migration tools

May 10, 2022



migra is a schema diff tool for Postgres, written in Python. Use it in your python scripts, or from the command line like this:

$ migra postgresql:///a postgresql:///b
alter table "public"."products" add column newcolumn text;

alter table "public"."products" add constraint "x" CHECK ((price > (0)::numeric));

migra magically figures out all the statements required to get from A to B.

Most features of PostgreSQL are supported.

Schema migrations are without doubt the most cumbersome and annoying part of working with SQL databases. So much so that some people think that schemas themselves are bad!

But schemas are actually good. Enforcing data consistency and structure is a good thing. It’s the migration tooling that is bad, because it’s harder to use than it should be. migra is an attempt to change that, and make migrations easy, safe, and reliable instead of something to dread.



Goose is a database migration tool. Manage your database schema by creating incremental SQL changes or Go functions.



ent's underlying migration tool

Atlas DDL is a declarative, Terraform-like configuration language designed to capture an organization’s data topology. Currently, it supports defining schemas for SQL databases such as MySQL, Postgres, SQLite and MariaDB.

how it handles migration conflicts: https://entgo.io/blog/2022/05/09/versioned-migrations-sum-file/

The atlas.sum file contains a sum of the whole directory as its first entry, and a checksum for each of the migration files (implemented by a reverse, one branch merkle hash tree)... As you can see the atlas.sum file contains one entry for each migration file generated. With the atlas.sum generation file enabled, both Team A and Team B will have such a file once they generate migrations for a schema change. Now the version control will raise a merge conflict once the second Team attempts to merge their feature.

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