perf/migrations/README.md - buildbot - Git at Google

 # SQL Migrations

 Pref can use SQL backends to store both trace data and other data like shortcuts
 and alerts. We need to have a system in place that allows changing the schema of
 the database and also upgrading an existing database to the schema that the
 version of Perf expects. To do that we use the
 [`github.com/golang-migrate/migrate/v4`](https://pkg.go.dev/github.com/golang-migrate/migrate/v4?tab=overview)
 library.

 Each directory below here represents a supported SQL dialect. Note that the
 directory names should match the values of sql.Dialect. Each directory contains
 a series of SQL files that migrate the database schema from one version to the
 next. The version number is the 0-padded prefix of each file. Also note that
 there is both an `.up.` and `.down.` version of each migration, so we can
 smoothly migrate in both directions. There are also tests that ensure that the
 migrations work in both directions.
	# SQL Migrations

	Pref can use SQL backends to store both trace data and other data like shortcuts
	and alerts. We need to have a system in place that allows changing the schema of
	the database and also upgrading an existing database to the schema that the
	version of Perf expects. To do that we use the
	[`github.com/golang-migrate/migrate/v4`](https://pkg.go.dev/github.com/golang-migrate/migrate/v4?tab=overview)
	library.

	Each directory below here represents a supported SQL dialect. Note that the
	directory names should match the values of sql.Dialect. Each directory contains
	a series of SQL files that migrate the database schema from one version to the
	next. The version number is the 0-padded prefix of each file. Also note that
	there is both an `.up.` and `.down.` version of each migration, so we can
	smoothly migrate in both directions. There are also tests that ensure that the
	migrations work in both directions.