From the MySQL docs

> There is a limit of 2^32 (~4.295E+09) rows in a MyISAM table. If you build MySQL with the --with-big-tables option, the row limitation is increased to (2^32)^2 (1.844E+19) rows. See Section 2.16.2, “Typical configure Options”. Binary distributions for Unix and Linux are built with this option.

So `18446744073709552000` as a limit should be fine 

Up to you, feel free to extend this PR or create a new one :)