On 10/12/18 10:51 AM, charettes wrote:
Hello Tobias,
From my understanding the introduction of chunk_size doest't help here.
The fundamental reason why iterator() cannot be used with
prefetch_related() is that the latter requires a set of model instance
to be materialized to work appropriately which chunk_size doesn't
control at all.
In other words chunk_size only controls how many rows should be fetched
from the database cursor and kept into memory at a time. Even when this
parameter is used, iterator() will only materialize a single model
instance per yield.
I inferred from the original post they were suggesting to do a set of
prefetch_related "filling" queries _per_ _chunk_
It wouldn't be as efficient as the 1+P (where P is number of prefetched
relations) of a normal prefetch_related, but at 1+(P x Chunks) it would
_probably_ be more efficient than the 1+(P x N-rows) it would otherwise
be [or worse!]
--
Curtis
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