MariaDB Java Client 3.3.1 - Java batched insrt on duplicate key does not work properly

Hi, this issue might be related to CONJ-920.

System setup

• MariaDB Connector J 3.3.1
• MariaDb 10.5.23
• Java 8
• HikariCP 4.0.3 JDBC connection pool

Issue

I'm trying to do a batch query with INSERT ON DUPLICATE KEY UPDATE statement and when inserting more than one row into a table where all keys already exist then the update performed properly but executeBatch() returns an array where all values are -2 instead of 2:
expected [2,2,2] but was [-2,-2-2]

However, if I insert only one row with the existing key then I get the correct value of 2.
If I have two rows (one new one and the second one existing) then I get [-2,-2] instead of [2,1]

In the case where all rows are new one works properly, and value 1 is returned for each row.

I've tried ?useBulkStmts=false&useBulkStmtsForInserts=true and ?useBulkStmts=true&useBulkStmtsForInserts=true and got the same result.

Is it supposed to work like that? To me it seems like a bug, I can not distinguish updates from inserts in this case.

To summarize:

• insert of multiple existing rows - produces [-2,-2,-2], expected [2,2,2]
• insert of multiple mixed rows (new and existing) - produces [-2,-2,-2], expected [2,1,2]
• insert of single existing row - produces [2] (as expected)
• insert of multiple new rows - produces [1,1,1] (as expected)
• insert of single new row - produces [1] (as expected)