--- title: Aggregation Optimization in MongoDB: Sorting With... description: This final installment of a five-part MongoDB optimization series shows how replacing an explicit $sort stage with an index-backed sort improved performance.... canonical: https://daily.dev/posts/aggregation-optimization-in-mongodb-sorting-with-indexes-part-5--ubdqt9zdr twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Aggregation Optimization in MongoDB: Sorting With Indexes (Part 5) | daily.dev og:description: This final installment of a five-part MongoDB optimization series shows how replacing an explicit $sort stage with an index-backed sort improved performance.... og:url: https://daily.dev/posts/aggregation-optimization-in-mongodb-sorting-with-indexes-part-5--ubdqt9zdr og:image: https://api.daily.dev/og/posts/uBdqt9ZdR.png og:image:alt: Aggregation Optimization in MongoDB: Sorting With Indexes (Part 5) og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Aggregation Optimization in MongoDB: Sorting With Indexes (Part 5) **[Foojay.io](https://daily.dev/sources/foojayio)** · 6 min read · 1 upvotes · 0 comments ## Summary This final installment of a five-part MongoDB optimization series shows how replacing an explicit $sort stage with an index-backed sort improved performance. By adding profileID to a compound index following the Equality-Sort-Range (ESR) rule, the pipeline avoided in-memory sorting of matched documents. Average query time dropped from 51ms to 14ms, and total time for 300 iterations fell from 1.2 seconds to 655 milliseconds, capping off a cumulative 230x+ improvement from the original 11.8-second pipeline. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How can I avoid an in-memory sort in a MongoDB aggregation pipeline? Add the sort field to a compound index instead of using an explicit $sort stage, since indexes return documents already ordered by key. In one case, adding profileID to an existing compound index on city and device name eliminated the $sort stage entirely, cutting average query time from 51ms to 14ms and total time for 300 iterations from 1.2 seconds to 655 milliseconds. _Track practical database performance techniques like this one on daily.dev as you tune MongoDB pipelines._ ### What is the Equality, Sort, Range (ESR) rule in MongoDB indexing? The ESR rule determines optimal field ordering in a compound index: fields used for equality matches should come first, followed by fields used for sorting, followed by fields used for range queries. Applying this rule, a compound index ordered as city, device name, then profileID let equality-matched documents be returned already sorted by profileID, removing the need for a separate sort stage. _Developers designing compound indexes can follow ESR guidance surfaced through daily.dev's database coverage._ ### How much can removing unnecessary $unwind stages and duplicating data improve a MongoDB aggregation pipeline's performance? In one video-streaming-style use case, removing unnecessary $unwind stages, refactoring a many-to-many relationship, and duplicating device name data brought average query time down from 11.8 seconds to 51 milliseconds, a roughly 230x improvement, before index-based sorting further reduced it to 14ms. _Follow multi-step MongoDB optimization case studies like this on daily.dev when tuning aggregation pipelines._ ## Similar posts on daily.dev - [Aggregation Optimization in MongoDB: A Case Study From the Field \(Part 1\)](https://daily.dev/posts/aggregation-optimization-in-mongodb-a-case-study-from-the-field-part-1--gzqybwhpz) · Foojay.io · 0 upvotes · 0 comments --- Tags: [#database](https://daily.dev/tags/database), [#mongodb](https://daily.dev/tags/mongodb) [View this post on daily.dev](https://daily.dev/posts/aggregation-optimization-in-mongodb-sorting-with-indexes-part-5--ubdqt9zdr) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Aggregation Optimization in MongoDB: Sorting With Indexes (Part 5)","url":"https://daily.dev/posts/aggregation-optimization-in-mongodb-sorting-with-indexes-part-5--ubdqt9zdr","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/aggregation-optimization-in-mongodb-sorting-with-indexes-part-5--ubdqt9zdr"},"datePublished":"2026-09-01T14:12:27.440Z","dateModified":"2026-09-01T14:12:54.508Z","description":"This final installment of a five-part MongoDB optimization series shows how replacing an explicit $sort stage with an index-backed sort improved performance....","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/eb1fb2748a8d0e7056484b44eb36763e?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/eb1fb2748a8d0e7056484b44eb36763e?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Foojay.io","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Foojay.io","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/1820f6a6ae944760aa322b67ed85f848","url":"https://daily.dev/sources/foojayio"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/aggregation-optimization-in-mongodb-sorting-with-indexes-part-5--ubdqt9zdr","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":1},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"database,mongodb","timeRequired":"PT6M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Foojay.io","item":"https://daily.dev/sources/foojayio"},{"@type":"ListItem","position":3,"name":"Aggregation Optimization in MongoDB: Sorting With Indexes (Part 5)"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/aggregation-optimization-in-mongodb-sorting-with-indexes-part-5--ubdqt9zdr#faq","mainEntity":[{"@type":"Question","name":"How can I avoid an in-memory sort in a MongoDB aggregation pipeline?","acceptedAnswer":{"@type":"Answer","text":"Add the sort field to a compound index instead of using an explicit $sort stage, since indexes return documents already ordered by key. 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