I am having a problem with custom general rules for deduping. Very inconsistent results that cause me to suspect that there may be significant issues. One strange observation is that at times a general clearing of caches makes a difference. But even that is not consistent and problematic if a rule is being used by a webform, for example.

Are users have success with general rules? Failures? My test case is using First Name, Last Name and birth date. Is this a case where a general rewrite is needed and perhaps a Make It Happen campaign?

Any insights would be appreciated. enter image description here

  • can you clarify your dedupe rule config ie the weighting and the threshold
    – petednz - fuzion
    Dec 5, 2018 at 19:09
  • sure - added to initial posting
    – Dave T
    Dec 5, 2018 at 19:27
  • I have now repeated failure > success cycle by clear Civi caches. The need to flush cache is not clear as it is not consistently due to any of the things I have tested. Matching via Webform is not working with this rule thus far even with cache clear.
    – Dave T
    Dec 5, 2018 at 19:32
  • Further testing - There is some sequence of events (not figured out yet) that seems to cause a need to clear cache to allow dedupe rule to be reset.
    – Dave T
    Dec 5, 2018 at 19:50
  • is there a reason for having values in the Length field? Dedupe may run faster without values in there
    – petednz - fuzion
    Dec 5, 2018 at 21:01

2 Answers 2


I just used a general rule for org contact type import yesterday and it worked.

Import Contacts creating dupes despite dedupe rules


I have at least one customer that uses dedupe rules regularly in their processes and they work. They have different general rules like:

  • Last name AND first name AND birth date
  • Last name AND first name AND postal code
  • E-mail OR (First Name AND Last Name AND Birth Date)

Mind you, they do this deduping in the backend, so in CiviCRM. Their CiviCRM is on a different server than their public website.

  • To make it more specific: when webforms come in this customer uses the Extended Contact Matcher extension to find contacts. They have separated matching (finding the correct contact, we want to get all input from activists from our website and then organise the data ourselves) which they do from the website and deduping which they do regularly internally. Apr 29, 2020 at 6:41

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