORDER BY [type]
对于得出的数据:
Memoryclerk_sqlbufferpool:正常来说这个汇总值最大。
CACHESTORE_OBJECP:触发器、存储过程、函数的执行计划缓存。
CACHESTORE_SQLCP:动态T-SQL语句、预编译TSQL语句的执行计划缓存。
CACHESTORE_PHDR:缓存视图、用户自定义函数信息,帮助SQL更快生成执行计划。
CACHESTORE_XPROC:缓存扩展存储过程,sp_executesql,sp_cursor*,sp_Trace*等。
CACHESTORE_TEMPTABLES:缓存临时对象。local temp table 、global temp table 、table variable等。
CACHESTORE_CLRPROC:SQLCLR过程缓存。
CACHESTORE_EVENTS:存储Service Broker的时间和消息。
CACHESTORE_CURSORS:存储所有的游标,包括LocalTSQLcursors、Global TSQL cursor和API cursors等。
USERSTORE_TOKENPERM:保存所有用户的安全上下文及各种跟安全相关的令牌,这些缓存条目用于检查查询累积性的权限。
USERSTORE_SXC:暂时存放正在执行中的语句的PRC参数,如果参数过长,这部分内存的使用量会比较大。
DECLARE @name NVARCHAR(100) DECLARE @cmd NVARCHAR(1000) DECLARE dbnames CURSOR FOR SELECT NAME FROM master.dbo.sysdatabases OPEN dbnames FETCH NEXT FROM dbnames INTO @name WHILE @@FETCH_STATUS = 0 BEGIN SET @cmd = ‘select b.database_id,db=db_name(b.database_id),p.object_id,p.index_id,buffer_count=count(*) from ‘ + @name + ‘.sys.allocation_units a, ‘ + @name + ‘.sys.dm_os_buffer_descriptors b, ‘ + @name + ‘.sys.partitions p where a.allocation_unit_id=b.allocation_unit_id and a.container_id=p.hobt_id and b.database_id=db_id(‘‘‘ + @name + ‘‘‘) group by b.database_id,p.object_id,p.index_id order by b.database_id,buffer_count desc ‘ EXEC (@cmd) FETCH NEXT FROM dbnames INTO @name END CLOSE dbnames DEALLOCATE dbnames GO
SELECT objtype , SUM(size_in_bytes) / 1024 AS sum_size_in_KB , COUNT(bucketid) AS cache_counts FROM sys.dm_exec_cached_plans GROUP BY objtype分析具体存储哪些对象:
SELECT usecounts , refcounts , size_in_bytes , cacheobjtype , objtype , TEXT FROM sys.dm_exec_cached_plans cp CROSS APPLY sys.dm_exec_sql_text(plan_handle) ORDER BY objtype DESC ; GO
--使用DMV分析SQL SERVER 启动以来做read最多的语句
--按照物理读的页面数排序,前50名 SELECT TOP 50 qs.total_physical_reads , qs.execution_count , qs.total_physical_reads / qs.execution_count AS [Avg IO] , SUBSTRING(qt.text, qs.statement_start_offset / 2, ( CASE WHEN qs.statement_end_offset = -1 THEN LEN(CONVERT(NVARCHAR(MAX), qt.text)) * 2 ELSE qs.statement_end_offset END - qs.statement_start_offset ) / 2) AS query_text , qt.dbid , dbname = DB_NAME(qt.dbid) , qt.objectid , qs.sql_handle , qs.plan_handle FROM sys.dm_exec_query_stats qs CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) AS qt ORDER BY qs.total_physical_reads DESC --按照逻辑读的页面数排序,前50名 SELECT TOP 50 qs.total_logical_reads , qs.execution_count , qs.total_logical_reads / qs.execution_count AS [Avg IO] , SUBSTRING(qt.text, qs.statement_start_offset / 2, ( CASE WHEN qs.statement_end_offset = -1 THEN LEN(CONVERT(NVARCHAR(MAX), qt.text)) * 2 ELSE qs.statement_end_offset END - qs.statement_start_offset ) / 2) AS query_text , qt.dbid , dbname = DB_NAME(qt.dbid) , qt.objectid , qs.sql_handle , qs.plan_handle FROM sys.dm_exec_query_stats qs CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) AS qt ORDER BY qs.total_logical_reads DESC
--用DBCC强制释放部分SQL SERVER 内存缓存:
DBCC FREESYSTEMCACHE
DBCC FREESESSIONCACHE
DBCC FREEPROCCACHE
--查看操作系统内存状况 SELECT total_physical_memory_kb / 1024 AS [物理内存(MB)] , available_physical_memory_kb / 1024 AS [可用物理内存(MB)] , system_cache_kb / 1024 AS [系统缓存内存总量(MB)] , ( kernel_paged_pool_kb + kernel_nonpaged_pool_kb ) / 1024 AS [内核池内存总量(MB)] , total_page_file_kb / 1024 AS [操作系统报告的提交限制的大小(MB)] , available_page_file_kb / 1024 AS [未使用的页文件的总量(MB)] , system_memory_state_desc AS [内存状态说明] FROM sys.dm_os_sys_memory
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