Change condition of users on public email index

db/post_migrate/20211124132705_change_index_users_on_public_email.rb

+# frozen_string_literal: true
+
+class ChangeIndexUsersOnPublicEmail < Gitlab::Database::Migration[1.0]
+  INDEX_NAME = 'index_users_on_public_email'
+  INDEX_EXCLUDING_NULL_NAME = 'index_users_on_public_email_excluding_null_and_empty'
+
+  disable_ddl_transaction!
+
+  def up
+    index_condition = "public_email != '' AND public_email IS NOT NULL"
+
+    add_concurrent_index :users, [:public_email], where: index_condition, name: INDEX_EXCLUDING_NULL_NAME
+    remove_concurrent_index_by_name :users, INDEX_NAME
+  end
+
+  def down
+    index_condition = "public_email != ''"
+
+    add_concurrent_index :users, [:public_email], where: index_condition, name: INDEX_NAME
+    remove_concurrent_index_by_name :users, INDEX_EXCLUDING_NULL_NAME
+  end
+end

db/schema_migrations/20211124132705

+4eacad00017890c71f3354d80061fae7af40499256475cdf035bdf41b916e5f3
\ No newline at end of file

db/structure.sql

@@ -27532,7 +27532,7 @@ CREATE INDEX index_users_on_name ON users USING btree (name);
 CREATE INDEX index_users_on_name_trigram ON users USING gin (name gin_trgm_ops);
-CREATE INDEX index_users_on_public_email ON users USING btree (public_email) WHERE ((public_email)::text <> ''::text);
+CREATE INDEX index_users_on_public_email_excluding_null_and_empty ON users USING btree (public_email) WHERE (((public_email)::text <> ''::text) AND (public_email IS NOT NULL));
 CREATE INDEX index_users_on_require_two_factor_authentication_from_group ON users USING btree (require_two_factor_authentication_from_group) WHERE (require_two_factor_authentication_from_group = true);