File compressed with tar gzip or zip has slightly the same size

I tried to compress the same file with different compression type :

tar cjf dump.sql.tar.bz dump.sql
tar czf dump.sql.tar.gz dump.sql
zip -r dump.sql.zip dump.sql

results :

size     file
79968725 dump.sql            ~77MB
 9846256 dump.sql.tar.bz     ~9.4MB
13863797 dump.sql.tar.gz     ~14MB
13863826 dump.sql.zip        ~14MB

The best compression comes with bzip2 file. Anyway, the original file was compressed with bzip2 but its size was around 7.7MB. How to get this level of compression ?

Is there some other compression types/options to get better performances ?

Also, why the gzipped file has slightly the same size as the zipped file ? I thought gzip had a better compression rate than zip. Am I missing something ?

Any tips/hints are welcomes and will be appreciated.

Thank you.

Solution

Pretty much every compressor out there (it's the case for gz, bz2, zip and xz) lets you choose the compression level (usually from 1 to 9 for instance). The faster it compresses, the lowest the compression ratio. The slower it is, the better compression you get. The best lossless compressor I know of is xz. It should give you better compression than bz2:

vfcJ dump.sql.tar.xz dump.sql

What file size do you get with this?