Make streaming opt-in

[ion-elgreco]

Description

Use Case
Currently I've enabled streaming when we see a potentially streaming source, I think we should add streaming parameter in python to merge and let users configure it. This makes it then possible to disable it or set it for sources that are not streamed but might still benefit from the streamed execution.

We should also raise an experimental warning when it's true and say users should share positive or negative findings :)

Related Issue(s)

[rtyler]

@ion-elgreco why not make it the default?

[ion-elgreco]

@rtyler non-streamed might be better in some cases since you can use min max statistics from the incoming source data to prune the target table.

Haven't found a way to do this during streaming