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Comment by petepete | Hacker News Reader

> about their test environment having the ability to automatically fork the database for every new test run, such that they could easily "revert" (in their case ignore/walk away from) the database after a test run

I think this should be really straightforward by using one database as a template for another. This is how Postgres's create database works and it defaults to Template1

https://www.postgresql.org/docs/current/manage-ag-templatedb...

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The intention of pg_branch is to optimize this process. They mention two problems:

1. The template database can't have active connections during the CREATE DATABASE process.

2. The CREATE DATABASE from a template database can be slow for large DBs.

> The template database can't have active connections during the CREATE DATABASE process.

Why would that be a problem ?

If you are trying to branch prod (or even a staging db) then you can't

Right. But the obvious solution is to just not do that. Create a template and base production/staging off it, then use that template. Or use the same bootstrap/migration process to create the template as you do staging.

Regular tests shouldn’t assume access to staging/prod, anyway.

So how do you test your migration? Will work fine with 10 records but perhaps not with 10 million.

I don’t consider that “a regular test” but something db-specific that would have a custom workflow.

Eliminating "custom workflows" seems like rather the point of such an extension.

Run it in a transaction, and if it fails, abort the transaction. nbd, did this for years in prod. Discovered some interesting assumptions about sequential IDs in the DB tests while running it against prod under peak load, too!

If you have lots of data, this can take some time

The appeal of this project is that it uses CoW (copy on write), so in theory it should be fast to copy as it only maintains writes.

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