Ask HN: Are Binary Logs a Thing?

I was wondering if there are any logging frameworks which write data in binary rather than utf-8 encoded text. For example, the datestamp might be a 64 bit integer rather than a formatted ISO string. It would probably make it harder to work with *nix-like tools (sed, grep), but would reduce storage usage and perhaps make it easier to do structured queries on the data using shells like powershell.

I know there are services which store this type of data as columns in a logging database, but I was wondering if there were frameworks which used binary files to do so