separating joins and eager loads

[WanWizard]

No description provided.

[WanWizard]

Person reporting this referred to Laravel's ORM.

A quick check reveils that it doesn't do joins at all, it runs a separate query for each relation included in the question, so it suffers from the N+1 problem, which is absolutely a bad idea. So we shouldn't go that route!

[emlynwest]

What was the original request/issue regarding this?

[WanWizard]

This was a comment in two stages: the first line was originally reported, and was triggered by the way we do it in v1: when you run a query with relations, ORM v1 does a full join, and then runs a hydration process to split each row into the different model instances.

Laravel's ORM runs separate queries and the statement was that it was faster. I did a quick check at the time, and it seemed to run a separate query for each parent->child relation, leading to my statement about the N+1 problem.

I think now it runs WHERE pk IN (list of FK's) queries on child tables, and uses a separate hydration process to create objects for these rows and link them to their parent.

There are heated debates which of the two solutions is faster, but I think the answer is "it depends". It might be a bit more memory efficient, since you don't pull the entire result into memory (before hydration) in one go.