missing_unique_indexes: Fix ignoring case insensitive columns

[fatkodima]

Case insensitive columns in missing_unique_indexes checker were not properly ignored.

[gregnavis]

@fatkodima, could you provide a bit more context on what this solves? I did a quick test and it seems that case-insensitive indexes can be ignored just fine via Context::User(email) (no need to call lower).

[fatkodima]

I do not remember, but I think the problem was that the gem suggested adding an index on lower(column) and so people might think that the ignore would contain that lower too. lower(column) is not actually a column, but I think for a good ux the checker can accept both.

[gregnavis]

I think a proper solution here would be to perform more extensive configuration validation: the user should be told that lower(email) isn't a column. I think configuration validation was mentioned somewhere already in the context of identifying non-existent models, columns, attributes, and so on.