Antek,
What method do you use to get the list of files you have to process?
If you use the standard Foreach file enumerator, you can setup it to
get only the files with .gz file extension. Set Files input like this:
*.gz
If that is not the case, you can use the SSIS expressions to detect
if the file extension ends with .gz. Use this expression in a
constraint before the decompression of a file.
Regards,
Ivan