## What does Atlan crawl from MongoDB (self-managed)?

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

> Atlan crawls and maps the following assets and properties from MongoDB (self-managed). Atlan currently doesn't support lineage for MongoDB (self-managed) assets.

This reference document details the MongoDB (self-managed) assets and properties that Atlan crawls and maps during metadata extraction. Atlan currently doesn't support lineage for MongoDB (self-managed) assets.

## Assets

Atlan crawls and maps the following asset types from MongoDB (self-managed): databases, Collections, and columns. After [crawling MongoDB (self-managed)](https://docs.atlan.com/llms/connectors/mongodb-onprem/crawl-mongodb-onprem/llms.txt), you can [use connector-specific filters](https://docs.atlan.com/llms/catalog/discovery/use-the-filters-menu/llms.txt) to discover assets. The **Collection type** filter is available for Collections, allowing you to filter by collection types including Time Series, Capped, and Clustered.

The following sections show how each asset type is mapped from MongoDB to Atlan, including source properties and their corresponding Atlan properties.

### Databases

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

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

### Collections

Atlan maps Collections from MongoDB to its `Collection` 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 maps the following metadata from MongoDB to its `Column` asset type. For details on how column schemas are consolidated and what limitations apply, see [How are column schemas consolidated and what are the limitations?](https://docs.atlan.com/llms/connectors/mongodb-onprem/field-extraction-and-schema-inference/llms.txt) in the FAQ.

| Atlan property | Where in Atlan |
| --- | --- |
| `name` | `name` |
| `order` | `order` |
| `dataType` | `dataType` |
| `rawdataTypeDefinition` (raw schema of nested columns in a given parent column) | `rawdataTypeDefinition` |
| `parentColumnQualifiedName` (complete hierarchy from parent column to child column) | `parentColumnQualifiedName` |
| `nosqlCollectionName` | `collection`|

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