Azure Document DB Dirty Read / Write

Question

Since Azure Documentdb updates the whole document doesn't it create a situation for dirty read /write /phantoms.

Suppose I have following document

{
id:"1",
markers:[1,2,3]
}

Client A reads the above document.. in a web app.. and sits with for it about 5 mins and in mean time Client B also reads the document but it updates it with

{
id:"1"
**markers:[1,2,3,4]**
}

Since the update from Client A would come in update of whole document it would corrupt the data ?

Is there any way to avoid this ?

Answer 1

The Azure DocumentDB support optimistic concurrency using ETAG. When updating document, you can use the ETAG to avoid the overwrite. Here is one detailed blog on this topic https://peter.intheazuresky.com/2016/04/28/documentdb-revisited-part-3-concurrency-in-documentdb/