feat(NODE-4079): estimated document count uses count

src/collection.ts

@@ -1044,7 +1044,9 @@ export class Collection<TSchema extends Document = Document> {
 
   /**
    * Gets an estimate of the count of documents in a collection using collection metadata.
+   * This will always run a count command on all server versions.
    *
+   * @see {@link https://www.mongodb.com/docs/manual/reference/command/count/#behavior|Count: Behavior}
    * @param options - Optional settings for the command
    * @param callback - An optional callback, a Promise will be returned if none is provided
    */

src/operations/estimated_document_count.ts

@@ -3,7 +3,7 @@ import type { Collection } from '../collection';
 import type { MongoServerError } from '../error';
 import type { Server } from '../sdam/server';
 import type { ClientSession } from '../sessions';
-import { Callback, maxWireVersion } from '../utils';
+import type { Callback } from '../utils';
 import { CommandOperation, CommandOperationOptions } from './command';
 import { Aspect, defineAspects } from './operation';
 
@@ -32,32 +32,6 @@ export class EstimatedDocumentCountOperation extends CommandOperation<number> {
     server: Server,
     session: ClientSession | undefined,
     callback: Callback<number>
-  ): void {
-    if (maxWireVersion(server) < 12) {
-      return this.executeLegacy(server, session, callback);
-    }
-    const pipeline = [{ $collStats: { count: {} } }, { $group: { _id: 1, n: { $sum: '$count' } } }];
-
-    const cmd: Document = { aggregate: this.collectionName, pipeline, cursor: {} };
-
-    if (typeof this.options.maxTimeMS === 'number') {
-      cmd.maxTimeMS = this.options.maxTimeMS;
-    }
-
-    super.executeCommand(server, session, cmd, (err, response) => {
-      if (err && (err as MongoServerError).code !== 26) {
-        callback(err);
-        return;
-      }
-
-      callback(undefined, response?.cursor?.firstBatch[0]?.n || 0);
-    });
-  }
-
-  executeLegacy(
-    server: Server,
-    session: ClientSession | undefined,
-    callback: Callback<number>
   ): void {
     const cmd: Document = { count: this.collectionName };
 
@@ -66,12 +40,12 @@ export class EstimatedDocumentCountOperation extends CommandOperation<number> {
     }
 
     super.executeCommand(server, session, cmd, (err, response) => {
-      if (err) {
+      if (err && (err as MongoServerError).code !== 26) {
         callback(err);
         return;
       }
 
-      callback(undefined, response.n || 0);
+      callback(undefined, response?.n || 0);
     });
   }
 }

test/spec/atlas-data-lake-testing/estimatedDocumentCount.json

@@ -15,24 +15,9 @@
         {
           "command_started_event": {
             "command": {
-              "aggregate": "driverdata",
-              "pipeline": [
-                {
-                  "$collStats": {
-                    "count": {}
-                  }
-                },
-                {
-                  "$group": {
-                    "_id": 1,
-                    "n": {
-                      "$sum": "$count"
-                    }
-                  }
-                }
-              ]
+              "count": "driverdata"
             },
-            "command_name": "aggregate",
+            "command_name": "count",
             "database_name": "test"
           }
         }

test/spec/atlas-data-lake-testing/estimatedDocumentCount.yml

@@ -13,9 +13,6 @@ tests:
       -
         command_started_event:
           command:
-            aggregate: *collection_name
-            pipeline:
-            - $collStats: { count: {} }
-            - $group: { _id: 1, n: { $sum: $count }}
-            command_name: aggregate
-            database_name: *database_name
+            count: *collection_name
+          command_name: count
+          database_name: *database_name