[openstreetmap-website] Changeset discussion feature (#772)

[Tom Hughes]

> @@ -0,0 +1,11 @@
> +require 'migrate'
> +class AddJoinTableBetweenUsersAndChangesets < ActiveRecord::Migration
> +  def change
> +    create_table :changesets_subscribers, id: false do |t|
> +      t.column :subscriber_id, :bigint, null: false
> +      t.column :changeset_id, :bigint, null: false
> +    end

We need to add indexes here on both `subscriber_id` and `changeset_id` or things will quickly collapse as we build up subscribers ;-) What I would suggest is a unique index on `[:subscriber_id, :changeset_id]` which will also make duplicate entries impossible, and an ordinary index on `[:changeset_id]` for finding the subscribers to a changeset.

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Reply to this email directly or view it on GitHub:
https://github.com/openstreetmap/openstreetmap-website/pull/772/files#r15405547
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