CiviCRM Community Forums (archive)

I have 550,000 contacts in my database with external IDs. I already know that these are all unique as they are coming from an electors list from our electoral authority.

What I would like to do is import our membership, and successfully match as many of these members as possible with their existing contact info in the database. This is only about 2,000 contacts.

So I would like to search the 2,000 contacts (w/o external ids) AGAINST the 550,000 contacts (w/ external ids)  to look for duplicates. The problem I have is that I see no way to do this through the UI.

Is there a way to say that if two contacts have a certain field that is unique (in my case external ids), then there is no way they are duplicates regardless of what else matches?

Or is there a way to look for duplicates of one set against another set?

If not, would this be something we could look at doing in a future release? I would try to help out as much as I could.

Brian