Question

我已经阅读了有关该文档的文档，但是似乎找不到上面明确说明的内容。

有帮助吗？

Answer 1

您不能修改现有表，但是可以编写覆盖现有表的查询。

请参见part

CREATE TABLE `fh-bigquery.wikipedia_v3.pageviews_2017`
PARTITION BY DATE(datehour)
CLUSTER BY wiki, title
OPTIONS(
   description="Wikipedia pageviews - partitioned by day, clustered by (wiki, title). Contact https://twitter.com/felipehoffa"
   , require_partition_filter=true
)
AS SELECT * FROM `fh-bigquery.wikipedia_v2.pageviews_2017`
WHERE datehour > '1990-01-01' # nag

Answer 2

如果表已分区，API 现在允许向现有表添加集群。不幸的是，您只能通过其中一个 API 执行此操作，而通过“bq”似乎无法做到。

以下是 Java 示例：

import com.google.cloud.bigquery.BigQuery;
import com.google.cloud.bigquery.BigQueryException;
import com.google.cloud.bigquery.BigQueryOptions;
import com.google.cloud.bigquery.Clustering;
import com.google.cloud.bigquery.Field;
import com.google.cloud.bigquery.FieldList;
import com.google.cloud.bigquery.LegacySQLTypeName;
import com.google.cloud.bigquery.Schema;
import com.google.cloud.bigquery.StandardTableDefinition;
import com.google.cloud.bigquery.StandardTableDefinition.Builder;
import com.google.cloud.bigquery.Table;
import com.google.common.collect.ImmutableList;
import java.util.ArrayList;
import java.util.List;

public class SetClustering {

  public static void main(String[] args) {
    String datasetName = args[0];
    String tableId = args[1];
    String columnName = args[2];
    setClusterByColumn(columnName, datasetName, tableId);
  }

  public static void setClusterByColumn(String columnName, String datasetName, String tableId) {
    try {
      BigQuery bigquery = BigQueryOptions.getDefaultInstance().getService();

      Table table = bigquery.getTable(datasetName, tableId);

      StandardTableDefinition definition = table.getDefinition();
      StandardTableDefinition newDefinition = definition.toBuilder()
        .setClustering(Clustering.newBuilder().setFields(ImmutableList.of("event_name")).build())
        .build();

      // Update the table with the new definition
      Table updatedTable =
          table.toBuilder().setDefinition(newDefinition).build();
      updatedTable.update();
      System.out.println("Clustering successfully added to table");
    } catch (BigQueryException e) {
      System.out.println("Clustering column was not added. \n" + e.toString());
    }
  }
}

可以将一天分区表更改为群集表吗？

2 个答案: