The transaction log is used to guarantee the data integrity of the database and for data recovery. The transaction log in a database maps over one or more physical files. Conceptually, the log file is a string of log records. Physically, the sequence of log records is stored efficiently in the set of physical files that implement the transaction log. The SQL Server Database Engine divides each physical log file internally into a number of virtual log files. Virtual log files have no fixed size, and there is no fixed number of virtual log files for a physical log file. The Database Engine chooses the size of the virtual log files dynamically while it is creating or extending log files. In the first exercise of this lab, we will look at the virtual log file and how no. of the virtual log file is directly proportional to the size of the log file. In the second exercise, we will observe the circular nature of the log file. In the third exercise, we will clear our understanding of log sequence number.
Exercise 1: VLF Overview
Exercise 2: Circular Nature of VLF
Exercise 3: Log Sequence Number