Nico Kruber created FLINK-22404:
-----------------------------------
Summary: Document inconsistencies around +I and +U generation in
retract streams
Key: FLINK-22404
URL: https://issues.apache.org/jira/browse/FLINK-22404
Project: Flink
Issue Type: Bug
Components: Documentation, Table SQL / API
Affects Versions: 1.12.2
Reporter: Nico Kruber
Filters can remove +I messages and let a new row start with +U; similarly, they
can remove the +U after -U which should instead have been reported as -D. This
makes the semantics described on
[https://ci.apache.org/projects/flink/flink-docs-release-1.12/dev/table/streaming/dynamic_tables.html#table-to-stream-conversion]
wrong which makes users believe they can rely on +U vs. +I and -U vs. -D.
Either this needs to be fixed, or a disclaimer should be added to the
respective paragraphs that +U/+I and -U/-D should be seem as the same.
Example:
{code:sql}
CREATE TEMPORARY VIEW test_cardinality AS
SELECT * FROM ( VALUES
('Alice', 'al...@test.com', ARRAY [ 'al...@test.com' ], 'Test Ltd'),
('Alice', 'al...@test.com', ARRAY [ 'al...@test.com' ], 'Test Ltd'),
('Alice', 'al...@test2.com', ARRAY [ 'al...@test.com', 'al...@test2.com' ],
'Test Ltd'))
AS t ( name, email, aliases, company );
{code}
{code:sql}
SELECT
name,
LEAD(CAST(company AS VARCHAR), 0) AS company
FROM test_cardinality
WHERE CARDINALITY(aliases) >= 2
GROUP BY name;
{code}
vs.
{code:sql}
SELECT
name,
LEAD(CAST(company AS VARCHAR), 0) AS company
FROM test_cardinality
GROUP BY name
HAVING COUNT(DISTINCT email) >= 2;
{code}
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