Yeah, or HDF5 which is essentially the same as a flat file, but it handles the structure and compression, so it might save some effortQuote from uexkuell:
Plain binary files.
Can't beat them. With todays fast computers any superimposed database layer will create unnecessary overhead (speed and code).

Quote from LeeD:
If you have budget for KDB you won't regret. Alternatively, flat files. Most relational databases are too inefficient at extracting long linear sequences of data.
Quote from promagma:
Yeah, or HDF5 which is essentially the same as a flat file, but it handles the structure and compression, so it might save some effort![]()