Querying Highly Nested JSON



I am writing a Reddit like comment store using Couchbase. For each comment, I am storing its parentId and a list of its childrenIds . Each top-level comment on a web page will have its parentId as null .

I want to retrieve a comment block efficiently. By a comment block, I mean a top-level comment along with all its children comments. So the first step in this can be to write a map function that emits the ids of all top-level comments.

How do I go about fetching the entire tree once I have the root. A very naive approach would be to find the children, and query them recursively. But this defeats the purpose of not using a relational database for this project (since I am dealing with highly nested data and relational databases are terrible at storing them).

Can someone guide me on this?


Couchbase doesn’t support CONNECT BY. You can use technique described here N1QL - array join


You can also get array of all ids or objects like below.

INSERT INTO default VALUES ("k01",
{ "id": "520707438", "pageURIHash": "3988665684",  "parentId": null, "content": "Here is a parent comment" , "children": [ { "id": "1-1", "pageURIHash": "3988665684", "children": [{ "id": "1-1-1"}], "parentId": null, "content": "Here is a parent comment" }, { "id": "1-2", "pageURIHash": "3988665684", "children": [{ "id": "1-2-1"}], "parentId": null, "content": "Here is a parent comment" } ]});

"results": [
    "ids": [