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= Database migration tool

This is used to keep track of database structure, content etc, and update it when need be via deploys.

A table by default called db_versions will be created, containing a single integer.

Scripts will be placed by default in process.cwd()/dbmigration/.js

Each migration script will be ran, and the db_version increased, until no more migration scripts exists.

== Installation

npm i larvitdbmigration-pg

== Usage

=== Application startup script

In your application startup script, do something like this:

[source,javascript]

const DbMigration = require('larvitdbmigration-pg'); const Db = require('larvitdb-pg'); const dbDriver = new Db({ user: 'foo', password: 'bar', }); const dbMigration = new DbMigration({ dbDriver, tableName: 'db_version', // Optional - defaults to 'db_version' migrationScriptPath: './dbmigration', // Optional, defaults to './dbmigration' log // Optional, will use log.silly(), log.debug(), log.verbose(), log.info(), log.warn() and log.error() if given. });

dbMigration.run().then(() => { console.log('Database migrated to latest version'); }).catch(err => { throw err; });

=== Example migration scripts

Lets say the current database have a table like this:

[source,SQL]

CREATE TABLE bloj (nisse serial);

And in the next deploy we'd like to change the column name "nisse" to "hasse". For this you can do one of two methods:

==== Javascript

Create the file process.cwd()/migrationScriptPath/1.js with this content:

.migrationScriptPath/1.js [source,javascript]

'use strict';

// Always make the function async (or return a promise, they are equal) exports = module.exports = async function (options) { const { db } = options;

await db.query('ALTER TABLE bloj RENAME COLUMN nisse TO hasse;');

};

==== SQL

IMPORTANT! SQL files will be ignored if a .js file exists.

Create the file process.cwd()/migrationScriptPath/1.sql with this content:

.migrationScriptPath/1.sql [source,SQL]

ALTER TABLE bloj RENAME COLUMN nisse TO hasse;

==== Summary

Tadaaa! Now this gets done once and the version will be bumped to 1. If you then create a script named "2.js" or "2.sql" you might guess what happends. :)

== Version history

=== v0.2.0

• Updated larvitdb-pg and the requirements of the database layer

=== v0.1.3

• Fixed bug with multiple concurrent migrations hangs