Luis E Fernandez created CASSANDRA-18988:
--------------------------------------------
Summary: Updating the column of a non-existent row in an Accord
transaction results in Atomicity violation
Key: CASSANDRA-18988
URL: https://issues.apache.org/jira/browse/CASSANDRA-18988
Project: Cassandra
Issue Type: Bug
Reporter: Luis E Fernandez
*System configuration and information:*
Single node Cassandra with Accord transactions enabled running on docker
Built from commit:
[a7cd114435704b988c81f47ef53d0bfd6441f38b|https://github.com/apache/cassandra/commit/a7cd114435704b988c81f47ef53d0bfd6441f38b]
CQLSH: [cqlsh 6.2.0 | Cassandra 5.0-alpha2-SNAPSHOT | CQL spec 3.4.7 | Native
protocol v5]
*Steps to reproduce in CQLSH:*
{code:java}
CREATE KEYSPACE accord WITH replication = {'class': 'SimpleStrategy',
'replication_factor': '1'} AND durable_writes = true;{code}
{code:java}
CREATE TABLE accord.accounts (
partition text,
account_id int,
balance int,
PRIMARY KEY (partition, account_id)
) WITH CLUSTERING ORDER BY (account_id ASC);
{code}
{code:java}
BEGIN TRANSACTION
INSERT INTO accord.accounts (partition, account_id, balance) VALUES
('default', 0, 100);
INSERT INTO accord.accounts (partition, account_id, balance) VALUES
('default', 1, 100);
COMMIT TRANSACTION;{code}
atomicity bug happens after executing the following statement:
Based on [Cassandra
documentation|https://cassandra.apache.org/doc/4.1/cassandra/cql/dml.html#update-statement]
regarding the use of UPDATE statements, I expect the result of this
transaction to be the insertion of a new account (\{ account_id: 3, balance: 10
}). The total balance across the three (3) accounts should be maintained (200).
After executing the below transaction, the total number of accounts remains at
two (2) and the total balance drops to 190. Basically, it appears as if only
one half of the transaction proceeds.
{code:java}
BEGIN TRANSACTION
UPDATE accord.accounts
SET balance -= 10
WHERE
partition = 'default'
AND account_id = 1;
UPDATE accord.accounts
SET balance += 10
WHERE
partition = 'default'
AND account_id = 3;
COMMIT TRANSACTION;{code}
Bug / Error:
======================================================================
The result of performing a table read after executing the buggy transaction is:
{code:java}
partition | account_id | balance
-----------+------------+---------
default | 0 | 100
default | 1 | 90
{code}
{color:#172b4d}Note that the above transactions are not possible without a
transaction block because only counter type columns can be updated with += or
-= syntax in normal (non-transactional) cql statements. Using counter type
columns also results in a separate, related bug:
[CASSANDRA-18987|https://issues.apache.org/jira/browse/CASSANDRA-18987]{color}
{color:#172b4d}This was found while testing Accord transactions with
[~henrik.ingo] and team.{color}
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