Remove compound index on (project_id, id) from vulnerabilities table

changelogs/unreleased/remove-project-id-and-id-index-on-vulnerabilities-table.yml

+---
+title: Remove duplicate index from the Vulnerabilities table
+merge_request: 44422
+author: Borivoje Tasovac @borivojetasovac
+type: performance

db/migrate/20201004163918_remove_project_id_and_id_index_from_vulnerabilities_table.rb

+class RemoveProjectIdAndIdIndexFromVulnerabilitiesTable < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+  INDEX_NAME = 'index_vulnerabilities_on_project_id_and_id'
+
+  disable_ddl_transaction!
+
+  def up
+    Gitlab::BackgroundMigration.steal('PopulateResolvedOnDefaultBranchColumn')
+    remove_concurrent_index_by_name :vulnerabilities, INDEX_NAME
+  end
+
+  def down
+    add_concurrent_index :vulnerabilities, [:project_id, :id], name: INDEX_NAME
+  end
+end

db/schema_migrations/20201004163918

+e25da3da50ed2396afe3bcb1ff441b5f1f0a43c0e23d66140a160d42f1b66a1a
\ No newline at end of file

db/structure.sql

@@ -21764,8 +21764,6 @@ CREATE INDEX index_vulnerabilities_on_milestone_id ON vulnerabilities USING btre
 
 CREATE INDEX index_vulnerabilities_on_project_id ON vulnerabilities USING btree (project_id);
 
-CREATE INDEX index_vulnerabilities_on_project_id_and_id ON vulnerabilities USING btree (project_id, id);
-
 CREATE INDEX index_vulnerabilities_on_resolved_by_id ON vulnerabilities USING btree (resolved_by_id);
 
 CREATE INDEX index_vulnerabilities_on_start_date_sourcing_milestone_id ON vulnerabilities USING btree (start_date_sourcing_milestone_id);