SQL Server Instances

  • Can someone please explain what is multiple sql server instances? How can that be used in a single database?

  • y_winny (6/15/2009)


    Can someone please explain what is multiple sql server instances? How can that be used in a single database?

    One database can be attached to only one instance.

    To give an bird's eye view, You have one physical server over which you install multiple SQl Servers (each of which is called an instance). You create databases in these different instances.

    Normally we create multiple instances of sql server only if we have multiple sql server versions.

    Eg. one for sql server 2000, another for sql server 2005..

    This link will give u more description on multiple instances.

    http://msdn.microsoft.com/en-us/library/aa174516(SQL.80).aspx



    Pradeep Singh

  • I thought when you install a newer version of sql server and it overrides the older version on the PC. Can that be achieved when you already have sql 2000 and want to install sql 2005 without overriding the sql 2000 on the same pc?

    Can you please give more example on multiple SQL Server instances?

  • y_winny (6/15/2009)


    I thought when you install a newer version of sql server and it overrides the older version on the PC. Can that be achieved when you already have sql 2000 and want to install sql 2005 without overriding the sql 2000 on the same pc?

    Can you please give more example on multiple SQL Server instances?

    yes that is possible. If you have a default instance of sql 2000 and you want to install sql 2005 as a seperate instance, it has to be a named instance (you provide a name to this instance). Both versions of sql can happily reside on one server with their own databases. you can check that out in services(click start->run->services.msc). you'll see seperate services for each instance for sql servers.

    I hope u went through the msdn url i provided in earlier post.

    here are some others.

    http://www.mssqltips.com/tip.asp?tip=1048

    http://technet.microsoft.com/hi-in/magazine/2006.03.sqlqa(en-us).aspx"> http://technet.microsoft.com/hi-in/magazine/2006.03.sqlqa(en-us).aspx -- read from 2nd question there..



    Pradeep Singh

  • Maybe another way to understand the concept of 'the instance', if you are not familiar with it, is to see an Instance of Sql Server as one installation. In other words, each time you install sql server you create an instance of it. Of course, this means that you can install multiple instances of Sql Server on one machine.

    Chim Kalunta

  • I have read through the material online and thanks for the url.

    Tried to install 2 versions (2000 & 2005) of sql server on same machine and i can see that there are 2 sqlserver agents services. Thanks.

  • Glad i could help you 🙂



    Pradeep Singh

  • Instances can also be useful if you have one server but need to pretend it's more! We have our development instance and our test instance co-existing happily on one server and they behave as two different servers.

  • Is that the same installing 2 difference version of sql servers on same machine?

  • Wintop (6/17/2009)


    Is that the same installing 2 difference version of sql servers on same machine?

    Yes. You can install same version of SQL Server multiple times as well. There is limitation for it. I guess in 2005 Std Edition/WorkGroup edition max no. of instances is 16 and in enterprize edition its 50. Just visit BOL to cross verify the max no. of instances.



    Pradeep Singh

  • One benefit of instances is that when you create a linked server connection to a database in another instance (of the same machine) then data does not have to travel through a network and the results are typically fast.

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  • mmartin (7/15/2009)


    One benefit of instances is that when you create a linked server connection to a database in another instance (of the same machine) then data does not have to travel through a network and the results are typically fast.

    I dont think we need to create linked servers for instances running on same server. or do we? we can access the data using four part notation. [instance Name].database.owner.object



    Pradeep Singh

  • I tried querying using your suggestion on a couple of instances on one of our machines. I was not successful. Maybe I am missing something.

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  • My understanding of an instance is that it acts as if it is another server without actually needing to buy another server. Thus I assume all the permissions/checkpoints you normally have in place to access data from another box still apply to instances the reside on the same disk as your reference database.

    regards, MMartin

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