Why is a .bacpac file so small compared to a .bak file of the same database?

A

• .bacpac file = Schema + Data. Note that Data is BCP'ed out using Native format (not readable by Human).

  • You can rename the .bacpac to .zip to see the actual contents.

  • You can use ...DAC\bin\sqlpackage.exe commandline to extract the .bacpac contents programatically.

  • It is a snapshot that includes User data + Schema from SQL Server or Azure SQL Database.

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• Backup (commonly have .bak extension) = A FULL database backup contains a complete copy of database and provides a single point-in-time to which the database can be restored. A full backup contains some transaction log records so that the restored component (database, file, or filegroup) can be made transactionally consistent.

A BACPAC is not a substitute for a FULL backup. Its just a snapshot that can be used to move a database from one server to another (or to cloud) and archiving an existing database in an open format.

From my test, below are the results