Add overload to BulkAll with IAsyncEnumerable

[nesterenko-kv]

It would be great to see support for IAsyncEnumerable, because, when pulling data from the database asynchronously, it requires to load data completely into memory in order to use synchronous enumeration (IEnumerable),

[russcam]

Hi @nesterenko-kv

when pulling data from the database asynchronously, it requires to load data completely into memory in order to use synchronous enumeration (IEnumerable),

The IEnumerable<T> implementation passed to BulkAll does not explicitly require loading data completely into memory. For example, it might be an implementation that executes queries against the database to fetch just a page of results at a time.

Were you referring to the loading of each page completely into memory (which currently happens)? There might be some benefit to changing this to support IAsyncEnumerable<T>, though I think it would also require extending how bulk requests are serialized to the request stream to take full advantage, since bulk operations are currently buffered on the request.

[ivanlegin]

I've actually encountered another problem related to EntityFramework. What's happening now is that EF at some point throws an error saying that the DbContext is being used in parallel. The problem, I assume, is that in the ForEachAsync function, await is used, and then when the next iteration of the loop fetches a new set of data, EF detects a thread change because of the await. I assume that if IAsyncEnumerable is used with await foreach() and MoveNextAsync in the PartitionHelper, then it would work.