Variable COLUMNAR_REPRESENTATION_MIN_ROWSConst Experimental

COLUMNAR_REPRESENTATION_MIN_ROWS: 100000 = 100_000

Estimated rows at or above which representation: "auto" selects columnar.

Set at the SDK's bounded-local materialization ceiling (MAX_LOCAL_MATERIALIZATION_ROWS): below it a result is small enough that feature objects stay affordable, at or above it the per-row object cost is exactly the problem a columnar batch exists to remove.