Add target_id column to audit_events table

For new record, we will write to this new `target_id` column, instead of
the existing nested hash structure in `details` field. This allows us to
create an explicit schema and query this field more efficiently.

changelogs/unreleased/220322-add-target-id-column-to-audit-events.yml

+---
+title: Add target_id column to audit_events table
+merge_request: 40954
+author:
+type: other

db/post_migrate/20200819113644_add_target_id_to_audit_events.rb

+# frozen_string_literal: true
+
+class AddTargetIdToAuditEvents < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::SchemaHelpers
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+  SOURCE_TABLE_NAME = 'audit_events'
+  PARTITIONED_TABLE_NAME = 'audit_events_part_5fc467ac26'
+  TRIGGER_FUNCTION_NAME = 'table_sync_function_2be879775d'
+
+  def up
+    with_lock_retries do
+      add_column(SOURCE_TABLE_NAME, :target_id, :bigint)
+      add_column(PARTITIONED_TABLE_NAME, :target_id, :bigint)
+
+      create_trigger_function(TRIGGER_FUNCTION_NAME, replace: true) do
+        <<~SQL
+          IF (TG_OP = 'DELETE') THEN
+            DELETE FROM #{PARTITIONED_TABLE_NAME} where id = OLD.id;
+          ELSIF (TG_OP = 'UPDATE') THEN
+            UPDATE #{PARTITIONED_TABLE_NAME}
+            SET author_id = NEW.author_id,
+              type = NEW.type,
+              entity_id = NEW.entity_id,
+              entity_type = NEW.entity_type,
+              details = NEW.details,
+              ip_address = NEW.ip_address,
+              author_name = NEW.author_name,
+              entity_path = NEW.entity_path,
+              target_details = NEW.target_details,
+              target_type = NEW.target_type,
+              target_id = NEW.target_id,
+              created_at = NEW.created_at
+            WHERE #{PARTITIONED_TABLE_NAME}.id = NEW.id;
+          ELSIF (TG_OP = 'INSERT') THEN
+            INSERT INTO #{PARTITIONED_TABLE_NAME} (id,
+              author_id,
+              type,
+              entity_id,
+              entity_type,
+              details,
+              ip_address,
+              author_name,
+              entity_path,
+              target_details,
+              target_type,
+              target_id,
+              created_at)
+            VALUES (NEW.id,
+              NEW.author_id,
+              NEW.type,
+              NEW.entity_id,
+              NEW.entity_type,
+              NEW.details,
+              NEW.ip_address,
+              NEW.author_name,
+              NEW.entity_path,
+              NEW.target_details,
+              NEW.target_type,
+              NEW.target_id,
+              NEW.created_at);
+          END IF;
+          RETURN NULL;
+        SQL
+      end
+    end
+  end
+
+  def down
+    with_lock_retries do
+      remove_column SOURCE_TABLE_NAME, :target_id
+
+      create_trigger_function(TRIGGER_FUNCTION_NAME, replace: true) do
+        <<~SQL
+          IF (TG_OP = 'DELETE') THEN
+            DELETE FROM #{PARTITIONED_TABLE_NAME} where id = OLD.id;
+          ELSIF (TG_OP = 'UPDATE') THEN
+            UPDATE #{PARTITIONED_TABLE_NAME}
+            SET author_id = NEW.author_id,
+              type = NEW.type,
+              entity_id = NEW.entity_id,
+              entity_type = NEW.entity_type,
+              details = NEW.details,
+              ip_address = NEW.ip_address,
+              author_name = NEW.author_name,
+              entity_path = NEW.entity_path,
+              target_details = NEW.target_details,
+              target_type = NEW.target_type,
+              created_at = NEW.created_at
+            WHERE #{PARTITIONED_TABLE_NAME}.id = NEW.id;
+          ELSIF (TG_OP = 'INSERT') THEN
+            INSERT INTO #{PARTITIONED_TABLE_NAME} (id,
+              author_id,
+              type,
+              entity_id,
+              entity_type,
+              details,
+              ip_address,
+              author_name,
+              entity_path,
+              target_details,
+              target_type,
+              created_at)
+            VALUES (NEW.id,
+              NEW.author_id,
+              NEW.type,
+              NEW.entity_id,
+              NEW.entity_type,
+              NEW.details,
+              NEW.ip_address,
+              NEW.author_name,
+              NEW.entity_path,
+              NEW.target_details,
+              NEW.target_type,
+              NEW.created_at);
+          END IF;
+          RETURN NULL;
+        SQL
+      end
+
+      remove_column PARTITIONED_TABLE_NAME, :target_id
+    end
+  end
+end

db/schema_migrations/20200819113644

+19c90689d0af6adb017dbd7127c6cd147d9c92581118dbfd99c87bc6a6dda3be
\ No newline at end of file

db/structure.sql

@@ -30,6 +30,7 @@ ELSIF (TG_OP = 'UPDATE') THEN
     entity_path = NEW.entity_path,
     target_details = NEW.target_details,
     target_type = NEW.target_type,
+    target_id = NEW.target_id,
     created_at = NEW.created_at
   WHERE audit_events_part_5fc467ac26.id = NEW.id;
 ELSIF (TG_OP = 'INSERT') THEN
@@ -44,6 +45,7 @@ ELSIF (TG_OP = 'INSERT') THEN
     entity_path,
     target_details,
     target_type,
+    target_id,
     created_at)
   VALUES (NEW.id,
     NEW.author_id,
@@ -56,6 +58,7 @@ ELSIF (TG_OP = 'INSERT') THEN
     NEW.entity_path,
     NEW.target_details,
     NEW.target_type,
+    NEW.target_id,
     NEW.created_at);
 END IF;
 RETURN NULL;
@@ -78,6 +81,7 @@ CREATE TABLE public.audit_events_part_5fc467ac26 (
     target_details text,
     created_at timestamp without time zone NOT NULL,
     target_type text,
+    target_id bigint,
     CONSTRAINT check_492aaa021d CHECK ((char_length(entity_path) <= 5500)),
     CONSTRAINT check_83ff8406e2 CHECK ((char_length(author_name) <= 255)),
     CONSTRAINT check_97a8c868e7 CHECK ((char_length(target_type) <= 255)),
@@ -9519,6 +9523,7 @@ CREATE TABLE public.audit_events (
     entity_path text,
     target_details text,
     target_type text,
+    target_id bigint,
     CONSTRAINT check_492aaa021d CHECK ((char_length(entity_path) <= 5500)),
     CONSTRAINT check_82294106dd CHECK ((char_length(target_type) <= 255)),
     CONSTRAINT check_83ff8406e2 CHECK ((char_length(author_name) <= 255)),

spec/db/schema_spec.rb

@@ -18,8 +18,8 @@ RSpec.describe 'Database schema' do
     approvals: %w[user_id],
     approver_groups: %w[target_id],
     approvers: %w[target_id user_id],
-    audit_events: %w[author_id entity_id],
-    audit_events_part_5fc467ac26: %w[author_id entity_id],
+    audit_events: %w[author_id entity_id target_id],
+    audit_events_part_5fc467ac26: %w[author_id entity_id target_id],
     award_emoji: %w[awardable_id user_id],
     aws_roles: %w[role_external_id],
     boards: %w[milestone_id],