hammer

hammer is a command-line tool to schema management for Google Cloud Spanner.

Installation

Download the single-binary executable from:

https://github.com/daichirata/hammer/releases

or

$ go install github.com/daichirata/hammer@latest

Usage

$ hammer -h
hammer is a command-line tool to schema management for Google Cloud Spanner.

Usage:
  hammer [command]

Examples:

* Export spanner schema
  hammer export spanner://projects/projectId/instances/instanceId/databases/databaseName > schema.sql

* Apply local schema file
  hammer apply spanner://projects/projectId/instances/instanceId/databases/databaseName /path/to/file

* Create database and apply local schema (faster than running database creation and schema apply separately)
  hammer create spanner://projects/projectId/instances/instanceId/databases/databaseName /path/to/file

* Copy database
  hammer create spanner://projects/projectId/instances/instanceId/databases/databaseName1 spanner://projects/projectId/instances/instanceId/databases/databaseName2

* Compare local files
  hammer diff /path/to/file /another/path/to/file

* Compare local file against spanner schema
  hammer diff /path/to/file spanner://projects/projectId/instances/instanceId/databases/databaseName

* Compare spanner schema against spanner schema
  hammer diff spanner://projects/projectId/instances/instanceId/databases/databaseName1 spanner://projects/projectId/instances/instanceId/databases/databaseName2

Available Commands:
  apply       Apply schema
  create      Create database and apply schema
  diff        Diff schema
  export      Export schema
  help        Help about any command

Flags:
  -h, --help   help for hammer

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

The DSN must be given in the following format.

spanner://projects/{projectId}/instances/{instanceId}/databases/{databaseName}?credentials=/path/to/file.json

Param	Required	Description
projectId	true	The Google Cloud Platform project id
instanceId	true	The id of the instance running Spanner
databaseName	true	The name of the Spanner database
credentials	false	The path to the keyfile. If not present, client will use your default application credentials.

Flags

apply, create, diff and export can accept the flags defined below

--ignore-alter-database   ignore alter database statements
--ignore-change-streams   ignore change streams statements

Examples

Suppose you have an existing SQL schema like the following:

CREATE TABLE users (
  user_id STRING(36) NOT NULL,
  email STRING(MAX),
) PRIMARY KEY(user_id);

And you want "upgrade" your schema to the following:

CREATE TABLE users (
  user_id STRING(36) NOT NULL,
  email STRING(MAX) NOT NULL,
  age INT64,
  name STRING(MAX) NOT NULL,
) PRIMARY KEY(user_id);
CREATE INDEX idx_users_name ON users (name);

Hammer changes the schema by applying the following SQL to the spanner:

hammer diff old.sql new.sql

UPDATE users SET email = '' WHERE email IS NULL;
ALTER TABLE users ALTER COLUMN email STRING(MAX) NOT NULL;
ALTER TABLE users ADD COLUMN age INT64;
ALTER TABLE users ADD COLUMN name STRING(MAX) NOT NULL DEFAULT ("");
ALTER TABLE users ALTER COLUMN name DROP DEFAULT;
CREATE INDEX idx_users_name ON users(name);

• When altering a nullable column to add the NOT NULL attribute, hammer update the column with the default value, and then add the NOT NULL attribute. (e.g. email)
• When adding a column with the NOT NULL attribute without the DEFAULT attribute, hammer add a default value to the column implicitly, and then drop the DEFAULT attribute. (e.g. name)

LICENSE

Unless otherwise noted, the hammer source files are distributed under the MIT License found in the LICENSE file.