58 lines
1.7 KiB
Markdown
58 lines
1.7 KiB
Markdown
# Migrate
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[](https://travis-ci.org/remind101/migrate)
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Migrate is a Go library for doing migrations. It's stupidly simple and gets out of your way.
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## Features
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* It's only dependency is `database/sql`.
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* It supports any type of migration you want to run (e.g. raw sql, or Go code).
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* It doesn't provide a command. It's designed to be embedded in projects and used exclusively as a library.
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## Usage
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```go
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migrations := []migrate.Migration{
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{
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ID: 1,
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Up: func(tx *sql.Tx) error {
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_, err := tx.Exec("CREATE TABLE people (id int)")
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return err
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},
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Down: func(tx *sql.Tx) error {
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_, err := tx.Exec("DROP TABLE people")
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return err
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},
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},
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{
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ID: 2,
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// For simple sql migrations, you can use the migrate.Queries
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// helper.
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Up: migrate.Queries([]string{
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"ALTER TABLE people ADD COLUMN first_name text",
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}),
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Down: func(tx *sql.Tx) error {
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// It's not possible to remove a column with
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// sqlite.
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_, err := tx.Exec("SELECT 1 FROM people")
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return err
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},
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},
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}
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db, _ := sql.Open("sqlite3", ":memory:")
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_ = migrate.Exec(db, migrate.Up, migrations...)
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```
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### Locking
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All migrations are run in a transaction, but if you attempt to run a single long running migration concurrently, you could run into a deadlock. For Postgres connections, `migrate` can use [pg_advisory_lock](http://www.postgresql.org/docs/9.1/static/explicit-locking.html) to ensure that only 1 migration is run at a time.
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To use this, simply instantiate a `Migrator` instance using `migrate.NewPostgresMigrator`:
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```go
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migrator := NewPostgresMigrator(db)
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_ = migrator.Exec(migrate.Up, migrations...)
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```
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