TechNet India - from the field : SQL Server

Want a Windows Mobile phone?

TechNetIndia — Wed, 19 Nov 2008 07:46:00 GMT

Yes, you heard us correct. If you have a solution build on top of Windows Server 2008 or SQL Server 2008 or Microsoft Unified Communications then here is the deal. Tell us what you did, submit a paper or a video of the same to us and if your solution is innovative etc then you stand a chance to win the cool phone ...

More about the contest is available here. Ofourse there are some rules for the contest and I urge you to take a look at them.

Q&A: Performance Tuning Redefined with SQL Server 2008

TechNetIndia — Sun, 19 Oct 2008 19:12:00 GMT

I am sure you folks are enjoying all the Q&A posted by my fellow Evangelists on this blog. The intentions are very much there to give you complete information even after our webcasts have got over. If you didnt get to read the Part I Q&A I wrote around the DMVs session, dont forget to read them too. Let me next give you the links to PPT and Session for your offline viewing if you missed them. Next, moving to the unanswered Q&A from the session. Here we go:

Question Asked: can we run data collector on sql server which is having sql server 2005 ?

The management data warehouse can only be installed on a server running SQL Server 2008.

Question Asked: different collection modes available for data collector

The Data Collector Architecture (http://msdn.microsoft.com/en-us/library/bb677355.aspx) explains the real backend work. Incidentally, this is an completely async process and uses a combination of SSIS, SQL Agent and SQL Relational engine magic. You can also manually collect and upload the data into SQL Server from the Management Studio.

Quesiton Asked: Could you plz tell something more about WMI event?

If you personally ask me, this is a super cool event one seems to miss-out from the SQL Server 2005 days itself. Anyways, check the complete documentation of WMI Events and SQL Server at: http://msdn.microsoft.com/en-us/library/ms180606.aspx. Infact, if you crank up your SQL Server Configuration Manager, it operates completely around the WMI Eventing Infrastructure. It is really powerfull and under-utilized.

Quesiton Asked: What is the Impact on Memory Usage and Performance of system of Data collection?

This my friend is a dicey question because the data collected is completely under your control. And everytime a collect and upload happens the runtime fires enough info into the database. Now when this happens is completely configurable and the purging is also configurable. Hence the stress on the IO and Memory is something in your hand. Moreover we use the SQL Server Agent infrastructure and it can also be configured to run at our specified interval rather than automatically every 10 sec or so.

Question Asked: Can we use data collector to pull the data from the the data provider or website that allows to fetch the data using webservices?

Though the question is vaugue I think if you get a chance to read through the Architecture (http://msdn.microsoft.com/en-us/library/bb677355.aspx) in detail things will get clear. There is nothing like a webservice or sorts available.

Question Asked: can we have single data collector to collect information from multiple instance ?

If you have multiple SQL Server instances you could configure the data collection processes on each of your instances to use a central MDW repository. In fact, It is recommended you do this to minimize the impact of the data collection process.

Question Asked: Can the Monitoring data be Stored outside the server being monitored

Your question seems to be similar to the one asked in the previous question. You can raise the collection as T-SQL Collector, SQL Trace, Perf Counter Collector and Query Activity Collector. You can read on each at: http://msdn.microsoft.com/en-us/library/bb677328.aspx.

Question Asked: Does it upload the data to the warehouse db on its own or we have to do it manually?

As described before, you have all the flexibility here. You can manually do it or schedule it at regular intervals via the SQL Server Agent process.

Question Asked: how much frequently is the data fed to dataware house from cache ?

Same as the previous question. You can completely customize it.

Question Asked: we can use this data collector for maintain performance related data for application or database or Visual studio application

Though this is a nice thought, currently we are restricted for collecting perf data using the DMVs inside of a SQL Server instance only.

Question Asked: Say If I run this tool, every 1 hour, for 30 days, how much of data space will it take?

There is no straight forward answer to this question. It depends on how much data you will be collecting. I have seen with an interval of 10 sec for the past ~25 days the current size is close to 400MB for me. But I this happens on my laptop which starts and shuts down often.

Question Asked: WIll Data collector effect MSDB ?

This is a good question. We do use msdb for DW activities. The data collector uses msdb for storing configuration information, run-time information, auditing, and collection history information. This database must be present on the instance of SQL Server that runs the data collector. Using msdb provides the following benefits: a) All the data needed to configure and run the data collector is in one location. b) Data collection configuration can be deployed across several servers without having to use the file system. c) The data collector can use existing SQL Server security mechanisms to protect the data. In addition, database roles can provide granular security, and there is no need to implement cross-database chaining. and finally d) Since msdb is a relational database, it is possible to ensure the referential integrity of the configuration and run-time data.

Hope these clarified some of your questions from the session and hope to meet you all again in the next VTD scheduled on Nov 25th and 26th. And guess what we will have 8 fabulous sessions around SQL Server. Dont miss the action and dont forget to register.

Q&A: Top 10 DMVs Admins must know in SQL Server

TechNetIndia — Wed, 08 Oct 2008 11:18:00 GMT

In the recent Virtual TechDays that got concluded we had a number of sessions and there were questions that couldnt be answered. You can download the PPT for the "Top 10 DMVs Admin must know in SQL Server" at: http://download.microsoft.com/download/6/1/A/61A76FEB-8035-47BC-9573-A438F7513E6A/DAY2/TRACK4/Top_10_DMVs.ppt

Question Asked: What is ITW in SQL 2000 and What are DMVs?

ITW is Index Tuning Wizard and was available in SQL 2000 days. We rewamped it as DTA (Database Tuning Wizard) in SQL Server 2005 which was far more powerful than the SQL 2000 ITW counterpart. Now to get into the second part, Dynamic Management Views (DMV) provide greater transparency and insight into the database and a powerful infrastructure for proactive monitoring of database health and performance to make managing data more flexible and secure.

Question Asked: do we need to run DMV on prod server or we can run on the restored DB also

We need to understand one fundamental thing here, DMV's are like pseudo views / tables that are exposing the in-memory structures of SQL Server. These are useful to diagnoze any potential problems that might occur in that system. Some of these views are transient and some are cummulative and some get fulshed from time-to-time. Typical examples in these categories would incude Locks data is transient and changes every micro-second while data like the Index usage (seeks, scans etc) are cummulative and data like the query cache can get flushed if there is memory pressure from any other side. Having said all this, these data are NOT like metadata (e.g. sys.tables) which can be restored on another DB and analyzed. There is a way in SQL Server 2008 using Data Collector that we can do this and check the architecture here: http://msdn.microsoft.com/en-us/library/bb677355.aspx

Question Asked: all these DMV are part of SQL 2005

DMV's were very much intrduced as concepts inside SQL Server 2005 itself. AFAIK, there were close to 80+ DMV's with SQL Server 2005 RTM build. We increased this set to ~136 with this new version of SQL Server 2008.

Question Asked: How to get a list of all DMVs available for us to query upon....?

Here is a simple query that will help you answer this part:
SELECT * FROM sys.all_objects
WHERE [name] LIKE '%dm_%'
AND [type] IN ('V', 'TF', 'IF')
ORDER BY [name]

With SQL 2008 we introduced a number of DMV's around auditing, Extended Events, CDC, Filestreams etc.

Question Asked: what will calculeted by awe_allocated_kb

This value shows the overall amount of memory that is allocated through the AWE mechanism on the 32-bit version of SQL Server. Or, this value shows the overall amount of memory that locked pages consume on the 64-bit version of the product. This value comes from the sys.dm_os_memory_clerks DMV and the documentation for the same is at: http://msdn.microsoft.com/en-us/library/ms175019.aspx.

Question Asked: What permission does a user need to access the DMV's

There are two types of dynamic management views and functions:
Server-scoped dynamic management views and functions (e.g OS, IO, Threads, tasks etc). These require VIEW SERVER STATE permission on the server.
Database-scoped dynamic management views and functions (e.g Index, Tables, partition, file etc). These require VIEW DATABASE STATE permission on the database.

Question Asked: Which DMV give me query plan or I will use old method to find query plan?

Here is a query that you can run to get the Total Elapsed time of queries and the number of times those queries were hit. It also give's you the query and the plan used for each of those.

select qs.execution_count
     , qs.total_elapsed_time, qs.last_elapsed_time
     , qs.min_elapsed_time, qs.max_elapsed_time
     , substring(st.text, (qs.statement_start_offset/2)+1
                        , ((case qs.statement_end_offset
                              when -1 then datalength(st.text)
                              else qs.statement_end_offset
                           end - qs.statement_start_offset)/2) + 1) as statement_text
      , qp.query_plan
from sys.dm_exec_query_stats as qs
cross apply sys.dm_exec_sql_text(qs.sql_handle) as st
cross apply sys.dm_exec_query_plan (qs.plan_handle) as qp

Question Asked: How are DMV's and DMF's changing the memory consumptions of SQL Server? consider the dm_exec_* which store the results of the current workload.

I think this has come a number of times from various people I have interacted. As described before, DMV's are in-memory structures and are anyway's used by SQL Server internally. It is with SQL Server 2005 that we started exposing them in an official manner rather than doing bit-manipulations with some DBCC commands. Hence there is nothing to be worried about the load or memory consumptions. It is not as alarming as you think.

Question Asked: does there is support for DMVs in SQL 2000?

DMV's were introduced with SQL Server 2005 onwards. Though these numbers are increasing from version to version these cannot be got with SQL 2000 version. If you are still using SQL Server 2000 version I would strongly recommend you to move to SQL Server 2008 version :).

Question Asked: it seems to be very hard to remember DMV names, is there any way to get list of DMV's and its usage?

Fair enough and I dont think you are the only person finding it difficult :). With SQL Server 2005 I gone to BOL a number of times, but with SQL 2008 the intellisense takes away half the problem. But if you want to learn more on DMV's and start using them then I would recommend you to book mark this page on MSDN: http://msdn.microsoft.com/en-us/library/ms188754.aspx

Due to time constraints we were not able to answer them during the session itself but I am sure these have got clarified now. Keep those questions coming and we will try our best to answer them during the session else dont forget to visit this blog post the event :). Hope this was of help, btw dont forget to login to the VTD site to register your views on Nov VTD Topics.

PS: These are the exact questions that were asked during the session. I have taken the relevant ones and compiled the same here for you. BTW, there are couple more blogs around other sessions that will get posted.

Vinod Kumar
Technology Evangelist
www.ExtremeExperts.com