SQL Server Configurations – Back to Basics

One thing that SQL Server does very well is come pre-configured in a lot of ways. These pre-configured settings would be called defaults. Having default settings is not a bad thing nor is it necessarily a good thing.

For me, the defaults lie somewhere in the middle ground and they are kind of just there. You see, having defaults can be good for a horde of people. On the other hand, the default settings can be far from optimal for your specific conditions.

The real key with default settings is to understand what they are and how to get to them. This article is going to go through some of the basics around one group of these defaults. That group of settings will be accessible via the sp_configure system stored procedure. You may already know some of these basics, and that is ok.

I do hope that there is something you will be able to learn from this basics article. If you are curious, there are more basics articles on my blog – here.

Some Assembly Required…

Three dreaded words we all love to despise but have learned to deal with over the past several years – some assembly required. More and more we find ourselves needing to assemble our own furniture, bookcases, barbecue grills, and bathroom sinks. We do occasionally want some form of set and forget it.

The problem with set it and forget it type of settings (or defaults) is as I mentioned – they don’t always work for every environment. We do occasionally need to manually adjust settings for what is optimal for that database, server, and/or environment.

When we fail to reconfigure the defaults, we could end up with a constant firefight that we just don’t ever seem to be able to win.

So how do we find some of these settings that can help us customize our environment for the better (or worse)? Let’s start taking a crack at this cool procedure called sp_configure! Ok, so maybe I oversold that a bit – but there is some coolness to it.

Looking at msdn about sp_configure I can see that it is a procedure to display or change global configuration settings for the current server.

If I run sp_configure without any parameters, I will get a complete result set of the configurable options via this procedure. Let’s look at how easy that is:

Ok, so that was exceptionally easy. I can see that the procedure returns the configurable settings, the max value for the setting, configured value, and the running value for each setting. That is basic information, right? If I want a little more detailed information, guess what? I can query a catalog view to learn even more about the configurations – sys.configurations.

That query will also show me (in addition to what I already know from sp_configure) a description for each setting, if the setting is a dynamic setting and whether or not the setting is an advanced configuration (and thus requires “show advanced options” to be enabled). Pro-tip: The procedure just queries the catalog view anyway. Here is a snippet from the proc text.

Seeing that we have some configurations that are advanced and there is this option called “show advanced options”, let’s play a little bit with how to enable or disable that setting.

With the result (on my system) being:

We can see there that the configuration had no effect because I already had the setting enabled. Nonetheless, the attempt to change still succeeded. Let’s try it a different way.

I ran a whole bunch of variations there for giggles. Notice how I continue to try different words or length of words until it finally errors? All of them have the same net effect (except the attempt that failed) they will change the configuration “show advanced options”. This is because all that is required (as portrayed in the failure message) is that the term provided is enough to make it unique. The uniqueness requirement (shortcut) is illustrated by this code block from sp_configure.

See the use of the wildcards and the “like” term? This is allowing us to shortcut the configuration name – as long as we use a unique term. If I select a term that is not unique, then the proc will output every configuration option that matches the term I used. From the example I used, I would get this output as duplicates to the term I used.

Ah, I can see the option I need! I can now just copy and paste that option (for the sake of simplicity) into my query and just proceed along my merry way. This is a great shortcut if you can’t remember the exact full config name or if you happen to be really bad at spelling.

The Wrap

In this article I have introduced you to some basics in regards to default server settings and how to quickly see or change those settings. Not every environment is able to rely on set-it and forget-it type of defaults. Adopting the mentality that “some assembly is required” with your environments is a good approach. It will help keep you on top of your configurations at the bare minimum. This article will help serve a decent foundation for some near future articles. Stay tuned!

This has been another post in the back to basics series. Other topics in the series include (but are not limited to): Backups, backup history and user logins.

Summiting that Technical Challenge

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Published on: January 9, 2018

Conquering Challenges

I really like the topic of the TSQLTuesday party today. Today we have been instructed in no uncertain terms to share a technical challenge with the world with which we were confronted. Ideally we will have conquered that challenge. Sometimes, we may not have conquered the technical challenge. We seldom like to share those stories though. That said, whether or not we conquer the technical challenge, there is another equally important part of the challenge – the journey.

Before getting too far astray with stories and challenges, it is important to note that the host of the party this month is Arun Sirpal (blog | twitter). Arun has posted the invite for the party here. Go ahead and check it out in all of its original glory!

Now back to the challenge at hand – conquering that technical problem and getting that high associated with the metaphorical high of summiting a tough task.

Summits

My technical challenge is not so much of a SQL Server challenge, and is minutely related to a database issue. Let’s start with the broad brushstrokes.

My blog was being hosted on an aging platform. The platform was old enough that it was several versions behind on php. Certain plugins were at a point that I could no longer use the full functionality. In addition, I just needed to ensure that it was updated. Because of this, I was informed that I had to migrate to a different platform provided by the same hosting provider. This is where the fun began.

The migration to the new platform was a simple button click. Unfortunately, despite the promise of a complete site migration – it was not. 99% of everything migrated. Little things like security and my domain name did not migrate. Ok – easy enough, I can update the site to use the domain name for my blog but I had to release it from the old platform first. Upon releasing the domain name from the old platform the “pageok” page error showed for a while until the change was fully propagated. This was a bit of a nuisance and somewhat bothersome for visitors. Believe me – it was a nuisance for me too!

After getting the site to start rendering pages properly, I soon found that there was no longer the appropriate security in place for various things. As I started to go through and try to fix the security, I found I no longer had the ability to manage any of the permissions on my site. In addition, the hosting company could not make the appropriate permissions changes either. What was the recommendation at this point? Another migration to another platform. Commence steam shooting from ears at this point. As I saw it, I had two choices go back to the old dying platform or go to this third platform. I opted for the new trendy flashy shiny platform.

Ruh Roh

At this point, I think it is a good idea to mention that all of this happened just as the new year turned. In addition, I was trying to get last minute edits made for a blog series I had running. This was all on January 2-3, 2018. What a way to kick off the New Year from a blogging point of view. Yeehaw!

I was assured I would have greater control over the new platform. In addition, I was assured it would not take very long. The process was straightforward as long as I had my backups. Believe me, I had my backups. They were even on two sites at this point.

What I did not know was that the hosting company had decided to come in behind me on my original site and decided to make changes. These were changes that complicated the whole process substantially. I only discovered they had made changes after I tried to go back to the original site and access my backups. Guess what? I could no longer access it due to the changes the hosting company had made. Steam is getting hotter now.

In the meantime, I had already started the transition of my domain name to the new platform. Given the new circumstances, this was a mistake. I should have waited to do this until the very end to ensure the site was at least accessible in the meantime.

Once the domain migration finally completed and all of my site files were transferred, users were at least greeted with something new.

Ok, this is in part due to a missing database. That took a while to finally get access back to the original site so I could grab my current backup (which was taken right before the migration). Once finally restored, I started getting this next one.

Lucky for me, this only took a bunch of google-fu to find exactly what I could do to fix it. It seems there was an issue in a config file and I was able to correct the database connection string. Yay – small victory, right? Well, sort of. The blog was fine as long as no links were clicked. You see, there was another change made that caused all of my permalinks to update to one of my alternate domains (again done by the hosting company). Any time I clicked a link I was stumped by why the link was trying to forward to the alternate domain. So because of this link issue, I was back to getting the constant 404 error from a few paragraphs back. (Pretty much straight flames shooting from the ears now.)

Again, more google-fu and I was able to find another fix. This one was part database related and part admin console. Having made the updates in all the requisite places, I was able to now click on most links and the site was at 90% functionality.

This was a full day of working on trying to fix this problem. At this point with the site up, I was able to confirm that I could enact the security policies I wanted/needed. I was also able to confirm most links were working. I did not that some plugins were working intermittently. That was an issue to save for the next day.

On the following day, I went back to work trying to fix various plugin issues that I or visitors had reported. In the end, I had to make some changes to tools I was using because they would no longer work. In addition, there was one specific plugin that was many other plugins to fail (depending on page load order). Once I removed that plugin, it was safe to say that the site was back up and running as expected.

 

The Wrap

TSQL2sDay150x150I did not enjoy this journey much at all. Much of the experience was due to outside forces. I can’t do much to control them, but I can do something to fix the net effect of what they caused. While the journey was rather unpleasant, I did finally achieve that Nirvana moment that comes from having conquered the problem.

I didn’t go into extreme technical details because there were many fixes along the path and my focus was on getting it working though I should have been documenting it all along the way. Despite the heat, steam and fire of the experience, I did rather enjoy being able to use some new mysql skills to alter data and fix various problems in the site.

 

Common Tempdb Trace Flags – Back to Basics

Once in a while I come across something that sounds fun or interesting and decide to dive a little deeper into it. That happened to me recently and caused me to preempt my scheduled post and work on writing up something entirely different. Why? Because this seemed like fun and useful.

So what is it I am yammering on about that was fun?

I think we can probably concede that there are some best practices flying around in regards to the configuration of tempdb. One of those best practices is in regards to two trace flags within SQL Server. These trace flags are 1117 and 1118. Here is a little bit of background on the trace flags and what they do.

A caveat I have now for the use of trace flags is that I err on the same side as Kendra (author of the article just mentioned). I don’t generally like to enable trace flags unless it is very warranted for a very specific condition. As Kendra mentions, TF 1117 will impact more than just the tempdb data files. So use that one with caution.

Ancient Artifacts

With the release of SQL Server 2016, these trace flags were rumored to be a thing of the past and hence completely unnecessary. That is partially true. The trace flag is unneeded and SQL 2016 does have some different behaviors, but does that mean you have to do nothing to get the benefits of these Trace Flags as implemented in 2016?

As it turns out, these trace flags no longer do what they did in previous editions. SQL Server now pretty much has it baked into the product. Buuuuut, do you have to do anything slightly different to make it work? This was something I came across while reading this post and wanted to double check everything. After all, I was also under the belief that it was automatically enabled. So let’s create a script that checks these things for me.

Holy cannoli batman – that is more than a simple script, right? Well, it may be a bit of overkill. I wanted it to work for version before and after and including SQL Server 2016 (when these sweeping changes went into effect). You see, I am checking for versions where the TF was required to make the change and also for versions after the change where the TF has no effect. In 2016 and later, these settings are database scoped and the TF is unnecessary.

The database scoped settings can actually be queried in 2016 more specifically with the following query.

In this query, I am able to determine if mixed_page_allocations and if is_autogrow_all_files are enabled. These settings can be retrieved from sys.databases and sys.filegroups respectively. If I run this query on a server where the defaults were accepted during the install, I would see something like the following.

You can see here, the default settings on my install show something different than the reported behavior. While autogrow all files is enabled, mixed_page_allocations is disabled. This matches what we expect to see by enabling the Trace Flags 1117 and 1118 – for the tempdb database at least. If I look at a user database, I will find that mixed pages is disabled by default still but that autogrow_all_files is also disabled.

In this case, you may or may not want a user database to have all data files grow at the same time. That is a great change to have implemented in SQL Server with SQL 2016. Should you choose to enable it, you can do so on a database by database basis.

As for the trace flags? My query checks to see if maybe you enabled them on your instance or if you don’t have them enabled for the older versions of SQL Server. Then the script generates the appropriate action scripts and allows you to determine if you want to run the generated script or not. And since we are changing trace flags (potentially) I recommend that you also look at this article of mine that discusses how to audit the changing of trace flags. And since that is an XEvent based article, I recommend freshening up on XEvents with this series too!

The Wrap

In this article I have introduced you to some basics in regards to default behaviors and settings in tempdb along with some best practices. It is advisable to investigate from time to time some of these recommendations and confirm what we are really being told so we can avoid confusion and mis-interpretation.

This has been another post in the back to basics series. Other topics in the series include (but are not limited to): Backups, backup history and user logins.

Changing Default Logs Directory – Back to Basics

Every now and then I find a topic that seems to fit perfectly into the mold of the theme of “Back to Basics”. A couple of years ago, there was a challenge to write a series of posts about basic concepts. Some of my articles in that series can be found here.

Today, my topic to discuss is in regards to altering the default logs directory location. Some may say this is no big deal and you can just use the default location used during install. Fair enough, there may not be massive need to change that location.

Maybe, just maybe, there is an overarching need to change this default. Maybe you have multiple versions of SQL Server in the enterprise and just want a consistent folder to access across all servers so you don’t have to think too much. Or possibly, you want to copy the logs from multiple servers to a common location on a central server and don’t want to have to code for a different directory on each server.

The list of reasons can go on and I am certain I would not be able to list all of the really good reasons to change this particular default. Suffice it to say, there are some really good requirements out there (and probably some really bad ones too) that mandate the changing of the default logs directory to a new standardized location.

Changes

The logs that I am referring to are not the transaction logs for the databases – oh no no no! Rather, I am referring to the error logs, the mini dumps, and the many other logs that may fall into the traditional “logs” folder during the SQL Server install. Let’s take a peek at a default log directory after the install is complete.

I picked a demo server that has a crap load of stuff available (and yeah not so fresh after install) but where the installation placed the logs by default. You can see I have traces, default XE files, some SQL logs, and some dump files. There is plenty going on with this server. A very fresh install would have similar files but not quite as many.

If I want to change the Log directory, it is a pretty easy change but it does require a service restart.

In SQL Server Configuration Manager, navigate to services then to “SQL Server Service”. Right click that service and select properties. From properties, you will need to select the “Startup Parameters” tab. Select the parameter with the “-e” and errorlog in the path. Then you can modify the path to something more appropriate for your needs and then simply click the update button. After doing that, click the ok button and bounce the SQL Service.

After you successfully bounce the service, you can confirm that the error logs have been migrated to the correct folder with a simple check. Note that this change impacts the errorlogs, the default Extended Events logging directory, the default trace directory, the dumps directory and many other things.

See how easy that was? Did that move everything over for us? As it turns out, it did not. The old directory will continue to have the SQL Agent logs. We can see this with a check from the Agent log properties like the following.

To change this, I can execute a simple stored procedure in the msdb database and then bounce the sql agent service.

With the agent logs now writing to the directory verified after agent service restart as shown here.

At this point, all that will be left in the previous folder will be the files that were written prior to the folder changes and the service restarts.

The Wrap

In this article I have introduced you to an easy method to move the logs for SQL Server and the SQL Server Agent to a custom directory that better suits your enterprise needs. This concept is a basic building block for some upcoming articles – stay tuned!

This has been another post in the back to basics series. Other topics in the series include (but are not limited to): Backups, backup history and user logins.

Sharepoint Diagnostics and XE

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Published on: January 3, 2018

One of the all-time greatest and most beloved applications among DBAs happens to be Sharepoint. Most of us would be lying if we said that we loved Sharepoint and the kind of performance issues it can cause on a SQL Server.

When you have an application that comes with a notoriety of causing performance pain, you will want to have some tools or find some tools that can help you find the pain points. Lucky for the savvy DBA, there are tools to be able to capture this kind of information. Hint: some of those tools can be found in this series.

Tools

One of the best tools for capturing performance impacting data is Extended Events. Extended Events is simply a tool that everybody needs to learn. And in this case, it provides an opportunity to support and troubleshoot Sharepoint as well as SQL Server.

Truth be told, the default XE session for Sharepoint does not come installed when you install Sharepoint. But, there is a session that gets installed when you configure SPDiag for your Sharepoint needs. I am not going to dive deeply into that tool or the Sharepoint tooling. That would be well outside the use and scope of this post. Here is the default session created by that tool.

As you can see, there is not much special about the session. This is a basic session to capture statements queries executed against the server. In fact, you will probably note it is similar to both of the default XE Profiler sessions I discussed here. The first caveat here is the application filter for Sharepoint apps. That said, if you are running multiple Sharepoint sites and configure SPDiag on both, and both share the same backend database server, guess what happens? Yup, you guessed it – you get two Sharepoint sessions that capture the exact same data.

The second caveat here is a fun thing about the service that gets created to support the Sharepoint XE Sessions. The SPDiag will alter each of your XE (sharepoint related) sessions many times every few seconds. Every alter of the sessions will be to either stop or restart the session. This seems rather unnecessary and huge miss. There are not many misses with XE, but there can be a misuse of XE similar to all of the abuses of profiler and this is one of those abuses in my opinion. You can easily discover the constant changes to these sessions via an XE session that I will be sharing in a future post. I would recommend you stay tuned for that article and also watch the 60 Day Series for an update that includes that post.

The next caveat here is that this particular session is only configured to go to the ring_buffer. What is the problem there? Well, the ring_buffer means the trace data is volatile and you can easily lose it. In addition, this particular session has been known to cause some memory issues on many installations. You can check for a memory issue by watching for a growing MEMORYCLERK_XE memory count. You can watch it with a query like the following.

In my opinion, I see no good value in running the session as currently built. I would just rather build a better XE session and leave it running instead of constantly stopping and starting the XE session.

The Wrap

In this article I have introduced you to a quick session setup that comes from using the SPDiag tool that could plausibly be useful in the troubleshooting of various different problems (most probably performance related) with Sharepoint. This assuredly is in the absence of a better alternative such as a custom session that you write yourself.

If we browse the data made available to us, we can see that there is adequate info to help us convert all of those SQL Traces to the high-performing XE versions that we should be using these days. I encourage you to browse the capabilities of XE as you work towards converting your profiler based traces to the much friendlier and more powerful counterparts.

If you are interested in learning more about Extended Events, I recommend you read my “60 day” series of articles on Extended Events. The series continues to grow and covers a pretty decent depth and breadth on the topic.

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