SQL Server stores its data in Primary data files (MDF) and Secondary data files (NDF). SQL Server log file also known as LDF (Log database file) has a primary functionality of recording all the transactions sequentially made in these associated databases. Microsoft SQL Server creates a log file for all of the databases which store the transactions and modifications done on the SQL databases. There is minimum one log file for each database however it can have more than one log file as well. All the of these MDF - Primary database, NDF – Secondary database, and LDF – Log database are important and hence it is highly advised to create backup of all of these database files.
Transaction Log Maintenance
Transaction logs hold all the transactions and have chances to grow more. Hence it is extremely important to keep a check on the file size and this can also make the database to stop functioning or adding any data further. Truncation as mentioned above can help to mark the old records inactive and it can be then overwritten with new data which prevents it from growing large. Regular backup of databases along with the log files can also maintain this file data very well.
Importance of SQL Log File
SQL server tends to write the changes or modification made by user to memory first and then writes it to the transaction log file before updating it to the data files. Thus, transaction log file is very much important and crucial factor which holds elements which can be used to recover the database in case of server crash.
Experts suggest truncating the file regularly so that the file can be stopped from filling up. Manually monitoring the file size should be also done in order to keep a check on exceeding size of the transaction file. The file should not be deleted or modified in any situation as it can help users to recover the database data from it and several operations like below can be executed using log database file;
One can also use these transaction log files to analyze the transactions made in SQL databases. This analysis can help you judge which transaction entries were responsible to initiate corruption in the main database of the server. Many third party utilities like SQL Log Analyzer can help to analyze the SQL log file and also helps to recover the primary database associated using this transaction log file.