The SQLite R*Tree Module

[bob1029]

I have started to play around with building a software rasterizer from scratch, and I am wondering if this might be something that I could potentially leverage to cheat at some of the math problems. The document mentions CAD, but I am not sure if the performance is such that real-time (i.e. 30+fps) queries would be feasible over meaningful datasets.

Does anyone have any experience directly using SQL for this sort of thing? I feel like there is something here with being able to define a 3d scene in terms of normalized SQL tables, and then running queries over them in order to produce intermediate/final output.

[kragen]

I don't have any experience using SQL for that kind of thing, but in http://canonical.org/~kragen/sw/dev3/sqlitescene.py I'm getting a bit over 800 frames per second on my laptop, including rotating the scene in SQL — about 2400 queries per second — so I think it's plausible to use SQLite for this kind of thing. But I don't know if that kind of performance is consistent, which is a big deal for real-time graphics. (The worst-case frame time I get on that data set over sixty thousand frames is 3.8 ms though so it might be OK.)

Using SQL for this kind of thing would definitely be a very weird choice. So it's super awesome and I look forward to hearing about whether it works out.

[jjmod]

It might be feasible if you use sqlite's in-memory feature, because hitting the disk on each query is way too slow for a real-time application.

Why not just use an r-tree library for the language you're using? It'll be faster and easier to work with. Since scene data is usually hierarchial, sql doesn't seem like a great choice for storing it

[daliusd]

https://www.sqlite.org/famous.html - there is at least one CAD company ;)

[phaedrus]

You might have some success using hand-coded routines for the last / hardest-working portion of the rasterizer, and just use SQLite to translate data from a format produced by the front-end to a format that matches the back-end.

I'm interested in relational programming for 3D meshes. For example what if we could use the form of a query to write a routine that splits a 3D mesh (creating new triangles at the boundary?)

[aidos]

I’ve used it by running it memory from python as a temporary dB. In my case it was just for simple bounds checking queries but it worked incredibly well.

I’m not sure about trying to get 30fps out of it though - might be a stretch!

[yowlingcat]

Having used this in production before, it's an absolutely fantastic tool for specific use cases. My use case was indexing fairly static medium cardinality geo data for lookup within a microservice that we hit from our primary monolith. You get fast spatial indexes and essentially zero additional operational overhead.

[centimeter]

I love SQLite's software model (embeddable library rather than a separate binary), but I often sorely miss the rich data model provided by postgres. I miss things like strong type checking, special types to represent times/coordinates/etc., and advanced index types like GiST indices.

[hagibborim]

How close does DuckDB get to fulfilling your needs?

[yread]

Note that even though it's a module lot of distributions of Sqlite come with it enabled. You can check it by running

PRAGMA compile_options;

and looking for ENABLE_RTREE

[jokoon]

Mmmmh does spatialite use it? I guess yes. Spatialite is great even though the queries are a little tedious.