wrench

README

wrench

wrench is a schema management tool for Cloud Spanner.

Please feel free to report issues and send pull requests, but note that this application is not officially supported as part of the Cloud Spanner product.

$ cat ./_examples/schema.sql
CREATE TABLE Singers (
  SingerID STRING(36) NOT NULL,
  FirstName STRING(1024),
) PRIMARY KEY(SingerID);

# create database with ./_examples/schema.sql
$ wrench create --directory ./_examples

# create migration file
$ wrench migrate create --directory ./_examples
_examples/migrations/000001.sql is created

# edit _examples/migrations/000001.sql
$ cat ./_examples/migrations/000001.sql
ALTER TABLE Singers ADD COLUMN LastName STRING(1024);

# execute migration
$ wrench migrate up --directory ./_examples

# load ddl from database to file ./_examples/schema.sql
$ wrench load --directory ./_examples

# show time and date of migrations
$ wrench migrate history
Version	Dirty	Created					Modified
1	false	2020-06-16 08:07:11.763755 +0000 UTC	2020-06-16 08:07:11.76998 +0000 UTC

# finally, we have successfully migrated database!
$ cat ./_examples/schema.sql
CREATE TABLE Singers (
  SingerID STRING(36) NOT NULL,
  FirstName STRING(1024),
  LastName STRING(1024),
) PRIMARY KEY(SingerID);

CREATE TABLE SchemaMigrations (
  Version INT64 NOT NULL,
  Dirty BOOL NOT NULL,
) PRIMARY KEY(Version);

CREATE TABLE SchemaMigrationsHistory (
  Version INT64 NOT NULL,
  Dirty BOOL NOT NULL,
  Created TIMESTAMP NOT NULL OPTIONS (
    allow_commit_timestamp = true
  ),
  Modified TIMESTAMP NOT NULL OPTIONS (
    allow_commit_timestamp = true
  ),
) PRIMARY KEY(Version);

Installation

Get binary from release page. Or, you can use Docker container: mercari/wrench.

Usage

Prerequisite

export SPANNER_PROJECT_ID=your-project-id
export SPANNER_INSTANCE_ID=your-instance-id
export SPANNER_DATABASE_ID=your-database-id

You can also specify project id, instance id and database id by passing them as command arguments.

Create database

$ wrench create --directory ./_examples

This creates the database with ./_examples/schema.sql.

Drop database

$ wrench drop

This just drops the database.

Reset database

wrench reset --directory ./_examples

This drops the database and then re-creates with ./_examples/schema.sql. Equivalent to drop and then create.

Load schema from database to file

$ wrench load --directory ./_examples

This loads schema DDL from database and writes it to ./_examples/schema.sql.

Create migration file

$ wrench migrate create --directory ./_examples

This creates a next migration file like _examples/migrations/000001.sql. You will write your own migration DDL to this file.

You can optionally set $WRENCH_SEQUENCE_INTERVAL or pass --sequence_interval with an integer e.g. 10 which will be used to generate the next sequence number by rounding up to the next sequence interval.

$ wrench migrate create --sequence_interval 10

This will create migration scripts like 000010.sql, 000020.sql, 000030.sql etc. These gaps allow hotfixes to be inserted into the sequence if needed.

Execute migrations

$ wrench migrate up --directory ./_examples

This executes migrations. This also creates SchemaMigrations & SchemaMigrationsHistory tables in your database to manage schema version if it does not exist.

Migrations history

$ wrench migrate history

This displays the history of migrations applied to your database, ordered by when they were first attempted. Migrations left in a dirty state and subsequently retried are reflected in the Modified timestamp.

Apply single DDL/DML

$ wrench apply --ddl ./_examples/ddl.sql

This applies single DDL or DML.

Use wrench [command] --help for more information about a command.

Onboarding existing databases to wrench

This fork of wrench uses two additional tables for tracking migrations, SchemaMigrationsHistory for all scripts applied and SchemaMigrationsLock to limit wrench migrations to a single invocation. If coming from a database managed by golang-migrate or the original wrench project then you will already have a SchemaMigrations table and no work is needed. You can proceed to use this version of wrench and during the next migration it will detect that the SchemaMigrationsHistory table is missing, then create and backfill the "history" data. Subsequent migrate up invocations will use the history table instead of the SchemaMigrations table to detect unapplied migrations.

If you have an existing database that is not controlled by any migration tools then you should export the current schema (you can use wrench load) and use this as the baseline version by saving as 000001.sql and manually creating a SchemaMigrations table with a 1 entry. This will initiate the backfill process, skipping the migration for existing databases but recreating for new databases.

Contributions

Please read the contribution guidelines before submitting pull requests.

License

Copyright 2019 Mercari, Inc.

Licensed under the MIT License.