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Episode 3 - Decoupling Database Migrations at Application Startup

13 mins
  • Data models change and evolve with your application.
  • There’s plenty of tools that keep track of database schemas and automatically generate scripts to upgrade or downgrade them.
  • It’s common for developers to run a migration at the start of their app before running app code.
  • Our author explains two common problems with this approach.
    1. Modern day production deployments and horizontal scaling can get you into a race condition.
    2. You start assuming that new code will only ever run with the new schema.
  • You can decouple migrations from code changes by disabling parallelism during this time.
  • Make it a separate command or lock the database during the upgrade.
  • We can easily implement locking ourselves in any language.
    • Use Redis locks if you’re ok with something external to the DB.
    • Use the DB itself by writing to an extra table to say that you’re upgrading it.
  • Plan your deployment appropriately so you can run old code with new by making migrations additive in the short term.
  • Using a script at startup that optionally performs the migration based on an environment variable integrates wel with Docker and cloud services.
  • Upgrades of both code and data should be part of your testing BEFORE releasing to production.
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Episode 2 - Writing README files

13 mins
2020-01-26 documentation
  • What’s a README?
  • Modern day added formatting. Mostly Markdown, sometimes Restructured Text.
  • What to include in a README?
    • Name the project
    • Intro / Summary / Overview
    • Prerequisites
    • Installation instructions
    • Usage instructions
    • Contribution instructions.
    • Credit for important contributors.
    • Acknowledgments of projects you based yours on.
    • Ways to communicate with you or the community.
    • License information.
    • Project status information in the form of badges.
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Episode 0 - Introductions

3 mins
2020-01-12
Our first episode introducing the podcast. We’ll go over the motivation and what to expect of the coming episodes.
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