## What does Atlan crawl from MongoDB Atlas?

URL: https://docs.atlan.com/apps/connectors/database/mongodb/references/what-does-atlan-crawl-from-mongodb

> During a MongoDB crawl, Atlan extracts metadata for Databases, Collections, and Columns. Reference tables map each MongoDB property to its Atlan asset.

Atlan extracts metadata for Databases, Collections, and Columns from MongoDB and maps each property to its internal asset model. The tables below list which MongoDB properties are read and how they appear on the corresponding Atlan asset. Atlan currently doesn't support lineage for MongoDB Atlas assets.

Once you have [crawled MongoDB](https://docs.atlan.com/llms/connectors/mongodb/crawl-mongodb/llms.txt), you can [use connector-specific filters](https://docs.atlan.com/llms/catalog/discovery/use-the-filters-menu/llms.txt) for quick asset discovery. The following filter is currently supported for [MongoDB collections](#collections):

- _Collection type_ filter - filtering options include _Time Series_, _Capped_, and _Clustered_ collection types

## Databases

Atlan maps databases from MongoDB to its `MongoDBDatabase` asset type.

| Source property | Atlan property |
| --- | --- |
| `TABLE_CAT` | `name` |
| `TABLE_COUNT` | `mongoDBDatabaseCollectionCount` |

## Collections

Atlan maps collections from MongoDB to its `MongoDBCollection` asset type.

| Source property | Atlan property |
| --- | --- |
| `TABLE_NAME` | `name` |
| `TABLE_CAT` | `databaseName` |
| `COLUMN_COUNT` | `columnCount` |
| `collStats.storageSize` | `sizeBytes` |
| `collStats.count` | `rowCount` |
| `type` | `mongoDBCollectionSubtype` |
| `schema` | `mongoDBCollectionSchemaDefinition` |
| `collStats.capped` | `mongoDBCollectionIsCapped` |
| `collStats.maxSize` | `mongoDBCollectionMaxSize` |
| `collStats.max` | `mongoDBCollectionMaximumDocumentCount` |
| `options.timeseries.timeField` | `mongoDBCollectionTimeField` |
| `options.timeseries.granularity` | `mongoDBCollectionTimeGranularity` |
| `options.expireAfterSeconds` | `mongoDBCollectionExpireAfterSeconds` |
| `collStats.numOrphanDocs` | `mongoDBCollectionNumOrphanDocs` |
| `collStats.nindexes` | `mongoDBCollectionNumIndexes` |
| `collStats.totalIndexSize` | `mongoDBCollectionTotalIndexSize` |
| `collStats.avgObjSize` | `mongoDBCollectionAverageObjectSize` |

## Columns

Atlan infers column metadata from MongoDB collection documents by analyzing document schemas during the crawl. Column extraction consolidates observed fields (including nested structures) into a unified view, with each unique field path represented as a column. Top-level columns have depth 1; nested fields have a parent column and a hierarchy path. Column-level lineage isn't supported for MongoDB Atlas.

Atlan maps the following metadata from MongoDB Atlas to its `Column` asset type:

| Source inferred property | Atlan property |
| --- | --- |
| field name (path) | `name` |
| precomputed qualified name | `qualifiedName` |
| position in collection | `order` |
| position within parent (nested) | `nestedColumnOrder` |
| inferred type | `dataType` |
| sub type (nested) | `subDataType` |
| raw type definition (for example JSON schema) | `rawDataTypeDefinition` |
| depth in hierarchy (1 = top-level) | `columnDepthLevel` |
| number of nested columns | `nestedColumnCount` |
| hierarchy path (nested) | `columnHierarchy` |
| parent field name (nested only) | `parentColumnName` |
| parent column qualified name (nested only) | `parentColumnQualifiedName` |
| collection name | `nosqlCollectionName` |
| collection qualified name | `nosqlCollectionQualifiedName` |
| database name | `databaseName` |
| database qualified name | `databaseQualifiedName` |
| (MongoDB fields are nullable) | `isNullable` |

## See also

- [Preflight checks for MongoDB Atlas](https://docs.atlan.com/llms/connectors/mongodb/preflight-checks-for-mongodb-atlas/llms.txt): Verify user privileges before crawling.
- [Crawl MongoDB assets](https://docs.atlan.com/llms/connectors/mongodb/crawl-mongodb/llms.txt): Run a crawl and use filters.
- [Set up MongoDB Atlas](https://docs.atlan.com/llms/connectors/mongodb/set-up-mongodb/llms.txt): Configure the connector.
- [Troubleshooting connectivity](https://docs.atlan.com/llms/connectors/mongodb/troubleshooting-mongodb-connectivity/llms.txt): Resolve connection issues.

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