Tables, Columns and Defaults Oh My!

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Published on: August 19, 2015

Picture this if you could. You inherit a new database either through the change of a job, or finding a black box database server, or maybe due to the acquisition of a new application.

No matter the cause, you are now responsible for maintaining that database and you also really need to become acquainted with it. Some of the acquaintance that is needed is learning how things are related and figuring out what data goes where. Not just what data, but what type of data.

I know that one of the things I am frequently asked is to figure out what data type belongs with which column. Furthermore, does this same column exist in more than one table. It’s nice when things are named consistently and you are able to tie things together by column name.

There are also times, when that column that is so consistently named, might need to be confirmed on data types between each of the implementations. I know I have run into cases when the column might be differently defined in different tables.

So, what to do to tie this all together and get that intimate acquaintance with your database?

Luckily, I have a script that will help you figure out some of these connections.

First, the script.

Now, let’s give it a trial run. See if you can spot the difference by running that against the AdventureWorks database using the value “AccountNumber” for the @ColName parameter.

ColData_Queryresult

 

Maybe there is a legitimate reason for that Column to have a different data type specification than the other two. Maybe it doesn’t. One thing for certain is that you will be able to walk away with some questions to ask and hopefully gain a better understanding!

Compressing Encrypted Backups

TSQL2sDayA common requirement, whether it be based out of pure want or truly out of necessity, is to make a large database backup file, that is encrypted, be much smaller.

This was a knock for the early days of Transparent Data encryption (circa SQL Server 2012). If TDE were enabled, then a compressed backup (though compression was available) was not an option. Not only did compression in the 2012 implementation of TDE make the database backup not smaller, it occasionally caused it to be larger.

This was a problem.  And it is still a problem if you are still on SQL 2012. Having potentially seen this problem, amongst many others, Ken Wilson (blog | twitter) decided to ask us to talk about some of these things as a part of the TSQL Tuesday Blog party. Read all about that invite here.

Encrypted and Compressed

dbsecurityWell, thankfully Microsoft saw the shortcoming as well. With SQL Server 2014, MS released some pretty cool changes to help us encrypt and compress our database backups at rest.

Now, instead of a database backup that could potentially get larger due to encryption and compression combined, we have a significant hope of reducing the encrypted backup footprint to something much smaller. Here is a quick example using the AdventureWorks2014 database.

In this little exercise, I will perform three backups. But before I can even get to those, I need to ensure I have a Master Key set and a certificate created. The encrypted backups will require the use of that certificate.

Do this in a sandbox environment please. Do not do this on a production server.

In the first backup, I will attempt to backup the AW database using both encryption and compression. Once that is finished, then a backup that utilizes the encryption feature only will be done. And the last backup will be a compressed only backup. The three backups should show the space savings and encryption settings of the backup if all goes well. The compressed and encrypted backup should also show an equivalent savings as the compression only backup.

With that script executed, I can query the backup information in the msdb database to take a peek at what happened.

This should produce results similar to the following:

backup_results

Looking at the results, I can see that the compression only backup and the compression with encryption backup show very similar space savings. The compression only dropped to 45.50MB and the Compression with encryption dropped to 45.53MB. Then the encryption only backup showed that, interestingly, the CompBackSizeMB (compressed_backup_size) got larger (which is the actual size on disk of this particular backup).

At any rate, the compression now works with an encrypted backup and your backup footprint can be smaller while the data is protected at rest. Just don’t go using the same certificate and password for all of your encrypted backups. That would be like putting all of your eggs in one basket.

With the space savings available in 2014, and if you are using SQL 2014, why not use encrypted backups?

What is DBCC?

DB Nuts and BoltsIf I ask you what is DBCC, what would your answer be?

I want you to think about that one for just a little bit. What comes to mind when you hear DBCC? Is it the default go-to used when talking about consistency checks? Is it something more involved? Maybe it is something entirely different?

I ponder this because I hear it from time to time used in complete replacement for CheckDB. I have to stop and think for a minute because as of SQL Server 2016, there are 35 DBCC statements of various use that are documented. Never-mind the bounty of un-documented statements (e.g. page, ind).

So, I ask, what does DBCC mean to you?

In trying to come up with some sort of answer, I did a little bit of research. If you look in the documentation (including the SQL 2000 documentation), one will find this definition for DBCC:

The Transact-SQL programming language provides DBCC statements that act as Database Console Commands for SQL Server.

It seems the documentation says it pretty clearly that DBCC is Database Console Commands. (And the SQL 2000 documentation says something similar). But every now and then you hear somebody say it means Database Consistency Checker. And it seems the root of that may come from the SQL 6.5 or earlier days. I found this snippet in BOL from SQL 6.5:

Used to check the logical and physical consistency of a database, check memory usage, decrease the size of a database, check performance statistics, and so on. DBCC is the SQL Server “database consistency checker.” DBCC helps ensure the physical and logical consistency of a database; however, DBCC is not corrective. It is recommended that you make periodic checks to ensure the logical and physical consistency of your data.

This seems a little odd to me since not all DBCC statements are used for database consistency checking as this definition would call it. It seems more of a documentation bug that has taken hold than a legitimate acronym. Just think about it. With that definition, one will also see a list of DBCC statements – many of which do not perform consistency checks. Let’s look at them:

For instance, DBCC PINTABLE is hardly useful for checking consistency. The TRACESTATUS is also one that does not quite fit this acronym. That is likely why you will see the difference in the SQL 2000 and beyond documentation for DBCC.

Don’t be surprised if you hear me ask which DBCC statement is being inferred if I hear somebody say they ran DBCCs. It is just plain more clear to hear “CheckDB came up clean” over the alternative “DBCC came up clean”. There is little room for interpretation there.

In short, DBCC is an acronym for Database Console Command, and it seems more of a documentation mistake when it was called Database Consistency Checker.

Another interesting thought. How many people say DBCC Command(s)? Think about that one for a minute – Database Console Command Command(s). That one is less of an issue imho than the prior.

Just remember, think about what you mean to say when talking about a specific DBCC statement and if you really mean a consistency check, try saying CheckDB instead. I bet the clarity in the conversation will improve and there will be less hair tugging.

HealthySQL – A Review

How well do you know the health of your SQL Servers and databases? Ever wonder about the current health or even what the health was like a few months back? Sure, one could anecdotally say the databases and servers are healthy, but how do you quantify it?

Many have asked or pondered what to do to quantify a healthy SQL server. How do you get the hard numbers to show whether the server is or is not healthy? How do you get the numbers to show that the server is performing just as well or better than it did three months ago?

dbhealth_maintNow we have a way to answer those questions and more! Robert Pearl has finally published his book on Healthy SQL. In the book, Robert takes you on a journey from mapping out a plan, to capturing data, storing that data, and then how to report on that data. You will learn what to capture and what some of the various things actually mean (e.g. waits and indexes).

Throughout the book, you will see that Robert will introduce you to various tools. These tools can either be native to SQL Server or they could be third party tools. You will get a healthyDBgood primer on what the tool is and how to quickly use it as you become acquainted with the internals and the Health of your database and server.

As you progress through the book and learn about what makes a database healthy, you will encounter a chapter on how to store the data and make a repository to track your database health. You will want to create a repository so you can progress into the sections on reporting about your database health. Who doesn’t want to market to management how healthy the databases are?

With the tools in this book, and the repository you will create, audits and discussions will become much easier. You will be able to implement processes to help make you more aware of the environment and help keep you from getting that annoying page in the middle of the night.

Take a look at the book and enjoy.  You can get it from Amazon here.

If you are a young DBA, new to being a DBA, an accidental DBA, or just any DBA looking for a little extra help in figuring out how to check and track the health of your server, it is worth reading this book.

Table Size Script Update for 2015

Categories: News, Professional, Scripts, SSC
Comments: 2 Comments
Published on: August 3, 2015

As was recently promised, I have an db_engineupdate to an old tried and true script for calculating the size of an object.

That promise was doled out in the previous article when I discussed the internal table types. You can read the article here. Information from that article was used in this script – so it could be of use prior to taking a gander at this new revision.

And of course, previous releases can be found through the link chain here.

The script was in need of an update the last time around due to the internal table types that had been updated in SQL Server. Those internal tables haven’t really changed in the latest release (at least as far as calculating space is concerned). But, I didn’t like needing to update multiple places in the script for one. For the other part of it, I did not like that It was difficult to know what exactly the internal table numbers actually represented. So I added that documentation to this script.

In addition to that little change, I also wanted to figure out if a table might have been spread across multiple filegroups. Due to this, I added in a delimited list of filegroups.

And the last minor update is that the script now has an option to exclude MS Shipped objects, or to include them, or to look just at the MS Shipped objects.

All of this is included in the effort of trying to get a more complete view of the size of the objects within a database and to be able to do so without needing to loop through the objects.

Note: A quick update to move the index creation outside of the table creation instead of inline since that is a feature not supported in older versions of SQL Server.

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