I wrote a tool[0] for manipulating elf files to support inline assembly for a compiler that doesn’t support it (based on a similar python tool). That required knowing any of the ELF sections that were being changed and how those changes would impact other sections.
sqlite would have made this pretty trivial. Replace the .text fields of a few rows. Insert a few rows for symbols, update a few from the old object.
The best part - there’s tons of library support for sqlite. If it was a new object format, there would be no support and I’d just have to write different parsers and generators.
The schema might the the biggest issue for efficiency. As others have noted, ELF->SELF->ELF might be the best use case for compatibility. That said, a big part of [0] was performance, and I don’t know how sqlite would have done compared to my naive elf parsing and manipulation.