gh-ost VS janet

I’ve been through multiple incidents where everything worked fine in the testing environment but ended up locking the production database for minutes when deployed. A category of open-source tools called OSC (Online Schema Change) exists to mitigate such pain, like gh-ost used by GitHub and OSC used by Meta. They work by creating a set of "ghost tables" to apply the migrations, copy over old data from the original tables, and catch up with new writes simultaneously. When all old data is migrated, you can trigger a cutover to make the "ghost tables" production. Check the post below for a great introduction and comparison:

Sounds like it's basically explained in the gh-ost readme https://github.com/github/gh-ost#how

I think it amounts to "use views to decouple access to the table with a fixed interface" and "use triggers for migrating data between tables"

Gh-ost is the new hotness. Simple to use and lots of great features: https://github.com/github/gh-ost

As they have said it depends on the size of the table on disk and the number of rows, but an alter in production is not difficult to last from seconds to days. I don't know if you are doing the alter as is but try to check https://docs.percona.com/percona-toolkit/pt-online-schema-change.html or https://github.com/github/gh-ost , they usually simplify a lot the alters.

Not sure which version of MySQL you're using, but one approach would be to use a tool like pt-online-schema-change (from Percona) or g-host -- which will create a duplicate table and then swap it in place of the original table. It's a safer approach when operating in production environments. Here's a good comparison of the tools many people use https://planetscale.com/docs/learn/online-schema-change-tools-comparison

Actually I never tried but I was scared by the small print of GH not using RDS themselves [1] and Ghost relying on lower-level features that might be not easily available in RDS. Also I had the impression you have to setup a normal non-RDS replica attached to your RDS master?

[1] https://github.com/github/gh-ost/blob/master/doc/rds.md

MySQL has some robust tooling in this space. Some of the tools use triggers to copy to a new table. GitHub's gh-ost[1] is probably the state of the art, and uses the binary log stream to replicate the data.

[1] https://github.com/github/gh-ost

https://github.com/github/gh-ost/issues/331#issuecomment-266...) it does become a little bit of a "you do not have google problems" type discussion.

(Perhaps you do have such problems, I don't know where you work! But 99%+ of companies don't have such problems and never will.)

GitHub doesn't use foreign keys[1], and there's likely many tables related to all the users, notifications, permissions, etc... that would need to be cleaned up. Without foreign keys they likely have some system process that does this instead of a simple `DELETE FROM` which cascades.

1. https://github.com/github/gh-ost/issues/331#issuecomment-266...

I like Clojure, but I never had any good opportunities to use it other than for a few small hobby projects. It is unfortunate that it is so huge with tons of dependencies and no simpler native implementation. I started looking at various LISPs and Schemes to find something lighter to use instead and ended up settling for Janet that I think is Clojure-like enough to be comfortable to use, but in a small native binary with no dependencies and can be embedded in other native programs. I am sure for big, real, projects that Clojure makes more sense, but for my hobby projects and scripts I do not think I will install it again. I am still happy for the things I learned from learning Clojure. It was a real eye-opener for an old OO-programmer.

https://janet-lang.org/

One might also check out Janet for quick scripting tasks.

https://janet-lang.org

Thanks!

I thought about another multiplatform, homoiconic, highly compact language: https://janet-lang.org/ (takes 803 kb on my machine).

It has no types though.

Racket is great, and if you like it you might find Rash interesting:

https://rash-lang.org/

Janet and Gerbil Scheme are also worth a look:

https://janet-lang.org/

https://cons.io/

If this project interests you but is a bit more minimal than you need, the Janet language is a slightly-less but still pretty lightweight embeddable Lisp with a strong library and community: https://janet-lang.org/

Scripting language of choice for WWWW became Janet. Technically, it's Lisp. Raw Lisp still adds plenty of overhead, making it not much better than JSON. That's when WDL was born.

But you can try Janet for fun https://janet-lang.org/