在Java中更新BigQuery架构/添加新列

Question

我需要通过Java更新BigQuery表模式。更改将是附加的（仅添加新列）

我正在努力找到实现这一目标的方法。在Python中，可以这样做：

table_ref = client.dataset(dataset_id).table(table_id)
table = client.get_table(table_ref)  # API request

original_schema = table.schema
new_schema = original_schema[:]  # creates a copy of the schema
new_schema.append(bigquery.SchemaField('phone', 'STRING'))

table.schema = new_schema
table = client.update_table(table, ['schema'])  # API request

在https://cloud.google.com/bigquery/docs/managing-table-schemas页上，声明将使用修补程序端点执行此任务

提出了一个改进补丁API的问题，但我不知道结果https://github.com/googleapis/google-cloud-java/issues/1564

这是到修补程序类文档的链接：https://developers.google.com/resources/api-libraries/documentation/bigquery/v2/java/latest/com/google/api/services/bigquery/Bigquery.Tables.Patch.html#set-java.lang.String-java.lang.Object-

任何帮助都将不胜感激。谢谢

Answer 1

Java中的想法与您共享的Python示例中的想法相同，即获取当前模式并向其添加一个新列。您可以通过我准备的代码片段来实现这一点，您可以在下面看到：

// Instantiate the BQ client
BigQuery bigquery = BigQueryOptions.getDefaultInstance().getService();

// Get the table, schema and fields from the already-existing table
Table table = bigquery.getTable(TableId.of("PROJECT_ID", "DATASET", "TABLE"));
Schema schema = table.getDefinition().getSchema();
FieldList fields = schema.getFields();

// Create the new field
Field newField = Field.of("column2", LegacySQLTypeName.STRING);

// Create a new schema adding the current fields, plus the new one
List<Field> field_list = new ArrayList<Field>();
for (Field f : fields) {
    field_list.add(f);
}
field_list.add(newField);
Schema newSchema = Schema.of(field_list);

// Update the table with the new schema
Table updatedTable = table.toBuilder().setDefinition(StandardTableDefinition.of(newSchema)).build().update();

这段代码使用的是com.google.cloud.bigquery包（参见其documentation here）。然后，它按照tables documentation中的示例指定模式定义，并最终更新它

Answer 2

我还通过另一个Google BigQuery软件包实现了这一点：

    HttpTransport transport = new NetHttpTransport();
    JsonFactory jsonFactory = new JacksonFactory();
    GoogleCredential credential;
    try {
        credential = GoogleCredential.getApplicationDefault(transport,
                jsonFactory);
    } catch (IOException e) {
        throw new RuntimeException(e);
    }
    if (credential.createScopedRequired()) {
        credential = credential.createScoped(BigqueryScopes.all());
    }

    Bigquery.Tables bqTables = new Bigquery.Builder(transport, jsonFactory, credential).build().tables();
    Bigquery.Tables.Get bqTableGet = bqTables.get(this.project, this.dataset, this.tablePrefix + strDate);

    Table bqTable = bqTableGet.execute();
    bqTable.setSchema(this.schema);

    Bigquery.Tables.Patch bqTablePatch = bqTables.patch(this.project, this.dataset, this.tablePrefix + strDate, bqTable);
    bqTablePatch.execute();