[CASSANDRA-14505] Removal of last element on a List deletes the entire row - ASF JIRA

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The behavior of an element removal from a list by an UPDATE differs by how the row was created:

Given the table

CREATE TABLE table_test (
id int PRIMARY KEY,
list list<text>
)

If the row is created by an INSERT, the row remains after the UPDATE to remove the last element on the list:

cqlsh:ks_test> INSERT INTO table_test (id, list ) VALUES ( 1, ['foo']) ;
cqlsh:ks_test> SELECT * FROM table_test;

id | list
---+-------
1 | ['foo']

(1 rows)
cqlsh:ks_test> UPDATE table_test SET list = list - ['foo'] WHERE id=1;
cqlsh:ks_test> SELECT * FROM table_test;

id | list
---+-----
1 | null

(1 rows)

But, if the row is created by an UPDATE, the row is deleted after the UPDATE to remove the last element on the list:

cqlsh:ks_test> UPDATE table_test SET list = list + ['foo'] WHERE id=2;
cqlsh:ks_test> SELECT * FROM table_test;

id | list
---+--------
2 | ['foo']

(1 rows)
cqlsh:ks_test> UPDATE table_test SET list = list - ['foo'] WHERE id=2;
cqlsh:ks_test> SELECT * FROM table_test;

id | list
---+-----

(0 rows)

Thanks in advance.

duplicates

CASSANDRA-11805 Row deleted when value updated to null

is related to

CASSANDRA-14478 Improve the documentation of UPDATE vs INSERT