[kmicinski]

> - I had worse performance with Soufflé than Ascent for my program for some query-planning reason that I couldn't figure out. I don't really know why; see https://github.com/souffle-lang/souffle/discussions/2557

I think the basic issue is that ADTs are simply not indexed--so to the degree that you write a query that would necessitate an index on a subtree of an ADT, you will face asymptotic blowup, as the way ADTs work will force you to scan-then-test across all ADTs (associated with that top-level tag). The issue is discussed in Section 5.2 of this paper here: https://arxiv.org/pdf/2411.14330

[arxanas]

Ah, yes, but I think Ascent also doesn't index ADTs. In this case, based on some other information, it seems like Soufflé _can_ plan the queries better if it has profiling data. It seems like Ascent just happened to pick a better query plan in my case without the profiling data.

Thanks for the link to the paper!

[kmicinski]

It's true that Ascent does not index ADTs either, but there are some tricks that you can use when you control the container type to get similar performance by, e.g., storing a pre-computed hash. I believe Arash, the main author of Ascent, was exploiting this trick for Rc<...> members and seeing good performance gains. It is a bit nuanced, you're right that Ascent doesn't pervasively index ADTs out of the box for sure.