Add lower path index to redirect_routesmk-add-lower-path-index-to-redirect-routes

1 files changed, 34 insertions, 0 deletions

diff --git a/db/migrate/20170724214302_add_lower_path_index_to_redirect_routes.rb b/db/migrate/20170724214302_add_lower_path_index_to_redirect_routes.rb
new file mode 100644
index 00000000000..db60c2087b9
--- /dev/null
+++ b/db/migrate/20170724214302_add_lower_path_index_to_redirect_routes.rb
@@ -0,0 +1,34 @@
+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class AddLowerPathIndexToRedirectRoutes < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+  INDEX_NAME = 'index_on_redirect_routes_lower_path'
+
+  disable_ddl_transaction!
+
+  def up
+    return unless Gitlab::Database.postgresql?
+
+    execute "CREATE INDEX CONCURRENTLY #{INDEX_NAME} ON redirect_routes (LOWER(path));"
+  end
+
+  def down
+    return unless Gitlab::Database.postgresql?
+
+    # Why not use remove_concurrent_index_by_name?
+    #
+    # `index_exists?` doesn't work on this index. Perhaps this is related to the
+    # fact that the index doesn't show up in the schema. And apparently it isn't
+    # trivial to write a query that checks for an index. BUT there is a
+    # convenient `IF EXISTS` parameter for `DROP INDEX`.
+    if supports_drop_index_concurrently?
+      disable_statement_timeout
+      execute "DROP INDEX CONCURRENTLY IF EXISTS #{INDEX_NAME};"
+    else
+      execute "DROP INDEX IF EXISTS #{INDEX_NAME};"
+    end
+  end
+end