## What does Atlan crawl from Google BigQuery?

URL: https://docs.atlan.com/apps/connectors/data-warehouses/google-bigquery/references/what-does-atlan-crawl-from-google-bigquery

> Atlan doesn't run any table scans. Atlan leverages the table preview options from [Google BigQuery](https://cloud.google.com/bigquery/docs/best-practices-costs#preview-data) that enable you to view data for free and without affecting any quotas using the `tabledata.list` API. Hence, [table](/apps/connectors/data-warehouses/google-bigquery/references/what-does-atlan-crawl-from-google-bigquery#tables) asset previews in Atlan are already cost-optimized. However, this doesn't apply to [views](/apps/connectors/data-warehouses/google-bigquery/references/what-does-atlan-crawl-from-google-bigquery#views) and [materialized views](/apps/connectors/data-warehouses/google-bigquery/references/what-does-atlan-crawl-from-google-bigquery#materialized-views).

Once you have [crawled Google BigQuery](https://docs.atlan.com/llms/connectors/google-bigquery/crawl-google-bigquery/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 filters are currently supported for these assets:

- [Tables](#tables) - BigQuery labels and [Is sharded](https://docs.atlan.com/llms/connectors/google-bigquery/crawl-google-bigquery/llms.txt) filters

Atlan doesn't run any table scans. Atlan leverages the table preview options from [Google BigQuery](https://cloud.google.com/bigquery/docs/best-practices-costs#preview-data) that enable you to view data for free and without affecting any quotas using the `tabledata.list` API. Hence, [table](https://docs.atlan.com/llms/connectors/google-bigquery/what-does-atlan-crawl-from-google-bigquery/llms.txt) asset previews in Atlan are already cost-optimized. However, this doesn't apply to [views](https://docs.atlan.com/llms/connectors/google-bigquery/what-does-atlan-crawl-from-google-bigquery/llms.txt) and [materialized views](https://docs.atlan.com/llms/connectors/google-bigquery/what-does-atlan-crawl-from-google-bigquery/llms.txt).

For Google BigQuery [views](#views) and [materialized views](#materialized-views), Atlan sends you a cost nudge before viewing a sample data preview. This informs you about the precise bytes that are spent during the execution of the query, helping you decide if you still want to run the preview.

:::info **Did you know?** 
 You also receive a cost nudge before [querying your Google BigQuery assets](https://docs.atlan.com/llms/catalog/insights/tips-and-tricks/llms.txt).
:::

Atlan crawls and maps the following assets and properties from Google BigQuery.

## Databases

Atlan maps projects from Google BigQuery to its `Database` asset type.

| Source property | Atlan property | Where in Atlan |
| --- | --- | --- |
| `Project ID` | `name` | asset preview, profile, and filter, overview sidebar |

## Schemas

Atlan maps datasets from Google BigQuery to its `Schema` asset type.

| Source property | Atlan property | Where in Atlan |
| --- | --- | --- |
| `TABLE_SCHEMA` | `name` | asset preview and profile, overview sidebar |
| `TABLE_COUNT` | `tableCount` | asset preview and profile |
| `VIEW_COUNT` | `viewsCount` | asset preview and profile, overview sidebar |
| `TABLE_CATALOG` | `databaseName` | asset preview |
| `REMARKS` | `description` | asset preview and profile, overview sidebar |
| `CREATED` | `sourceCreatedAt` | asset profile and properties sidebar |
| `MODIFIED` | `sourceUpdatedAt` | asset profile and properties sidebar |

## Tables

:::info **Did you know?** 
 [Table](#tables) asset previews are already cost-optimized. [Google BigQuery](https://cloud.google.com/bigquery/docs/best-practices-costs#preview-data) enables you to use the table preview options to view data for free and without affecting any quotas. Note that this isn't currently supported for [Google BigQuery views and materialized views](https://docs.atlan.com/llms/connectors/google-bigquery/what-does-atlan-crawl-from-google-bigquery/llms.txt) in Atlan.

:::

Atlan maps tables from Google BigQuery to its `Table` asset type.

| Source property | Atlan property | Where in Atlan |
| --- | --- | --- |
| `TABLE_NAME` | `name` | asset preview and profile, overview sidebar |
| `REMARKS` | `description` | asset preview and profile, overview sidebar |
| `COLUMN_COUNT` | `columnCount` | asset preview and profile, overview sidebar |
| `ROW_COUNT` | `rowCount` | asset preview, profile, and filter, overview sidebar |
| `SIZE_BYTES` | `sizeBytes` | asset filter and overview sidebar |
| `TABLE_TYPE` | `subType` | asset preview and profile |
| `LABELS` | `assetTags` | overview sidebar |
| `CREATED` | `sourceCreatedAt` | asset profile and properties sidebar |
| `MODIFIED` | `sourceUpdatedAt` | asset profile and properties sidebar |
| `OPTION_NAMES (require_partition_filter)` | `isPartitioned` | API only |

## Views

Atlan maps views from Google BigQuery to its `View` asset type.

| Source property | Atlan property | Where in Atlan |
| --- | --- | --- |
| `TABLE_NAME` | `name` | asset preview and profile, overview sidebar |
| `REMARKS` | `description` | asset preview and profile, overview sidebar |
| `COLUMN_COUNT` | `columnCount` | asset preview and profile, overview sidebar |
| `TABLE_TYPE` | `subType` | asset preview and profile |
| `CREATED` | `sourceCreatedAt` | asset profile and properties sidebar |
| `MODIFIED` | `sourceUpdatedAt` | asset profile and properties sidebar |
| `OPTION_NAMES (require_partition_filter)` | `isPartitioned` | API only |
| `DDL` | `definition` | asset profile and overview sidebar |

## Materialized views

Atlan maps materialized views from Google BigQuery to its `MaterialisedView` asset type.

| Source property | Atlan property | Where in Atlan |
| --- | --- | --- |
| `TABLE_NAME` | `name` | asset preview and profile, overview sidebar |
| `REMARKS` | `description` | asset preview and profile, overview sidebar |
| `COLUMN_COUNT` | `columnCount` | asset preview and profile, overview sidebar |
| `ROW_COUNT` | `rowCount` | asset preview, profile, and filter, overview sidebar |
| `SIZE_BYTES` | `sizeBytes` | asset filter and overview sidebar |
| `TABLE_TYPE` | `subType` | asset preview and profile |
| `CREATED` | `sourceCreatedAt` | asset profile and properties sidebar |
| `MODIFIED` | `sourceUpdatedAt` | asset profile and properties sidebar |
| `OPTION_NAMES (require_partition_filter)` | `isPartitioned` | API only |
| `DDL` | `definition` | asset profile and overview sidebar |

## Columns

Atlan supports [nested columns up to level 15](https://docs.atlan.com/llms/connectors/google-bigquery/troubleshooting-google-bigquery-connectivity/llms.txt) for Google BigQuery to help you enrich your semi-structured data types. You can view nested columns in the Tree view or the asset sidebar of your table assets. Atlan also supports [policy tagging](https://docs.atlan.com/llms/connectors/google-bigquery/manage-google-bigquery-tags/llms.txt) on nested columns, so you can apply column-level security to fields at any nesting depth. Atlan maps columns from Google BigQuery to its `Column` asset type.

:::warning Important
Atlan doesn't crawl primary key (PK) and foreign key (FK) information from Google BigQuery.
:::

| Source property | Atlan property | Where in Atlan |
| --- | --- | --- |
| `COLUMN_NAME` | `name` | asset preview and profile, overview sidebar |
| `REMARKS, DESCRIPTION` | `description` | asset preview and profile, overview sidebar |
| `ORDINAL_POSITION` | `order` | asset profile |
| `TYPE_NAME` | `dataType` | asset preview, profile, and filter, overview sidebar |
| `IS_NULLABLE` | `isNullable` | API only |
| `IS_PARTITIONING_COLUMN` | `isPartition` | asset preview, profile, and filter |
| `CLUSTERING_COLUMN_LIST` | `isClustered` | asset preview, profile, and filter |

## Routines

Atlan maps routines (user-defined functions, table-valued functions and stored procedures) from Google BigQuery to its `BigqueryRoutine` asset type.

| Source property | Atlan property | Where in Atlan |
| --- | --- | --- |
| `ROUTINE_NAME` | `name` | asset preview and profile, overview sidebar and filter |
| `REMARKS` | `description` | asset preview and profile, overview sidebar |
| `ROUTINE_DEFINITION` | `definition` | asset profile and overview sidebar |
| `CREATED` | `sourceCreatedAt` | asset profile and overview sidebar |
| `MODIFIED` | `sourceUpdatedAt` | asset profile and overview sidebar |
| `ROUTINE_TYPE` | `BigqueryRoutineType` | asset preview and profile, overview sidebar and filter |
| `ROUTINE_ARGUMENTS` | `BigqueryRoutineArguments` | asset profile and overview sidebar |

---