dotConnect for Google BigQuery provides metadata on the datasets of the Google Cloud project specified in the Project Id connection string parameter: datasets, tables and views, their columns, and primary keys. If the DataSet Id connection string parameter is specified, the metadata covers only this dataset; otherwise, it covers all datasets of the project.

dotConnect for Google BigQuery retrieves metadata through the BigQuery REST API when metadata is required for the first time and caches it in memory for the lifetime of the connection pool. As a result, the metadata is not requested again each time a connection is opened.

Primary keys are returned either as defined in BigQuery (PRIMARY KEY ... NOT ENFORCED) or as specified by the Primary Key Column connection string parameter. Foreign keys and unique keys aren't returned. BigQuery doesn't have indexes.

There are two ways to access metadata with dotConnect for Google BigQuery: using the GetSchema method of BigQueryConnection or querying the information schema tables. For more information, see the corresponding topics: Using GetSchema Method and Information Schema.

If tables or columns were changed after the metadata was retrieved, call the RefreshMetadata method of BigQueryConnection. It discards the retrieved metadata, and the metadata is requested again the next time it is needed.

See Also

Metadata | Information Schema | Using GetSchema Method