Basics:

• An asset is a persisten object in storage, such as a table, ML model or a file
• An op is a core unit of computation in Dagster.
• a graph is a DAG of ops or other graphs
• a Software-defined asset is a declaration of an asset that should exist and a description of how to compute it: the op or graph that needs to run and the upstream assets that it should run on

Software-defined assets aren’t a replacement for Dagster’s core computational concepts - ops are, in fact, the core unit of computation that occurs within an asset. Think of them as a top layer that links ops, graphs, and jobs to the long-lived objects they interact with.

Debugging Dagster

The tutorials have you run Dagster from command line which I find quite awful. Luckily its also possible run it directly from python:

if __name__ == "__main__":
    materialize([sfo_q2_weather_sample])

However, if you try to run it in interactive debugger, VS Code complains about the “justmycode” flag. So, before being actually able to debug the Dagster code, I needed to add this to my launch.json file (in .vscode dir at the root of the project):

    {
        "name": "Debug all",
        "type": "python",
        "request": "launch",
        "purpose": [
            "debug-in-terminal"
        ],
        "console": "integratedTerminal",
        "justMyCode": false,
    }