Of course, this doesn't matter now, I just ask an LLM to make the query for me if it's so complex that I can't do it by hand within seconds.
I suspect my use cases are less complex than yours. Or maybe jq just fits the way I think for some reason.
I dream of a world in which all CLI tools produce and consume JSON and we use jq to glue them together. Sounds like that would be a nightmare for you.
Here's an example of my white whale, converting JSON arrays to TSV.
cat input.json | jq -S '(first|keys | map({key: ., value: .}) | from_entries), (.[])' | jq -r '[.[]] | @tsv' > out.tsv
<input.json jq -S -r '(first | keys) , (.[]| [.[]]) | @tsv'
<input.json # redir
jq
-S # sort
-r # raw string out
'
(first | keys) # header
, # comma is generator
(.[] | # loop input array and bind to .
[ # construct array
.[] # with items being the array of values of the bound object
])
| @tsv' # generator binds the above array to . and renders to tsvI knew cat was an anti-pattern, but I always thought it was so unreadable to redirect at the end
cat input.json | jq -r '(first | keys) as $cols | $cols, (.[] | [.[$cols[]]]) | @tsv'
look at $cols | $cols
my brain says hmm that's a typo, clearly they meant ; instead of | because nothing is getting piped, we just have two separate statements. Surely the assignment "exhausts the pipeline" and we're only passing null downstream
the pipelining has some implicit contextual stuff going on that I have to arrive at by trial and error each time since it doesn't fit in my worldview while I'm doing other shell stuff
It's not unique in that regard. 'sed' is Turing complete[1][2], but few people get farther than learning how to do a basic regex substitution.
[1] https://catonmat.net/proof-that-sed-is-turing-complete
[1] And arguably a Turing tarpit.
jq is the CLI I like the most, but sometimes even I struggled to understand the queries I wrote in the past. celq uses a more familiar language (CEL)
# Common Expression Language
The Common Expression Language (CEL) implements common
semantics for expression evaluation, enabling different
applications to more easily interoperate.
## Key Applications
- Security policy: organizations have complex infrastructure
and need common tooling to reason about the system as a whole
- Protocols: expressions are a useful data type and require
interoperability across programming languages and platforms.I think my personal preference for syntax would be Python’s. One day I want to try writing a query tool with https://github.com/pydantic/monty
this and other reasons is why I built: https://github.com/dhuan/dop
No more fiddling around trying to figure out the damn selector by trying to track the indentation level across a huge file. Also easy to pipe into fzf, then split on "=", trim, then pass to jq
I was working at lot with Rego (the DSL for Open Policy Agent) and realized it was actually a pretty nice syntax for jq type use cases.
I’ve never seen AI “hallucinate” on basic data transformation tasks. If you tell it to convert JSON to YAML, that’s what you’re going to get. Most LLMs are probably using something like jq to do the conversion in the background anyway.
AI experts say AI models don’t hallucinate, they confabulate.
When I'm deciding what tool to use, my question is "does this need AI?", not "could AI solve this?" There's plenty of cases where its hard to write a deterministic script to do something, but if there is a deterministic option, why would you choose something that might give you the wrong answer? It's also more expensive.
The jq script or other script that an LLM generates is way easier to spot check than the output if you ask it to transform the data directly, and you can reuse it.
Because the input might be huge.
Because there is a risk of getting hallucinations in the output.
Isn't this obvious?
It's an important idea in computer science. Go and learn.
Sure there are 0.000001% edge cases where that MIGHT be the next big bottleneck.
I see the same thing repeated in various front end tooling too. They all claim to be _much_ faster than their counterpart.
9/10 whatever tooling you are using now will be perfectly fine. Example; I use grep a lot in an ad hoc manner on really large files I switch to rg. But that is only in the handful of cases.
The difference between 2ms and 0.2ms might sound unneeded, or even silly to you. But somebody, somewhere, is doing stream processing of TB-sized JSON objects, and they will care. These news are for them.
People would say, "Why use this when it's harder to read and only saves N ms?" He'd reply that you'd care about those ms when you had to read a database from 500 remote servers (I'm paraphrasing. He probably had a much better example.)
Turns out, he wrote a book that I later purchased. It appears to have been taken over by a different author, but the first release was all him and I bought it immediately when I recognized the name / unix.com handle. Though it was over my head when I first bought it, I later learned enough to love it. I hope he's on HN and knows that someone loved his posts / book.
https://www.amazon.com/Pro-Bash-Programming-Scripting-Expert...
Also performance improvements on heavy used systems unlocks:
Cost savings
Stability
Higher reliability
Higher throughput
Fewer incidents
Lower scaling out requirements.
For example, doing dangerous thing might be faster (no bound checks, weaker consistency guarantee, etc), but it clearly tend to be a reliability regression.
And how does performance improve reliability? Well, a more performant service is harder to overwhelm with a flood of requests.
Of course this is a very artificial and almost nonsensical example, but that is how you optimize bounds checks away - you just make it impossible for the bounds to be exceeded through means other than explicitly checking.
That's crazy to think about. My JSON files can be measured in bytes. :-D
https://developer.nvidia.com/blog/accelerating-json-processi...
So went not compare that case directly? We'd also want to see the performance of the assumed overheads i.e. how it scales.
Either way, I have really big doubts that there will be ever a significant amount of people who'd choose jq for that.
It’s the same sentiment as “Individuals don’t matter, look at how tiny my contribution is.”. Society is made up of individuals, so everybody has to do their part.
> 9/10 whatever tooling you are using now will be perfectly fine.
It is not though. Software is getting slower faster than hardware is getting quicker. We have computers that are easily 3–4+ orders of magnitudes faster than what we had 40 years ago, yet everything has somehow gotten slower.
Out of curiosity, have you read the jq manpage? The first 500 words explain more or less the entire language and how it works. Not the syntax or the functions, but what the language itself is/does. The rest follows fairly easily from that.
If I/you was working with JSON of that size where this was important, id say you probably need to stop using JSON! and some other binary or structured format... so long as it has some kinda tooling support.
And further if you are doing important stuff in the CLI needing a big chain of commands, you probably should be programming something to do it anyways...
that's even before we get to the whole JSON isn't really a good data format whatsoever... and there are many better ways. The old ways or the new ways. One day I will get to use my XSLT skills again :D
Say a number; make a real argument. Don't just wave your hand and say "just imagine how right I could be about this vague notion if we only knew the facts"
I don't think I remember one case where jq wasn't fast enough
Now what I'd really want is a jq that's more intuitive and easier to understand
Unfortunately I don’t recall the name, but there was something submitted to HN not too long ago (I think it was still 2026) which was like jq but used JavaScript syntax.
>
> 9/10 whatever tooling you are using now will be perfectly fine
Are you working in frontend? On non-trivial webapps? Because this is entirely wrong in my experience. Performance issues are the #1 complaint of everyone on the frontend team. Be that in compiling, testing or (to a lesser extend) the actual app.
Either the team I worked at was horrible, or you are from Google/Meta/Walmart where either everyone is smart or frondend performance is directly related to $$.
It is. Company size is moot. See https://wpostats.com for starters.
From that I completely agree with your statement - however, you're not addressing the point he makes which kinda makes your statement completely unrelated to his point
99.99% of all performance issues in the frontend are caused by devs doing dumb shit at this point
The frameworks performance benefits are not going to meaningfully impact this issue anymore, hence no matter how performant yours is, that's still going to be their primary complaint across almost all complex rwcs
And the other issue is that we've decided that complex transpiling is the way to go in the frontend (typescript) - without that, all built time issues would magically go away too. But I guess that's another story.
It was a different story back when eg meteorjs was the default, but nowadays they're all fast enough to not be the source of the performance issues
Opencode, ClaudeCode, etc, feel slow. Whatever make them faster is a win :)
The vast majority of Linux kernel performance improvement patches probably have way less of a real world impact than this.
unlikely given that the number they are multiplying by every improvement is far higher than "times jq is run in some pipeline". Even 0.1% improvement in kernel is probably far far higher impact than this
For about a month now I've been working on a suite of tools for dealing with JSON specifically written for the imagined audience of "for people who like CLIs or TUIs and have to deal with PILES AND PILES of JSON and care deeply about performance".
For me, I've been writing them just because it's an "itch". I like writing high performance/efficient software, and there's a few gaps that it bugged me they existed, that I knew I could fill.
I'm having fun and will be happy when I finish, regardless, but it would be so cool if it happened to solve a problem for someone else.
You could probably do something similar for a faster jq.
> The query language is deliberately less expressive than jq's. jsongrep is a search tool, not a transformation tool-- it finds values but doesn't compute new ones. There are no filters, no arithmetic, no string interpolation.
Mind me asking what sorts of TB json files you work with? Seems excessively immense.
> Hadoop: bro
> Spark: bro
> hive: bro
> data team: bro
<https://adamdrake.com/command-line-tools-can-be-235x-faster-...>
Command-line Tools can be 235x Faster than your Hadoop Cluster (2014)
Conclusion: Hopefully this has illustrated some points about using and abusing tools like Hadoop for data processing tasks that can better be accomplished on a single machine with simple shell commands and tools.I'm sure there are reasons against switching to something more efficient–we've all been there–I'm just surprised.
I'm not OP,but structured JSON logs can easily result in humongous ndjson files, even with a modest fleet of servers over a not-very-long period of time.
I'd probably just shove it all into Postgres, but even a multi terabyte SQLite database seems more reasonable.
Even if it's once off, some people handle a lot of once-offs, that's exactly where you need good CLI tooling to support it.
Sure jq isn't exactly super slow, but I also have avoided it in pipelines where I just need faster throughput.
rg was insanely useful in a project I once got where they had about 5GB of source files, a lot of them auto-generated. And you needed to find stuff in there. People were using Notepad++ and waiting minutes for a query to find something in the haystack. rg returned results in seconds.
The comment I was replying to implied this was something more regular.
EDIT: why is this being downvoted? I didn't think I was rude. The person I responded to made a good point, I was just clarifying that it wasn't quite the situation I was asking about.
If you work at a hyperscaler, service log volume borders on the insane, and while there is a whole pile of tooling around logs, often there's no real substitute for pulling a couple of terabytes locally and going to town on them.
Fully agree. I already know the locations of the logs on-disk, and ripgrep - or at worst, grep with LC_ALL=C - is much, much faster than any aggregation tool.
If I need to compare different machines, or do complex projections, then sure, external tooling is probably easier. But for the case of “I know roughly when a problem occurred / a text pattern to match,” reading the local file is faster.
- Someone likes tool X
- Figures, that they can vibe code alternative
- They take Rust for performance or FAVORITE_LANG for credentials
- Claude implements small subset of features
- Benchmark subset
- Claim win, profit on showcase
Note: this particular project doesn't have many visible tells, but there's pattern of overdocumentation (17% comment-to-code ratio, >1000 words in README, Claude-like comment patterns), so it might be a guided process.
I still think that the project follows the "subset is faster than set" trend.
Usually, a perceptive user/technical mind is able to tweak their usage of the tools around their limitations, but if you can find a tool that doesn't have those limitations, it feels far more superior.
The only place where ripgrep hasn't seeped into my workflow for example, is after the pipe and that's just out of (bad?) habit. So much so, sometimes I'll do this foolishly rg "<term>" | grep <second filter>; then proceed to do a metaphoric facepalm on my mind. Let's see if jg can make me go jg <term> | jq <transformation> :)
Prioritizing SEO-ing speed over supporting the same features/syntax (especially without an immediately prominent disclosure of these deficiencies) = marketing bullshit
A faster jq except it can't do what jq does... maybe I can use this as a pre-filter when necessary.
(Honestly, who even still writes shell scripts? Have a coding agent write the thing in a real scripting language at least, they aren't phased by the boilerplate of constructing pipelines with python or whatever. I haven't written a shell script in over a year now.)
Plus, for any script that’s going to be fetching or posting anything over a network, the LLM will almost certainly want to include requests, so now you either have to deal with dependencies, or make it use urllib.
In contrast, there’s an extremely high likelihood of the environment having a POSIX-compatible interpreter, so as long as you don’t use bash-isms (or zsh-isms, etc.), the script will probably work. For network access, the odds of it having curl are also quite high, moreso (especially in containers) than Python.
But every now and then a well-optimised tool/page comes along with instant feedback and is a real pleasure to use.
I think some people are more affected by that than others.
Obligatory https://m.xkcd.com/1205
If jq is something you run a few times by hand, a "faster jq" is about as compelling as a faster toaster. A lot of these tools still get traction because speed is an easy pitch, and because some team hit one ugly bottleneck in CI or a data pipeline and decided the old tool was now unacceptable.
However, as someone who always loved faster software and being an optimisation nerd, hat's off!
If you don't mind me asking, which yq? There's a Go variant and a Python pass-through variant, the latter also including xq and tomlq.
It looks like jaq has already progressed much further in the right direction than jsongrep has just started in the not-quite-as-right direction.
Unedited vibe documentation is unforgivable.
I gave instruction to Claude to add a toggle button to a website where the value needs to be stored in local storage.
It is a very straightforward change. Just follow exactly how it is done for a different boolean setting and you are set. An intern can do that on the first day of their job.
Everything is done properly except that on page load, the stored setting is not read.
Which can be easily discovered if the author, with or without AI tools, has a test or manually goes through the entire workflow just once. I discovered the problem myself and fixed it.
Setting all of that aside -- even if this is not AI coded, at the least it shows the site owner doesn't have the basic care for its visitors to go through this important workflow to check if everything works properly.
And who cares if it's vibe-coded or not. Since when do we care more on the how than on the what? Are people looking at how a tool was coded before using it, as if it would accelerate confidence?
Also, there are lots of charts without comparison so the numbers mean nothing...
Had to spend some efforts to set up completions, also there some small rough edges around commands discoverability, but anyway, much better than the previous oh-my-zsh setup
Ideally, wish it also had a flag to enforce users to write type annotations + compiling scripts as static binaries + a TUI library, and then I'd seriously consider it for writing small apps, but I like and appreciate it in the current state already
Second, some comments on the presentation: the horizontal violin graphs are nice, but all tools have the same colours, and so it's just hard to even spot where jsongrep is. I'd recommend grouping by tool and colour coding it. Besides, jq itself isn't in the graphs at all (but the title of the post made me think it would be!).
Last, xLarge is a 190MiB file. I was surprised by that. It seems too low for xLarge. I daily check 400MiB json documents, and sometimes GiB ones.
[0]: https://catalog.data.gov/dataset/?res_format=JSON
[1]: https://catalog.data.gov/dataset/crimes-2001-to-present
It's just sparkling memory safe high performance software