Support OmniSci Sample method

ibis-project / ibis

the portable Python dataframe library

https://ibis-project.org

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Closed saulshanabrook closed 5 years ago

saulshanabrook commented 5 years ago

OmniSci supports the SAMPLE aggregate method that:

Returns one sample value from aggregated column x.

I don't believe this is implemented in the Ibis wrapper.

saulshanabrook commented 5 years ago

cc @xmnlab

To implement this, would we:

Add an aggregate for mapd here: https://github.com/ibis-project/ibis/blob/master/ibis/mapd/operations.py#L482-L491
Add a Sample aggregate to ibis expressions. Is this the same as the existing Arbitrary expression?

saulshanabrook commented 5 years ago

I think Arbitrary could be the right operation: https://github.com/ibis-project/ibis/issues/1230

So we would just have to add a mapping to OmniSci to map this to sample

saulshanabrook commented 5 years ago

saulshanabrook commented 5 years ago

I am working on adding this.

xmnlab commented 5 years ago

in the documentation:

Note: This was previously LAST_SAMPLE, which is now deprecated.

so a translation from arbitrary last to sample should works fine