A rf is effective if it could filter target data.
In this pr, a rf is effective if any one of following conditions is satisfied:
A filter is applied on rf src, like T.A =1
A effective rf applied on this rf's src,
denote X as src and target insertsection range. src.ndv with respect to X is smaller than target.ndv
explaination of condition 2
Supplier join Nation on s_nationkey = n_nationkey
join Region on n_regionkey = r_regionkey
RF(nation->supplier) is effective because nation is filtered by an effective rf: RF(region->nation)
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