Compression formats with good support for random access within archives?

Question

This is similar to a previous question, but the answers there don\'t satisfy my needs and my question is slightly different:

I currently use gzip compression for som

Answer 1

The gzip format can be randomly accessed provided an index has been previously created, as it is demonstrated on zlib's zran.c source code.

I've developed a command line tool upon zlib's zran.c which creates indexes for gzip files: https://github.com/circulosmeos/gztool

It can even create an index for a still-growing gzip file (for example a log created by rsyslog directly in gzip format) thus reducing in the practice to zero the time of index creation. See the -S (Supervise) option.