106 karma · joined May 17, 2022
Rather than taking the usual path of bundling a workload and execution into one neat package, we decided to build a reusable database benchmark runner based on grafana/k6 first.
This interview with Tantivy creator Paul Masurel looks at how wrong I would have been; discussing challenging solved domains, open-source competition done right, and why long-fermented frustration is an underrated driver.
Best feature for me being was being able to detect intermittent jitter to my gateway. I never managed to catch this with speed-tests alone.
A few takeaway: - Postgres’s native `tsvector/ts_rank` stuff works ok for basic text matching, but it doesn’t account for global term frequency like BM25 does , so rankings can feel “flat” or noisy as soon as you go beyond simple queries (it's also slow). - Using a BM25 index (via extensions like `pg_search`) actually gives you relevance scores similar to what you’d expect out of modern search engines, and you can use stemmers/tokenization directly in SQL. BM25 is the star of this story. - Vector search fills in the semantic gaps (so “database optimization” isn’t limited to exact keywords), but you still don’t want to throw out lexical relevance. The trick is making it additive, not just adding scores together. - RRF (Reciprocal Rank Fusion) is a neat practical tool here. It sidesteps trying to normalize totally different scoring systems by just focusing on rank positions.
If you’re building anything where relevance matters (docs, product search, help articles) having BM25 + vector makes a big difference over vanilla FTS + embeddings alone. It also keeps everything in Postgres, which simplifies consistency/ops compared to an external search cluster.
You get the same faceting features you'd expect from a dedicated search engine while maintaining full ACID compliance. Happy to answer technical questions about the implementation!
However, even though the approach is “old fashioned” it’s still widely used for English. I’m not sure there is a universal approach that semantic search could use that would be both fast and accurate?
At the end of the day people choose a tokenizer that matches their language.
I will update the article to make all this clearer though!
I'm curious, after reading this article how many people can tell me why that title would have been great?
(also I'd love feedback on the interactive components, I think they came out well!)
Hi everyone A lot of you will probably see the title of this post and immediately think “of course, just use the right tool for the job.”
But for those who don’t … here's a thing for you.
I’d really love to hear from both sides:
- Folks who’ve been burned by using Elastic as a primary datastore.
- Folks who haven’t — and can make the case for why it works just fine. (I know some of you are out there!)
Let me know what you think.
Let me know if you have any questions or suggestions for next articles.
I wrote this article comparing TimescaleDB's SkipScan feature to vanilla Postgres performance for DISTINCT queries (get me the last row for all IDs) while a 200K rows per second ingest was happening.
I'm going to be writing more of these smaller performance pieces (sometimes Timescale related, sometimes Postgres related) - I'd love to hear some suggestions (especially around PG performance) from the HN community
A lot of the data is stored using Timescale's Tiering feature, but all that data is still ingested into Postgres and queryable as normal.
It’s amazing what Postgres can do if you architect your solution well.
This is exactly where we see ourselves contributing: both making pgvector faster and more efficient through pgvectorscale, and working to make the AI on Postgres developer experience first class.
The pgvectorscale repo is at: https://github.com/timescale/pgvectorscale
But also, point taken. The article this comment thread describes also needs to be written.
I didn't want to go down that path for this article because I didn't want it to end up as a sales pitch. The article you describe needs to be written, but it's a follow-up in my mind (and much more technical, for a slightly different audience).