Upserting a document in CosmosDb, but only if "newer"

Question

I need to update documents in a CosmosDb.

{
firstname: "...",
lastname: "...",...
lastmodified: "2022-01-13T12:06:18.712Z"
}

Due to "concurrency" ( i.e. multiple concurrent "updaters" ), the update ( or insertion, hence Upsert? ) should only take place if the data I update is "newer" ( data.lastmodified ) than the one already persisted.

What is the proposed way to achieve this?

In plain SQL I'd opt for: UPDATE address SET ... WHERE address.lastmodified < newdata.lastmodified or INSERT ON DUPLICATE KEY UPDATE

If Upsert had the possibility for specifying contraints when to effectively upsert ( i.e. address.lastmodified < newdata.lastmodified ), I'd use these. But I guess ItemRequestOptions is not meant for that?

"concurrency"-context: updates are being posted into a service bus queue and an event-triggered AzureFunction handles the Events. Chances are, that multiple Events for the same data end up "concurrently" in the queue and hence are being executed "concurrently"

Thx for your advices
Clemens ( being new to ComosDb et al )

Answer 1

This can be achieved using partial document update with conditional update. You can use Add or Set patch operations and specify your WHERE clause of WHERE address.lastmodified < newdata.lastmodified to specify whether it executes or not.

For more information see, Partial Document Updates in Azure Cosmos DB