# Index Sufficiency Warning > Depth-first rabbithole dossier for Index Sufficiency Warning; source-anchored research pack. Parent: [Archive Rules](https://llms-explorer.com/tree/archive-rules/) · 3 facets · 5 facts · page: https://llms-explorer.com/tree/index-sufficiency-warning/ ## How it works - [medium] Atlas runs an index sufficiency query during the first archive run to determine the efficiency of the archival process. Sources: https://www.mongodb.com/docs/atlas/online-archive/configure-online-archive-standard.md, https://www.mongodb.com/docs/atlas/online-archive/configure-online-archive-time-series.md — source: `~/.global-ai-hub/research/.pipeline/mongodb-2026-10-14/frb/index-sufficiency-warning-29593cac14/rabbithole-synthesis.md#core` ## Problems, failure modes and limitations - [high] If the ratio of documents scanned to documents returned is 10 or more, the query result triggers an `Index Sufficiency Warning`. Sources: https://www.mongodb.com/docs/atlas/online-archive/configure-online-archive-standard.md, https://www.mongodb.com/docs/atlas/online-archive/configure-online-archive-time-series.md, https://www.mongodb.com/community/forums/t/sort-exceeded-memory-limit-of-104857600-bytes/269787 — source: `~/.global-ai-hub/research/.pipeline/mongodb-2026-10-14/frb/index-sufficiency-warning-29593cac14/rabbithole-synthesis.md#core` - [medium] The index sufficiency query stops running after sufficient indexes are detected, and Atlas does not issue an `Index Sufficiency Warning` if an index is dropped later and slows down the archiving process. Sources: https://www.mongodb.com/docs/atlas/online-archive/configure-online-archive-standard.md, https://www.mongodb.com/docs/atlas/online-archive/configure-online-archive-time-series.md — source: `~/.global-ai-hub/research/.pipeline/mongodb-2026-10-14/frb/index-sufficiency-warning-29593cac14/rabbithole-synthesis.md#core` - [low] For date-based archives, you must index the date field; an index sufficiency error occurs only if there are no indexes or compound indexes containing the date time field. Sources: https://www.mongodb.com/community/forums/t/sort-exceeded-memory-limit-of-104857600-bytes/269787 — source: `~/.global-ai-hub/research/.pipeline/mongodb-2026-10-14/frb/index-sufficiency-warning-29593cac14/rabbithole-synthesis.md#core` ## Facts and statements - [low] The `ONLINE_ARCHIVE_INSUFFICIENT_INDEXES_CHECK` alert indicates an Online Archive Insufficient Indexes Alert, while `ONLINE_ARCHIVE_INSUFFICIENT_INDEXES_RESOLVED` indicates the alert is resolved. Sources: https://www.mongodb.com/docs/atlas/reference/atlas-alert-event-types.md — source: `~/.global-ai-hub/research/.pipeline/mongodb-2026-10-14/frb/index-sufficiency-warning-29593cac14/rabbithole-synthesis.md#core` ## Related concepts - Index — is a part of Index Sufficiency Warning - Sufficiency — is a part of Index Sufficiency Warning - Warning — is a part of Index Sufficiency Warning