AI / Apache Paimon Interview questions
How does the Deduplicate merge engine handle a DELETE record?
Under the default Deduplicate merge engine, if the newest record Paimon sees for a given primary key is a DELETE, that key's earlier records are removed entirely from the merged result — the key effectively disappears from the table.
CREATE TABLE my_table ( pk BIGINT PRIMARY KEY NOT ENFORCED, v STRING ) WITH ( 'merge-engine' = 'deduplicate', 'ignore-delete' = 'false' -- the default );
Setting ignore-delete to true changes this: Paimon then treats any incoming DELETE for that key as a no-op, silently discarding it and keeping whichever record was previously merged in. This is useful when a downstream job wants to build a full-history table from a CDC stream but should never lose a row just because the source row was later deleted.
By default, if the newest record for a key under Deduplicate is a DELETE, Paimon:
Setting ignore-delete to true under Deduplicate causes DELETE records to be:
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