How to manage schema migrations (track database changes)

A list. Alternatives to the popular/enterprise options:

• DBIx::Class::Migration - Perl. works but fiddly

• App::JESP - Perl. Simpler

• Flyway - popular

• Liquibase - popular

• MyBatis migrations - popular

• DBDeploy - popular

• Active Record Migrations - Ruby?

• Squitch - standalone

• Skeema - stands out

How to use DBIx::Class::Migration

There is a tutorial (note: links are broken), but this is a cheat sheet:

Use case A: Developing - initial setup

Step 0: Set up a database instance

Use dbdeployer, it's great.

Step 1: Generate the DBIx::Class Result classes

• dbicdump
• dbicdump -o dump_directory=lib -o components='["InflateColumn::DateTime"]' Smurf::Foo::DB 'dbi:mysql:database=foo;host=127.0.0.1;port=8022;user=msandbox;password=msandbox'
• ...this will create:
• lib/Smurf/Foo/DB.pm
• Manually add: our $VERSION = 1; to this at the end.
• lib/Smurf/Foo/DB/Result/Table1.pm, etc.

Step 2: Generate the DBIx::Class::Migration files

• dbic-migration prepare
• dbic-migration -I lib prepare --schema_class Smurf::Foo::DB --target_dir=share --dsn='dbi:mysql:database=foo;...etc'
• ...this will create:
• share/migrations/_source/deploy/1/001-auto.yml
• share/migrations/_source/deploy/1/001-auto-__VERSION.yml
• share/migrations/MySQL/deploy/1/001-auto-__VERSION.sql
• share/migrations/MySQL/deploy/1/001-auto.sql
• share/fixtures/1/conf/all_tables.json

Notes and gotchas

• If you see a definition for dbix_class_deploymenthandler_versions anywhere, i.e. in lib/Smurf/Foo/DB/Result/DbixClassDeploymenthandlerVersion.pm then you're gonna have a bad time. This could mean you accidentally ran dbicdump after dbic-migration prepare. It will cause migrations to fail when they try to create the dbix_class_deploymenthandler_versions table from both 001-auto-__VERSION.sql and 001-auto.sql

Use case B: Making changes to the database

Step 3: Make changes and update files

• Do not write any SQL
• Make changes to the DBIC classes under `lib/Smurf/Foo/DB/Result`, but DO NOT MODIFY THE FIRST PART OF THE FILE (see DBIx::Class::Schema::Loader comments in those files)
• Bump the version in `lib/Smurf/Foo/DB.pm` (or add it - at the bottom outside the auto-generated section: `our $VERSION = 2;`
• Run `dbic-migration prepare --schema_class Smurf::Foo::DB --target_dir=share --dsn='dbi:mysql:database=foo;...etc'` to create a new migration in the `share` directory
• Run `dbicdump -o dump_directory=lib -o components='["InflateColumn::DateTime"]' Smurf::Foo::DB 'dbi:mysql:database=foo;...etc'` to see if it makes any updates to the first part of the DBIC classes under `lib/Smurf/Foo/DB/Result`

Use case C: Not making changes to the database

Step 4: Install and upgrade as needed

• Run dbic-migration install --schema_class Smurf::Foo::DB --target_dir=share --dsn='dbi:mysql:database=foo;...etc'
• Run dbic-migration upgrade ...etc

Migrate everything from iPhone to Android

How to transfer all your stuff from iPhone to Android:

• Photos - install Google Photos app on iPhone and it will back up everything to the Google cloud.
• Contacts - Add a gmail account on your iPhone and configure it to sync contacts (alternatively, you could export a vCard/VCF).
• Calendar - Add a gmail account to the iPhone and configure it to sync calendar.
• Notes - Add a gmail account to the iPhone and configure it to sync notes (there are also other ways).
• SMS text messages - Use iSMS2droid
• Email - on the Android phone, go to Settings | Accounts | Add account, and choose Personal IMAP/POP3 or Exchange, according to the type of email account you have
• WhatsApp chat history - Use WhazzapMigrator (source, source)
• Apps - you will have to install new Android apps manually. Your app data will be lost unless they have their own cloud backup.

Remember to TURN OFF iMessage before you switch over, otherwise your SMS may get lost (source)

Afterward, you can easily check some of your data has been migrated at:

• photos.google.com
• contacts.google.com
• calendar.google.com
• mail.google.com - for notes, if you used that method

Finally, bask in the satisfaction that Android is better than iPhone.