Add index on project_id and sha to deployments table

Merge Request: gitlab.com/gitlab-org/gitlab/-/merge_requests/43836

changelogs/unreleased/add_index_for_sha_to_deployments.yml

+---
+title: Add index for project_id and sha to deployments table
+merge_request: 43836
+author:
+type: performance

db/migrate/20200930131343_add_index_on_project_id_and_sha_to_deployments.rb

+# frozen_string_literal: true
+
+# See https://docs.gitlab.com/ee/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class AddIndexOnProjectIdAndShaToDeployments < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+  DOWNTIME = false
+  INDEX_NAME = 'index_deployments_on_project_id_sha'
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_index :deployments, [:project_id, :sha], name: INDEX_NAME
+  end
+
+  def down
+    remove_concurrent_index_by_name(:deployments, INDEX_NAME)
+  end
+end

db/schema_migrations/20200930131343

+45530bb3090d9e8df3a79f42a06b042e0c40f6e185078c6d79d7ec334175c7d5
\ No newline at end of file

db/structure.sql

@@ -19985,6 +19985,8 @@ CREATE INDEX index_deployments_on_project_id_and_status_and_created_at ON deploy
 
 CREATE INDEX index_deployments_on_project_id_and_updated_at_and_id ON deployments USING btree (project_id, updated_at DESC, id DESC);
 
+CREATE INDEX index_deployments_on_project_id_sha ON deployments USING btree (project_id, sha);
+
 CREATE INDEX index_deployments_on_user_id_and_status_and_created_at ON deployments USING btree (user_id, status, created_at);
 
 CREATE INDEX index_description_versions_on_epic_id ON description_versions USING btree (epic_id) WHERE (epic_id IS NOT NULL);