Create partial index for gitlab-monitor CI metrics

This creates a partial index intended to speed up queries on
`ci_builds`. Particularly, `gitlab-monitor` has rather heavy queries.
Those have been changed to only look back 7 days and benefit from this
index tremendously.

Relates to
https://gitlab.com/gitlab-org/gitlab-exporter/merge_requests/101.

1 files changed, 19 insertions, 0 deletions

diff --git a/db/migrate/20190902152329_add_index_for_ci_builds_metrics.rb b/db/migrate/20190902152329_add_index_for_ci_builds_metrics.rb
new file mode 100644
index 00000000000..b755d60e311
--- /dev/null
+++ b/db/migrate/20190902152329_add_index_for_ci_builds_metrics.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+class AddIndexForCiBuildsMetrics < ActiveRecord::Migration[5.2]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  INDEX_NAME = 'ci_builds_gitlab_monitor_metrics'
+
+  def up
+    add_concurrent_index(:ci_builds, [:status, :created_at, :project_id], where: "type = 'Ci::Build'", name: INDEX_NAME)
+  end
+
+  def down
+    remove_concurrent_index_by_name(:ci_builds, INDEX_NAME)
+  end
+end