创建具体化视图

创建具体化视图。

深入探索

如需查看包含此代码示例的详细文档，请参阅以下内容：

• 创建具体化视图

代码示例

Go

尝试此示例之前，请按照《BigQuery 快速入门：使用客户端库》中的 Go 设置说明进行操作。如需了解详情，请参阅 BigQuery Go API 参考文档。

在 GitHub 上查看 反馈

import (
	"context"
	"fmt"

	"cloud.google.com/go/bigquery"
)

// createMaterializedView demonstrates generated a materialized view based on an existing
// base table.
func createMaterializedView(projectID, datasetID, baseTableID, viewID string) error {
	// projectID := "my-project-id"
	// datasetID := "mydatasetid"
	// baseTableID := "mytableid"
	// viewID := "myviewid"
	ctx := context.Background()

	client, err := bigquery.NewClient(ctx, projectID)
	if err != nil {
		return fmt.Errorf("bigquery.NewClient: %v", err)
	}
	defer client.Close()

	// Get an appropriately escaped table identifier suitable for use in a standard SQL query.
	tableStr, err := client.Dataset(datasetID).Table(baseTableID).Identifier(bigquery.StandardSQLID)
	if err != nil {
		return fmt.Errorf("couldn't construct identifier: %v", err)
	}

	metaData := &bigquery.TableMetadata{
		MaterializedView: &bigquery.MaterializedViewDefinition{
			Query: fmt.Sprintf(`SELECT MAX(TimestampField) AS TimestampField, StringField,
					  MAX(BooleanField) AS BooleanField FROM %s GROUP BY StringField`, tableStr),
		}}

	viewRef := client.Dataset(datasetID).Table(viewID)
	if err := viewRef.Create(ctx, metaData); err != nil {
		return err
	}
	return nil
}

Java

试用此示例之前，请按照《BigQuery 快速入门：使用客户端库》中的 Java 设置说明进行操作。如需了解详情，请参阅 BigQuery Java API 参考文档。

在 GitHub 上查看 反馈

import com.google.cloud.bigquery.BigQuery;
import com.google.cloud.bigquery.BigQueryException;
import com.google.cloud.bigquery.BigQueryOptions;
import com.google.cloud.bigquery.MaterializedViewDefinition;
import com.google.cloud.bigquery.TableId;
import com.google.cloud.bigquery.TableInfo;

// Sample to create materialized view
public class CreateMaterializedView {

  public static void main(String[] args) {
    // TODO(developer): Replace these variables before running the sample.
    String datasetName = "MY_DATASET_NAME";
    String tableName = "MY_TABLE_NAME";
    String materializedViewName = "MY_MATERIALIZED_VIEW_NAME";
    String query =
        String.format(
            "SELECT MAX(TimestampField) AS TimestampField, StringField, "
                + "MAX(BooleanField) AS BooleanField "
                + "FROM %s.%s GROUP BY StringField",
            datasetName, tableName);
    createMaterializedView(datasetName, materializedViewName, query);
  }

  public static void createMaterializedView(
      String datasetName, String materializedViewName, String query) {
    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.
      BigQuery bigquery = BigQueryOptions.getDefaultInstance().getService();

      TableId tableId = TableId.of(datasetName, materializedViewName);

      MaterializedViewDefinition materializedViewDefinition =
          MaterializedViewDefinition.newBuilder(query).build();

      bigquery.create(TableInfo.of(tableId, materializedViewDefinition));
      System.out.println("Materialized view created successfully");
    } catch (BigQueryException e) {
      System.out.println("Materialized view was not created. \n" + e.toString());
    }
  }
}

Python

尝试此示例之前，请按照《BigQuery 快速入门：使用客户端库》中的 Python 设置说明进行操作。如需了解详情，请参阅 BigQuery Python API 参考文档。

在 GitHub 上查看 反馈

from google.cloud import bigquery

bigquery_client = bigquery.Client()

view_id = "my-project.my_dataset.my_materialized_view"
base_table_id = "my-project.my_dataset.my_base_table"
view = bigquery.Table(view_id)
view.mview_query = f"""
SELECT product_id, SUM(clicks) AS sum_clicks
FROM  `{base_table_id}`
GROUP BY 1
"""

# Make an API request to create the materialized view.
view = bigquery_client.create_table(view)
print(f"Created {view.table_type}: {str(view.reference)}")

后续步骤

如需搜索和过滤其他 Google Cloud 产品的代码示例，请参阅 Google Cloud 示例浏览器。