Merge branch 'mwaw/add_index_to_events_table' into 'master'

Add index on events using created at and id  to support UMAU metric

See merge request gitlab-org/gitlab!73273

db/post_migrate/20211028123412_add_async_index_on_events_using_btree_created_at_id.rb

+# frozen_string_literal: true
+
+class AddAsyncIndexOnEventsUsingBtreeCreatedAtId < Gitlab::Database::Migration[1.0]
+  INDEX_NAME = 'index_events_on_created_at_and_id'
+  TABLE = :events
+  COLUMNS = %i[created_at id]
+  CONSTRAINTS = "created_at > '2021-08-27'"
+
+  def up
+    prepare_async_index TABLE, COLUMNS, name: INDEX_NAME, where: CONSTRAINTS
+  end
+
+  def down
+    unprepare_async_index TABLE, COLUMNS, name: INDEX_NAME, where: CONSTRAINTS
+  end
+end

db/schema_migrations/20211028123412

+d7655fb2a01e389f59990b395ed7ef683b21a3371b7e68d3eb29def85eea1888
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