Description:
Upload data to the specified location in HDFS.
Syntax:
hdfs_write(hd,file,A/cs,x:F)
Note:
The external library function (See External Library Guide) uploads a table sequence, a record sequence or a cursor to the specified location in HDFS.
Parameter:
|
hd |
An hd connection |
|
file |
The location and name of the file to be loaded to HDFS; can be .txt file or .csv file |
|
A/cs |
A table sequence/record sequence/cursor; do not support a random access file, such as .btx |
|
x |
The field(s) to be uploaded; upload all fields when the parameter is absent |
|
F |
The result field name(s) in the form of string; use original field names when the parameter is absent |
Option:
|
@a |
Appen-write; the to-be-appended content should have same structure as the original file content, otherwise error will be reported; ignore @t option when the target file already has content; overwrite the original file by default |
|
@t |
Write the field name information (titles) to the target file as the first row |
Return value:
Boolean value
Example:
|
|
A |
|
|
1 |
|
Connect to hdfs. |
|
2 |
|
Return a table sequence. |
|
3 |
=hdfs_write@t(A1,"/test1.txt",A2) |
Upload all fields of A2’s table sequence to test1.txt. |
|
4 |
|
Return a cursor. |
|
5 |
=hdfs_write@a(A1,"/test1.txt",A4) |
Upload all fields of A4’s cursor to test1.txt. |
|
6 |
=hdfs_write@t(A1,"/test2.txt",A2,EID,ENAME:name) |
Upload specified fields of A2’s table sequence to test2.txt. |