Question

1. I can define constants in file and then include them, or

2. I can store them in DB and seed them.

From your experience, which one is better/faster/less resource costly for say .. dozens, hundreds, thousands defined?

Answer 1

This is an ever-present question, which differs from person to person, and is a bit of a balancing act. For me, it all depends on how big and static the data-set is presumed to be. In my applications I have about 10 code points where I will refer to constants rather than going through all the overhead to pull data from a database.

Another benefit of using constants, is you can refer to them throughout the codebase which will help reduce defects and improve semantics, for example:

class Ad
{
    const ID_AD_TYPE_BANNER = 1;
    const ID_AD_TYPE_SKYSCRAPER = 2;
}

// Somewhere in app
if (array_key_exists(Ad::ID_AD_TYPE_BANNER, $array)) {

However there are a few hmmm downsides? I hesitate to call them downsides because they are not difficult to work around. First, if your constants are ints, and your application ever inputs these contants into a table, you will not be able to join to a ‘lookup’ table and see the lookup values as part of the query results. Instead you will just have to know what an id of 1 means in the query.

Second, be sure to place constants in common sense locations, and try to namespace if you can, that way you can easily find the values if you end up forgetting what they are. If you have a clever IDE, it will do this for you. Also know that if a constant changes, you will have to do a code push vs manipulating database data directly.

I’d say yes to constants, if the list is relatively small (<25) and not prone to change much, however, if your data won’t match these constraints, I would suggest popping them into a database.