The bioinformatics community uses block based gzip compression (bgzip) [0]. The gzip standard allows for blocks so, using an additional index file, you can use

The bioinformatics community uses block based gzip compression (bgzip) [0]. The gzip standard allows for blocks so, using an additional index file, you can use it to seek to arbitrary locations and uncompress the block. gzip compression is maybe not optimal now and the block segmentation reduces the efficiency even further. Though not very standard, there is also a tar indexer program [1] that allows you to create an index on tar files to do the same. My information is at least a couple years old so things may have changed. [0] http://www.htslib.org/doc/bgzip.html http://www.htslib.org/doc/bgzip.html [1] https://github.com/devsnd/tarindexer https://github.com/devsnd/tarindexer