High concurrency can expose subtle performance bottlenecks in SQL Server, particularly those stemming from spinlocks and latch contention. Both mechanisms exist to synchronize access to shared data structures, yet they operate differently and require distinct troubleshooting approaches. By recognizing how they work and knowing what causes them to overload a system, DBAs can reduce CPU spikes, timeouts, and overall application slowdowns.
Five Helpful Queries for SQL Server DBAs
As a SQL Server DBA, having the right set of queries can significantly streamline your workflow, enhance monitoring, and aid in troubleshooting. This post shares five essential queries that address common administrative tasks, each accompanied by a detailed explanation to help you understand their purpose, interpret the results, and take appropriate action.
SQL Server Always On Health Check and Lease Timeout Monitoring
SQL Server Always On Availability Groups are a robust solution for achieving high availability and disaster recovery for SQL Server databases. However, simply configuring them is not enough—you also need a solid monitoring strategy to ensure data integrity and system reliability. One key aspect of this monitoring process is keeping an eye on lease timeouts, which can signal larger issues and help prevent potentially catastrophic split-brain scenarios. In this post, we’ll walk through the various health checks available for Always On Availability Groups, discuss how lease timeouts work, and explore practical methods for monitoring and troubleshooting.
Reading SQL Server’s XML Deadlock Report Captured by the system_health Event
SQL Server includes an Extended Events session called system_health, which runs by default and, among other things, captures information about deadlocks as they occur. When two or more sessions block each other in such a way that no progress can be made (a deadlock), SQL Server chooses one session as the “victim,” rolls back its transaction, and frees resources so other sessions can continue. By reviewing the deadlock report in the system_health session’s XML output, you can see precisely why the deadlock happened and identify which queries or procedures were involved.
Understanding and Resolving TempDB Contention in SQL Server
TempDB contention is a common challenge in SQL Server when running highly concurrent workloads. In this post, we will explore why it occurs, how to identify it, and some practical solutions—especially leveraging In-Memory OLTP and memory-optimized table variables.
Optimizing Table Width and Data Types in SQL Server
Organizing data effectively in SQL Server can be a juggling act. You may be tempted to make tables as all-encompassing as possible by giving columns very large data types or piling on extra fields for convenience. While this seems harmless in the short term, it can lead to heavier storage requirements, slower queries, and frequent obstacles when updating the schema. Narrower tables, carefully chosen data types, and a normalized design often work together to keep a database agile and efficient.
SQL Server 2025 Teaser – Exploring the Innovations in SQL Server 2025
SQL Server 2025 is a significant milestone in database technology. Its advanced features empower developers, streamline operations, and support modern application scenarios. Find out why SQL Server 2025 will be such an exciting release!
Handling Compatibility Level Changes During SQL Server Upgrades
Compatibility levels determine how certain features of SQL Server behave, allowing databases to maintain functionality even as the server itself evolves. However, changing compatibility levels requires careful consideration to balance the benefits of new features against the potential risks of disrupting existing applications. This blog explores the importance of handling compatibility level changes thoughtfully during SQL Server upgrades, highlighting the risks of making changes too hastily and the advantages of adopting new compatibility levels within a reasonable timeframe.
Leveraging SQL Server 2019’s Last Known Actual Query Plan for Troubleshooting
Troubleshooting production performance issues is often challenging because detailed query execution data can vanish before you realize there’s a problem. Many times, you end up piecing together incomplete clues from runtime statistics or the plan cache. Fortunately, SQL Server 2019 introduced a powerful feature to address this pain point: the Last Known Actual Query Plan.
Using sp_getapplock to Prevent Concurrent Execution of Stored Procedures in SQL Server
In multi-user database environments, ensuring the integrity and consistency of data is essential. One common challenge is preventing multiple instances of the same stored procedure from executing at the same time, which can lead to data conflicts, race conditions, and unpredictable results. To address this, SQL Server provides a powerful tool called sp_getapplock. This post explains what sp_getapplock is, what you are actually locking when you use it, how to implement it to prevent concurrent executions of a stored procedure, and the difference between transaction-level and session-level locks.