$let is not working in Cosmos DB 4.0

Hi!
In aggregation

 {
   $lookup:
     {
       from: <collection to join>,
       let: { <var_1>: <expression>, …, <var_n>: <expression> },
       pipeline: [ <pipeline to execute on the collection to join> ],
       as: <output array field>
     }
}

is not working in 4.0 version
I am using cosmoDB 4.0 version in Azure
someone please help me to solve this issue

A very valid reason to consider atlas on azure :wink:

It will never happen there…

Hi @Ganesh_ND,

As other commenters have noted, CosmosDB is an incomplete emulation of MongoDB (even for the claimed MongoDB server versions).

Some important feature support is lacking, for example index collation:

The let syntax for Join Conditions & Uncorrelated Sub-queries was added in MongoDB 3.6 (November 2017).

As per @Pavel_Duchovny, MongoDB Atlas is available on Azure if you want a managed database service with genuine MongoDB feature support.

Regards,
Stennie

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