What is the difference between the option here to “include in merge file if one or more constituent…”:
And this one in the criteria sets “filter” window?
And a third option that I’m not sure about – how does this one relate to the others? It seems to be a mandatory field if I use criteria sets.
The first option lets you include only constituents who appear in a query (for example a recently imported list). The merge file creation will run as usual. For each merge pair, if one of the constituents is in the query then the merge will be included in the file. If neither are in the query then the pair will not be included in the merge file. Critically you can choose this option whatever method you choose to find duplicates, be it email, RE criteria or criteria sets (although given that the criteria sets work slightly differently you probably wouldn't use this option if using criteria set matching).
In terms of the options only available on criteria sets, this is not completely obvious so let me try and explain:
You are required to choose a place to look for duplicates so you can exclude certain records if you choose (celebrities or trustees for example), the only reason for this is that the functionality comes originally from another application and we plan to remove this mandatory option in a future version. However in the meantime to de-dupe the whole database just select a query that includes everybody e.g. add query criteria such as “Constituent Import Id is not blank”.
The filter option essentially lets you do the same thing, so for now, I'd ignore this one as it doesn't offer any additional functionality but in future it will let you exclude certain constituents.