Comment by didgetmaster

I am building a new data management system that can also handle relational data well. It is really good at finding anomalies in data to help clean it up after the fact, but I wanted to find a way to prevent the errors from polluting the data set in the first place.

My solution was to enable the user to create a 'dictionary' of valid values for each column in the table. In your case you would create a list of all valid country names for that particular column. When inserting a new row, it checks to make sure the country name matches one of the values. I thought this might slow things down significantly, but testing shows I can insert millions of rows with just a minor performance hit.

The next step is to 'auto correct' error values to the closest matching one instead of just rejecting it.