Below is a script to check the database mirroring synchronization state.
SELECT @@SERVERNAME as Server_Name, DB_NAME(database_id) as Database_Name, mirroring_state_desc, mirroring_role_desc, mirroring_safety_level_desc FROM sys.database_mirroring WHERE mirroring_role IS NOT NULL
The script below will retrieve the size of all your databases in MB and GB.
SELECT d.NAME ,ROUND(SUM(CAST(mf.size AS bigint)) * 8 / 1024, 0) Size_MBs ,(SUM(CAST(mf.size AS bigint)) * 8 / 1024) / 1024 AS Size_GBs FROM sys.master_files mf INNER JOIN sys.databases d ON d.database_id = mf.database_id WHERE d.database_id > 4 -- Skip system databases GROUP BY d.NAME ORDER BY d.NAME
SQL Server will look at each query and check if it has a plan cache already compiled for. If it has, then it will reuse the plan in the cache. If it does not have, then an execution plan is compiled and added to the plan cache.
When identical queries ran over many times, its plan will be reused. This will save resources from having to compile repeatedly.
Now what happens when you have hundreds or thousands of different queries that are only executed once? In this case there are no execution plan to be reused. This is what we call PLAN CACHE BLOAT.
Plan cache bloat is bad because it steals memory from the buffer pool that are better used for database pages. When you execute the script below, and if you see “Adhoc” Cache type to be on top, then that means that there are a lot of queries that are executed once and are causing plan cache bloat.
SELECT objtype AS [CacheType] , count_big(*) AS [Total Plans] , sum(cast(size_in_bytes as decimal(18,2)))/1024/1024 AS [Total MBs] , avg(usecounts) AS [Avg Use Count] , sum(cast((CASE WHEN usecounts = 1 THEN size_in_bytes ELSE 0 END) as decimal(18,2)))/1024/1024 AS [Total MBs - USE Count 1] , sum(CASE WHEN usecounts = 1 THEN 1 ELSE 0 END) AS [Total Plans - USE Count 1] FROM sys.dm_exec_cached_plans GROUP BY objtype ORDER BY [Total MBs - USE Count 1] DESC GO
Plan cache bloat can be prevented by enabling “Optimize for Adhoc Workloads” by only caching the full execution plan of queries that are known to be used more than once.
To enable the optimize for ad hoc workloads setting, use sp_configure, as shown below.
EXEC sp_configure 'show advanced options',1 RECONFIGURE EXEC sp_configure 'optimize for ad hoc workloads',1 RECONFIGURE
One of our users encountered the error below.
I was able to fix the problem by granting the user direct access to the procedure.
USE master GO GRANT EXECUTE ON [sys].[xp_instance_regread] TO [DOMAIN\USER]; --To veriy that the user has been granted the privilege EXECUTE AS USER = 'DOMAIN\USER';Select * from fn_my_permissions('xp_instance_regread','Object')
The T-SQL script below can be used to check the Filenames and paths of your data and log files.
SELECT DB_NAME ([database_id]) AS [Database Name] ,name ,physical_name ,type_desc ,state_desc ,CONVERT(bigint, size/128.0) AS [Total Size in MB] ,CONVERT(decimal(18,2), size/131072.0) AS [Total Size in GB] FROM sys.master_files WITH(NOLOCK) WHERE [database_id] > 4 AND [database_id] <> 32767 OR [database_id] = 2 ORDER BY DB_NAME ([database_id]) OPTION(RECOMPILE)
Output
Below is a script to get the VLF count for all databases on an instance.
CREATE TABLE #VLFInfo ( RecoveryUnitID INT ,FileID INT ,FileSize BIGINT ,StartOffset BIGINT ,FSeqNo BIGINT ,Status BIGINT ,Parity BIGINT ,CreateLSN NUMERIC(38) ); CREATE TABLE #VLFCountResults ( DatabaseName sysname ,VLFCount INT ) EXEC sp_MSforeachdb N'Use [?]; INSERT INTO #VLFInfo EXEC sp_executesql N''DBCC LOGINFO([?])''; INSERT INTO #VLFCountResults SELECT DB_NAME(), COUNT(*) FROM #VLFInfo; TRUNCATE TABLE #VLFInfo;' SELECT DatabaseName ,VLFCount FROM #VLFCountResults ORDER BY VLFCount DESC DROP TABLE #VLFInfo DROP TABLE #VLFCountResults -- High VLF counts can affect write performance -- and they can make database restored and recovery take much longer
