GZ is no doubt one of the best choices for database compression. We use it quite often when importing and exporting files. In fact, we recently used it for migrating our MySQL databases to Amazon RDS.
To extract a GZ file, use Gunzip command:
gunzip file.gz
If that had no success, try this:
gzip -d file.gz
To check if new extracted file exists, enter the following:
ls -l