ElasticSearch - logstash ( 8.2.0 )

Hi, all.
I'am new to Elasticsearch and finding the best way to store data in elastic-search engine using log stash.
Reading tables from input JDBC and output to elastic-search.
Currently i have create single index but different document_type for searching without creating any parent-child relationships.

So my question is, suppose i have user , post and comment table. Post is linked to User via owner field and to comments table via comments field. So how should i do the data modelling to fetch the data from all the tables.

Please guide me with explanation of best practise.