Doctrine Fetch Modes (Symfony)

Use when

• A list or detail endpoint runs one query per row (N+1) on a relation.
• A read-only list needs a few columns, not full managed entities.
• Choosing LAZY, EAGER or EXTRA_LAZY on a mapping, or porting ORM 2 code that relied on PARTIAL objects.
• A report or projection query drops to raw SQL through DBAL 4.

Default workflow

1. Confirm the N+1 or over-fetch in the Symfony profiler before changing any mapping.
2. Keep relations on fetch: 'LAZY'; set fetch: 'EXTRA_LAZY' on large collections so count(), contains() and slice() run targeted SQL.
3. Load the relations a use case needs with a fetch join in the repository (addSelect() plus leftJoin()).
4. For read-only lists, project into a readonly DTO with SELECT NEW (constructor argument order must match the NEW list).
5. Use Query::HINT_READ_ONLY or an index-by alias (createQueryBuilder('p', 'p.id')) when the result is only displayed or looked up by id.
6. For raw SQL, use the DBAL 4 methods (fetchAllAssociative(), fetchOne(), executeStatement()).