From 44de03857a3db8d7fbd5e7ca48b69f9afaffc868 Mon Sep 17 00:00:00 2001
From: Simon Tomlinson <stomlinson@gitlab.com>
Date: Tue, 27 Jul 2021 11:36:00 +0000
Subject: [PATCH] Add a database view for postgres foreign keys
---
.../20210719145532_add_foreign_keys_view.rb | 26 ++++++++++++
db/schema_migrations/20210719145532 | 1 +
db/structure.sql | 12 ++++++
lib/gitlab/database/postgres_foreign_key.rb | 15 +++++++
.../database/postgres_foreign_key_spec.rb | 41 +++++++++++++++++++
5 files changed, 95 insertions(+)
create mode 100644 db/migrate/20210719145532_add_foreign_keys_view.rb
create mode 100644 db/schema_migrations/20210719145532
create mode 100644 lib/gitlab/database/postgres_foreign_key.rb
create mode 100644 spec/lib/gitlab/database/postgres_foreign_key_spec.rb
diff --git a/db/migrate/20210719145532_add_foreign_keys_view.rb b/db/migrate/20210719145532_add_foreign_keys_view.rb
new file mode 100644
index 000000000000..2d31371e7820
--- /dev/null
+++ b/db/migrate/20210719145532_add_foreign_keys_view.rb
@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+class AddForeignKeysView < ActiveRecord::Migration[6.1]
+ def up
+ execute(<<~SQL)
+ CREATE OR REPLACE VIEW postgres_foreign_keys AS
+ SELECT
+ pg_constraint.oid AS oid,
+ pg_constraint.conname AS name,
+ constrained_namespace.nspname::text || '.'::text || constrained_table.relname::text AS constrained_table_identifier,
+ referenced_namespace.nspname::text || '.'::text || referenced_table.relname::text AS referenced_table_identifier
+ FROM pg_constraint
+ INNER JOIN pg_class constrained_table ON constrained_table.oid = pg_constraint.conrelid
+ INNER JOIN pg_class referenced_table ON referenced_table.oid = pg_constraint.confrelid
+ INNER JOIN pg_namespace constrained_namespace ON constrained_table.relnamespace = constrained_namespace.oid
+ INNER JOIN pg_namespace referenced_namespace ON referenced_table.relnamespace = referenced_namespace.oid
+ WHERE contype = 'f';
+ SQL
+ end
+
+ def down
+ execute(<<~SQL)
+ DROP VIEW IF EXISTS postgres_foreign_keys
+ SQL
+ end
+end
diff --git a/db/schema_migrations/20210719145532 b/db/schema_migrations/20210719145532
new file mode 100644
index 000000000000..a9afd7a18ed4
--- /dev/null
+++ b/db/schema_migrations/20210719145532
@@ -0,0 +1 @@
+5e088e5109b50d8f4fadd37a0382d7dc4ce856a851ec2b97f8d5d868c3cb19fd
\ No newline at end of file
diff --git a/db/structure.sql b/db/structure.sql
index 6075cd812f98..c5d2b0806d65 100644
--- a/db/structure.sql
+++ b/db/structure.sql
@@ -16519,6 +16519,18 @@ CREATE SEQUENCE pool_repositories_id_seq
ALTER SEQUENCE pool_repositories_id_seq OWNED BY pool_repositories.id;
+CREATE VIEW postgres_foreign_keys AS
+ SELECT pg_constraint.oid,
+ pg_constraint.conname AS name,
+ (((constrained_namespace.nspname)::text || '.'::text) || (constrained_table.relname)::text) AS constrained_table_identifier,
+ (((referenced_namespace.nspname)::text || '.'::text) || (referenced_table.relname)::text) AS referenced_table_identifier
+ FROM ((((pg_constraint
+ JOIN pg_class constrained_table ON ((constrained_table.oid = pg_constraint.conrelid)))
+ JOIN pg_class referenced_table ON ((referenced_table.oid = pg_constraint.confrelid)))
+ JOIN pg_namespace constrained_namespace ON ((constrained_table.relnamespace = constrained_namespace.oid)))
+ JOIN pg_namespace referenced_namespace ON ((referenced_table.relnamespace = referenced_namespace.oid)))
+ WHERE (pg_constraint.contype = 'f'::"char");
+
CREATE VIEW postgres_index_bloat_estimates AS
SELECT (((relation_stats.nspname)::text || '.'::text) || (relation_stats.idxname)::text) AS identifier,
(
diff --git a/lib/gitlab/database/postgres_foreign_key.rb b/lib/gitlab/database/postgres_foreign_key.rb
new file mode 100644
index 000000000000..94f747242955
--- /dev/null
+++ b/lib/gitlab/database/postgres_foreign_key.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+module Gitlab
+ module Database
+ class PostgresForeignKey < ApplicationRecord
+ self.primary_key = :oid
+
+ scope :by_referenced_table_identifier, ->(identifier) do
+ raise ArgumentError, "Referenced table name is not fully qualified with a schema: #{identifier}" unless identifier =~ /^\w+\.\w+$/
+
+ where(referenced_table_identifier: identifier)
+ end
+ end
+ end
+end
diff --git a/spec/lib/gitlab/database/postgres_foreign_key_spec.rb b/spec/lib/gitlab/database/postgres_foreign_key_spec.rb
new file mode 100644
index 000000000000..ec39e5bfee73
--- /dev/null
+++ b/spec/lib/gitlab/database/postgres_foreign_key_spec.rb
@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Database::PostgresForeignKey, type: :model do
+ # PostgresForeignKey does not `behaves_like 'a postgres model'` because it does not correspond 1-1 with a single entry
+ # in pg_class
+
+ before do
+ ActiveRecord::Base.connection.execute(<<~SQL)
+ CREATE TABLE public.referenced_table (
+ id bigserial primary key not null
+ );
+
+ CREATE TABLE public.other_referenced_table (
+ id bigserial primary key not null
+ );
+
+ CREATE TABLE public.constrained_table (
+ id bigserial primary key not null,
+ referenced_table_id bigint not null,
+ other_referenced_table_id bigint not null,
+ CONSTRAINT fk_constrained_to_referenced FOREIGN KEY(referenced_table_id) REFERENCES referenced_table(id),
+ CONSTRAINT fk_constrained_to_other_referenced FOREIGN KEY(other_referenced_table_id)
+ REFERENCES other_referenced_table(id)
+ );
+ SQL
+ end
+
+ describe '#by_referenced_table_identifier' do
+ it 'throws an error when the identifier name is not fully qualified' do
+ expect { described_class.by_referenced_table_identifier('referenced_table') }.to raise_error(ArgumentError, /not fully qualified/)
+ end
+
+ it 'finds the foreign keys for the referenced table' do
+ expected = described_class.find_by!(name: 'fk_constrained_to_referenced')
+
+ expect(described_class.by_referenced_table_identifier('public.referenced_table')).to contain_exactly(expected)
+ end
+ end
+end
--
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