Copying a mailing results in thousands of entries in civicrm_mailing_group, rendering page unresponsive
I'll start by saying I haven't been able to replicate this - but I've seen it happen multiple times on Civi 5.39 to 5.41. I'm hoping someone else finds this and it rings a bell.
Sometimes, when a client goes to edit a mailing, the page is either a) unresponsive, or b) doesn't allow saving. The "calculating recipients" SQL is running indefinitely. When investigating, there are tens of thousands of entries in civicrm_mailing_group for that mailing - the entity_ids repeat.
While I'm unable to replicate, this seems to happen when:
- Users copy an existing mailing rather than starting from a new mailing;
- In both cases, mailings were going out to 17-24 groups.
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