Description:
Open a specified directory and return an HDFS file flow.
Syntax:
hdfs_file(hd,file:cs )
Note:
The external library function (See External Library Guide) returns an HDFS file flow. The file extension determines the compression method; support writing data in a stream style into a non-segmental file, but there is no such a restriction on reading data in.
Parameter:
|
hd |
An hd connection |
|
file |
The name of the to-be-loaded Hadoop file |
|
cs |
The charset embedded in JVM; by default it is the default value for a virtual machine |
Return value:
File object
Example:
|
|
A |
|
|
1 |
=hdfs_open("hdfs://192.168.0.8:9000") |
Connect to the HDFS file system. |
|
2 |
=hdfs_file(A1,"/user/stu.txt":"GBK") |
Read the HDFS file and return a file object. |
|
3 |
=A2.read@n() |
Read the content of the file object as a string and return it. |
|
4 |
=A2.import@t() |
Read the content of the file object as the records to form a table sequence and return it.
|
|
5 |
=A2.cursor().fetch () |
Create a cursor based on a file object and fetch records from the cursor. |
|
6 |
=hdfs_close(A1) |
Close the HDFS connection. |