November 2013 Update: Over at the Linchpin People blog, I’ve created and shared a script that I use to look at configuration values in SQL Server. Script is free to download and currently works in SQL Server 2008, 2008R2 and 2012. Update soon to follow with support for 2005 and 2000. You can see the post about and a link to the SQL Server Configuration Check Script here.
A Blog Post About Using SP_CONFIGURE ??
I use SP_Configure a lot. I use it to quickly view server settings or to make config changes. It is quicker and, in my mind, safer than using the GUI in SQL Server Management Studio. I recently learned a tip that I had never known from a Kalen Delaney course (that tip is below) and I’ve saved time and memory using it.
That got me thinking about writing a post about SP_CONFIGURE. What it is, what it does and what that tip from Kalen is. So… This post is for you if you find yourself asking, “How do I use SP_Configure?”.
So yes, really, a post about sp_configure.
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What is SP_CONFIGURE?
Simply put – it’s a tool to display and change SQL Server settings. It seems to me that a lot of reluctant and newer DBAs are well versed in the GUI based configuration options but not always changing them through a query (or even viewing them). Not all options are changed through a GUI, some are only changeable through sp_configure – read on to learn some tips to using it better.
How do I use SP_CONFIGURE?
Well it depends on what you are trying to do. Here are some tips for each use:
Take a look at your SQL Settings? Open a query window and just type and run sp_configure; you’ll likely get a partial list of settings. To see them all you have to enable an option called ‘Show Advanced Options’
Be careful.. Changing settings affects your instance, a lack of understanding of a result could dramatically affect your instance, performance, availability, etc. Look up a setting in books online and understand it first! This post is not about the settings, it is about the tool used to change the settings. Books Online is a great, free, resource when you have SQL Server installed, you can also get Books Online on the web (2005,2008). No excuses here about making a setting change without understanding it and testing it (Remember, I like to see empirical evidence before trying something)
Alright, now that my conscience is clear. You use sp_configure to change settings as well. You simply type sp_configure ‘setting name’ (*) followed by the value. Execute that and you either have to restart the instance (if the option is not dynamic – able to be changed on the fly while the instance is running) or execute the statement “RECONFIGURE” if the setting is dynamic.
For example – if you wanted to show advanced options you would have to type:
‘show advanced options’, 1
Then when you run sp_configure again, you will see all of the available options.
* The Tip I learned from Kalen
You don’t have to type the entire option text in! At least in SQL Server 2005 and above. I never knew this. It’s right there in books online but I never went there for sp_configure because I’ve been using it all this time. So maybe this isn’t as exciting to you as it is me. I mean you can copy and paste the value. Perhaps you don’t mix up your L’s when typing Parallelism (see… I had to pause while typing it…) but I do. You just have to type in an unambiguous portion of the text.. Try it.. Don’t make a change but run: sp_configure ‘degree’ and you will see the setting for max degree of parallelism. This is great!
Output Columns of SP_CONFIGURE
Pretty self explanatory but:
name – The name of the value to be changed, again you can look up the definition for these values in books online.
minimum – The minimum value setting that is allowed
maximum – Yea, the maximum value that is allowed
config_value – What value is currently configured?
run_value – What value is currently running?
Difference Between Config_Value and Run_Value
The difference may already be clear but it’s important to take note. When you first make a change by running exec SP_CONFIGURE (‘parameter’),newvalue the Config_Value has changed only. It is not until you either run reconfigure (if the setting is dynamic – that is no restart of SQL or reboot required) or restart your SQL Server instance (if the setting is not dynamic) that the run_value changes.
The view only twin of sp_configure. You can select from this catalog view to see configuration options. No changing of settings necessary to see all options here since you can’t change them, it is a way to view your options and you can filter with a where clause.
This catalog view has several columns, the ones that are an exact match to a column in sp_configure will be ignored but the rest:
configuration_id – Just an internal ID of the configuration setting. Good for trivia? I don’t use it for anything…
value – same as config_value above
value_in_use – the twin of run_value above.
description – nice. A little less cryptic then the name column here or in sp_configure. I was going to say it might save you a trip to books online but if you didn’t know what it meant before reading a couple more words, you should still visit books online and understand the setting.
is_dynamic – This very helpful tells you if a value is dynamic or not. 1 = Dynamic, just run reconfigure after changing and it changes “on the fly”. 0 = not dynamic – need to stop and start SQL Server service.
is_advanced – Like the above, ever wonder if you have to change the show advanced option to display a value? Well you can find out here. It’s a flag, 1 is yes, 0 is no, like the is_dynamic flag.
Does This Change Require A Restart?
Just running SP_CONFIGURE, you can’t tell, can you? That’s why it’s important to pay attention above to SYS.CONFIGURATIONS (SELECT * FROM sys.Configurations). That is_dynamic value will come in handy. The Next time your manager asks you, “Does changing the max memory in SQL Server require a reboot?” you can look here and see the dynamic flag of 1 meaning, yes it’s dynamic so “no boss, we can change it on the fly.” Or see a value of 0 meaning, “Sorry boss, need to have an outage while we restart SQL Server).
But SP_CONFIGURE flushes the procedure cache!
No, it doesn’t. At least not in SQL 2005 and above. I don’t have access to SQL 2000 to verify that, but I believe it doesn’t there either. Something some people still say that used to be true in 6.5 and below (maybe 7.0 also, and possibly 2000 but I am pretty sure not.. test and see.. test and see..)
There, I gave you a few other basic knowledge items around sp_configure all to justify my shock, awe and desire to tell everyone that you don’t have to type the entire configuration name into sp_configure! Whoever said it’s the simple things in life had me in mind…
Lesson learned: Visit books online on occassion. Even if you think you know it all and it is a simple feature. Always something new to learn.
Also Check Out
I have posted some other tips and tricks of items I wish I knew when starting out or earlier in my career. Some are technical how-to’s, some are DBA career related.
- Advice to beginning DBAs wondering, “Where do I start?!?!”
- Shrinking – several posts on the topic.
- Troubleshooting Methodology Woes (I also wrote an article for SQL Server Central on this topic)
- Empirical Evidence
- Documentation (or how I learned to stop procrastinating and love tolerate a chore necessary task)
- A little Paranoia and Control Freak attitude can help a DBA
- Checklists, Recipes and Algorithms – Learning about these great tools from other professions (Pilots, Chefs and Doctors)
- How do I find all of my SQL Servers? – Maybe after listening to us you’ll want to spend more time with the instances at your network. Check this link out to learn about a tool that I use to find all the SQL Servers in my network.
- Questions to ask a software vendor – Working with a new vendor with their own database? Here are some questions I ask them.
- Benchmarking… Who needs it? – The answer, I hope you will agree, is everyone. Here I talk about how easy it is to do with tools you already have and a tool you can download free from codeplex.