Hi, Hadrik.
Pls check
https://solr.apache.org/guide/solr/latest/query-guide/block-join-query-parser.html#block-mask
A common mistake is to try and use a which parameter that is more
restrictive then the set of all parent documents, in order to filter the
parents that are matched, as in this bad ex
[
{
"id": "doc_1",
"name": "Harpreet Chaggar",
"_childDocuments_": [
{ "id": "child_doc_a", "number":
22,"created_at":"2020-03-20T00:00:00Z" },
{ "id": "child_doc_b", "number": 10
,"created_at":"2021-05-28T00:00:00Z"},
]
},
{
