Index: sql/perf/indexes.sql
===================================================================
--- sql/perf/indexes.sql	(revision 2853f2ebbc643ed265db27aa0af19878c14db48c)
+++ sql/perf/indexes.sql	(revision 2853f2ebbc643ed265db27aa0af19878c14db48c)
@@ -0,0 +1,20 @@
+SET search_path TO perf;
+
+-- Foreign keys with no supporting index. PostgreSQL indexes primary keys and
+-- UNIQUE constraints automatically, but never the referencing side of a
+-- foreign key, and a composite index only helps queries that use its
+-- leading column.
+CREATE INDEX IF NOT EXISTS ix_semesters_subjects_subject   ON semesters_subjects (subjects_id);
+CREATE INDEX IF NOT EXISTS ix_semesters_subjects_professor ON semesters_subjects (professor_id);
+CREATE INDEX IF NOT EXISTS ix_enrolled_semesters_semester  ON enrolled_semesters (semester_id);
+CREATE INDEX IF NOT EXISTS ix_enrolled_semesters_major     ON enrolled_semesters (major_id);
+CREATE INDEX IF NOT EXISTS ix_payment_enrollment           ON payment (enrollment_id);
+CREATE INDEX IF NOT EXISTS ix_major_subjects_subject       ON major_subjects (subject_id);
+CREATE INDEX IF NOT EXISTS ix_professour_subjects_semester ON professour_subjects (active_semester_id, subject_id);
+CREATE INDEX IF NOT EXISTS ix_user_documents_document      ON user_documents (document_id);
+CREATE INDEX IF NOT EXISTS ix_token_user                   ON token (user_id);
+
+-- Supports the very common "this student's grades" path without touching the heap.
+CREATE INDEX IF NOT EXISTS ix_passed_subjects_enrolled_grade ON passed_subjects (enrolled_id, grade);
+
+ANALYZE;