Description
Overview
Instantiate a MongoDB DB with a collection of N documents. Run a simple aggregation against that collection with a batchSize that is lower than N and that's not a multiple of N.
Examples:
N= 100,batchSize= 40N= 102,batchSize= 101 (default value)
For all those cases, cursor.next(&mut session) will return the following error:
Error: Command failed (CursorNotFound): cursor id XXXXXXXXX not found)
Reproduction
Below is a minimal reproduction example:
use anyhow::Result;
use mongodb::{
bson::{doc, Document},
options::{AggregateOptions, ClientOptions},
Client, Collection,
};
use tokio;
#[tokio::main]
async fn main() -> Result<()> {
let client_options = ClientOptions::parse("MONGO_URL").await?;
let client = Client::with_options(client_options)?;
let mut session = client.start_session(None).await?;
let db = client.database("DATABASE_NAME");
let coll: Collection<Document> = db.collection("COLLECTION_NAME");
// Default batchSize is 101. Have at least 102 documents for the error to happen
// or set a `batchSize` according to the rules above depending on the number of documents in your collection
let opts = AggregateOptions::builder().build();
let mut res = coll
.aggregate_with_session(
vec![doc! {
"$project": { "_id": 1 }
}],
opts,
&mut session,
)
.await?;
let mut docs = vec![];
while let Some(result) = res.next(&mut session).await {
match result {
Ok(document) => docs.push(document),
Err(e) => return Err(e.into()),
}
}
println!("Number of documents: {}", docs.len());
Ok(())
}