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Posted to issues@flink.apache.org by "lincoln lee (Jira)" <ji...@apache.org> on 2023/04/18 02:07:00 UTC
[jira] [Created] (FLINK-31830) Coalesce on nested fields with different nullabilities will get wrong plan
lincoln lee created FLINK-31830:
-----------------------------------
Summary: Coalesce on nested fields with different nullabilities will get wrong plan
Key: FLINK-31830
URL: https://issues.apache.org/jira/browse/FLINK-31830
Project: Flink
Issue Type: Bug
Components: Table SQL / Planner
Affects Versions: 1.14.6
Reporter: lincoln lee
A test case similar to FLINK-31829, only changes the nullable field `a.np` to not null, will get a wrong plan in 1.14.x (reported from the community user):
{code}
@Test
def testCoalesceOnNestedColumns(): Unit = {
val tEnv = util.tableEnv
val tableDescriptor = TableDescriptor.forConnector("datagen")
.schema(Schema.newBuilder
.column("id", DataTypes.INT.notNull)
.column("a", DataTypes.ROW(DataTypes.FIELD("np", DataTypes.INT.notNull())).nullable)
.build)
.build
tEnv.createTemporaryTable("t1", tableDescriptor)
tEnv.createTemporaryTable("t2", tableDescriptor)
val res = tEnv.executeSql("EXPLAIN SELECT a.id, COALESCE(a.a.np, b.a.np) c1, IFNULL(a.a.np, b.a.np) c2 FROM t1 a left JOIN t2 b ON a.id=b.id where a.a is null or a.a.np is null")
res.print()
}
== Abstract Syntax Tree ==
LogicalProject(id=[$0], c1=[CAST($1.np):INTEGER], c2=[IFNULL($1.np, $3.np)])
+- LogicalFilter(condition=[OR(IS NULL($1), IS NULL(CAST($1.np):INTEGER))])
+- LogicalJoin(condition=[=($0, $2)], joinType=[left])
:- LogicalTableScan(table=[[default_catalog, default_database, t1]])
+- LogicalTableScan(table=[[default_catalog, default_database, t2]])
{code}
the top project in the ast is wrong: `LogicalProject(id=[$0], c1=[CAST($1.np):INTEGER], c2=[IFNULL($1.np, $3.np)])`, the `c1=[CAST($1.np):INTEGER]` relate to `COALESCE(a.a.np, b.a.np) c1` is incorrect,
but this works fine when using sql ddl to create tables
{code}
@Test
def testCoalesceOnNestedColumns2(): Unit = {
val tEnv = util.tableEnv
tEnv.executeSql(
s"""
|create temporary table t1 (
| id int not null,
| a row<np int not null>
|) with (
| 'connector' = 'datagen'
|)
|""".stripMargin)
tEnv.executeSql(
s"""
|create temporary table t2 (
| id int not null,
| a row<np int not null>
|) with (
| 'connector' = 'datagen'
|)
|""".stripMargin)
val res = tEnv.executeSql(
"EXPLAIN SELECT a.id, COALESCE(a.a.np, b.a.np) c1, IFNULL(a.a.np, b.a.np) c2 FROM t1 a left JOIN t2 b ON a.id=b.id where a.a is null or a.a.np is null")
res.print()
}
{code}
from 1.15, the coalesce will be a new builtin function, and the ast looks correct in version 1.15+, while before 1.15 it was rewritten as `case when`
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