Add composite indexes to events table to improve query performance (#4982)

We observed that certain queries were taking 30+ seconds on a large, production foundation. After exploring what was happening, we managed to cut query time down to sub-millisecond by adding a few composite indexes.

Author: joyvuu-dave

db/migrations/20260324120000_add_composite_indexes_to_events.rb

@@ -0,0 +1,72 @@
+# rubocop:disable Metrics/BlockLength
+Sequel.migration do
+  no_transaction # required for concurrently option on postgres
+
+  up do
+    if database_type == :postgres
+      VCAP::Migration.with_concurrent_timeout(self) do
+        add_index :events, %i[actee created_at guid],
+                  name: :events_actee_created_at_guid_index,
+                  if_not_exists: true,
+                  concurrently: true
+
+        add_index :events, %i[space_guid created_at guid],
+                  name: :events_space_guid_created_at_guid_index,
+                  if_not_exists: true,
+                  concurrently: true
+
+        add_index :events, %i[organization_guid created_at guid],
+                  name: :events_organization_guid_created_at_guid_index,
+                  if_not_exists: true,
+                  concurrently: true
+      end
+    else
+      alter_table(:events) do
+        # rubocop:disable Sequel/ConcurrentIndex
+        unless @db.indexes(:events).key?(:events_actee_created_at_guid_index)
+          add_index %i[actee created_at guid],
+                    name: :events_actee_created_at_guid_index
+        end
+        unless @db.indexes(:events).key?(:events_space_guid_created_at_guid_index)
+          add_index %i[space_guid created_at guid],
+                    name: :events_space_guid_created_at_guid_index
+        end
+        unless @db.indexes(:events).key?(:events_organization_guid_created_at_guid_index)
+          add_index %i[organization_guid created_at guid],
+                    name: :events_organization_guid_created_at_guid_index
+        end
+        # rubocop:enable Sequel/ConcurrentIndex
+      end
+    end
+  end
+
+  down do
+    if database_type == :postgres
+      VCAP::Migration.with_concurrent_timeout(self) do
+        drop_index :events, nil,
+                   name: :events_actee_created_at_guid_index,
+                   if_exists: true,
+                   concurrently: true
+
+        drop_index :events, nil,
+                   name: :events_space_guid_created_at_guid_index,
+                   if_exists: true,
+                   concurrently: true
+
+        drop_index :events, nil,
+                   name: :events_organization_guid_created_at_guid_index,
+                   if_exists: true,
+                   concurrently: true
+      end
+    else
+      alter_table(:events) do
+        # rubocop:disable Sequel/ConcurrentIndex
+        drop_index nil, name: :events_actee_created_at_guid_index if @db.indexes(:events).key?(:events_actee_created_at_guid_index)
+        drop_index nil, name: :events_space_guid_created_at_guid_index if @db.indexes(:events).key?(:events_space_guid_created_at_guid_index)
+        drop_index nil, name: :events_organization_guid_created_at_guid_index if @db.indexes(:events).key?(:events_organization_guid_created_at_guid_index)
+        # rubocop:enable Sequel/ConcurrentIndex
+      end
+    end
+  end
+end
+# rubocop:enable Metrics/BlockLength

spec/migrations/20260324120000_add_composite_indexes_to_events_spec.rb

@@ -0,0 +1,47 @@
+require 'spec_helper'
+require 'migrations/helpers/migration_shared_context'
+
+RSpec.describe 'migration to add composite indexes to events table', isolation: :truncation, type: :migration do
+  include_context 'migration' do
+    let(:migration_filename) { '20260324120000_add_composite_indexes_to_events.rb' }
+  end
+
+  describe 'events table' do
+    it 'adds composite indexes and handles idempotency gracefully' do
+      # Before migration: composite indexes should not exist
+      expect(db.indexes(:events)).not_to include(:events_actee_created_at_guid_index)
+      expect(db.indexes(:events)).not_to include(:events_space_guid_created_at_guid_index)
+      expect(db.indexes(:events)).not_to include(:events_organization_guid_created_at_guid_index)
+
+      # Test up migration
+      expect { Sequel::Migrator.run(db, migrations_path, target: current_migration_index, allow_missing_migration_files: true) }.not_to raise_error
+
+      expect(db.indexes(:events)).to include(:events_actee_created_at_guid_index)
+      expect(db.indexes(:events)).to include(:events_space_guid_created_at_guid_index)
+      expect(db.indexes(:events)).to include(:events_organization_guid_created_at_guid_index)
+
+      # Verify index column order
+      expect(db.indexes(:events)[:events_actee_created_at_guid_index][:columns]).to eq(%i[actee created_at guid])
+      expect(db.indexes(:events)[:events_space_guid_created_at_guid_index][:columns]).to eq(%i[space_guid created_at guid])
+      expect(db.indexes(:events)[:events_organization_guid_created_at_guid_index][:columns]).to eq(%i[organization_guid created_at guid])
+
+      # Test up migration idempotency: running again should not fail
+      expect { Sequel::Migrator.run(db, migrations_path, target: current_migration_index, allow_missing_migration_files: true) }.not_to raise_error
+      expect(db.indexes(:events)).to include(:events_actee_created_at_guid_index)
+      expect(db.indexes(:events)).to include(:events_space_guid_created_at_guid_index)
+      expect(db.indexes(:events)).to include(:events_organization_guid_created_at_guid_index)
+
+      # Test down migration
+      expect { Sequel::Migrator.run(db, migrations_path, target: current_migration_index - 1, allow_missing_migration_files: true) }.not_to raise_error
+      expect(db.indexes(:events)).not_to include(:events_actee_created_at_guid_index)
+      expect(db.indexes(:events)).not_to include(:events_space_guid_created_at_guid_index)
+      expect(db.indexes(:events)).not_to include(:events_organization_guid_created_at_guid_index)
+
+      # Test down migration idempotency: running again should not fail
+      expect { Sequel::Migrator.run(db, migrations_path, target: current_migration_index - 1, allow_missing_migration_files: true) }.not_to raise_error
+      expect(db.indexes(:events)).not_to include(:events_actee_created_at_guid_index)
+      expect(db.indexes(:events)).not_to include(:events_space_guid_created_at_guid_index)
+      expect(db.indexes(:events)).not_to include(:events_organization_guid_created_at_guid_index)
+    end
+  end
+end