Question

我有以下选择：

select * from system.schema_columns where keyspace_name = 'automotive' and columnfamily_name = 'cars';

我希望将此返回的数据插入到另一个表中并进行一些修改：

-i想要插入列的数据类型

- 删除审计列，如created_at，created_by等..

在我的SQL中我们可以通过以下方式完成：

insert into formUtil(table_name, column_name, ordinal_position, is_nullable, data_type)
SELECT 
    col.table_name, 
    col.column_name, 
    col.ordinal_position, 
    case when col.is_nullable = 'YES' then 1 else 0 end, 
    col.data_type
from 
    information_schema.COLUMNS col 
where 
    col.table_schema = 'i2cwac' and
    col.column_name not in ('id','modifiedAt','modifiedBy','createdAt','createdBy') and
    col.table_name = 'users';

我们如何在cassandra中做到这一点？

Answer 1

您可以使用Spark

来实现这一目标

import java.nio.ByteBuffer;
import com.datastax.spark.connector._;

case class SchemaColumns(keyspaceName: String, tableName: String, clusteringOrder: String, columnNameBytes: ByteBuffer, kind: String, position: Int, type: String)
case class AnotherTable(keyspaceName: String, tableName: String, type: String)

sc.cassandraTable[SchemaColumns]("system", "schema_columns")
    .map(schemaColumns -> AnotherTable(schemaColumns.keyspaceName,schemaColumns.tableName, schemaColumns.type)
    .saveToCassandra("my_keyspace","another_table")

cassandra system.schema_columns在其他表中插入并进行修改

1 个答案: