What are .mdf and .ldf Files in SQL Database?

Question

Aryan Kumar · Answer

.mdf and .ldf files are database files used by Microsoft SQL Server.

MDF file (Primary Data File): It stores all the data in a SQL Server database. This includes the tables, columns, rows, indexes, views, and stored procedures. The MDF file is typically the largest file in a SQL Server database.
LDF file (Log Database File): It stores the transaction log for a SQL Server database. The transaction log is a record of all the changes that are made to the database. It is used to recover the database in case of a failure or to restore the database to a previous point in time. The LDF file is typically much smaller than the MDF file, but it can grow quickly if there is a lot of activity on the database.

Here is a table summarizing the key differences between .mdf and .ldf files:

Feature	.mdf file	.ldf file
Data stored	All data in the database	Transaction log
Size	Typically larger	Typically smaller
Purpose	Stores the data in the database	Stores the transaction log
Role in recovery	Not used for recovery	Used for recovery

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