Some more wisdom from Randolf Geist, this time about dynamic sampling…
As it turns out, the default behavior for dynamic sampling is to only be used for selectivity estimation, if cardinality is available from statistics (if not, then dynamic sampling will be used for both selectivity and cardinality). This can occasionally lead to very confusing behavior. In such cases one can use a “dynamic_sampling_est_cdn” hint.
A few interesting links kindly provided by Randolf:
