# MongoDB Atlas Online Archive > Online Archive automatically moves documents matching an archival rule out of the live Atlas cluster into Atlas-managed object storage, while keeping those documents queryable through the cluster's FD Parent: [MongoDB Atlas](https://llms-explorer.com/tree/mongodb-atlas/) · 19 facets · 65 facts · page: https://llms-explorer.com/tree/mongodb-atlas-online-archive/ ## Overview - Online Archive automatically moves documents matching an archival rule out of the live Atlas cluster into Atlas-managed object storage, while keeping those documents queryable through the cluster's FDI endpoint (transparent to the application). — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#overview` ## Requirements - Dedicated cluster M10+ (not available on M0/Flex/Serverless) — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#requirements` - MongoDB 5.0+ on the source cluster — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#requirements` ## DATE (most common) - dateFormat options: "ISODATE" (default ISODate), "EPOCH_MILLISECONDS", "EPOCH_SECONDS" — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#date-most-common` ## Partition Fields Strategy - Partition fields organize archived data into S3 prefix paths for efficient filtering. Critical for query performance. Choose fields commonly used in query filters: — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#partition-fields-strategy` - Maximum 2 partition fields per archive rule — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#partition-fields-strategy` - First field MUST match the dateField (for DATE criteria) or be the most selective filter field (for CUSTOM criteria) — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#partition-fields-strategy` - Order matters: highest-selectivity filter field should be first — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#partition-fields-strategy` - Supported partition pruning operators: $eq, $gt, $lt, $gte, $lte, $ne, $in — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#partition-fields-strategy` - Fields NOT in partitionFields trigger full archive scan when queried — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#partition-fields-strategy` ## Archive Job Timing & Processing - Runs every 5 minutes — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#archive-job-timing-processing` - Max throughput: 2 GB per 5-minute interval — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#archive-job-timing-processing` - Max file size: 100 MB per archive file — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#archive-job-timing-processing` - Documents deleted from live cluster AFTER successful write to object storage — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#archive-job-timing-processing` - Schedule window: Archive jobs can be limited to off-hours to reduce production impact — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#archive-job-timing-processing` ## Query Routing - When querying via the cluster's FDI endpoint: — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#query-routing` - Recent data → live cluster (fast, indexed) — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#query-routing` - Archived data → Online Archive object storage (slower, partition-based) — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#query-routing` - Combined queries → both, results merged transparently — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#query-routing` - Applications do not need to change query patterns after data is archived - same connection string, same MQL. — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#query-routing` ## Cost Model - $5/TB cost applies when QUERYING archived data. Storage itself is much cheaper than cluster storage (NVMe/GP3). — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#cost-model` - Minimum: 10 MB per archive query (no benefit from very small queries). — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#cost-model` ## Restore / Rehydration - Archive data is immutable (append-only). To restore to the live cluster: — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#restore-rehydration` ## Limitations - No updates/deletes on archived data: Archive is immutable object storage; updateMany or deleteMany against archived documents will not affect them — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#limitations` - No Atlas Search on archived data: Full-text $search doesn't work on archived data — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#limitations` - No indexes on archived data: All archived queries use partition pruning only — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#limitations` - $sample not random: Returns first N documents, not a statistical random sample — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#limitations` - No transactions crossing live+archive: Cannot span a transaction across live and archived documents — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#limitations` - Maximum query timeout: 6 hours (inherits from Data Federation limit) — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#limitations` ## Archive Not Moving Data - Check Atlas → Online Archive → [collection] → Activity tab for job status and errors — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#archive-not-moving-data` - Verify dateField name is exact (case-sensitive) and matches documents — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#archive-not-moving-data` - Confirm correct dateFormat - ISODATE requires actual ISODate values, not Unix epoch integers — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#archive-not-moving-data` - Confirm cluster tier is M10+ and MongoDB version 5.0+ — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#archive-not-moving-data` ## Archive Backlog Growing - Archive jobs process 2 GB per 5-minute window — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#archive-backlog-growing` - If data accumulates faster than 2 GB/5 minutes, backlog will grow — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#archive-backlog-growing` - Mitigation: narrow the archive rule to reduce concurrent archiving volume, or contact MongoDB for higher throughput — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#archive-backlog-growing` ## Slow Archive Queries - Partition fields not aligned with query filter → full archive scan — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#slow-archive-queries` - Check partitionFields match the most common query filter fields — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#slow-archive-queries` - Run explain() on the FDI endpoint to check nPartitionsScanned — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#slow-archive-queries` ## MACC / Cost Tracking - Archive storage costs appear on the Atlas invoice under Tools & Services → Online Archive. Query processing costs under Data Federation. Monitor in Atlas Billing → Current Invoice. — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#macc-cost-tracking` ## Anti-Patterns - Choosing partition fields that don't match query patterns: Full archive scan on every query → high $5/TB cost — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#anti-patterns` - Using CUSTOM criteria without an index on the filter field: Archive job itself will do slow scans to find matching documents - add an index on filter fields — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#anti-patterns` - Querying archived data without partition-aligned filters: Always include a partition field in $match when querying archive — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#anti-patterns` - Expecting consistency between live and archive: Documents are copied to archive and then deleted from live - there is no transactional guarantee between the two — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#anti-patterns` - Using Online Archive as a backup system: Archive only stores the final document state at archival time - not a substitute for backup snapshots with PITR — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#anti-patterns` ## References - Online Archive Documentation — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#references` - Configure an Online Archive — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#references` - Query Archived Data — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#references` - Online Archive Billing — source: `https://llms-explorer.com/sources/mdb-context-hub/mongodb-atlas-online-archive/#references` ## Where this helps - Reducing live-cluster storage cost for time-based data, such as event logs or historical orders, that's rarely queried after a certain age, without changing application query patterns. — [source](https://llms-explorer.com/tree/mongodb-atlas-online-archive/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - Meeting a data-retention requirement where old data must remain queryable but doesn't need to sit on expensive cluster storage. — [source](https://llms-explorer.com/tree/mongodb-atlas-online-archive/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - Designing partition fields so archived-data queries stay fast instead of triggering a full archive scan. — [source](https://llms-explorer.com/tree/mongodb-atlas-online-archive/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - Deciding Online Archive is the wrong tool because the use case actually needs a real backup with PITR, not an archive. — [source](https://llms-explorer.com/tree/mongodb-atlas-online-archive/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* ## Project ideas - Configure an Online Archive rule on a DATE field with well-chosen partition fields matching the most common query filter, then run explain() on the FDI endpoint to check nPartitionsScanned. — [source](https://llms-explorer.com/tree/mongodb-atlas-online-archive/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - Build a query-routing test that confirms combined live+archive queries return merged results through the same connection string and MQL the application already uses. — [source](https://llms-explorer.com/tree/mongodb-atlas-online-archive/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - Set up a CUSTOM-criteria archive rule with a supporting index on the filter field, and compare archive job throughput against a DATE-based rule. — [source](https://llms-explorer.com/tree/mongodb-atlas-online-archive/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - Build a cost dashboard tracking the $5/TB archived-data query charge separately from Online Archive storage cost, using the Atlas Billing Dashboard. — [source](https://llms-explorer.com/tree/mongodb-atlas-online-archive/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* ## Common mistakes - Choosing partition fields that don't match actual query filters, forcing a full archive scan, and the associated $5/TB cost, on every query. — [source](https://llms-explorer.com/tree/mongodb-atlas-online-archive/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - Using CUSTOM archive criteria without an index on the filter field, which makes the archive job itself do slow scans to find matching documents. — [source](https://llms-explorer.com/tree/mongodb-atlas-online-archive/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - Assuming transactional consistency between live and archived data — documents are copied to archive storage and then deleted from the live cluster, with no transactional guarantee linking the two. — [source](https://llms-explorer.com/tree/mongodb-atlas-online-archive/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - Treating Online Archive as a backup — it only stores the final document state at archival time, so it's not a substitute for PITR-backed snapshots. — [source](https://llms-explorer.com/tree/mongodb-atlas-online-archive/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* ## Known issues - Archived data is immutable — updateMany or deleteMany against archived documents has no effect, and there is no in-place update path. — [source](https://llms-explorer.com/tree/mongodb-atlas-online-archive/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - There is no Atlas Search or index support on archived data; all archived queries rely purely on partition pruning. — [source](https://llms-explorer.com/tree/mongodb-atlas-online-archive/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - $sample against archived data is not a true random sample — it returns the first N documents rather than a statistically random selection. — [source](https://llms-explorer.com/tree/mongodb-atlas-online-archive/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - Archive job throughput is capped at 2 GB per 5-minute interval, so a source collection generating archival-eligible data faster than that will build a growing backlog. — [source](https://llms-explorer.com/tree/mongodb-atlas-online-archive/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)*