Question

I am designing a room booking system which has nine entities, which all relate to each other. In this specific instance I am retrieving 10-30 rows from the entity entry which has 25 properties. Each entry has one room which has 10 properties. I need all of the entry information as well as entry->room->id and entry->room->name. But it seems like doctrine is loading the entire room when I use Query::HYDRATE_ARRAY. It seems to be lazy-loading in Query::HYDRATE_OBJECT more easily.

So, I am wondering if using the Query::HYDRATE_OBJECT mode is faster or “better” than Query::HYDRATE_ARRAY / Query::HYDRATE_SCALAR/ Query::HYDRATE_SINGLE_SCALAR. Since I am reusing some older code I’d like to use HYDRATE_ARRAY but only if it won’t slow the application down.

Answer 1

My 2 cents:

HYDRATE_OBJECT is best for when you plan on using a lot of business logic with your objects. Especially if you’re doing a lot of data manipulation. It’s also probably the slowest (depending on the situation).

HYDRATE_ARRAY is usually reserved for when you only need a result and 1 degrees of relational data and it’s going to be used for printing/viewing purposes only.

HYDRATE_NONE is another one I use when I’m only selecting a very small subset of data (like one or two fields instead of the entire row). This behaves much like a raw query result would.

This might also be of interest http://www.doctrine-project.org/2010/03/17/doctrine-performance-revisited.html

This is from the 1.2 docs but I think the Hydration tips apply in 2.0 http://doctrine.readthedocs.org/en/latest/en/manual/improving-performance.html

Another important rule that belongs in this category is: Only fetch objects when you really need them. Doctrine has the ability to fetch “array graphs” instead of object graphs. At first glance this may sound strange because why use an object-relational mapper in the first place then? Take a second to think about it. PHP is by nature a precedural language that has been enhanced with a lot of features for decent OOP. Arrays are still the most efficient data structures you can use in PHP. Objects have the most value when they’re used to accomplish complex business logic. It’s a waste of resources when data gets wrapped in costly object structures when you have no benefit of that

On using HYDRATE_ARRAY:

Can you think of any benefit of having objects in the view instead of arrays? You’re not going to execute business logic in the view, are you? One parameter can save you a lot of unnecessary processing:

$blogPosts = $q->execute(array(1), Doctrine_Core::HYDRATE_ARRAY);