FW: [nesting] Any way to return the whole hierarchical structure when doing Block Join queries?

-----Original Message-----
From: Jan Høydahl [mailto:jan.asf@cominvent.com]
Sent: 15 March 2018 21:38
To: solr-user@lucene.apache.org
Subject: Re: [nesting] Any way to return the whole hierarchical structure
when doing Block Join queries?

> 14. mar. 2018 kl. 15:45 skrev Anshum Gupta <anshum@anshumgupta.net>:
>
> Hi Jan,
>
> The way I remember it was done (or at least we did it) is by storing
> the depth information as a field in the document using an update
> request processor and using a custom transformer to reconstruct the
> original multi-level document from it.

Right, you either have to store pointer to parent or a depth info.
If you only have depth (1, 2, 3) it will not be possible to reconstruct a
complex document with multiple child docs each having grandchildren?

I found this code in AddUpdateCommand.iterator()
<https://github.com/apache/lucene-solr/blob/c50806824005b979a7e4854af38b2d80
71bc52c0/solr/core/src/java/org/apache/solr/update/AddUpdateCommand.java#L18
8>:
return new Iterator<Document>() {
Iterator<SolrInputDocument> iter;

{
List<SolrInputDocument> all = flatten(solrDoc);

String idField = getHashableId();

boolean isVersion = version != 0;

for (SolrInputDocument sdoc : all) {
sdoc.setField(IndexSchema.ROOT_FIELD_NAME, idField);
if(isVersion) sdoc.setField(CommonParams.VERSION_FIELD, version);
// TODO: if possible concurrent modification exception (if
SolrInputDocument not cloned and is being forwarded to replicas)
// then we could add this field to the generated lucene document
instead.
}

iter = all.iterator();
}

It recursively finds all child docs and turns it into an iterator, adding a
pointer to root in all children. Guess it would be possible to rewrite this
part to add a _parent_ field as well?
That would lay the foundation for rewriting [child] transformer to
reconstruct grandchildren?


Jan