Issue on docs

Path:/zh-CN/docs/4.x/data-operate/update/unique-update-concurrent-control

Maybe there is a problem on partial column update? The Broker Load is:
LOAD LABEL db1.label1
(
DATA INFILE("hdfs://host:port/user/data/*/test.txt")
INTO TABLE `tbl1`
COLUMNS TERMINATED BY ","
(k1,k2,source_sequence,v1,v2)
ORDER BY source_sequence
)
WITH BROKER 'broker'
(
"username"="user",
"password"="pass"
)
PROPERTIES
(
"timeout" = "3600"
);
it means the file is terminated by ","，and the third column is mapped to modify_date as the sequence_col, however the input file is:
1 2020-02-22 1 2020-02-22 a
1 2020-02-22 1 2020-03-23 w

i think there are two question:
1.the file has no ',', the TERMINATED should be '\t' or some other
2.the third column is '1,1' ,which obviously mismatch modify_date, and conflict which the blew explain，i think the correct Broker load should be"COLUMNS TERMINATED BY "\t"
(k1,k2,v1,source_sequence,v2)"

Open /zh-CN/docs/4.x/data-operate/update/unique-update-concurrent-control and compare the documented Broker Load example with the tab-separated input shown in the issue. Verify the delimiter and source_sequence column mapping against the surrounding documentation; done means the example accurately matches the stated input and sequence-column behavior.

Written by the indexing model from the issue text.