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Why Your Slow SQL Server Doesn’t Need a SQL Consultant (or Does It?)

Your SQL Server is slow – but should you call us in? Jeremiah and Brent had a throw-down the other day, and we figured we’d capture it here on the blog.

Brent Says You Do, and Here’s Why

5. You’ve been blindly throwing money at the problem without results. You’re on a first name basis with your local SAN salesperson. Your server racks are glistening with blue and green lights. But somehow, when users hit your app, they’re not as happy as your sysadmins – or your SAN salesperson. Before you burn another stack of Benjamins, it’s time to get an outside opinion.

brent-ozar

4. You’re doing something for the first time. Sure, you’re pretty good at Googling your way out of trouble, but the company’s starting to make riskier and riskier gambles on data storage. Maybe you should talk to someone who’s faced this problem before.

3. You’re relying on the manual. I love Microsoft as much as the next guy – especially now that they brought out a new ergonomic keyboard – but Books Online doesn’t tell the whole truth. When Microsoft unveils a new feature, they talk about all the positives, but they don’t always disclose the drawbacks. Get a reality check before you bet the farm on PowerFilePivotProRT, and hear what our other clients are doing to accomplish the same goal.

2. You need answers faster. We get together on a Monday, and by end of day Wednesday, you’ve got a prioritized action plan showing you how to make the pain go away by the end of the week. You get the knowledge and confidence to keep going without expensive long-term consultants. You’re really close – you just need our 3-day SQL Critical Care® to unlock the tips and tricks to make it work.

1. Developers can get back to adding features. Your real business isn’t SQL Server administration – it’s adding features to your app to make your end user happier. Bring us in, get the answers, and get back to work.

Jeremiah Says You Don’t, and Here’s Why

5. You’re probably blindly throwing money at the problem without results. Unless a consultant is willing to provide a list of happy customers, there’s no way to verify that they know something. Heck, even if they do provide a list of happy customers, you have no way of knowing that Luanne in IT management isn’t really someone’s Aunt Mavis.

jeremiah-peschka

4. Best practices aren’t universal. Every situation is different and the most complicated scenarios require a deep understanding of business goals, features, and SLAs. Consultants can help you understand best practices, but you’re the only person who knows what’s right in your environment. If you’re doing something for the first time and your Google-fu is running out, you can’t expect much help from outside.

3. Peer pressure shouldn’t change your decisions. We jokingly call this “design by Hacker News”. Just because a startup, our clients, or your next door neighbor are doing something, that doesn’t mean it’s the right fit for you. For many application feature decisions, it’s easy to build two or three prototype solutions and decide on the best one.

2. You need performance yesterday. Rather than wait a few weeks for a reputable consultant to show up, have you considered buying memory? If you’re on SQL Server Standard Edition and you have less than 64GB of memory, just buy more RAM. If you’re on EE and you have less RAM than you have data, why not max out that server with 16GB DIMMs; they’re cheap and you can solve most code sins with memory. Heck, we even recommend buying memory as one of the first ways to solve problems quickly.

1. Developers: understand your features. While developers should be adding features, they also need to understand the consequences of those features. Some functionality that’s possible in SQL Server requires an understanding of how to write queries to take advantage of those features – filtered indexes, indexed views, and ColumnStore indexes immediately spring to mind. The best way to understand a feature is to get in the database, make it work, and then make it work fast.

Brent’s Upcoming User Group Presentations

In a world where servers rule their administrators, one man will change your life. It just won't be this man.

In a world where servers rule their administrators, one man will change your life. It just won’t be this man.

Coming soon to a user group near you, it’s…me.

March 5 – South Florida SQL Server User Group (Remotely)

The Best Free SQL Server Downloads – You’re trying to manage SQL Server databases, and every time you Google for something, you get overwhelmed with all kinds of free tools, white papers, blogs, and newsletters. There’s so many that suck, and you’re tired of wasting time on bad ones. Microsoft Certified Master Brent Ozar has been using SQL Server for over a decade, and he’s built a killer list of the very best freebies. He’ll show you where to get the good stuff and how to use it.

March 12 – Philadelphia SQL Server User Group

How to Think Like the SQL Server Engine -
You’re a developer or a DBA, and you’re comfortable writing queries to get the data you need. You’re much less comfortable trying to design the right indexes for your database server. In this 90-minute session with Microsoft Certified Master Brent Ozar, you’ll role play as the database engine while Brent gives you queries. You’ll learn first-hand about clustered indexes, nonclustered indexes, execution plans, sargability, statistics, TempDB spills, and T-SQL anti-patterns. Register here.

March 13 – PASS DC (Chevy Chase) User Group

How to Think Like the SQL Server Engine – You’re a developer or a DBA, and you’re comfortable writing queries to get the data you need. You’re much less comfortable trying to design the right indexes for your database server. In this 90-minute session with Microsoft Certified Master Brent Ozar, you’ll role play as the database engine while Brent gives you queries. You’ll learn first-hand about clustered indexes, nonclustered indexes, execution plans, sargability, statistics, TempDB spills, and T-SQL anti-patterns. Register now.

March 14 – Richmond SQL Server User Group

How to Think Like the SQL Server Engine – You’re a developer or a DBA, and you’re comfortable writing queries to get the data you need. You’re much less comfortable trying to design the right indexes for your database server. In this 90-minute session with Microsoft Certified Master Brent Ozar, you’ll role play as the database engine while Brent gives you queries. You’ll learn first-hand about clustered indexes, nonclustered indexes, execution plans, sargability, statistics, TempDB spills, and T-SQL anti-patterns. Register now.

April 11-12 – SQLSaturday #267 Lisbon, Portugal

Brent is flying across the pond to go visit one of the best-regarded SQLSaturdays in Europe. Join Brent for a one-day Friday pre-con on virtualization, storage, and hardware for just 100€. Register now for the pre-con, and then register for the SQLSaturday too.

April 26 – SQLSaturday Chicago

The sessions haven’t been picked yet, but Brent’s fingers are crossed that he’ll be one of the chosen ones. You can register now.

Using SQL Server’s Table Valued Parameters

Table valued parameters (TVPs) are nothing new – they were introduced in SQL Server 2008. TVPs are a great way to get data into SQL Server, and yet very few developers use them.

Getting Started with TVPs

In order to get started, we need to create a user defined type. This type is necessary so we have a well defined interface between SQL Server and the outside world – you can just pass a bunch of junk in as a parameter to SQL Server… well, you could, but that’s called XML.

Let’s create that user defined type:

CREATE TYPE dbo.SalesPersonTerritory AS TABLE
(
    SalesPersonID INT,
    TerritoryID INT
);

Now we can create variables using the dbo.SalesPersonTerritory type whenever we want. It’s just this easy:

DECLARE @spt SalesPersonTerritory;
SELECT * FROM @spt;

Using Table Valued Parameters With Stored Procedures

Having a special table type is really convenient, but it doesn’t help if you can’t use it, right? Let’s assume that you’re calling a stored procedure and you’re sick of joining lists of strings on the client and then splitting them apart on the server. What you really need is the ability to pass a fully fledged table across the wire and into SQL Server.

This is relatively easy to accomplish. From C#, the code would look something like this:

string cnString = @"data source=.;initial catalog=TVPTester;user id=tvptester;password=tvptester;";

using (var connection = new SqlConnection(cnString))
{
    connection.Open();
    using (SqlCommand cmd = new SqlCommand("SELECT * FROM @tvp;", connection))
    {
        var pList = new SqlParameter("@tvp", SqlDbType.Structured);
        pList.TypeName = "dbo.SalesPersonTerritory";
        pList.Value = SalesPersonTerritoryTable();

        cmd.Parameters.Add(pList);

        using (var dr = cmd.ExecuteReader())
        {
            while (dr.Read())
                Console.WriteLine(dr["Item"].ToString());
        }
    }
}

That’s really all there is to it.

C# Tips for Table Valued Parameters

There are a few other things that developers can do to make their life easier when working with table valued parameters. A DataTable, just like a table in SQL Server, should have types declared for all columns. While it’s easy enough for developers to create these tables on the fly, that won’t cut it in production code – boiler plate code means that people can make mistakes.

To make life easier, developers can create methods in their application to make it easier to work with table valued parameters. We can create a special chunk of code that will make it easy for developers to instantiate and use a DataTable that matches up with the table valued parameter.

static DataTable SalesPersonTerritoryTable()
{
    var dt = new DataTable();
    dt.Columns.Add("SalesPersonID", typeof(int));
    dt.Columns.Add("TerritoryID", typeof(int));
    return dt;
}

Seasoned developers will even create methods that let them drop a list of objects straight into an appropriate DataTable. There are many different ways to build convenience methods into code and make it easy for development teams to work with TVPs.

For simple data type matching, this works well. If you’re dealing with more complex data types, you’ll want to check out SQL-CLR Type Mapping to make sure you get the right data type. You’ll notice that some datatypes (varchar for instance) have no direct corollary in the .NET Framework. Sometimes you just have to lose some fidelity – make wise decisions, it gets crazy out there.

These same techniques can be used with a string of ad hoc SQL, too. TVPs aren’t limited to stored procedures, they can be used anywhere that you are executing parameterized code.

Gotchas of TVPs

There are two big gotchas with TVPs.

First: the table variable that comes in as a table valued parameter cannot be changed. You’re stuck with whatever values show up. No inserts, updates, or deletes can be applied.

Second: table valued parameters are still table variables – they get terrible cardinality estimates.

We can get around both of these problems with the same technique – copy the contents of the TVP into a temp table. Although it adds an extra step to using the TVP, I’ve found that copying the contents of the TVP to a temporary table lead to better execution plans and much less confusion during development and troubleshooting.

Summary – Using Table Valued Parameters isn’t Hard.

TVPs aren’t difficult to use. They’re just different and require a different mindset. By using TVPs, developers can pass many rows into a stored procedure and create far more complex logic and behavior that is possible using only single parameter values.

What If You Knew The Server Would Crash Today?

This morning you woke up with a terrible premonition – you were absolutely sure your most important production database server was going to crash today.

What would you do?

Step 0: stop for coffee, because it's gonna be a long day.

Step 0: stop for coffee, because it’s gonna be a long day.

Here’s a quick list of places to start:

  1. Identify where the most recent backups are kept
  2. Make sure the backup schedule and frequency lines up with what the business wants
  3. Make sure the backups are getting offsite
  4. Make sure the monitoring software is watching this server, and sending me alerts

When was the last time you made a list like this and checked it twice? Do it this week, and schedule yourself a recurring task in your favorite to-do software to check this every quarter.

Because you’re not going to get these visions.

Satya Slips a SQL Server Standard Secret?

Everybody wants to know the next SQL Server release date, pricing, and feature lists, but anybody who knows those facts is bound by non-disclosure agreement and can’t say it publicly. Every now and then, though, we get lucky and someone from Microsoft slips up. That’s why I pay particular attention to Microsoft interviews as we approach release dates.

Microsoft’s perhaps-next-CEO new CEO Satya Nadella sat down for an interview with Gigaom. It included this interesting line:

…everybody who buys a SQL server, in fact in this release, gets an always-on secondary in Azure.

Satya Nadella

Satya Nadella

Well isn’t that special? Satya would be the guy to know, too – he used to run the Server and Tools group (which includes SQL Server), and he’s since been promoted to Cloud and Enterprise (which includes both SQL Server and Azure).

Will SQL Server 2014 Standard Include AlwaysOn AGs?

Right now, SQL 2012 only offers AlwaysOn Availability Groups in the expensive Enterprise Edition. 2012 Standard Edition’s closest HA/DR feature in Standard Edition is database mirroring, but that’s listed on the Walking Dead Deprecated Features List.

But what if Standard Edition includes a crippled AlwaysOn AG? Currently, SQL Server 2012 Standard Edition includes a crippled version of database mirroring that only offers synchronous replication, not asynchronous. It’s less desirable for many customers due to the transaction slowdowns if you have to commit at both servers before a transaction is considered committed. Microsoft could treat Standard AGs the same way – only offering the less-desirable version in Standard.

Standard’s AlwaysOn AGs could also be limited in numbers. While 2014 Enterprise will offer up to 8 readable replicas, perhaps Satya’s “an always-on secondary” means Standard gets exactly one secondary.

Satya could even mean that only an Azure-based replica is included – not an on-premise one. This would be an interesting turn of events because it would require vendor lock-in to just Microsoft’s cloud rather than Amazon’s or a colo vendor.

What Did Satya Mean by “Gets an AlwaysOn Secondary”?

Could he mean that Microsoft is really willing to include the AlwaysOn virtual machine? Like you get some kind of licensing key that unlocks one free Azure VM running SQL Server 2014, and an easy way to set up HA/DR between your on-premise SQL Server and your new free virtual machine?

This would be revolutionary because Microsoft would be seen as a real vendor partner to SQL Server users. Instead of buying expensive hardware and data center space to protect your SQL Servers, you could just rely on Microsoft’s cloud.

At first glance, this would look like Microsoft going into competition with server vendors like Dell, HP, and IBM Lenovo, plus competing with cloud vendors and data centers like Amazon and Rackspace. But hey, that’s exactly what Microsoft has been doing lately – going directly into competition with vendors that used to be partners. The Surface competes with laptop partners, and the Nokia deal competes with Windows Phone partners. This could just be the next step, especially given another Satya quote in the interview:

So one of the things is, I have an always-on database, where is it running? The always on database is kind of on your private cloud and kind of on Azure and so the distinction even goes away.

If Microsoft can move your database into their cloud, they stand to sell more virtual machines and services. Maybe your database’s disaster recovery is becoming Microsoft’s loss leader. I’d love this, because we all need to do a better job of protecting our databases from disaster.

Or DID Gigaom Misquote Satya?

Maybe Satya said “Everybody who buys SQL Server Enterprise Edition gets an AlwaysOn Secondary in Azure.” After all, in this one quote, Gigaom managed to mis-capitalize both SQL Server and AlwaysOn. It’s not inconceivable that the quote was butchered.

What Do You Ask the Leaving DBA?

The last DBA had an unfortunate accident in Alaska.

The last DBA had an unfortunate accident in Alaska.

When the database administrator turns in her notice, what questions should you ask her in her last couple of weeks?

I’m assuming, of course, that it was a friendly departure and you’ve got the full two weeks to have good conversations.

Or maybe the DBA is about to go on vacation, and you need to quickly get up to speed about things that might break while they’re gone.

One of my clients’ DBAs turned in their resignation, so I was presented with this very task. I haven’t done it in a while, so I asked Twitter, and here’s what I got:

I kind of expected answers like that – a lay of the land, and Buck Woody’s runbook is a good example – but there were so many good creative ideas:

When you look at someone else’s server, it’s so easy to think, “This guy couldn’t have known what he was doing – nobody should ever set this trace flag or this database option or use this cumulative update.” Maybe not, though – maybe it’s critical to making the application work.

How many of us left little snippets of code around that ended up becoming mission-critical? Often we don’t have source code control on these, either.

Does the company even have one?

Have you tested a restore lately?

And a followup – are you getting value out of it, or have you just set up email rules to bozo-bin all of the monitoring emails? It helps to know what to expect when the emails start coming your way.

Wow – that’s a fantastic answer. Often we just didn’t have the time to automate all of our problems, and we know that the flux capacitor will leak if we don’t clean it out weekly. Followed up with:

Now might be a good time to get that project approved.

Being a DBA takes soft skills. Getting this inside info on the squeaky wheels helps me prepare for the incoming support requests. Which brings me to:

And I’d follow that up with, “Why are you leaving?” Sometimes that helps reveal some of the biggest land mines.

Reporting in Production: SQL Server (video)

Everyone wants reports but nobody wants to build out a separate reporting server. What options do you have short of throwing up your hands in defeat? Join Jeremiah to learn about four SQL Server technologies that help with reporting in production. This session is for DBAs and developers looking for a place to get started with reporting against SQL Server.

For the links and scripts, check out the Reporting in Production: SQL Server page.

Exploring the Magic of the Plan Cache

The plan cache holds a lot of secrets about what’s going on inside SQL Server. In the First Responder Kit we shared one of our plan cache scripts to find the top resource consuming queries. That query works well, but over time we’ve added some additional functionality to the query. I figured it was time to share the new query that we’re using to analyze SQL Server performance.

Our existing query looks at individual query stats, but it doesn’t take into account stored procedure or trigger execution stats. During our SQL Critical Care checks, we’ve found it helpful to look at both procedures and triggers to figure out if they were causing problems for overall server health.

What Are We Looking At?

The original query just looked at sys.dm_exec_query_stats and looked at average and total metrics across CPU, duration, and logical reads.

Plan cache query: classic flavor

Plan cache query: classic flavor

 

This was a helpful approach, but over time it’s become apparent that we needed to look at more than just individual statements – what if a single procedure was causing problems that only show up in aggregate?

The Bigger Picture

To get a view of the bigger picture, we added in two more DMVs - sys.dm_exec_trigger_stats and sys.dm_exec_procedure_stats. This gives us a big picture view of what’s going on inside SQL Server – the only thing that would make this better would be a DMV for function execution stats.

To avoid skewing results, data is aggregated by the query_hash - unfortunately this means the queries won’t work against SQL Server 2005. Not only do we rank queries by CPU, IO, duration, and execution count, but a second level of ranking is provided that ranks queries within their logical grouping – by statement, procedure, and trigger. If you want to see what your most expensive trigger is doing, it’s easy enough to make a quick change to the query.

Check it out:

New and Improved Output

New and Improved Output

You can download the script in the usual way – by agreeing to our crazy terms of service, selling your email address to a foreign government, and clicking “download”.

Using the Query

This query is easy enough to start using right way – just download the file and run it. Once you’re familiar with it, scroll to the bottom and you’ll see two separate queries you can run. The first is suitable for pasting into Excel – it has no query plan and the SQL text is shortened to easily paste into a single cell. The second query has everything that you want.

Since data is dumped into a temporary table during analysis, it’s easy to keep re-querying the temporary table as you re-sort data or refine what you’re looking for.

Watch Brent Tune Queries

Ever wonder how someone else does it? There’s no right way or wrong way, but in this 20-minute session, you can peer over Brent’s shoulder (virtually) while he takes a few Stack Overflow queries, tries various techniques to make them faster, and shows how he measures the before-and-after results.

For the links and scripts, check out the Watch Brent Tune Queries page.

Did Microsoft Stop Releasing SQL Server Service Packs?

Check out SQLServerBuilds.blogspot.com, a site that lists cumulative updates and service packs. Here’s a remixed version:

SQL Server Service Pack Release Dates

SQL Server Service Pack Release Dates

The first service pack seems to come out fairly quickly, but after the first one, it’s a year or more. Makes sense – you find a lot of bugs quickly, right?

Microsoft released at least one service pack per year, but … not last year. 2013 saw no service pack releases, and it’s been 442 days since the last service pack (SQL 2012 SP1) shipped.

Is Microsoft taking too long? Let’s look at each current version missing a service pack:

  • SQL 2012 has been waiting 442 days for SP2 – but that’s actually right in the range for normal SP2 releases. SQL Server 2008 went 540 days before SP2.
  • SQL 2008R2 has been waiting 545 days for SP3 – but that’s also less time than it took for SQL 2005 to get its SP3, so no cause for panic here yet.
  • SQL 2008 has been waiting 839 days for SP4 – here we actually do see some cause for alarm, because no supported SQL Server version has gone that long without a service pack.

442-DAYSWhen you step back and take the long view, we’re not really in that bad of shape yet – but I can see why people would be disturbed that no service packs have been released in over a year. It might just be a timing coincidence, or it might be something more.

But it does beg the question – what if Microsoft just stopped releasing SQL Server service packs altogether, and the only updates from here on out were hotfixes and cumulative updates? How would that affect your patching strategy? Most shops I know don’t apply cumulative updates that often, preferring to wait for service packs. There’s an impression – correct or not – that service packs are better-tested than CUs.

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