Database Reference
In-Depth Information
CREATE EXTERNAL TABLE dbo.HDFS_FactInternetSales
WITH
(
LOCATION = 'hdfs://102.16.250.100:5000/files/
HDFS_FactInternetSales'
, FORMAT_OPTIONS ( FIELD_TERMINATOR = '|')
)
AS SELECT T1.*
FROM dbo.FactInternetSales T1
JOIN dbo.DimCustomer T2 ON T1.CustomerKey =
T2.CustomerKey
OPTION (HASH JOIN);
Note that once the CETAS has executed, three things will have happened:
1. An external table will have been created.
2. The data will have been exported.
3. Statistics will have been collected on the exported data.
To export the data, PDW uses a new DMS movement type called the
ExternalExportDistributedOperation
. This operation selects the
data out from the compute nodes and pushes it out in parallel to Hadoop.
You
can
see
the
select
used
by
the
ExternalExportDistributedOperation
in
Figure 10.13
.
