Import CSV with multi-valued (collection) attributes to Cassandra - csv

Question

Suppose I would like to import a csv file into the following table:
CREATE TABLE example_table (
id int PRIMARY KEY,
comma_delimited_str_list list<ascii>,
space_delimited_str_list list<ascii>
);
where comma_delimited_str_list and space_delimited_str_list are two list-attributes which use comma and space as their delimiter respectively.
An example csv record would be:
12345,"hello,world","stack overflow"
where I would like to treat "hello,world" and "stack overflow" as two multi-valued attributes.
Can I know how to import such CSV file into its corresponding table in Cassandra? Preferably using CQL COPY?

Answer 1

CQL 1.2 is able to port CSV file with multi-valued fields directly to a table. However, the format of those multi-valued fields must match the CQL format.
For example, lists must be in the form ['abc','def','ghi'], and sets must be in the form {'123','456','789'}.
Below is an example of importing CSV formatted data to the example_table mentioned in the OP from STDIN:
cqlsh:demo> copy example_table from STDIN;
[Use \. on a line by itself to end input]
[copy] 12345,"['hello','world']","['stack','overflow']"
[copy] 56780,"['this','is','a','test','list']","['here','is','another','one']"
[copy] \.
2 rows imported in 11.304 seconds.
cqlsh:demo> select * from example_table;
id | comma_delimited_str_list | space_delimited_str_list
-------+---------------------------+--------------------------
12345 | [hello, world] | [stack, overflow]
56780 | [this, is, a, test, list] | [here, is, another, one]
Importing incorrect formatted list or set values from a CSV file will raise an error:
cqlsh:demo> copy example_table from STDIN;
[Use \. on a line by itself to end input]
[copy] 9999,"hello","world"
Bad Request: line 1:108 no viable alternative at input ','
Aborting import at record #0 (line 1). Previously-inserted values still present.
The above input should be replaced by 9999,"['hello']","['world']":
cqlsh:demo> copy example_table from STDIN;
[Use \. on a line by itself to end input]
[copy] 9999,"['hello']","['world']"
[copy] \.
1 rows imported in 16.859 seconds.
cqlsh:demo> select * from example_table;
id | comma_delimited_str_list | space_delimited_str_list
-------+---------------------------+--------------------------
9999 | [hello] | [world]
12345 | [hello, world] | [stack, overflow]
56780 | [this, is, a, test, list] | [here, is, another, one]