FAQ

FAQ¶

Q: I just saw “UserWarning: metadata could not be determined; a compute on the first partition will occur.” what does that mean?

A: When dask-awkward stages a new computation it runs the operation on a typetracer array to generate metadata for the new collection. If this is not possible, that is, awkward array itself (independent of Dask) was not able to execute the operation on the existing metadata, then the first partition will be computed to determine the new metadata.

You can bypass the automatic metadata determination using Dask’s configuration manager. The configuration parameter is called awkward.compute-unknown-meta. The default setting is True. In code you can do something like this:
```
with dask.config.set({"awkward.compute-unknown-meta": False}):
    # ... your code
```
Or you can modify the configuration with environment variables or a YAML file. See Dask’s documentation linked above.

Optimization

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