Do you backup the present schema and data before the new migration is done ?
And then if you rewind, you "simply" point to that backup scehma and data instead of the newly migration?
I know it's very simplified, but is this the gist of it?
And then if you rewind, you "simply" point to that backup scehma and data instead of the newly migration?
I know it's very simplified, but is this the gist of it?
Rewind does not move you back to an old snapshot, but rather keeps you on your current timeline, with the current data, but with the old schema.
Technically, there are two tables involved, yes! And a synching mechanism that compensates for the structural differences between them. But perhaps I should just point to this technical explanation of how this works internally: https://planetscale.com/blog/behind-the-scenes-how-we-built-...
this is not correct, for example pt-online-schema-change has long had a --reverse-triggers option which reverses the direction of the triggers to keep the old table up to date