Note: This is an update of a blog I posted in 2006 with a lot of additional information (I was less wordy in my 30s apparently). It is just as relevant today. I have a presentation I do occasionally on concurrency entitled “Let Me Finish” that covers many of the different types of concurrency behaviors … Read more
SQL Server replication works well on a low latency, high bandwidth network. When actual networks have high latency or limited bandwidth, problems may occur. Such conditions can be emulated with hardware or software tools. You can quickly set up a test environment to emulate high latency and limited bandwidth by using free, open source software. … Read more
In this book Kalen Delaney introduces and explains how the 2016 In-Memory OLTP engine works. The Hekaton internals knowledge offered in this book will help you migrate existing tables or databases to Hekaton, and get faster performance from your SQL Server applications than you ever thought possible.… Read more
Every SQL Server Database programmer needs to be familiar with the System Functions. These range from the sublime (such as @@rowcount or @@identity) to the ridiculous (IsNumeric()) Robert Sheldon provides an overview of the most commonly used of them.… Read more
The SQL Server 2016 Query Store can give you valuable performance insights by providing several new ways of troubleshooting queries, studying their plans, exploring their context settings, and checking their performance metrics. However, it can also directly affect the performance of queries by forcing Execution Plans for specific queries.… Read more
As well as its multidimensional model, SQL Server Analysis Services (SSAS) now has a tabular model of database that either runs in-memory or in DirectQuery mode. The in-memory analytics engine allows the users of Excel or Power View to base reports on tabular model objects. Having shown how to handle date-based information using the Multi-dimensional model, Dennes now turns his attention on the in-memory tabular model.… Read more
To be able to make full use of the system catalog to find out more about a database, you need to be familiar with the metadata functions. They save a great deal of time and typing when querying the metadata. Once you get the hang of these functions, the system catalog suddenly seems simple to use, as Robert Sheldon demonstrates in this article.… Read more
When your SQL Server database is set to have its statistics automatically updated, you will probably conclude that, whenever the distribution statistics are out-of-date, they will be updated before the next query is executed against that index or table. Curiously, this isn't always the case. What actually happens is that the statistics only gets updated if needed by the query optimiser to determine an effective query plan.… Read more
A walk-through can be a great help to understanding SQL Server Analysis Services, especially when it solves the problem of providing an effective date dimension to a cube. Dennes takes Adventureworks, and demonstrates all the twists and turns of creating a cube that provides meaningful historical information.… Read more
SQL Server instances are generally poorly-documented. How easily can you tell if something has changed? How easily can you check that there is adequate space for growth? Are you up-to-date with licenses? What errors are happening? Who has accessing the system? Before PowerShell, it was difficult to be on top of all this. Now you can, with the help of Sander's database documenter.… Read more
When maintaining or refactoring an unfamiliar database, you'll need a fast way to uncover all sorts of facts about the database, its tables, columns keys and indexes. SQL Server's plethora of system catalog views, INFORMATION_SCHEMA views, and dynamic management views contain all the metadata you need, but it isn't always obvious which views are best to use for which sort of information. Many of us could do with a simple explanation, and who better to provide one than Rob Sheldon?… Read more
The SQL Server 2016 Query Store provides several new ways of troubleshooting queries, studying their plans, exploring their context settings, and checking their performance metrics. In using the Query Store to ensure that performance is as good as possible, it isn't long before it becomes important to be familiar with the DMVs that are associated with the query store, and using them in custom queries.… Read more
Although SQL Server Data Tools (SSDT) encourages 'disconnected' database development, it also provides the SQL Server Object Explorer (SSOX) tool in SSDT's Visual Studio shell to connect to a live development instance or view an SSDT project once all references have been resolved.… Read more
One of the most important features of the SQL Server 2016's new Query Store is the reporting. With these features, it is now possible to get a wealth of information on how your query workload is performing, either aggregated for the entire query workload or for a single query. With this information, you can see the effects of 'forcing' an execution plan for specific queries and get feedback of the consequences.… Read more
At last, SQL Server has caught up with other RDBMSs by providing a useful measure of JSON-support. It is a useful start, even though it is nothing like as comprehensive as the existing XML support. For many applications, what is provided will be sufficient. Robert Sheldon describes what is there and what isn't.… Read more
PowerShell is an ideal tool for doing health checks of a collection of SQL Server instances, and there are several examples around, but few acknowledge the fact that individual DBAs have their own priorities for tests, and need something easily changed to suit circumstances. Omid's health check allows tests to be SQL or PowerShell and requires only adding, altering or deleting files in directories. … Read more
SQL Server's Query Store, introduced in SQL Server 2016, helps to troubleshoot query performance by capturing a range of information about query usage, CPU, memory consumption, I/O and execution time, and retaining every Execution Plan for analysis. Much of this information is available through queries.
It looks set to be the most significant enhancement of SQL Server 2016.… Read more
SQL Server Data Tools (SSDT) provides, via the DacPac, interesting support for verifying not only those references within the database, but also those to other databases even if they are on other servers. Although it is adds an extra level of complexity to deployments, it can increase the probability that deployments will succeed without errors due to broken references or binding errors.… Read more
In SQL Server, heaps are rightly treated with suspicion. Although there are rare cases where they perform well, they are likely to be the cause of poor performance. If a table is likely to have a large number of changes, then it can become fragmented due to way that space is allocated and forward pointers used. How does one detect this problem? Is it significant? How does one deal with it, if necessary?… Read more
If you're making a report from table-based data, an MS Word document is often a good option. In the second part of his introduction to SQL Server best-practice monitoring, Laerte Junior shows how to use PowerShell scripts to create a Word-based report with colour-coded alerts where there are problems or best practices aren't being followed.… Read more
