In case of Buffer table has columns of AggregateFunction type,
aggregate states for such columns will be allocated from the query
context but those states can be destroyed from the server context (in
case of background flush), and thus memory will be leaked from the query
since aggregate states can be shared, and eventually this will lead to
MEMORY_LIMIT_EXCEEDED error.
To avoid this, prohibit sharing the aggregate states.
But note, that this problem only about memory accounting, not memory
usage itself.
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
