我有以下选择:
select * from system.schema_columns where keyspace_name = 'automotive' and columnfamily_name = 'cars';
我想将由此返回的数据插入另一个表中,并进行一些修改:
-我想插入列的数据类型
-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实现:
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';
我们怎么能在卡桑德拉做到这一点?
您可以通过使用Spark 来实现这一点
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")