compress file size bigger than uncompress in gzip format

kumartnj · 04-10-2009, 01:40 AM

All,

when i tried to compress a file with gzip format the output gives me as compressed file size is bigger than uncompressed file size.

output given below:
-------------------

#gzip -l kk.dmp.gz
compressed uncompressed ratio uncompressed_name
4655006947 1978884096 -135.2% kk.dmp

please let me know ASAP if someone can answer to this questions. Thanks

- Kumar

colucix · 04-10-2009, 02:28 AM

The gzip file format stores the length of the uncompressed file in a 4 byte integer, so that the maximum value can be 2^32 = 4294967296. If the original file was bigger than 4 Gbyte, the information returned by gzip -l is wrong. To compute the actual size of the uncompressed file, you have to add 4294967296, that is

Code:

1978884096 + 4294967296 = 6273851392

resulting in a compress ratio of 74%.