[dba-SQLServer] So Far, So Good ...

Stuart, Susan, Gary, John, Arthur, Francisco, Mark, Rocky, Jim, Steve (and
whoever I inadvertently left out .)

 

Since you guys (and Susan) will be my primary "go to" experts in the event
that I run into a serious SQL Server problem, I thought now would be a good
time for a Progress Report.

 

I have just completed Section 1 (i.e. the first 80 pages) of the "Murach SQL
Server 2008 for Developers" book.  The primary thrust of Chapter 2 was a
basic introduction to the Management Studio and Books Online.  Chapter 3 of
the book will begin exploring T-SQL with approximately 40 pages devoted
exclusively to the SELECT statement and its syntax for data retrieval from a
single table.

 

So far, so good - no major problems - although I'm still not totally clear
as to what (exactly) constitutes a SQL Server instance.  From the references
I keep running across in the book (as well as in BOL), I get the impression
that an "instance" of SQL Server implies a separate full up SQL Server
installation on the same server or the same computer.  (This is like
installing SQL Server twice on the same machine and assigning each
installation its own "named instance".)  If this is correct, then different
users can work with different application databases with each database
attached to its own copy (or "instance") of SQL Server.  So, in theory, you
can have two (or more) instances of SQL Server installed (and running) on
the same machine/server with each instance attaching a different database to
the database engine (for a specific named instance) of SQL Server.

 

Why in the world you would want to have multiple full up SQL Server editions
installed on the same machine is beyond me.  (It's kind of like: "Why would
you want to have three copies of Windows XP, Windows Vista or Windows 7
installed on drives C:, D:, and E: of your hard disk when you really need
only one operating system?)

 

It must be related to overall system performance.  If you have too many
users simultaneously accessing multiple databases attached to the same SQL
Server database engine, response time [for all the users] will slow to a
crawl.  By installing multiple copies (instances) of SQL Server on the same
machine, you can attach multiple (large) databases to their own SQL Server
instance and greatly reduce the "strain" on any one database engine.

 

Is that what the book is talking about when it refers to SQL Server
"instances" - multiple editions of SQL Server installed (and running) on the
same machine or the same server?

 

Alan