Peter Rozsa created IMPALA-15197:
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Summary: Iceberg V2 UPDATE with join can miss duplicate-row
detection in distributed execution
Key: IMPALA-15197
URL: https://issues.apache.org/jira/browse/IMPALA-15197
Project: IMPALA
Issue Type: Bug
Reporter: Peter Rozsa
Assignee: Peter Rozsa
UPDATE ... FROM on an unpartitioned Iceberg V2 table that joins against a
reference table may not detect when the same target row matches multiple
reference rows. In that case the UPDATE should fail with Duplicated row in
DELETE sink. but instead succeeds silently and produces a duplicate row in the
table.
{code:java}
create table tgt (id int, val bigint)
stored by iceberg tblproperties ('format-version'='2');
insert into tgt values (0,0),(1,10),(2,20),(3,30),(4,40),(5,50),(6,60),(7,70);
compute stats tgt;
-- Reference table with no stats so the planner puts it on the probe side
create table ref_pq (i int, bi bigint) stored as parquet;
insert into ref_pq values
(0,100),(1,101),(2,102),(3,103),(4,104),(5,105),(6,106),(7,107);
insert into ref_pq values
(0,200),(1,201),(2,202),(3,203),(4,204),(5,205),(6,206),(7,207);
-- Each id in ref_pq appears twice -> multiple matches per target row
update tgt set val = bi + 1 from tgt, ref_pq where id = i;
select count(*) total, count(distinct id) distinct_ids from tgt; {code}
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