nots dmv

The wait state is an important means of isolating SQL Server performance issues, starting at the instance level. You can probably see if SQL Server is in a tight state of resources for some time in the past. It depends on whether you have an effective performance data collection mechanism in place. Sys.dm_os_wait_stats This DMV data is collected from the last boot of the instance. withWaits as ( SELECTWait_type, Wait_time_ms/ +. aswait_time_s, -.*W

again. During this operation, your performance will degrade because you have just deactivated an important cache layer for SQL Server! When you plan to deploy cache pool extensions for your production environment, you must be aware of this!!! In addition you can not reduce the size of the extension file, the file must be larger than the previous. Otherwise you will receive the following error message: MSG 868, Level A, State 1, line 3Buffer pool extension size must is larger than the current m

I gave you an introduction to WinDbg in the previous article and how you can attach to SQL Server. Today's article, we go ahead and I'll show you the steps required to debug a SQL Server query using WinDbg. Sounds interesting? Here we go!Suppose you have a simple query in front of you, and you want to debug that particular query in WinDbg. It sounds simple, but once you start thinking about it, you get a lot of questions: How do I identify the correct worker thread on my particular exec

2008 is that executing an extended stored procedure causes type preemptive_os_getprocaddress to accumulate time continuously. Calculate the approximate time of the extended stored procedure execution as described above: DECLARE @WaitTime bigint Select @WaitTime = Wait_time_ms from sys.dm_os_wait_stats where wait_type = ' msql_xp ' se Lect @WaitTime-wait_time_ms from sys.dm_os_wait_stats where wait_type = ' preemptive_os_getprocaddress ' The results of 2 instances are also less than 300 millise

of indexes. It seems that the previous DBAs liked to add indexes to individual table columns and some combinations after asking. I don't think all indexes are necessary, but how do I find the indexes that can be safely deleted? We are running SQL Server 2005. A: Yes, a large number of indexes can be a major contributor to poor performance. Each time you insert, update, or delete rows in a table, you need to perform the appropriate action in each non-clustered index. This adds a lot of administ

. Figure 1. The column storage index only supports scan operations So how does a column index store? Column index storage can be words too literally, or stored by columns. This process can be divided into 3 stages, first of all a bunch of rows grouped, this is called "row group", after the grouping is completed, and then split by column, and finally the column compression, as shown in Figure 2. Figure 2. The process of column storage We notice that some of them are not grouped enough, s

statements are executed Steps for SQL Server query execution if you look at it from a microscopic perspective, it will be very much. In order to describe the concepts of logical reading, I look at the higher levels of abstraction: The figure is a bit rough. Let me explain the diagram below. When a query statement is encountered, the SQL Server takes the first step, generating execution plans (consuming CPU and memory resources), synchronizing with estimated data to obtain the required

First, the DMV will give you a packet of license plate screws, a total of 4 pieces, a large and divided into 5 small parts, the car before and after 2 large, which is a license plate with 2, 2 car number, the following figure: You can see many kinds of installation methods on the Internet, there are 2 kinds of commonly used: (a) Self-tapping screws installed (is installed themselves, do not need to dismantle the car) This installation is the simp

THEN ' System Transaction ' if 4 THEN ' distributed Transaction ' end as Transactionty PE, Case at.transaction_state if 0 THEN ' transaction not initialized ' when 1 THEN ' Transact Ion initialized not started ' When 2 THEN ' Active Transaction ' when 3 THEN ' Transaction Ended ' When 4 THEN ' distributed Transaction initiated Commit Process ' when 5 THEN ' Transaction in Prepared Stat E Waiting Resolution ' When 6 THEN ' Transaction committed ' if 7 THEN ' Transaction ro

state are also queried, and finally, the FROM clause references the DMV, with the WHERE clause specifying two resource types. RESOURCE_TYPE specifies a locked resource type, such as a database\object\file\page\key\rid\extent\metadata\application\allocation_unit or hobt type. The resource_associated_entity_id of the dependent resource type, determining whether the ID is an object ID, allocation unit ID, or HOBT ID. If the resource_associated_entity_i

, You need to specify the output file path in SQLdiag. Examples are entered under cmd: Format:sqldiag.exe/i I use the Sd_general.xml configuration file, configure F:\SQLDIAOUT as the output directory, this folder does not have to be created in advance, he most help you create automatically sqldiag.exe/i sd_general.xml/o F:\SQLDIAOUT You can see SQLdiag open perfmon (Addingperfmon counters) and trace (starting Profiler trace) while running When the problem is tracked, pressing the CTRL

the datasheet and can be placed in different filegroups with different I/O. The index uses a B-tree as the storage structure, so the operations required to query a particular row are minimized. 1.2. Indexing overhead: Too many indexes can cause (the cud part of the Insert/update/delete/crud) to take a longer time. When you design an index, you do it from two angles: For existing production systems, the overall impact of indexes needs to be measured to ensure that the benefits of performance o

classification function that the resource Governor needs. --Create a new classifier function for Resource Governor create FUNCTION dbo. Myclassifierfunction () RETURNS SYSNAME with schemabinding as BEGIN DECLARE @GroupName SYSNAME IF suser_name () = ' Dbauser ' Begin Set @GroupName = ' Dbagroup ' end ELSE begin Set @GroupName = ' Default ' end return @GroupName; End Go In the classification function we evaluate by login. If the login is Dbauser, the incoming session will b

, streamed from SalesOrderDetail directly to MyTable. Rather, it is streamed from SalesOrderDetail to the Parameter Table. And the Parameter table, as it turns out, are in actuality a hidden temporary table. And not until all of the data has streamed to that hidden temporary the table are control resumed by the EXEC context, and on Ly then does the data start moving into its final home. The natural question you might are asking yourself at this point are, just how much overhead does this Par

blog post that looks at the DMV in Sys.dm_os_wait_stats. This blog post can find out why your server is causing the most blocking. If you find that the Pagelatch type is waiting, you can use this script to see if the problem is caused by Fps,gam or sgam contention. If you encounter latch contention, you can mitigate this by tracking tag 1118 or by building a tempdb file (the principle can be found in KB 328551), and I've written a long blog about wh

determines which thread runs at which point in time, through a thing called scheduler, let's look at scheduler. Scheduler Each logical CPU in SQL Server has a corresponding scheduler, only the task that gets scheduler ownership is allowed to be executed, scheduler can be regarded as a logical CPU of a team Sqlos. You can look at all the scheduler in the system by sys.dm_os_schedulers this DMV, as shown in Figure 1. Figure 1. View Sys.dm_os_sched

after indexingBut as the volume of data grows, index fragmentation occurs, and many of the stored data is not properly paginated, causing fragmentation (spreads, fragments, fill factors) that need to be re-indexed to speed performanceThe DMV statement can be used to query its index conditionSELECT Index_type_desc,alloc_unit_type_desc,avg_fragmentation_in_percent,fragment_count,avg_fragment_size_in_ Pages,page_count,record_count,avg_page_space_used_in

Tags: des style blog http ar io color os useYou can use the following statement to use the sys.dm_os_wait_stats this DMV to get the statistical value of the thread's waiting information (the line thread is waiting and so on, etc.). with[Waits] as(SELECT[Wait_type], [Wait_time_ms]/ 1000.0 as[WaitS], ([Wait_time_ms]- [Signal_wait_time_ms]) / 1000.0 as[ResourceS], [Signal_wait_time_ms]/ 1000.0 as[Signals], [Waiting_tasks_coun

data is less than 500 rowsRecord update identity is greater than 500 and 20% rows Change (rowcnt) When table data is greater than 500 rowsNote: The Temporary table table is small (0 rows or less than 6 rows). 6 changes trigger the update.Table Variable No statisticsAbout record update identification (modification Counters)Rowmodctr sql2000 and used before. Recorded in Sys.sysindexes.Note: Although this parameter is highly dependent on its use, Microsoft still maintains this parameter change as

, you will find that most of the principles are interlinked. For example, the principle of technical implementation, there are some concepts, just changed the noun yier For example: 1, SQL Server user-defined functions , in the MySQL and Dameng database called storage functions 2, MySQL inside the event, is SQL Server inside the job (Job) 3. Dynamic Performance View in the database of dreams, called dynamic management view (