From 25e15bbd1410e0551bb3e82da64738fa4f289672 Mon Sep 17 00:00:00 2001
From: Jamil <jamilbk@users.noreply.github.com>
Date: Wed, 6 Aug 2025 11:04:34 -0400
Subject: [PATCH] chore(portal): drop id in favor of lsn pkey (#10152)

On the `change_logs` table, we want to minimize write overhead as much
as possible. One major way to do this is the minimize the number of
indexes maintained.

Because `lsn` is guaranteed to be unique, we can use it as the primary,
saving us an index (and column).

**NOTE**: This migration will need to acquire a lock on the table, so
it's added as a manual migration to execute out of band. Since we don't
read ChangeLogs anywhere, it should be fine for the app servers to come
up without this migration applied.
---
 .../lib/domain/change_logs/change_log.ex      |  3 ++-
 ...081944_move_pkey_to_lsn_on_change_logs.exs | 23 +++++++++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 elixir/apps/domain/priv/repo/manual_migrations/20250806081944_move_pkey_to_lsn_on_change_logs.exs

diff --git a/elixir/apps/domain/lib/domain/change_logs/change_log.ex b/elixir/apps/domain/lib/domain/change_logs/change_log.ex
index 48b7037b4..bbcf7dee4 100644
--- a/elixir/apps/domain/lib/domain/change_logs/change_log.ex
+++ b/elixir/apps/domain/lib/domain/change_logs/change_log.ex
@@ -1,10 +1,11 @@
 defmodule Domain.ChangeLogs.ChangeLog do
   use Domain, :schema
 
+  @primary_key false
   schema "change_logs" do
     belongs_to :account, Domain.Accounts.Account
 
-    field :lsn, :integer
+    field :lsn, :integer, primary_key: true
     field :table, :string
     field :op, Ecto.Enum, values: [:insert, :update, :delete]
     field :old_data, :map
diff --git a/elixir/apps/domain/priv/repo/manual_migrations/20250806081944_move_pkey_to_lsn_on_change_logs.exs b/elixir/apps/domain/priv/repo/manual_migrations/20250806081944_move_pkey_to_lsn_on_change_logs.exs
new file mode 100644
index 000000000..b0beb1e79
--- /dev/null
+++ b/elixir/apps/domain/priv/repo/manual_migrations/20250806081944_move_pkey_to_lsn_on_change_logs.exs
@@ -0,0 +1,23 @@
+defmodule Domain.Repo.Migrations.MovePkeyToLsnOnChangeLogs do
+  use Ecto.Migration
+
+  def up do
+    alter table(:change_logs) do
+      remove(:id)
+    end
+
+    drop(index(:change_logs, [:lsn]))
+
+    execute("ALTER TABLE change_logs ADD PRIMARY KEY (lsn)")
+  end
+
+  def down do
+    execute("ALTER TABLE change_logs DROP CONSTRAINT change_logs_pkey")
+
+    alter table(:change_logs) do
+      add(:id, :uuid, default: fragment("gen_random_uuid()"), primary_key: true)
+    end
+
+    create(index(:change_logs, [:lsn]))
+  end
+end