Some doctrine best practises and lazy load

These are some facts about doctrine and the list will grow when time goes by. Note: If you're using symfony framework make sure you're using profiler bar because it gives us a lot of information about queries run.

Facts

• Try to create your own queries with createQueryBuilder() in repository classes if the targeted entity has associations with others because, depending on what you’re doing doctrine lazy load might kick in and run additional queries for associations later on so it is better to select all associations with leftJoin() up front.


• If what you’re doing is not going to interact with associated entities then using built-in find methods for fetching record(s) is better option since it uses slightly less memory and takes shorter to run.


• Depending on the cascade options in entities, removing a parent entity which is associated to other entities will highly likely run additional queries against associated entities so make sure that you already selected all associated entities by using leftJoin() with createQueryBuilder() in repository class.


• Database level remove/delete cascades are much faster than ORM level cascades because most of the process is handled by database.


• Use query hydrators where possible but be careful with joins.


• Select what column you need by specifying the name rather than selecting all the columns otherwise size of the result might be very big, especially for joins.


• To prevent lazy loading/selecting associated entities directly in your query then you can add ...->getQuery()...->setHint(Query::HINT_FORCE_PARTIAL_LOAD, true)...->getResult(); method to your query builder.


• If you're doing a batch-processing job such as batch-update, batch-delete, list then make sure you're using Query#iterate() in your QueryBuilder to avoid loading the whole result into memory at once. For more info, click here.