Renaming Postgres index, FK, PK, sequences

cblavier · November 4, 2024, 2:23pm

Hi everyone,

I wanted to share some code that might be useful for those dealing with table renaming in Ecto migrations. While using Ecto.Migration.rename/2 is straightforward, we’ve encountered an issue: the associated indexes, primary keys, and foreign keys retain their original naming conventions, which can lead to confusion.

To address this, our team developed some helper functions that streamline the renaming process and ensure that all related database objects are renamed consistently.

A bonus is that you get rollback for free.

gist.github.com

https://gist.github.com/cblavier/a0d56d859cd3615beb7d247e68e2cf9c

20241104111301_renaming_example.exs

defmodule PhenixDisplays.Repo.Migrations.RenamingExample do
  use Ecto.Migration
  import EctoMigrationHelpers

  @from_table "old_table_name"
  @to_table "new_table_name"

  def change do
    rename_index(from: @from_table, to: @to_table, fields: [:uuid])
    rename_index(from: @from_table, to: @to_table, fields: [:deal_id])

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ecto_migration_helpers.ex

defmodule EctoMigrationHelpers do
  import Ecto.Migration, only: [execute: 2]

  def rename_fkey(
        from: from_table_name,
        to: to_table_name,
        from_field: from_field,
        to_field: to_field
      ) do
    from_fkey = build_identifier(from_table_name, from_field, :fkey)

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Feel free to leave any comments or suggestions!
Hope this helps!

sodapopcan · November 4, 2024, 3:12pm

This is great, thank you! I’ve faced this several times recently and it’s a slog. It feels like this could be in Ecto. Are there some edge cases that would make this a maintenance burden?

cblavier · November 4, 2024, 3:21pm

Thanks!
There may be edge cases, but I still haven’t spotted any