xuguangheng opened a new pull request #15744:
URL: https://github.com/apache/flink/pull/15744
## What is the purpose of the change
Implement the column uniqueness checking to avoid losing uniqueness
information during join operations.
More specifically,
```
CREATE TEMPORARY TABLE passengers (
passenger_key STRING,
PRIMARY KEY (passenger_key) NOT ENFORCED
) WITH (
'connector' = 'values'
)
CREATE TEMPORARY TABLE booking_channels (
booking_channel_key STRING,
PRIMARY KEY (booking_channel_key) NOT ENFORCED
) WITH (
'connector' = 'values'
)
CREATE TEMPORARY TABLE train_activities (
passenger_key STRING,
booking_channel_key STRING,
PRIMARY KEY (booking_channel_key) NOT ENFORCED
) WITH (
'connector' = 'values'
)
SELECT t.booking_channel_key as booking_channel_key, t.passenger_key as
passenger_key, b.booking_channel_key as booking_channel_key_0
FROM train_activities t
LEFT JOIN booking_channels b
ON t.booking_channel_key = b.booking_channel_key
LEFT JOIN passengers p
on t.passenger_key = p.passenger_key
== Optimized Physical Plan ==
Calc(select=[booking_channel_key, passenger_key, booking_channel_key0 AS
booking_channel_key_0])
+- Join(joinType=[LeftOuterJoin], where=[=(passenger_key, passenger_key0)],
select=[passenger_key, booking_channel_key, booking_channel_key0,
passenger_key0], leftInputSpec=[HasUniqueKey],
rightInputSpec=[JoinKeyContainsUniqueKey])
:- Exchange(distribution=[hash[passenger_key]])
: +- Join(joinType=[LeftOuterJoin], where=[=(booking_channel_key,
booking_channel_key0)], select=[passenger_key, booking_channel_key,
booking_channel_key0], leftInputSpec=[JoinKeyContainsUniqueKey],
rightInputSpec=[JoinKeyContainsUniqueKey])
: :- Exchange(distribution=[hash[booking_channel_key]])
: : +- TableSourceScan(table=[[default_catalog, default_database,
train_activities]], fields=[passenger_key, booking_channel_key])
: +- Exchange(distribution=[hash[booking_channel_key]])
: +- TableSourceScan(table=[[default_catalog, default_database,
booking_channels]], fields=[booking_channel_key])
+- Exchange(distribution=[hash[passenger_key]])
+- TableSourceScan(table=[[default_catalog, default_database,
passengers]], fields=[passenger_key])
```
VS
```
SELECT t.booking_channel_key as booking_channel_key, t.passenger_key as
passenger_key
FROM train_activities t
LEFT JOIN booking_channels b
ON t.booking_channel_key = b.booking_channel_key
LEFT JOIN passengers p
on t.passenger_key = p.passenger_key
== Optimized Physical Plan ==
Calc(select=[booking_channel_key, passenger_key])
+- Join(joinType=[LeftOuterJoin], where=[=(passenger_key, passenger_key0)],
select=[passenger_key, booking_channel_key, passenger_key0],
leftInputSpec=[NoUniqueKey], rightInputSpec=[JoinKeyContainsUniqueKey])
:- Exchange(distribution=[hash[passenger_key]])
: +- Calc(select=[passenger_key, booking_channel_key])
: +- Join(joinType=[LeftOuterJoin], where=[=(booking_channel_key,
booking_channel_key0)], select=[passenger_key, booking_channel_key,
booking_channel_key0], leftInputSpec=[JoinKeyContainsUniqueKey],
rightInputSpec=[JoinKeyContainsUniqueKey])
: :- Exchange(distribution=[hash[booking_channel_key]])
: : +- TableSourceScan(table=[[default_catalog, default_database,
train_activities]], fields=[passenger_key, booking_channel_key])
: +- Exchange(distribution=[hash[booking_channel_key]])
: +- TableSourceScan(table=[[default_catalog, default_database,
booking_channels]], fields=[booking_channel_key])
+- Exchange(distribution=[hash[passenger_key]])
+- TableSourceScan(table=[[default_catalog, default_database,
passengers]], fields=[passenger_key])
```
**_The only difference is that we select booking_channel_key from both left
and right table in the first case and only booking_channel_key from left table
in the second case. The result is one has uniqueKey and the other doesn't._**
`t.booking_channel_key, t.passenger_key` can be the unique key of the first
join output, but it seems we lost this unique information.
## Brief change log
- *Implement the column uniqueness checking for TableSourceTable*
- *Add some test cases of uniqueness checking and getUniqueKey for
TableSourceTable*
## Verifying this change
Existing and added test cases, manually rerun the example above and the
uniqueness information was remained successfully.
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): no
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: no
- The serializers: no
- The runtime per-record code paths (performance sensitive): no
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Kubernetes/Yarn/Mesos, ZooKeeper: no
- The S3 file system connector: no
## Documentation
- Does this pull request introduce a new feature? no
- If yes, how is the feature documented? not documented
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