Query an existing materialized view.

## Code sample

### Java


Before trying this sample, follow the Java setup instructions in the
[BigQuery quickstart using
client libraries](https://docs.cloud.google.com/bigquery/docs/quickstarts/quickstart-client-libraries).


For more information, see the
[BigQuery Java API
reference documentation](https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/overview).


To authenticate to BigQuery, set up Application Default Credentials.
For more information, see

[Set up authentication for client libraries](https://docs.cloud.google.com/bigquery/docs/authentication#client-libs).

    import com.google.cloud.bigquery.https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.BigQuery.html;
    import com.google.cloud.bigquery.https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.BigQueryException.html;
    import com.google.cloud.bigquery.https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.BigQueryOptions.html;
    import com.google.cloud.bigquery.https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.QueryJobConfiguration.html;
    import com.google.cloud.bigquery.https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.TableResult.html;

    public class QueryMaterializedView {

      public static void main(String[] args) throws InterruptedException {
        // TODO(developer): Replace these variables before running the sample.
        String datasetName = "MY_DATASET_NAME";
        String materializedViewName = "MY_MATERIALIZED_VIEW_NAME";
        String query = String.format("SELECT * FROM %s.%s", datasetName, materializedViewName);
        queryMaterializedView(query);
      }

      public static void queryMaterializedView(String query) throws InterruptedException {
        try {
          // Initialize client that will be used to send requests. This client only needs to be created
          // once, and can be reused for multiple requests.
          https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.BigQuery.html bigquery = https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.BigQueryOptions.html.getDefaultInstance().getService();

          https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.TableResult.html results = bigquery.https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.BigQuery.html#com_google_cloud_bigquery_BigQuery_query_com_google_cloud_bigquery_QueryJobConfiguration_com_google_cloud_bigquery_BigQuery_JobOption____(https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.QueryJobConfiguration.html.of(query));
          results
              .https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.TableResult.html#com_google_cloud_bigquery_TableResult_iterateAll__()
              .forEach(row -> row.forEach(val -> System.out.printf("%s\n", val.toString())));

          System.out.println("Query performed successfully.");
        } catch (https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquery/latest/com.google.cloud.bigquery.BigQueryException.html e) {
          System.out.println("Query was not performed. \n" + e.toString());
        }
      }
    }

## What's next


To search and filter code samples for other Google Cloud products, see the
[Google Cloud sample browser](https://docs.cloud.google.com/docs/samples?product=bigquery).