srittau / dbupgrade

Database Upgrading Framework

dbupgrade

Database Migration Tool

Basic Usage

Usage: dbupgrade [OPTIONS] [-l API_LEVEL|-L] DBNAME SCHEMA DIRECTORY

Upgrade the given SCHEMA in the database specified as DBNAME with SQL scripts from DIRECTORY. DIRECTORY is searched for all files with the .sql suffix. These files are SQL scripts with a special header sections:

-- Schema: my-db-schema
-- Version: 25
-- API-Level: 3
-- Dialect: postgres

CREATE TABLE ...

The following headers are required:

• Schema
  Name of the schema to update.
• Dialect
  Database dialect of this script. Use SQLalchemy's database URL scheme identifier, e.g. postgres or sqlite.
• Version
  The new version of the schema after this script was applied. It is an error if two scripts have the same schema, dialect, and version.
• API-Level
  The new API level of the schema after this script was applied. For a given schema, the API level of a subsequent version must either be equal or higher by one than the API level of the preceding version. For example, if script version 44 has API level 3, script version 45 must have API level 3 or 4.
• Transaction (optional)
  Possible values are yes (default) and no. When this header is yes, all statements of a single upgrade file and the corresponding version upgrade statements are executed within a single transaction. Otherwise each statement is executed separately. The former is usually preferable so that all changes will be rolled back if a script fails to apply, but the latter is required in some cases.

The database must contain a table db_config with three columns: schema, version, and api_level. If this table does not exist, it is created. This table must contain exactly one row for the given schema. If this row does not exist, it is created with version and api_level initially set to 0.

The current version and API level of the schema are requested from the database and all scripts with a higher version number are applied, in order. If there are any version numbers missing, the script will stop after the last version before the missing version.

Unless the -l or -L option is supplied, only scripts that do not increase the API level will be applied. If the -l option is given, all scripts up to the given API level will be applied. -L will apply all scripts without regard to the API level.

Each script is executed in a seperate transaction. If a script fails, all changes in that script will be rolled back and the script will stop with an error message and a non-zero return status.

JSON Output

When supplying the --json option, dbupgrade will information about the applied scripts as JSON to the standard output. Sample output:

{
  "success": true,
  "oldVersion": {
    "version": 123,
    "apiLevel": 15
  },
  "newVersion": {
    "version": 125,
    "apiLevel": 16
  },
  "appliedScripts": [
    {
      "filename": "0124-create-foo.sql",
      "version": 124,
      "apiLevel": 15
    },
    {
      "filename": "0125-delete-bar-sql",
      "version": 125,
      "apiLevel": 16
    }
  ],
  "failedScript": {
    "filename": "0126-change-stuff.sql",
    "version": 126,
    "apiLevel": 16
  }
}

success is true if all scripts were applied successfully or no scripts were to be applied. In this case, the failedScript key is not defined. The appliedScripts key is always defined. In case no scripts were applied, it's an empty array.

dbupgrade's Issues

Is dbupgrade's database schema migration concurrent safe (between 2 instances of dbupgrade running at the same time) ?