Perf/api mongo projections

src/dataLoaders.ts

@@ -68,27 +68,36 @@
    * Batching function for resolving entities from their ids
    * @param collectionName - collection name to get entities
    * @param ids - ids for resolving
+   * @param projection - optional mongo projection to limit returned fields
    */
   private async batchByIds<T extends { _id: ObjectId }>(
     collectionName: string,
-    ids: ReadonlyArray<string>
+    ids: ReadonlyArray<string>,
+    projection?: Record<string, 0 | 1>
   ): Promise<(WithId<T> | null)[]> {
-    return this.batchByField<T, '_id'>(collectionName, '_id', ids.map(id => new ObjectId(id)));
+    return this.batchByField<T, '_id'>(
+      collectionName,
+      '_id',
+      ids.map(id => new ObjectId(id)),
+      projection
+    );
   }
 
   /**
    * Batching function for resolving entities by certain field
    * @param collectionName - collection name to get entities
    * @param fieldName - field name to resolve
    * @param values - values for resolving
+   * @param projection - optional mongo projection to limit returned fields
    */
   private async batchByField<
     T extends Record<string, any>,
     FieldType extends keyof T
   >(
     collectionName: string,
     fieldName: FieldType,
-    values: ReadonlyArray<T[FieldType]>
+    values: ReadonlyArray<T[FieldType]>,
+    projection?: Record<string, 0 | 1>
   ): Promise<(WithId<T> | null)[]> {
     type Doc = WithId<T>;
     const valuesMap = new Map<string, FieldType>();
@@ -99,9 +108,10 @@
 
     const queryResult = await this.dbConnection
       .collection<T>(collectionName)
-      .find({
-        [fieldName]: { $in: Array.from(valuesMap.values()) },
-      } as any)
+      .find(
+        { [fieldName]: { $in: Array.from(valuesMap.values()) } } as any,
+        projection ? { projection } : {}
+      )
       .toArray();
 
     /**
@@ -120,7 +130,7 @@
   }
 }
 
 /**
  * Create DataLoader for events in dynamic collections `events:<projectId>` stored in the events DB
  *
  * @param eventsDb - MongoDB connection to the events database

src/models/eventsFactory.js

@@ -403,6 +403,17 @@ class EventsFactory extends Factory {
       return { 'event.assignee': String(assignee) };
     })();
 
+    /** When false, $limit can move before the $lookups. */
+    const hasContentFilters =
+      escapedSearch.length > 0 ||
+      Boolean(release) ||
+      Boolean(assignee) ||
+      Object.keys(matchFilter).length > 0;
+
+    if (!hasContentFilters) {
+      pipeline.push({ $limit: limit + 1 });
+    }
+
     pipeline.push(
       /**
        * Left outer join original event on groupHash field
@@ -434,21 +445,25 @@ class EventsFactory extends Factory {
           path: '$repetition',
           preserveNullAndEmptyArrays: true,
         },
-      },
-      {
-        $match: {
-          ...matchFilter,
-          ...searchFilter,
-          ...releaseFilter,
-          ...assigneeFilter,
-        },
-      },
-      { $limit: limit + 1 },
-      {
-        $unset: 'groupHash',
       }
     );
 
+    if (hasContentFilters) {
+      pipeline.push(
+        {
+          $match: {
+            ...matchFilter,
+            ...searchFilter,
+            ...releaseFilter,
+            ...assigneeFilter,
+          },
+        },
+        { $limit: limit + 1 }
+      );
+    }
+
+    pipeline.push({ $unset: 'groupHash' });
+
     const cursor = this.getCollection(this.TYPES.DAILY_EVENTS).aggregate(pipeline);
     const result = await cursor.toArray();