Jing Zhang created FLINK-25593:
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Summary: A redundant scan could be skipped if it is an input of
join and the other input is empty after partition prune
Key: FLINK-25593
URL: https://issues.apache.org/jira/browse/FLINK-25593
Project: Flink
Issue Type: Sub-task
Components: Table SQL / Planner
Reporter: Jing Zhang
A redundant scan could be skipped if it is an input of join and the other input
is empty after partition prune.
For example:
ltable has two partitions: pt=0 ad pt=1, rtable has one partition pt1=0.
The schema of ltable is (lkey string, value int).
The schema of rtable is (rkey string, value int).
{code:java}
SELECT * FROM ltable, rtable WHERE pt=2 and pt1=0 and `lkey`=rkey
{code}
The plan is as following.
{code:java}
Calc(select=[lkey, value, CAST(2 AS INTEGER) AS pt, rkey, value1, CAST(0 AS
INTEGER) AS pt1])
+- HashJoin(joinType=[InnerJoin], where=[=(lkey, rkey)], select=[lkey, value,
rkey, value1], build=[right])
:- Exchange(distribution=[hash[lkey]])
: +- TableSourceScan(table=[[hive, source_db, ltable, partitions=[],
project=[lkey, value]]], fields=[lkey, value])
+- Exchange(distribution=[hash[rkey]])
+- TableSourceScan(table=[[hive, source_db, rtable, partitions=[{pt1=0}],
project=[rkey, value1]]], fields=[rkey, value1])
{code}
There is no need to scan right side because the left input of join has 0
partitions after partition prune.
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