alt Hacker NewsShow HN: SQL-tap – Real-time SQL traffic viewer for PostgreSQL and MySQL
sql-tap is a transparent proxy that captures SQL queries by parsing the PostgreSQL/MySQL wire protocol and displays them in a terminal UI. You can run EXPLAIN on any captured query. No application code changes needed — just change the port.
Comments
This is very neat! IMO inspecting the queries the agents run on the database is a better approach to understand how the code works, even more than reviewing the code.
I just tried and it works smoothly. For those who doesn't want to plug in the agents to their database directly, I built a similar tool https://dbfor.dev for the exact purpose, it just embeds PGLite and implements PG wire protocol to spin up quick PG databases with a traffic viewer included.
IMO transparent proxies for observability are not the best pattern. And I speak from experience, we developed the Postgres plugin for Envoy [1], [2] and we use it in StackGres [3], among others, for this very same reason, observability.
There's two main problems with said proxies:
* Latency. Yes, yes, yes, they add "microseconds" vs "milliseconds for queries", and that's true, but just part of the story. There's an extra hop. There's two extra sets of TCP layers being traversed. If the hop is local (say a sidecar, as we do in StackGres) it adds complexity in its deployment and management (something we solved by automation, but was an extra problem to solve) and consumes resources. If it's a network hop, then adds milliseconds, and not microseconds.
* Performance. It's not that hard to write a functioning PG wire proxy (it's not trivial either). But it is extremely hard to make it perform well under high load scenarios. Most of the proxies I have seen crack down under moderate to high performance.
What's the solution then? The Postgres extension model to capture the metrics (we also experimented with eBPF, but it causes too many kernel-user space context switches when you can do the same in an extension without them), and a small sidecar to push the metrics out via a standardized protocol like OTEL.
[1]: https://www.envoyproxy.io/docs/envoy/latest/configuration/li...
[2]: https://www.cncf.io/blog/2020/08/13/envoy-1-15-introduces-a-...
[3]: https://stackgres.io
Edit: formatting
I run two production RDS instances by myself. I never thought I really needed something like this. What I usually did was just check the details on the AWS dashboard. Thanks for building this. I love it.
Could I put this into default docker-compose for developers, so when they work on project with micro services they can quickly inspect SQL queries if something weird is happening? How would this UI work with that scenario, feels like React frontend would better serve that purpose.
Why do you need a proxy? Pull the queries off the network. You’re adding latency to every query!
We do something similar in adaptive [1].
What you can also do is add frontend and backend user to the proxy and then agents won't ever get the actual db user and password. You can make it throwaway too as well as just in time if you want.
Traditionally it was database activity monitoring which kind of fell out of fashion, but i think it is going to be back with advent of agents.
Can you explain how this is a better option than just enabling the general log for MySQL as needed?
what are the latency implications of going through this proxy? looks good
Maybe consider renaming this since pgTAP [0] exists and has nothing to do with this.
[0]: https://pgtap.org/
Looks really cool, will try it out soon
Nice. I like how you made it an easy to drop in proxy. Will definitely use this when debugging issues!
Really been wanting something like this. Thanks!
Not to be confused with sqltap which is also great for debugging queries: https://github.com/inconshreveable/sqltap
I prefer to use eBPF; no additional software, proxy or configuration needed.
Was AI used to build this? It looks a lot like the kind of scratch-an-itch projects I have been grinding out with AI lately, in size, timeline, code, and function. If not, you are a very very productive programmer.
If so, would you mind sharing which model(s) you used and what tooling?
That's some sick observability, nice.
[dead]
[dead]
[dead]
[dead]
Just tried it out. Works fine. Love it! I tried it with a wordpress site. It is showing hundreds of sql queries in one request (thats probably why that wordpress site is so slow lol)
What I would love to see here is:
- some kind of sorting: eg. by excecution time or order. So I can see the slowest queries.
- search/filter feature.
- faster scrolling with pgup/pgdown keys.
- maybe how often the same query was executed. I could check the code and maybe optimize the queries.