TransactionalBatchRequestOptions.SessionToken Property
Definition
Important
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Gets or sets the token for use with session consistency in the Azure Cosmos DB service.
public string SessionToken { get; set; }member this.SessionToken : string with get, setPublic Property SessionToken As StringProperty Value
The token for use with session consistency.
Remarks
One of the ConsistencyLevel for Azure Cosmos DB is Session. In fact, this is the default level applied to accounts.
When working with Session consistency, each batch request with write operation to Azure Cosmos DB is assigned a new SessionToken. The CosmosClient will use this token internally with each read/query/batch request to ensure that the set consistency level is maintained.
In some scenarios you need to manage this Session yourself; Consider a web application with multiple nodes, each node will have its own instance of CosmosClient If you wanted these nodes to participate in the same session (to be able read your own writes consistently across web tiers) you would have to send the SessionToken from TransactionalBatchResponse of the write action on one node to the client tier, using a cookie or some other mechanism, and have that token flow back to the web tier for subsequent reads. If you are using a round-robin load balancer which does not maintain session affinity between requests, such as the Azure Load Balancer, the read could potentially land on a different node to the write request, where the session was created.
If you do not flow the Azure Cosmos DB SessionToken across as described above you could end up with inconsistent read results for a period of time.
https://docs.microsoft.com/azure/cosmos-db/consistency-levels
