> ## Documentation Index
> Fetch the complete documentation index at: https://docs.artbucket.io/llms.txt
> Use this file to discover all available pages before exploring further.

# 0008: Migrations are only added, and run on start

> Accepted, v0.9.

## Context

Self-hosters skip versions. An upgrade that needs a manual step per version
is an upgrade that doesn't happen.

## Decision

The server applies every migration it has that the database doesn't, in
order, in one transaction, under an advisory lock, before serving. Released
migrations are never edited. CI fails a pull request that edits one, that
changes the schema without one, or whose migrations don't take the base
branch's database, filled with rows, to the new schema.

## Consequences

* Any release upgrades from any earlier one by starting it.
* Destructive schema changes take two releases: stop using, then drop.
* `scripts/upgrade-fixture.sql` has to be kept in step with the schema.