Test for missing FK indexes

test/fixtures/unindexed_fk.sql

@@ -0,0 +1,27 @@
+-- Unindexed FK -- Missing indexes - For CI
+
+WITH y AS (
+SELECT
+pg_catalog.format('%I', c1.relname)  AS referencing_tbl,
+pg_catalog.quote_ident(a1.attname) AS referencing_column,
+(SELECT pg_get_expr(indpred, indrelid) FROM pg_catalog.pg_index WHERE indrelid = t.conrelid AND indkey[0] = t.conkey[1] AND indpred IS NOT NULL LIMIT 1) partial_statement
+FROM pg_catalog.pg_constraint t
+JOIN pg_catalog.pg_attribute  a1 ON a1.attrelid = t.conrelid AND a1.attnum = t.conkey[1]
+JOIN pg_catalog.pg_class  c1 ON c1.oid = t.conrelid
+JOIN pg_catalog.pg_namespace  n1 ON n1.oid = c1.relnamespace
+JOIN pg_catalog.pg_class  c2 ON c2.oid = t.confrelid
+JOIN pg_catalog.pg_namespace  n2 ON n2.oid = c2.relnamespace
+JOIN pg_catalog.pg_attribute  a2 ON a2.attrelid = t.confrelid AND a2.attnum = t.confkey[1]
+WHERE t.contype = 'f'
+AND NOT EXISTS (
+SELECT 1
+FROM pg_catalog.pg_index i
+WHERE i.indrelid = t.conrelid
+AND i.indkey[0] = t.conkey[1]
+AND indpred IS NULL
+)
+)
+SELECT  referencing_tbl || '.' || referencing_column as "column"
+FROM y
+WHERE (partial_statement IS NULL OR partial_statement <> ('(' || referencing_column || ' IS NOT NULL)'))
+ORDER BY 1;

test/pleroma/schema_test.exs

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+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2022 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.SchemaTest do
+  use Pleroma.DataCase, async: true
+
+  alias Pleroma.Repo
+
+  test "No unindexed foreign keys" do
+    query = File.read!("test/fixtures/unindexed_fk.sql")
+
+    {:ok, result} = Repo.query(query)
+
+    assert Enum.empty?(result.rows)
+  end
+end