A number of techniques help here. These are useful whether or not you're using continuous deployment.
A simple approach is not to delete data, but rather simply set a flag which marks the data as deleted. The application storage layer acts as if this data were deleted. A separate process (changed separately) is responsible for actually purging data which has remained deleted for a certain period of time.
In any case, do you really wish to delete the data? Keep it around -- it might be useful. The only reason to delete data, outside legal concerns, is to control the cost to retain it. Given that you mostly never really want to delete data, you probably want to orient your schema toward hiding it instead. In that case, if you need to roll back application changes, you can do so by backfilling the data to restore it to a visibile status.
Keeping detailed programmatic logs is also helpful for making the backfill easy to execute. For example, in addition to your main textual log file, you keep something like a log consisting of JSON objects, one per line, each which represent the essential details of some application action.
A simple approach is not to delete data, but rather simply set a flag which marks the data as deleted. The application storage layer acts as if this data were deleted. A separate process (changed separately) is responsible for actually purging data which has remained deleted for a certain period of time.
In any case, do you really wish to delete the data? Keep it around -- it might be useful. The only reason to delete data, outside legal concerns, is to control the cost to retain it. Given that you mostly never really want to delete data, you probably want to orient your schema toward hiding it instead. In that case, if you need to roll back application changes, you can do so by backfilling the data to restore it to a visibile status.
Keeping detailed programmatic logs is also helpful for making the backfill easy to execute. For example, in addition to your main textual log file, you keep something like a log consisting of JSON objects, one per line, each which represent the essential details of some application action.