* [Forbidden](Vec) Switch to non-vec engine when outer join + not null column
Vectorized code will occur `core` in the case of ```outer join + not null column```, such as issue #7901
So we need to fall back from vectorized mode to non-vectorized mode when we encounter this situation.
If the nullside column of the outer join is a column that must return non-null like count(*)
then there is no way to force the column to be nullable.
At this time, vectorization cannot support this situation,
so it is necessary to fall back to non-vectorization for processing.
For example:
Query: set enable_vectorized_engine=true
Query: select * from t1 left join (select k1, count(k2) as count_k2 from t2 group by k1) tmp on t1.k1=tmp.k1
Result: Query goes non-vectorized engine
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