Hi Dario I see your point. As you already know how it behaves in most of the cases you are outlining, I encourage you to update the doc by yourself and open a pull request. The doc-files are in the git repo, here the one you are referring to: https://github.com/apache/solr/blob/main/solr/solr-ref-guide/modules/indexing-guide/pages/partial-document-updates.adoc
You are able to edit the file directly on Github and open a PR without closing the repo, not sure how practical this is for adoc-files though. Thanks, Renato > On 29 Jul 2026, at 14:53, <[email protected]> <[email protected]> wrote: > > Dear Solr Team > > What happens when you send a partial document update like the following? > > > { > "id":"mydoc", > "price":{"set":99} > } > > but no document with the id "mydoc" exists at this moment. > > Or what happens if the partial document update is missing the id field? > > Or what happens if you send a mixed request, containing fields with modifiers > and fields containing only the value? > > { > "id":"mydoc", > "name": "product", > "price":{"set":99} > } > > > I personally know that in the first case it acts as an upsert. so inserting > the document if its missing, and updating it if it already exists. > And in the second case it always inserts a new document, with its id being > generated. > > For the third case I am not entirely sure, but I think if there is at least > one field in the request with a modifier the whole request acts as a partial > document update and fields without modifiers are handled as if they have the > modifier "set". Thats what the behaviour on solr 9.10.1 looks like at least. > > The Documentation does not really explain any of the above cases clearly. > This also leads to AI making very questionable statements that are just wrong. > > https://share.google/aimode/rZE2udrRajAUNDD6y > Google just casually tells us that it only acts as an upsert but ONLY if the > document already exists in the collection, which is wrong and also does not > make any sense as that would not be an upsert. > > https://chatgpt.com/s/t_6a69f66582dc81919da8e03451e267f1 > Also Chatgpt is just wrong about it. > > As far as I understand it, partial document updates were introduced in solr 4 > and the upsert behaviour was introduced in solr 4.1. but as its not clearly > documented I am not 100% sure. > https://stackoverflow.com/questions/14886814/can-solr-perform-an-upsert#comment21025920_14888083 > > Kind Regards >
