mirror of https://github.com/status-im/fathom.git
290 lines
8.9 KiB
Markdown
290 lines
8.9 KiB
Markdown
# sql-migrate
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> SQL Schema migration tool for [Go](http://golang.org/). Based on [gorp](https://github.com/go-gorp/gorp) and [goose](https://bitbucket.org/liamstask/goose).
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[](https://travis-ci.org/rubenv/sql-migrate) [](https://godoc.org/github.com/rubenv/sql-migrate)
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Using [modl](https://github.com/jmoiron/modl)? Check out [modl-migrate](https://github.com/rubenv/modl-migrate).
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## Features
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* Usable as a CLI tool or as a library
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* Supports SQLite, PostgreSQL, MySQL, MSSQL and Oracle databases (through [gorp](https://github.com/go-gorp/gorp))
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* Can embed migrations into your application
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* Migrations are defined with SQL for full flexibility
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* Atomic migrations
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* Up/down migrations to allow rollback
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* Supports multiple database types in one project
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## Installation
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To install the library and command line program, use the following:
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```bash
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go get -v github.com/rubenv/sql-migrate/...
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```
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## Usage
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### As a standalone tool
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```
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$ sql-migrate --help
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usage: sql-migrate [--version] [--help] <command> [<args>]
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Available commands are:
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down Undo a database migration
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new Create a new migration
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redo Reapply the last migration
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status Show migration status
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up Migrates the database to the most recent version available
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```
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Each command requires a configuration file (which defaults to `dbconfig.yml`, but can be specified with the `-config` flag). This config file should specify one or more environments:
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```yml
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development:
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dialect: sqlite3
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datasource: test.db
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dir: migrations/sqlite3
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production:
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dialect: postgres
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datasource: dbname=myapp sslmode=disable
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dir: migrations/postgres
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table: migrations
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```
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The `table` setting is optional and will default to `gorp_migrations`.
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The environment that will be used can be specified with the `-env` flag (defaults to `development`).
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Use the `--help` flag in combination with any of the commands to get an overview of its usage:
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```
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$ sql-migrate up --help
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Usage: sql-migrate up [options] ...
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Migrates the database to the most recent version available.
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Options:
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-config=config.yml Configuration file to use.
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-env="development" Environment.
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-limit=0 Limit the number of migrations (0 = unlimited).
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-dryrun Don't apply migrations, just print them.
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```
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The `new` command creates a new empty migration template using the following pattern `<current time>-<name>.sql`.
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The `up` command applies all available migrations. By contrast, `down` will only apply one migration by default. This behavior can be changed for both by using the `-limit` parameter.
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The `redo` command will unapply the last migration and reapply it. This is useful during development, when you're writing migrations.
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Use the `status` command to see the state of the applied migrations:
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```bash
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$ sql-migrate status
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+---------------+-----------------------------------------+
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| MIGRATION | APPLIED |
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+---------------+-----------------------------------------+
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| 1_initial.sql | 2014-09-13 08:19:06.788354925 +0000 UTC |
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| 2_record.sql | no |
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+---------------+-----------------------------------------+
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```
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### MySQL Caveat
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If you are using MySQL, you must append `?parseTime=true` to the `datasource` configuration. For example:
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```yml
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production:
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dialect: mysql
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datasource: root@/dbname?parseTime=true
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dir: migrations/mysql
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table: migrations
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```
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See [here](https://github.com/go-sql-driver/mysql#parsetime) for more information.
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### As a library
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Import sql-migrate into your application:
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```go
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import "github.com/rubenv/sql-migrate"
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```
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Set up a source of migrations, this can be from memory, from a set of files or from bindata (more on that later):
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```go
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// Hardcoded strings in memory:
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migrations := &migrate.MemoryMigrationSource{
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Migrations: []*migrate.Migration{
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&migrate.Migration{
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Id: "123",
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Up: []string{"CREATE TABLE people (id int)"},
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Down: []string{"DROP TABLE people"},
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},
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},
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}
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// OR: Read migrations from a folder:
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migrations := &migrate.FileMigrationSource{
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Dir: "db/migrations",
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}
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// OR: Use migrations from a packr box
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migrations := &migrate.PackrMigrationSource{
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Box: packr.NewBox("./migrations"),
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}
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// OR: Use migrations from bindata:
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migrations := &migrate.AssetMigrationSource{
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Asset: Asset,
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AssetDir: AssetDir,
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Dir: "migrations",
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}
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```
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Then use the `Exec` function to upgrade your database:
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```go
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db, err := sql.Open("sqlite3", filename)
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if err != nil {
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// Handle errors!
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}
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n, err := migrate.Exec(db, "sqlite3", migrations, migrate.Up)
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if err != nil {
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// Handle errors!
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}
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fmt.Printf("Applied %d migrations!\n", n)
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```
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Note that `n` can be greater than `0` even if there is an error: any migration that succeeded will remain applied even if a later one fails.
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Check [the GoDoc reference](https://godoc.org/github.com/rubenv/sql-migrate) for the full documentation.
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## Writing migrations
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Migrations are defined in SQL files, which contain a set of SQL statements. Special comments are used to distinguish up and down migrations.
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```sql
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-- +migrate Up
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-- SQL in section 'Up' is executed when this migration is applied
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CREATE TABLE people (id int);
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-- +migrate Down
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-- SQL section 'Down' is executed when this migration is rolled back
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DROP TABLE people;
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```
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You can put multiple statements in each block, as long as you end them with a semicolon (`;`).
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You can alternatively set up a separator string that matches an entire line by setting `sqlparse.LineSeparator`. This
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can be used to imitate, for example, MS SQL Query Analyzer functionality where commands can be separated by a line with
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contents of `GO`. If `sqlparse.LineSeparator` is matched, it will not be included in the resulting migration scripts.
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If you have complex statements which contain semicolons, use `StatementBegin` and `StatementEnd` to indicate boundaries:
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```sql
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-- +migrate Up
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CREATE TABLE people (id int);
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-- +migrate StatementBegin
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CREATE OR REPLACE FUNCTION do_something()
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returns void AS $$
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DECLARE
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create_query text;
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BEGIN
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-- Do something here
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END;
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$$
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language plpgsql;
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-- +migrate StatementEnd
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-- +migrate Down
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DROP FUNCTION do_something();
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DROP TABLE people;
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```
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The order in which migrations are applied is defined through the filename: sql-migrate will sort migrations based on their name. It's recommended to use an increasing version number or a timestamp as the first part of the filename.
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Normally each migration is run within a transaction in order to guarantee that it is fully atomic. However some SQL commands (for example creating an index concurrently in PostgreSQL) cannot be executed inside a transaction. In order to execute such a command in a migration, the migration can be run using the `notransaction` option:
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```sql
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-- +migrate Up notransaction
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CREATE UNIQUE INDEX people_unique_id_idx CONCURRENTLY ON people (id);
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-- +migrate Down
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DROP INDEX people_unique_id_idx;
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```
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## Embedding migrations with [packr](https://github.com/gobuffalo/packr)
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If you like your Go applications self-contained (that is: a single binary): use [packr](https://github.com/gobuffalo/packr) to embed the migration files.
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Just write your migration files as usual, as a set of SQL files in a folder.
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Use the `PackrMigrationSource` in your application to find the migrations:
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```go
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migrations := &migrate.PackrMigrationSource{
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Box: packr.NewBox("./migrations"),
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}
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```
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If you already have a box and would like to use a subdirectory:
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```go
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migrations := &migrate.PackrMigrationSource{
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Box: myBox,
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Dir: "./migrations",
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}
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```
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## Embedding migrations with [bindata](https://github.com/shuLhan/go-bindata)
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As an alternative, but slightly less maintained, you can use [bindata](https://github.com/shuLhan/go-bindata) to embed the migration files.
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Just write your migration files as usual, as a set of SQL files in a folder.
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Then use bindata to generate a `.go` file with the migrations embedded:
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```bash
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go-bindata -pkg myapp -o bindata.go db/migrations/
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```
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The resulting `bindata.go` file will contain your migrations. Remember to regenerate your `bindata.go` file whenever you add/modify a migration (`go generate` will help here, once it arrives).
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Use the `AssetMigrationSource` in your application to find the migrations:
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```go
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migrations := &migrate.AssetMigrationSource{
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Asset: Asset,
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AssetDir: AssetDir,
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Dir: "db/migrations",
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}
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```
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Both `Asset` and `AssetDir` are functions provided by bindata.
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Then proceed as usual.
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## Extending
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Adding a new migration source means implementing `MigrationSource`.
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```go
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type MigrationSource interface {
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FindMigrations() ([]*Migration, error)
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}
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```
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The resulting slice of migrations will be executed in the given order, so it should usually be sorted by the `Id` field.
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## License
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This library is distributed under the [MIT](LICENSE) license.
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