An efficient way to architecht a YouTube like comments section in DB
Quick explanation of the comments‑section bottleneck
I’m rewriting our prototype (React + json‑server) in Next.js with Convex and hit a data‑model problem around threaded comments.
Current model
- A Post keeps the IDs of its top‑level comments.
- Every Comment keeps the IDs of its direct replies (so replies are just more
2. Paginate that list.
3. For each comment, recursively fetch every reply to build a tree. On a post with 10 comments where one branch is 13 levels deep this becomes dozens of round‑trips plus a lot of in‑route JSON stitching. Works with json‑server but will hammer a real DB in production. What I’m after A data‑model / query pattern that lets me fetch a comment tree (or at least the first N levels) in one cheap call instead of a cascade of recursive fetches. Example in production (might take a minute to load, because json cold start): https://sheru.vercel.app/posts/1 Take a look at the network tab in dev inspector, and the sheer amount of API roud trips happening for a single comments section chain assembly. Any and all suggestion apreciated.
Comment docs).
Why it’s breaking down
To show one post I now:
1. Read the post → get the list of top‑level comment IDs.2. Paginate that list.
3. For each comment, recursively fetch every reply to build a tree. On a post with 10 comments where one branch is 13 levels deep this becomes dozens of round‑trips plus a lot of in‑route JSON stitching. Works with json‑server but will hammer a real DB in production. What I’m after A data‑model / query pattern that lets me fetch a comment tree (or at least the first N levels) in one cheap call instead of a cascade of recursive fetches. Example in production (might take a minute to load, because json cold start): https://sheru.vercel.app/posts/1 Take a look at the network tab in dev inspector, and the sheer amount of API roud trips happening for a single comments section chain assembly. Any and all suggestion apreciated.
2 Replies
Thanks for posting in <#1088161997662724167>.
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Thank you!
Hi. sounds like a problem that query streams might fix: https://stack.convex.dev/merging-streams-of-convex-data
Merging Streams of Convex data
New convex-helpers are available now for fetching streams of documents, merging them together, filtering them them out, and paginating the results. Wi...