We observed that for TPC-E, this simple call to estimateNDV() from our INLJ costing code takes almost 1ms on average! Because this NDV estimate is requested with $eq semantics, it is not able to be served by persisted HLL estimates for compound indexes because the all-$eq semantics sketch is not persisted.

For now, let's just request NDV information with $expr semantics (1-line change here) until we do SERVER-134537, such that persisted NDV estimates can help answer this request when available.