Cache decorator

Caching stores the result of slow function calls so they only need to run once. This persists objects across reruns and makes UDFs faster.

Basic

To cache a function decorate it with @fused.cache.

@fused.udf
def udf():
    import pandas as pd

    @fused.cache
    def load_data(i):
        return pd.DataFrame({'id': i})

    first = load_data(i=1)
    second = load_data(i=2)
    return pd.concat([first, second])

The first time Fused sees the function code and parameters, Fused runs the function and stores the return value in a cache. The next time the function is called with the same parameters and code, Fused skips running the function and returns the cached value.

Advanced

This UDF illustrates the use of:

• Passing bbox to make the output unique to each Tile
• Setting a custom cache directory with the optional path parameter
• Reseting the cache by running the function once with reset=True

@fused.udf
def udf(bbox: fused.types.TileGDF=None):

    @fused.cache(path='optional_cache_dir', reset=True)
    def set_name(bbox, name):
        bbox['name'] = name
        return bbox

    return set_name(bbox, "San Francisco")