# Online Archive query performance optimization > Source-anchored research for Online Archive query performance optimization. Run status: COMPLETED. Parent: [DATE Criteria](https://llms-explorer.com/tree/date-criteria/) · 5 facets · 10 facts · page: https://llms-explorer.com/tree/online-archive-query-performance-optimization/ ## Structure and components - Atlas Data Federation `explain` output for Online Archive partitions includes an `optimizationPlan`; MongoDB’s documentation says queries are likely to be optimized when they contain the archive’s configured partition keys. (medium confidence) (verified as of 2026-10-14) — [source](https://www.mongodb.com/docs/atlas/data-federation/supported-unsupported/diagnostic-commands.md) ## How it works - For Date Match archives, the date field is first in the partition path by default, but a more frequently queried field can be moved ahead of it. Choose partition order from actual query patterns because omitting an earlier partition field makes later fields less efficient to use. (high confidence) — [source](https://www.mongodb.com/docs/atlas/online-archive/configure-online-archive-standard.md) ## Problems, failure modes and limitations - Archive reads are generally slower than live Atlas cluster reads. DBTA describes archival retrieval as slower than native-cluster queries, and Vanta reported that Online Archive reads were too slow and expensive for its own live-product workload; these reports describe workload tradeoffs, not a universal latency benchmark. (medium confidence) (verified as of 2026-10-14) — [source](https://www.mongodb.com/docs/atlas/online-archive/overview.md) - A predicate on a nonpartitioned field cannot use the archive partition layout effectively; MongoDB warns that such queries can require scanning all archived documents, increasing query time and data-processing costs. (high confidence) — [source](https://www.mongodb.com/docs/atlas/online-archive/configure-online-archive-standard.md) - MongoDB's documentation warns that high-cardinality string partition fields can create many partitions and are not recommended for Online Archives created before June 2023; it says this warning does not apply to archives created after June 2023. (high confidence) (verified as of 2026-10-23) — [source](https://www.mongodb.com/docs/atlas/online-archive/configure-online-archive-standard.md) ## Comparisons and alternatives - A 2021 independent guide recommends moderate-to-high-cardinality partition fields for general query targeting. It warns that low-cardinality fields partition poorly and extremely high-cardinality fields such as `_id` can create many partitions and slow archival writes; validate this tradeoff against the current archive and workload. (low confidence) (verified as of 2021-06-30) — [source](https://www.joekarlsson.com/blog/how-to-use-custom-archival-rules-and-partitioning-on-mongodb-atlas-online-archive/) ## Facts and statements - For Online Archive queries, Atlas Data Federation uses the configured partition fields in order. Queries that include all configured fields in that order target specific partitions and minimize scanned data; queries on unpartitioned fields are less performant. (high confidence) — [source](https://www.mongodb.com/docs/atlas/data-federation/query/query-federated-database.md) - MongoDB’s 2023 product announcement says its newer Online Archive storage engine captures metadata during archival and uses sorting and ongoing rebalancing to reduce query scans and improve query performance and cost. (low confidence) — [source](https://www.mongodb.com/company/blog/product-release-announcements/new-online-archive-performance-improvements-enhanced-metrics) - In a federated query across the cluster and archive, blocking operations such as sorts wait for all input data and inherit the slower source's performance; streaming finds can return results as they become available. (low confidence) — [source](https://www.mongodb.com/docs/atlas/online-archive/manage-online-archive.md) - MongoDB's 2023 announcement says the new Online Archive storage engine captures metadata during archival and uses sorting and ongoing rebalancing to reduce query scans. The initial rollout applied to archives created on or after 2023-06-07, and MongoDB described migration of older archives as a plan for the following year. A MongoDB staff forum reply said latency to list old-backend partitions grew with archive size and described the redesign as a response. (medium confidence) (verified as of 2025-03-12) — [source](https://www.mongodb.com/company/blog/product-release-announcements/new-online-archive-performance-improvements-enhanced-metrics)