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  • What's the importance of restoring SQL Server system databases (model, master, etc.)?

    - by Zero Subnet
    I had to restore some production databases to a different drive on the same Microsoft SQL Server 2005 machine. That worked fine and the application using the databases is back online. However, i have not restored the system (or default?) databases that SQL Server creates on its own (model, master, etc.). My question is, what is the role of these databases? and how important it is that i restore them?

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  • SQL SERVER – Tricks to Comment T-SQL in SSMS – SQL in Sixty Seconds #019 – Video

    - by pinaldave
    Code commeting is the one of the most common tasks developers perform. There are two major reasons why developer comment code. 1) During Debug 2) Documenting the code. While debugging the T-SQL code I have often seen developers struggling to comment code.  They spend (or waste) more time in commenting and uncommenting  than doing actual debugging of the procedure.  When I see developer struggling to comment the code I feel little uncomfortable as commenting should be a very easy task over. Today we will see three quick method to comment T-SQL code in Query Editor. There are three different method to comment and uncomment statements in SQL Server Management Studio Using Keyboard Shortcuts Using Tool Bar Using Menu Bar Method 1: Using Keyboard Shortcuts Commenting the statement – CTRL+K, CTRL+C Commenting the statement – CTRL+K, CTRL+U Method 2: Using Tool Bar Using Tool bar buttons. (See Video) Method 3: Using Menu Bar Commenting the statement – Menu Bar >> Edit >> Advanced >> Click on Comment Selection. Unommenting the statement – Menu Bar >> Edit >> Advanced >> Click on Uncomment Selection. More on Importing CSV Data: Two Different Ways to Comment Code – Explanation and Example I encourage you to submit your ideas for SQL in Sixty Seconds. We will try to accommodate as many as we can. If we like your idea we promise to share with you educational material. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Database, Pinal Dave, PostADay, SQL, SQL Authority, SQL in Sixty Seconds, SQL Query, SQL Scripts, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology, Video

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  • SQL SERVER – CTRL+SHIFT+] Shortcut to Select Code Between Two Parenthesis

    - by pinaldave
    Every weekend brings creative ideas and accidents brings best unknown secrets in front of us. Just a day while working with complex SQL Server code in SSMS I came across very interesting shortcut which I have never used before and instantly fell in love with it. It is totally possible that you are familiar with this but for me it was the first time and I was surprised that I did know know this short cut so far. Shortcut key is CTRL+SHIFT+]. This key can be very useful when dealing with multiple subqueries, CTE or query with multiple parentheses. When exercised this shortcut key it selects T-SQL code between two parentheses. Let us see the examples to understand the same. In each of the examples I have put the cursor at the position displayed and pressed CTRL+SHIFT+] and it has selected the code between two corresponding parentheses. Cursor position 1 Cursor position 2 Cursor position 3 If you are a developer and have to code with complex queries, you will totally appreciate that this feature can save so much of the time for development. I often remember my experience as a developer when I have lost a lot of hours to just balance parentheses. As I said yesterday I found this shortcut accidently. How many of you were aware of this feature? Is there any other useful feature you would like to share with us? Please leave a comment and if I have not covered it earlier, I will share it due credit on this blog. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology Tagged: SQL Shortcut

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  • SQL SERVER – Find Most Active Database in SQL Server – DMV dm_io_virtual_file_stats

    - by pinaldave
    Few days ago, I wrote about SQL SERVER – Find Current Location of Data and Log File of All the Database. There was very interesting conversation in comments by blog readers. Blog reader and SQL Expert Sreedhar has very interesting DMV presented which lists the most active database in SQL Server. For quick reference he has included the size of the disk in KB, MB and GB as well. SELECT DB_NAME(mf.database_id) AS databaseName, name AS File_LogicalName, CASE WHEN type_desc = 'LOG' THEN 'Log File' WHEN type_desc = 'ROWS' THEN 'Data File' ELSE type_desc END AS File_type_desc ,mf.physical_name ,num_of_reads ,num_of_bytes_read ,io_stall_read_ms ,num_of_writes ,num_of_bytes_written ,io_stall_write_ms ,io_stall ,size_on_disk_bytes ,size_on_disk_bytes/ 1024 AS size_on_disk_KB ,size_on_disk_bytes/ 1024 / 1024 AS size_on_disk_MB ,size_on_disk_bytes/ 1024 / 1024 / 1024 AS size_on_disk_GB FROM sys.dm_io_virtual_file_stats(NULL, NULL) AS divfs JOIN sys.master_files AS mf ON mf.database_id = divfs.database_id AND mf.FILE_ID = divfs.FILE_ID ORDER BY num_of_Reads DESC If you like to read and practice with DMVs, I suggest to read the blog of my very good friend Glenn Berry. He is one DMV expert. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – How to Set Variable and Use Variable in SQLCMD Mode

    - by Pinal Dave
    Here is the question which I received the other day on SQLAuthority Facebook page. Social media is a wonderful thing and I love the active conversation between blog readers and myself – actually I think social media adds lots of human factor to any conversation. Here is the question - “I am using sqlcmd in SSMS – I am not sure how to declare variable and pass it, for example I have a database and it has table, how can I make the table variable dynamic and pass different value everytime?” Fantastic question, and here is its very simple answer. First of all, enable sqlcmd mode in SQL Server Management Studio as described in following image. Now in query editor type following SQL. :SETVAR DatabaseName “AdventureWorks2012″ :SETVAR SchemaName “Person” :SETVAR TableName “EmailAddress“ USE $(DatabaseName); SELECT * FROM $(SchemaName).$(TableName); Note that I have set the value of the database, schema and table as a sqlcmd variable and I am executing the query using the same parameters. Well, that was it, sqlcmd is a very simple language to master and it also aids in doing various tasks easily. If you have any other sqlcmd tips, please leave a comment and I will publish it with due credit. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology Tagged: sqlcmd

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  • SQL SERVER – Powershell – Get a List of Fixed Hard Drive and Free Space on Server

    - by pinaldave
    Earlier I have written this article SQL SERVER – Get a List of Fixed Hard Drive and Free Space on Server. I recently received excellent comment by MVP Ravikanth. He demonstrated that how the same can be done using Powershell. It is very sweet and quick solution. Here is the powershell script. Run the same in your powershell windows. Get-WmiObject -Class Win32_LogicalDisk | Select -Property DeviceID, @{Name=’FreeSpaceMB’;Expression={$_.FreeSpace/1MB} } | Format-Table -AutoSize Well, I ran this script in my powershell window, it gave me following result – very accurately and easily. Thanks Ravikanth one more time for excellent tip. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Stored Procedure, SQL Tips and Tricks, T SQL, Technology Tagged: Powershell

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  • Problem with MS DTC on SQL2008 win server 2k8 with linked server from sql2000 win server 2k

    - by user31648
    Hi, We have migrated our db from sql2000 win server 2k to sql2008 win server 2k8. We have linked server from sql2000 win server 2k. By our opinion the problem is with DTC and we have made a lot of setting that we found as solution for our problem, but still the problem exist. There is no any error or worning or information niether in the sql log nor in win event viewer. The application is hanging out and at the end the time out exception is shown. What we have done till now: Enable Network DTC Access with inbound and outbound with No Authentication Required on win 2k8 We have opened RPC dynamic port allocation through registry on 2k and 2k8 We have entered subkey TurnOffRpcSecurity in the registry HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSDTC and made it enable on 2k and 2k8 We have added exception for DTC in firewall for all entities What we have notice that when we restart SQL service and make the first try for our transaction the following is shown: "Attempting to initialize Microsoft Distributed Transaction Coordinator (MS DTC). This is an informational message only. No user action is required." and after it: "Recovery of any in-doubt distributed transactions involving Microsoft Distributed Transaction Coordinator (MS DTC) has completed. This is an informational message only. No user action is required." Does someone have any idea what else can be done in order to solve the problem? Thanks in advance. Regards, Snezana

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  • SSIS Reporting Pack – a performance tip

    - by jamiet
    SSIS Reporting Pack is a suite of open source SQL Server Reporting Services (SSRS) reports that provide additional insight into the SQL Server Integration Services (SSIS) 2012 Catalog. You can read more about SSIS Reporting Pack here on my blog or had over to the home page for the project at http://ssisreportingpack.codeplex.com/. After having used SSRS Reporting Pack on a real project for a few months now I have come to realise that if you have any sizeable data volumes in [SSISDB] then the reports in SSIS Reporting Pack will suffer from chronic performance problems – I have seen the “execution” report take upwards of 30minutes to return data. To combat this I highly recommend that you create an index on the [SSISDB].[internal].[event_messages].[operation_id] & [SSISDB].[internal].[operation_messages].[operation_id] fields. Phil Brammer has experienced similar problems himself and has since made it easy for the rest of us by preparing some scripts to create the indexes that he recommends and he has shared those scripts via his blog at http://www.ssistalk.com/SSIS_2012_Missing_Indexes.zip. If you are using SSIS Reporting Pack, or even if you are simply querying [SSISDB], I highly recommend that you download Phil’s scripts and test them out on your own SSIS Catalog(s). Those indexes will not solve all problems but they will make some of your reports run quicker. I am working on some further enhancements that should further improve the performance of the reports. Watch this space. @Jamiet

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  • Folders in SQL Server Data Tools

    - by jamiet
    Recently I have begun a new project in which I am using SQL Server Data Tools (SSDT) and SQL Server Integration Services (SSIS) 2012. Although I have been using SSDT & SSIS fairly extensively while SQL Server 2012 was in the beta phase I usually find that you don’t learn about the capabilities and quirks of new products until you use them on a real project, hence I am hoping I’m going to have a lot of experiences to share on my blog over the coming few weeks. In this first such blog post I want to talk about file and folder organisation in SSDT. The predecessor to SSDT is Visual Studio Database Projects. When one created a new Visual Studio Database Project a folder structure was provided with “Schema Objects” and “Scripts” in the root and a series of subfolders for each schema: Apparently a few customers were not too happy with the tool arbitrarily creating lots of folders in Solution Explorer and hence SSDT has gone in completely the opposite direction; now no folders are created and new objects will get created in the root – it is at your discretion where they get moved to: After using SSDT for a few weeks I can safely say that I preferred the older way because I never used Solution Explorer to navigate my schema objects anyway so it didn’t bother me how many folders it created. Having said that the thought of a single long list of files in Solution Explorer without any folders makes me shudder so on this project I have been manually creating folders in which to organise files and I have tried to mimic the old way as much as possible by creating two folders in the root, one for all schema objects and another for Pre/Post deployment scripts: This works fine until different developers start to build their own different subfolder structures; if you are OCD-inclined like me this is going to grate on you eventually and hence you are going to want to move stuff around so that you have consistent folder structures for each schema and (if you have multiple databases) each project. Moreover new files get created with a filename of the object name + “.sql” and often people like to have an extra identifier in the filename to indicate the object type: The overall point is this – files and folders in your solution are going to change. Some version control systems (VCSs) don’t take kindly to files being moved around or renamed because they recognise the renamed/moved file simply as a new file and when they do that you lose the revision history which, to my mind, is one of the key benefits of using a VCS in the first place. On this project we have been using Team Foundation Server (TFS) and while it pains me to say it (as I am no great fan of TFS’s version control system) it has proved invaluable when dealing with the SSDT problems that I outlined above because it is integrated right into the Visual Studio IDE. Thus the advice from this blog post is: If you are using SSDT consider using an Visual-Studio-integrated VCS that can easily handle file renames and file moves I suspect that fans of other VCSs will counter by saying that their VCS weapon of choice can handle renames/file moves quite satisfactorily and if that’s the case…great…let me know about them in the comments. This blog post is not an attempt to make people use one particular VCS, only to make people aware of this issue that might rise when using SSDT. More to come in the coming few weeks! @jamiet

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  • Windows Server 2008 R2 RAS VPN: access server on internal interface ip

    - by Mathias
    short question: I'm usually a linux admin but need to setup a Win2k8 R2 server for a student project. The server is running as VM on a root server and has a public internet IP assigned. Additionally I need a VPN server to access some services running on the server. I managed to set up a working VPN gateway via the Routing and RAS service which assigns clients an IP in the private subnet 192.168.88.0/24 with the Interface "Internal" listening on 192.168.88.1. Additionally I set up the external interface as NAT interface. So I can connect to the VPN server, get an IP assigned and the server additionally does NAT and I can access the internet over the VPN connection. The only thing I additionally need, is that I can access the server itself over that internal IP (e.g. client 192.168.88.2, server 192.168.88.1) as I want to access some services which I don't like to expose to the internet and restrict them to connected VPN clients. Does anybody have a hint, which configuration I'm missing here to be able to access the server over the VPN connection? EDIT: VPN clients get assigned the IP from the private subnet with subnetmask 255.255.255.255, I guess that might be the reason I can't access the server on the private IP address although it's in the same network range. Any ideas how to change this? I defined a static address pool in the Routing and RAS service, but I can't change the netmask there. EDIT2: I can't access the server from the client, but I can fully access the client from the server (ping, HTTP). I guess it has to do with firewall configuration. Thanks in advance, Mathias

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  • Windows Server 2008 R2 RAS VPN: access server on internal interface ip

    - by Mathias
    Hey, short question: I'm usually a linux admin but need to setup a Win2k8 R2 server for a student project. The server is running as VM on a root server and has a public internet IP assigned. Additionally I need a VPN server to access some services running on the server. I managed to set up a working VPN gateway via the Routing and RAS service which assigns clients an IP in the private subnet 192.168.88.0/24 with the Interface "Internal" listening on 192.168.88.1. Additionally I set up the external interface as NAT interface. So I can connect to the VPN server, get an IP assigned and the server additionally does NAT and I can access the internet over the VPN connection. The only thing I additionally need, is that I can access the server itself over that internal IP (e.g. client 192.168.88.2, server 192.168.88.1) as I want to access some services which I don't like to expose to the internet and restrict them to connected VPN clients. Does anybody have a hint, which configuration I'm missing here to be able to access the server over the VPN connection? EDIT: VPN clients get assigned the IP from the private subnet with subnetmask 255.255.255.255, I guess that might be the reason I can't access the server on the private IP address although it's in the same network range. Any ideas how to change this? I defined a static address pool in the Routing and RAS service, but I can't change the netmask there. EDIT2: I can't access the server from the client, but I can fully access the client from the server (ping, HTTP). I guess it has to do with firewall configuration. Thanks in advance, Mathias

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  • Visual studio 2010 and Sql Server

    - by Mendy
    Do visual studio 2010 include already Sql Server instance, or I need to install Sql Server developer edition to develop an application that need a Sql Server db. If it installs a Sql Server express edition, it this enough or it's better to have Sql Server developer edition?

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  • attach / detach mssql 2008 sql server manager [SOLVED]

    - by Tillebeck
    An external consult wrote a guide on how to copy a database. Step two was detach the database using Sql Server Manager. After the detach the database was not visible in the SQL Server Manager... Not much to do but write a mail to the service provider asking to have the database attached again. The service porviders answer: Not posisble to attach again since the SQL Server security has been violated". Rolling back to last backup is not the option I want to use. Can any one give feedback if this seems logic and reasonable to assume that a detached database in a SQL Server 2008 accessed through SQL Server Manager cannot be reattached. It was done by rightclicking the database and choosing detach. -- update -- Based on the comments below I update the question with the server setup. There are two dedicated servers: srv1: Web server with remote desktop and an Sql Server Manager srv2: Sql server that can be accessed through the Sql Server Manager on the web server -- update2 -- After a restart of the server the DBA could suddenly do the attachment of the database. And I guess that after the restart it was a simple task. So all of your answer were rigth! It seems that I can only mark one as a correct answer so I marked the first answer correct. But all are correct answer. Thanks a lot. Without posting the link to this thread then we might had so suffer while watching our database beeing restored by a backup :-) Thanks a lot. BR. Anders

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  • SQL Server 2005 - Linked Visual Foxpro Authorization

    - by John
    Here's the Scenario: We have an existing SQL 2000 Server that has a linked server to a share directory (on another server) containing Visual FoxPro tables; all connections work correctly. Porting the SQL 2000 server to a new SQL 2005 server results in questionable behavior: If you connect to the server, remotely, using Windows Authentication, you receive this error when running a query against the linked server: OLE DB provider "MSDASQL" for linked server "[linked server name]" returned message "[Microsoft][ODBC Visual FoxPro Driver]File 'MyTable.dbf' does not exist.". Msg 7350, Level 16, State 2, Line 2 Cannot get the column information from OLE DB provider "MSDASQL" for linked server "[linked server name]". However, logged in locally, the query works fine. The query also works correctly when logged in remotely, but using a SQL login. The only scenario I receive the error is when connected remotely, using windows authentication. As I mentioned before, this works on the SQL 2000 server, and both the old and new servers are running under the same network account (which has access to the folder the FoxPro files are in). Doing a little searching on the internet it looks like others have run into this situation, but I haven't found a resolution. Has anyone run into this before?

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  • How do I secure Sql Server 2008 R2

    - by Mark Tait
    I have both a dedicated and a VPS (from Fasthosts) virtual server - the web sites/applications I run on these, access Sql Server stored on the same web server. Until now, I have logged onto Sql Server on both the deidicated and VPS server, from Sql Server Management Studio - until I noticed in my server application logs, multiple attempts to logon to Sql Server using the 'sa' username, but failed password. So someone/bot is trying hard (repeatedly every couple of hours, for approx 20 attempts during each instance) to log on... so obviously I have to lock down access to Sql Sever remotely. What I have done is gone into Configuration Manager, and in Sql Server Network Configuration - Protocols for Sql2008 and also in Sql Native Client 10.0 Configuration - Client Protocols - I have diabled Named Pipes, TCP/IP (and VIA by default). I have left Shared Memory enabled. I also disabled in Sql Server Services, the Sql Server Browser. Now the only way I can manage the databases on these servers, is by logging on to them via Remote Desktop. Can anyone confirm if this is the correct way of stopping anyone maliciously logging on to Sql Server? (I'm not a DBA or security expert - and there are hundreds of articles advising all different ways - but I was hoping for the experts here to confirm, or otherwise, if what I've done is correct) Thank you, Mark

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  • Anonymous access to SMB share hosted on Server 2008 R2 Enterprise

    - by bwerks
    Hi all, First off, I have read through this post and a whole slew of non-SF posts which seem to address the same or a similar problem, however I was still unable to fix my problem. I've got three machines in this situation: a domain-joined server that runs Server 2008 R2 Enterprise ("share server") a domain-joined workstation running XP Pro SP3 ("test server") a domain-unjoined test server running Server 2003 R2 SP2 ("workstation") The share server is exposing a share on the network that the test server must access--it's a Source/Symbol Server share for our debugging purposes. I believe visual studio simply accesses the the share with its own credentials in this case, meaning that the share must be accessible anonymously since the test server isn't joined to the domain and there's no opportunity to supply domain authentication. I've attempted a lot of things to avoid the authentication window when accessing the share: I've enabled the Guest account on the share server and given Guest full sharing/NTFS permissions for the share. I've given ANONYMOUS LOGON full sharing/NTFS permissions for the share. I've added my share to “Network Access: Shares that can be accessed anonymously” in LSP. I've disabled “Network access: Restrict anonymous access to Named Pipes and Shares” in LSP. I've enabled “Network access: Let Everyone permissions apply to anonymous users” in LSP. Added ANONYMOUS LOGON to “Access this computer from the network” in LSP. Added the Guest account to “Access this computer from the network” in LSP. Attempted to provision the share using the Share and Storage Management MMC snap-in. Unfortunately when I attempt to access the share from the test server, I still see the prompt and I'm forced to enter "Guest" manually. I also tried this workflow using the local administrator account on a workstation, and the same thing happens both with and without XP Simple File Sharing enabled. Any idea why I'm getting these results, or what I should have done differently?

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  • An XEvent a Day (11 of 31) – Targets Week – Using Multiple Targets to Debug Orphaned Transactions

    - by Jonathan Kehayias
    Yesterday’s blog post Targets Week – etw_classic_sync_target covered the ETW integration that is built into Extended Events and how the etw_classic_sync_target can be used in conjunction with other ETW traces to provide troubleshooting at a level previously not possible with SQL Server. In today’s post we’ll look at how to use multiple targets to simplify analysis of Event collection. Why Multiple Targets? You might ask why you would want to use multiple Targets in an Event Session with Extended...(read more)

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  • SQL SERVER – Guest Post – Jonathan Kehayias – Wait Type – Day 16 of 28

    - by pinaldave
    Jonathan Kehayias (Blog | Twitter) is a MCITP Database Administrator and Developer, who got started in SQL Server in 2004 as a database developer and report writer in the natural gas industry. After spending two and a half years working in TSQL, in late 2006, he transitioned to the role of SQL Database Administrator. His primary passion is performance tuning, where he frequently rewrites queries for better performance and performs in depth analysis of index implementation and usage. Jonathan blogs regularly on SQLBlog, and was a coauthor of Professional SQL Server 2008 Internals and Troubleshooting. On a personal note, I think Jonathan is extremely positive person. In every conversation with him I have found that he is always eager to help and encourage. Every time he finds something needs to be approved, he has contacted me without hesitation and guided me to improve, change and learn. During all the time, he has not lost his focus to help larger community. I am honored that he has accepted to provide his views on complex subject of Wait Types and Queues. Currently I am reading his series on Extended Events. Here is the guest blog post by Jonathan: SQL Server troubleshooting is all about correlating related pieces of information together to indentify where exactly the root cause of a problem lies. In my daily work as a DBA, I generally get phone calls like, “So and so application is slow, what’s wrong with the SQL Server.” One of the funny things about the letters DBA is that they go so well with Default Blame Acceptor, and I really wish that I knew exactly who the first person was that pointed that out to me, because it really fits at times. A lot of times when I get this call, the problem isn’t related to SQL Server at all, but every now and then in my initial quick checks, something pops up that makes me start looking at things further. The SQL Server is slow, we see a number of tasks waiting on ASYNC_IO_COMPLETION, IO_COMPLETION, or PAGEIOLATCH_* waits in sys.dm_exec_requests and sys.dm_exec_waiting_tasks. These are also some of the highest wait types in sys.dm_os_wait_stats for the server, so it would appear that we have a disk I/O bottleneck on the machine. A quick check of sys.dm_io_virtual_file_stats() and tempdb shows a high write stall rate, while our user databases show high read stall rates on the data files. A quick check of some performance counters and Page Life Expectancy on the server is bouncing up and down in the 50-150 range, the Free Page counter consistently hits zero, and the Free List Stalls/sec counter keeps jumping over 10, but Buffer Cache Hit Ratio is 98-99%. Where exactly is the problem? In this case, which happens to be based on a real scenario I faced a few years back, the problem may not be a disk bottleneck at all; it may very well be a memory pressure issue on the server. A quick check of the system spec’s and it is a dual duo core server with 8GB RAM running SQL Server 2005 SP1 x64 on Windows Server 2003 R2 x64. Max Server memory is configured at 6GB and we think that this should be enough to handle the workload; or is it? This is a unique scenario because there are a couple of things happening inside of this system, and they all relate to what the root cause of the performance problem is on the system. If we were to query sys.dm_exec_query_stats for the TOP 10 queries, by max_physical_reads, max_logical_reads, and max_worker_time, we may be able to find some queries that were using excessive I/O and possibly CPU against the system in their worst single execution. We can also CROSS APPLY to sys.dm_exec_sql_text() and see the statement text, and also CROSS APPLY sys.dm_exec_query_plan() to get the execution plan stored in cache. Ok, quick check, the plans are pretty big, I see some large index seeks, that estimate 2.8GB of data movement between operators, but everything looks like it is optimized the best it can be. Nothing really stands out in the code, and the indexing looks correct, and I should have enough memory to handle this in cache, so it must be a disk I/O problem right? Not exactly! If we were to look at how much memory the plan cache is taking by querying sys.dm_os_memory_clerks for the CACHESTORE_SQLCP and CACHESTORE_OBJCP clerks we might be surprised at what we find. In SQL Server 2005 RTM and SP1, the plan cache was allowed to take up to 75% of the memory under 8GB. I’ll give you a second to go back and read that again. Yes, you read it correctly, it says 75% of the memory under 8GB, but you don’t have to take my word for it, you can validate this by reading Changes in Caching Behavior between SQL Server 2000, SQL Server 2005 RTM and SQL Server 2005 SP2. In this scenario the application uses an entirely adhoc workload against SQL Server and this leads to plan cache bloat, and up to 4.5GB of our 6GB of memory for SQL can be consumed by the plan cache in SQL Server 2005 SP1. This in turn reduces the size of the buffer cache to just 1.5GB, causing our 2.8GB of data movement in this expensive plan to cause complete flushing of the buffer cache, not just once initially, but then another time during the queries execution, resulting in excessive physical I/O from disk. Keep in mind that this is not the only query executing at the time this occurs. Remember the output of sys.dm_io_virtual_file_stats() showed high read stalls on the data files for our user databases versus higher write stalls for tempdb? The memory pressure is also forcing heavier use of tempdb to handle sorting and hashing in the environment as well. The real clue here is the Memory counters for the instance; Page Life Expectancy, Free List Pages, and Free List Stalls/sec. The fact that Page Life Expectancy is fluctuating between 50 and 150 constantly is a sign that the buffer cache is experiencing constant churn of data, once every minute to two and a half minutes. If you add to the Page Life Expectancy counter, the consistent bottoming out of Free List Pages along with Free List Stalls/sec consistently spiking over 10, and you have the perfect memory pressure scenario. All of sudden it may not be that our disk subsystem is the problem, but is instead an innocent bystander and victim. Side Note: The Page Life Expectancy counter dropping briefly and then returning to normal operating values intermittently is not necessarily a sign that the server is under memory pressure. The Books Online and a number of other references will tell you that this counter should remain on average above 300 which is the time in seconds a page will remain in cache before being flushed or aged out. This number, which equates to just five minutes, is incredibly low for modern systems and most published documents pre-date the predominance of 64 bit computing and easy availability to larger amounts of memory in SQL Servers. As food for thought, consider that my personal laptop has more memory in it than most SQL Servers did at the time those numbers were posted. I would argue that today, a system churning the buffer cache every five minutes is in need of some serious tuning or a hardware upgrade. Back to our problem and its investigation: There are two things really wrong with this server; first the plan cache is excessively consuming memory and bloated in size and we need to look at that and second we need to evaluate upgrading the memory to accommodate the workload being performed. In the case of the server I was working on there were a lot of single use plans found in sys.dm_exec_cached_plans (where usecounts=1). Single use plans waste space in the plan cache, especially when they are adhoc plans for statements that had concatenated filter criteria that is not likely to reoccur with any frequency.  SQL Server 2005 doesn’t natively have a way to evict a single plan from cache like SQL Server 2008 does, but MVP Kalen Delaney, showed a hack to evict a single plan by creating a plan guide for the statement and then dropping that plan guide in her blog post Geek City: Clearing a Single Plan from Cache. We could put that hack in place in a job to automate cleaning out all the single use plans periodically, minimizing the size of the plan cache, but a better solution would be to fix the application so that it uses proper parameterized calls to the database. You didn’t write the app, and you can’t change its design? Ok, well you could try to force parameterization to occur by creating and keeping plan guides in place, or we can try forcing parameterization at the database level by using ALTER DATABASE <dbname> SET PARAMETERIZATION FORCED and that might help. If neither of these help, we could periodically dump the plan cache for that database, as discussed as being a problem in Kalen’s blog post referenced above; not an ideal scenario. The other option is to increase the memory on the server to 16GB or 32GB, if the hardware allows it, which will increase the size of the plan cache as well as the buffer cache. In SQL Server 2005 SP1, on a system with 16GB of memory, if we set max server memory to 14GB the plan cache could use at most 9GB  [(8GB*.75)+(6GB*.5)=(6+3)=9GB], leaving 5GB for the buffer cache.  If we went to 32GB of memory and set max server memory to 28GB, the plan cache could use at most 16GB [(8*.75)+(20*.5)=(6+10)=16GB], leaving 12GB for the buffer cache. Thankfully we have SQL Server 2005 Service Pack 2, 3, and 4 these days which include the changes in plan cache sizing discussed in the Changes to Caching Behavior between SQL Server 2000, SQL Server 2005 RTM and SQL Server 2005 SP2 blog post. In real life, when I was troubleshooting this problem, I spent a week trying to chase down the cause of the disk I/O bottleneck with our Server Admin and SAN Admin, and there wasn’t much that could be done immediately there, so I finally asked if we could increase the memory on the server to 16GB, which did fix the problem. It wasn’t until I had this same problem occur on another system that I actually figured out how to really troubleshoot this down to the root cause.  I couldn’t believe the size of the plan cache on the server with 16GB of memory when I actually learned about this and went back to look at it. SQL Server is constantly telling a story to anyone that will listen. As the DBA, you have to sit back and listen to all that it’s telling you and then evaluate the big picture and how all the data you can gather from SQL about performance relate to each other. One of the greatest tools out there is actually a free in the form of Diagnostic Scripts for SQL Server 2005 and 2008, created by MVP Glenn Alan Berry. Glenn’s scripts collect a majority of the information that SQL has to offer for rapid troubleshooting of problems, and he includes a lot of notes about what the outputs of each individual query might be telling you. When I read Pinal’s blog post SQL SERVER – ASYNC_IO_COMPLETION – Wait Type – Day 11 of 28, I noticed that he referenced Checking Memory Related Performance Counters in his post, but there was no real explanation about why checking memory counters is so important when looking at an I/O related wait type. I thought I’d chat with him briefly on Google Talk/Twitter DM and point this out, and offer a couple of other points I noted, so that he could add the information to his blog post if he found it useful.  Instead he asked that I write a guest blog for this. I am honored to be a guest blogger, and to be able to share this kind of information with the community. The information contained in this blog post is a glimpse at how I do troubleshooting almost every day of the week in my own environment. SQL Server provides us with a lot of information about how it is running, and where it may be having problems, it is up to us to play detective and find out how all that information comes together to tell us what’s really the problem. This blog post is written by Jonathan Kehayias (Blog | Twitter). Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: MVP, Pinal Dave, PostADay, Readers Contribution, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • An XEvent a Day (18 of 31) – A Look at Backup Internals and How to Track Backup and Restore Throughput (Part 2)

    - by Jonathan Kehayias
    In yesterday’s blog post A Look at Backup Internals and How to Track Backup and Restore Throughput (Part 1) , we looked at what happens when we Backup a database in SQL Server.  Today, we are going to use the information we captured to perform some analysis of the Backup information in an attempt to find ways to decrease the time it takes to backup a database.  When I began reviewing the data from the Backup in yesterdays post, I realized that I had made a mistake in the process and left...(read more)

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  • An XEvent a Day (15 of 31) – Tracking Ghost Cleanup

    - by Jonathan Kehayias
    If you don’t know anything about Ghost Cleanup, I recommend highly that you go read Paul Randal’s blog posts Inside the Storage Engine: Ghost cleanup in depth , Ghost cleanup redux , and Turning off the ghost cleanup task for a performance gain .  To my knowledge Paul’s posts are the only things that cover Ghost Cleanup at any level online. In this post we’ll look at how you can use Extended Events to track the activity of Ghost Cleanup inside of your SQL Server.  To do this, we’ll first...(read more)

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  • An XEvent a Day (13 of 31) – The system_health Session

    - by Jonathan Kehayias
    Today’s post was originally planned for this coming weekend, but seems I’ve caught whatever bug my kids had over the weekend so I am changing up today’s blog post with one that is easier to cover and shorter.  If you’ve been running some of the queries from the posts in this series, you have no doubt come across an Event Session running on your server with the name of system_health.  In today’s post I’ll go over this session and provide links to references related to it. When Extended Events...(read more)

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  • An XEvent a Day (3 of 31) – Managing Event Sessions

    - by Jonathan Kehayias
    Yesterdays post, Querying the Extended Events Metadata , showed how to discover the objects available for use in Extended Events.  In todays post, we’ll take a look at the DDL Commands that are used to create and manage Event Sessions based on the objects available in the system.  Like other objects inside of SQL Server, there are three DDL commands that are used with Extended Events; CREATE EVENT SESSION , ALTER EVENT SESSION , and DROP EVENT SESSION .  The command names are self...(read more)

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  • SQL SERVER – Online Session on What is New in Denali – Today Online

    - by pinaldave
    I will be presenting today on subject Inside of Next Generation SQL Server – Denali online at Zeollar.com. This sessions are really fun as they are online, downloadable, and 100% demo oriented. I will be using SQL Server ‘Denali’ CTP 1 to present on the subject of What is New in Denali. The webcast will start at 12:30 PM sharp and will end at 1 PM India Time. It will be 100% demo oriented and no slides. I will be covering following topics in the session. SQL SERVER – Denali Feature – Zoom Query Editor SQL SERVER – Denali – Improvement in Startup Options SQL SERVER – Denali – Clipboard Ring – CTRL+SHIFT+V SQL SERVER – Denali – Multi-Monitor SSMS Windows SQL SERVER – Denali – Executing Stored Procedure with Result Sets SQL SERVER – Performance Improvement with of Executing Stored Procedure with Result Sets in Denali SQL SERVER – ‘Denali’ – A Simple Example of Contained Databases SQL SERVER – Denali – ObjectID in Negative – Local TempTable has Negative ObjectID SQL SERVERServer Side Paging in SQL Server Denali – A Better Alternative SQL SERVERServer Side Paging in SQL Server Denali Performance Comparison SQL SERVER – Denali – SEQUENCE is not IDENTITY SQL SERVER – Denali – Introduction to SEQUENCE – Simple Example of SEQUENCE If time permits we will cover few more topics as well. The session will be recorded as well. My earlier session on the Topic of Best Practices Analyzer is also available to watch online here: SQL SERVER – Video – Best Practices Analyzer using Microsoft Baseline Configuration Analyzer Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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  • An XEvent a Day (2 of 31) – Querying the Extended Events Metadata

    - by Jonathan Kehayias
    In yesterdays post, An Overview of Extended Events , I provided some of the necessary background for Extended Events that you need to understand to begin working with Extended Events in SQL Server. After receiving some feedback by email (thanks Aaron I appreciate it), I have changed the post naming convention associated with the post to reflect “2 of 31” instead of 2/31, which apparently caused some confusion in Paul Randal’s and Glenn Berry’s series which were mentioned in the round up post for...(read more)

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  • An XEvent a Day (16 of 31) – How Many Checkpoints are Issued During a Full Backup?

    - by Jonathan Kehayias
    This wasn’t my intended blog post for today, but last night a question came across #SQLHelp on Twitter from Varun ( Twitter ). #sqlhelp how many checkpoints are issued during a full backup? The question was answered by Robert Davis (Blog|Twitter) as: Just 1, at the very start. RT @ 1sql : #sqlhelp how many checkpoints are issued during a full backup? This seemed like a great thing to test out with Extended Events so I ran through the available Events in SQL Server 2008, and the only Event related...(read more)

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