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.
Category: Data Integrity
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.
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.
Exploring Programming Constructs in T-SQL – Part 3: Error Handling and Transaction Management
Welcome back to our series on programming constructs in T-SQL! In the previous installments, we explored variables, conditional IF statements, loops, and CASE expressions. These tools have helped us write dynamic and efficient SQL scripts. In this third part, we’ll focus on two essential concepts for writing reliable SQL code: Error Handling with TRY…CATCH Blocks and Transaction Management.
Understanding SQL Server’s TRUSTWORTHY Database Setting
In SQL Server, the TRUSTWORTHY database setting can grant elevated permissions across a database boundary, influencing how certain modules execute, particularly those using WITH EXECUTE AS or unsafe CLR assemblies. Enabling TRUSTWORTHY allows SQL Server to “trust” that the database owner and associated users won’t misuse elevated permissions to perform unauthorized actions. However, this setting comes with significant security risks if used improperly.
Using TRUNCATE TABLE with Table Partitions in SQL Server
In SQL Server, the TRUNCATE TABLE command is often favored over DELETE for its efficiency when removing data from a table. However, when working with partitioned tables, the locking behavior changes slightly. Additionally, the LOCK_ESCALATION = AUTO setting can further optimize performance by managing lock escalation at the partition level. We explore how these features interact, providing an in-depth look at locking behavior when truncating partitioned tables and the role of LOCK_ESCALATION = AUTO.
Five More SQL Server Error Log Messages You Should Care About
In a previous post, we explored five significant SQL Server error log messages that demand immediate attention. However, the SQL Server error log contains a wealth of additional information essential for maintaining the health and performance of your databases. In this sequel, we will highlight five more error log messages that should be on your radar. We’ll look into what each error means and offer suggestions for when you encounter them.
Manually Synchronizing a Lagging Secondary Replica in SQL Server Always On Availability Groups
In high-availability environments, SQL Server Always On Availability Groups (AG) are essential for minimizing downtime and preventing data loss. However, situations can arise where a secondary replica lags behind the primary, disrupting synchronization and risking potential data inconsistencies. This blog provides instructions on how to manually catch up a lagging secondary replica using transaction log backups.
Securing NorthPine Bank’s Data: How SQL Server 2022 Can Help
NorthPine Bank, a fictitious yet representative financial institution, recognized the necessity to modernize its data infrastructure to safeguard sensitive customer information against emerging threats. The bank decided to migrate its operations to SQL Server 2022, leveraging its advanced security features to enhance data protection, ensure regulatory compliance, and maintain operational efficiency. This blog explores the specific security challenges faced by NorthPine Bank and details how SQL Server 2022 addresses these issues through its robust, built-in features.
The Hidden Layers of Dynamic Data Masking in SQL Server
Dynamic Data Masking (DDM) in SQL Server is a feature that helps prevent unauthorized access to sensitive data by obfuscating it at the display level. This blog post discusses the various types of masks available, such as default, email, custom string, and random masks. We explore permissions and access control, demonstrating how users can modify masked data without viewing its actual content. Additionally, we discuss the new permission enhancements in SQL Server 2022 that allow for more granular control over unmasked data.