migrate package - github.com/rubenv/sql-migrate - Go Packages (original) (raw)

SQL Schema migration tool for Go.

Key features:

Installation

To install the library and command line program, use the following:

go get -v github.com/rubenv/sql-migrate/...

Command-line tool

The main command is called sql-migrate.

$ sql-migrate --help usage: sql-migrate [--version] [--help] []

Available commands are: down Undo a database migration new Create a new migration redo Reapply the last migration status Show migration status up Migrates the database to the most recent version available

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:

development: dialect: sqlite3 datasource: test.db dir: migrations/sqlite3

production: dialect: postgres datasource: dbname=myapp sslmode=disable dir: migrations/postgres table: migrations

The `table` setting is optional and will default to `gorp_migrations`.

The environment that will be used can be specified with the -env flag (defaults to development).

Use the --help flag in combination with any of the commands to get an overview of its usage:

$ sql-migrate up --help Usage: sql-migrate up [options] ...

Migrates the database to the most recent version available.

Options:

-config=config.yml Configuration file to use. -env="development" Environment. -limit=0 Limit the number of migrations (0 = unlimited). -dryrun Don't apply migrations, just print them.

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.

The redo command will unapply the last migration and reapply it. This is useful during development, when you're writing migrations.

Use the status command to see the state of the applied migrations:

$ sql-migrate status +---------------+-----------------------------------------+ | MIGRATION | APPLIED | +---------------+-----------------------------------------+ | 1_initial.sql | 2014-09-13 08:19:06.788354925 +0000 UTC | | 2_record.sql | no | +---------------+-----------------------------------------+

MySQL Caveat

If you are using MySQL, you must append ?parseTime=true to the datasource configuration. For example:

production: dialect: mysql datasource: root@/dbname?parseTime=true dir: migrations/mysql table: migrations

See https://github.com/go-sql-driver/mysql#parsetime for more information.

Library

Import sql-migrate into your application:

import "github.com/rubenv/sql-migrate"

Set up a source of migrations, this can be from memory, from a set of files or from bindata (more on that later):

// Hardcoded strings in memory: migrations := &migrate.MemoryMigrationSource{ Migrations: []*migrate.Migration{ &migrate.Migration{ Id: "123", Up: []string{"CREATE TABLE people (id int)"}, Down: []string{"DROP TABLE people"}, }, }, }

// OR: Read migrations from a folder: migrations := &migrate.FileMigrationSource{ Dir: "db/migrations", }

// OR: Use migrations from bindata: migrations := &migrate.AssetMigrationSource{ Asset: Asset, AssetDir: AssetDir, Dir: "migrations", }

Then use the Exec function to upgrade your database:

db, err := sql.Open("sqlite3", filename) if err != nil { // Handle errors! }

n, err := migrate.Exec(db, "sqlite3", migrations, migrate.Up) if err != nil { // Handle errors! } fmt.Printf("Applied %d migrations!\n", n)

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.

The full set of capabilities can be found in the API docs below.

Writing migrations

Migrations are defined in SQL files, which contain a set of SQL statements. Special comments are used to distinguish up and down migrations.

-- +migrate Up -- SQL in section 'Up' is executed when this migration is applied CREATE TABLE people (id int);

-- +migrate Down -- SQL section 'Down' is executed when this migration is rolled back DROP TABLE people;

You can put multiple statements in each block, as long as you end them with a semicolon (;).

If you have complex statements which contain semicolons, use StatementBegin and StatementEnd to indicate boundaries:

-- +migrate Up CREATE TABLE people (id int);

-- +migrate StatementBegin CREATE OR REPLACE FUNCTION do_something() returns void AS DECLAREcreatequerytext;BEGIN−−DosomethinghereEND;DECLARE create_query text; BEGIN -- Do something here END;DECLAREcreateq​uerytext;BEGIN−−DosomethinghereEND; language plpgsql; -- +migrate StatementEnd

-- +migrate Down DROP FUNCTION do_something(); DROP TABLE people;

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.

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:

-- +migrate Up notransaction CREATE UNIQUE INDEX people_unique_id_idx CONCURRENTLY ON people (id);

-- +migrate Down DROP INDEX people_unique_id_idx;

Embedding migrations with packr

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.

Just write your migration files as usual, as a set of SQL files in a folder.

Use the PackrMigrationSource in your application to find the migrations:

migrations := &migrate.PackrMigrationSource{ Box: packr.NewBox("./migrations"), }

If you already have a box and would like to use a subdirectory:

migrations := &migrate.PackrMigrationSource{ Box: myBox, Dir: "./migrations", }

Embedding migrations with bindata

As an alternative, but slightly less maintained, you can use bindata (https://github.com/shuLhan/go-bindata) to embed the migration files.

Just write your migration files as usual, as a set of SQL files in a folder.

Then use bindata to generate a .go file with the migrations embedded:

go-bindata -pkg myapp -o bindata.go db/migrations/

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).

Use the AssetMigrationSource in your application to find the migrations:

migrations := &migrate.AssetMigrationSource{ Asset: Asset, AssetDir: AssetDir, Dir: "db/migrations", }

Both Asset and AssetDir are functions provided by bindata.

Then proceed as usual.

Extending

Adding a new migration source means implementing MigrationSource.

type MigrationSource interface { FindMigrations() ([]*Migration, error) }

The resulting slice of migrations will be executed in the given order, so it should usually be sorted by the Id field.

This section is empty.

Execute a set of migrations

Returns the number of applied migrations.

Execute a set of migrations with an input context.

Returns the number of applied migrations.

Execute a set of migrations

Will apply at most `max` migrations. Pass 0 for no limit (or use Exec).

Returns the number of applied migrations.

Execute a set of migrations with an input context.

Will apply at most `max` migrations. Pass 0 for no limit (or use Exec).

Returns the number of applied migrations.

Execute a set of migrations

Will apply at the target `version` of migration. Cannot be a negative value.

Returns the number of applied migrations.

Execute a set of migrations with an input context.

Will apply at the target `version` of migration. Cannot be a negative value.

Returns the number of applied migrations.

func SetDisableCreateTable(disable bool)

SetDisableCreateTable sets the boolean to disable the creation of the migration table

func SetIgnoreUnknown(v bool)

SetIgnoreUnknown sets the flag that skips database check to see if there is a migration in the database that is not in migration source.

This should be used sparingly as it is removing a safety check.

SetSchema sets the name of a schema that the migration table be referenced.

Set the name of the table used to store migration info.

Should be called before any other call such as (Exec, ExecMax, ...).

Skip a set of migrations

Will skip at most `max` migrations. Pass 0 for no limit.

Returns the number of skipped migrations.

Migrations from a bindata asset set.

type EmbedFileSystemMigrationSource struct { FileSystem embed.FS

Root [string](/builtin#string)

}

A set of migrations loaded from an go1.16 embed.FS

type FileMigrationSource struct { Dir string }

A set of migrations loaded from a directory.

func (f FileMigrationSource) FindMigrations() ([]*Migration, error)

type HttpFileSystemMigrationSource struct { FileSystem http.FileSystem }

type MemoryMigrationSource struct { Migrations []*Migration }

A hardcoded set of migrations, in-memory.

func ToApply(migrations []Migration, current string, direction MigrationDirection) []Migration

Filter a slice of migrations into ones that should be applied.

func (m Migration) NumberPrefixMatches() []string

type MigrationDirection int

type MigrationRecord struct { Id string db:"id" AppliedAt time.Time db:"applied_at" }

type MigrationSet struct {

TableName [string](/builtin#string)

SchemaName [string](/builtin#string)


IgnoreUnknown [bool](/builtin#bool)

DisableCreateTable [bool](/builtin#bool)

}

MigrationSet provides database parameters for a migration execution

Returns the number of applied migrations.

Returns the number of applied migrations.

Returns the number of applied migrations.

Returns the number of applied migrations, but applies with an input context.

Returns the number of applied migrations.

Plan a migration to version.

type MigrationSource interface {

FindMigrations() ([]*[Migration](#Migration), [error](/builtin#error))

}

Avoids pulling in the packr library for everyone, mimicks the bits of packr.Box that we need.

type PackrMigrationSource struct { Box PackrBox

Dir [string](/builtin#string)

}

Migrations from a packr box.

type PlanError struct { Migration *Migration ErrorMessage string }

PlanError happens where no migration plan could be created between the sets of already applied migrations and the currently found. For example, when the database contains a migration which is not among the migrations list found for an operation.

type PlannedMigration struct { *Migration

DisableTransaction [bool](/builtin#bool)
Queries            [][string](/builtin#string)

}

Plan a migration to version.

func ToCatchup(migrations, existingMigrations []*Migration, lastRun Migration) []PlannedMigration

type TxError struct { Migration *Migration Err error }

TxError is returned when any error is encountered during a database transaction. It contains the relevant *Migration and notes it's Id in the Error function output.