Change the default depth from 2 to 1 to improve Payload performance out of the box

[MurzNN]

The defaultDepth in Payload CMS is set to 2 for now, and I believe that this is too much from the performance point of view!

This too deep depth looks convenient from the developers' point of view, because they get all the relationship documents available in the response by default, and no need for additional queries!

But from the performance point of view, the depth=2 produces very heavy and slow queries! But most of developers don't think about the database queries, they just use the default settings, believing that they are optimal and no need to change them. Also, many developers are just not aware of this "depth" setting at all.

Just imagine just a simple query "Posts" on a page "Latest posts" that displays 50 recent posts. Each post document contains at least 4 relationship fields (authors, category, tags, media), each of which will lead to additional database query or join/aggregate construction.

In result, with an almost empty database, everything works well, but when their database grows, they start to face performance issues, but decreasing the depth on already working project requires a lot of internal changes, which is hard.

So, I believe that setting the default depth to 1 should improve the Payload performance by default, without significantly decreasing the developer experience, especially because developers can set the per-query depth to the desired value on that places, only where the depth>1 is really needed.

P.S. In addition to this, I have one more feature request to allow passing the depth value on a per-field basis: #15244 that should give much more flexibility for developers.

[willemmulder]

Yes please! The default depth of 2 is crazy resource-intensive on bigger DBs.

[jacobsfletch]

Thanks for raising this @MurzNN. I agree that the default should favor fast, predictable queries, with deeper relationship population explicitly requested where it is needed.

I've opened #17510 for v4 to reduce defaultDepth from 2 to 1. This improves query performance out of the box for every application without requiring configuration changes. Queries that need second-level relationship data can continue to specify depth: 2, and applications that prefer the existing behavior can preserve it globally with defaultDepth: 2.

We also considered going directly to 0. While that would produce the fastest possible default queries, depth: 1 strikes a better balance between performance and DX. 2 is unnecessarily expensive as a default, while the tradeoff between 0 and 1 is less clear. Ultimately, 1 gives us the best of both worlds: substantially less relationship population by default without making the default response shape too limited.

[willemmulder]

Thanks for that! Would you also consider a defaultJoins option that we could set to false? Right now, we have to explicitly set joins:false on every individual query.

[MurzNN]

Yes, taking into account that even images require separate joins to be attached to the document, because of the missing feature, described in #15343 - the defaultDepth: 1 seems like the optimal choice!

About joins - agree too, because doing the same - joins: false on almost each request.

[MurzNN]

But the optimal solution could be a per-field depth control, described here: #16811