Hi Konstantin,
I also vimdiff nodeAgg.c in your PG13 branch with nodeAgg.c in pg's main repo.
Many functions has changed from PG96 to PG13, e.g. 'advance_aggregates', 'lookup_hash_entry'
The vectorized nodeAgg seems still follow the PG96 way of implementing these functions.
In general, I think we'd better port executor of PG13 to vectorized executor of PG13 instead of merge some PG13 code into vectorized executor of PG96 to make it works. Because It's hard to determine which functions need to be merged and it's buggy if the executor code of both PG13 and PG96 exist in one branch.
What's your opinion?