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Posted to issues@calcite.apache.org by "Vladimir Steshin (Jira)" <ji...@apache.org> on 2025/06/19 17:50:00 UTC
[jira] [Updated] (CALCITE-7062) Row type of UNION may ignore a column's nullability
[ https://issues.apache.org/jira/browse/CALCITE-7062?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Vladimir Steshin updated CALCITE-7062:
--------------------------------------
Description:
I'm not sure this is a problem. Is that ok? I found it by one of our type casting tests.
Consider:
{code:java}
package org.apache.calcite.test;
class ServerTest {
@Test void testNullableCoercionInUnion() throws Exception {
try (Connection c = connect(); Statement s = c.createStatement()) {
s.execute("create table t1 (i smallint not null)");
s.execute("create table t2 (i bigint)");
s.executeUpdate("insert into t1 values (1)");
s.executeUpdate("insert into t2 values (10), (null)");
try (ResultSet r = s.executeQuery("select i from t1 union all select i from t2")) {
assertTrue(r.next());
assertThat(r.getLong("i"), is(1L));
assertTrue(r.next());
assertThat(r.getLong("i"), is(10L));
assertTrue(r.next());
// The result has a null value. It is ok.
assertNull(r.getObject("i"));
}
// The plan.
try (ResultSet r = s.executeQuery("explain plan for select i from t1 union all select i from t2")) {
assertTrue(r.next());
String plan = r.getString(1);
// Fails here. It actually casts to a BIGINT NOT NULL whereas the actual resuls contains a NULL.
assertTrue(plan.contains("[CAST($t0):BIGINT]"));
}
}
}
} {code}
The least restrictive type is _nullable BIGINT._ Looks ok. However, _StandardConvertletTable#convertCast(...)_ produces a _CAST_ to a {_}NOT NULLABLE{_}.
Regarding my research, the nullability is lost somewhere around
{code:java}
class AbstractTypeCoercion
RelDataType syncAttributes(
RelDataType fromType,
RelDataType toType) {
RelDataType syncedType = toType;
if (fromType != null) {
syncedType = factory.createTypeWithNullability(syncedType, fromType.isNullable());
...
}{code}
It doesn't take in account {_}toType.isNullable(){_}.
And also in
{code:java}
class SqlCastFunction
private static RelDataType createTypeWithNullabilityFromExpr(RelDataTypeFactory typeFactory,
RelDataType expressionType, RelDataType targetType, boolean safe) {
boolean isNullable = expressionType.isNullable() || safe;
...
} {code}
The same: _targetType.isNullable()_ is ignored.
was:
I'm not sure this is a problem. Is that ok? I found it by one of our type casting tests.
Consider:
{code:java}
package org.apache.calcite.test;
class ServerTest {
@Test void testNullableCoercionInUnion() throws Exception {
try (Connection c = connect(); Statement s = c.createStatement()) {
s.execute("create table t1 (i smallint not null)");
s.execute("create table t2 (i bigint)");
s.executeUpdate("insert into t1 values (1)");
s.executeUpdate("insert into t2 values (10), (null)");
try (ResultSet r = s.executeQuery("select i from t1 union all select i from t2")) {
assertTrue(r.next());
assertThat(r.getLong("i"), is(1L));
assertTrue(r.next());
assertThat(r.getLong("i"), is(10L));
assertTrue(r.next());
// The result has a null value. It is ok.
assertNull(r.getObject("i"));
}
// The plan.
try (ResultSet r = s.executeQuery("explain plan for select i from t1 union all select i from t2")) {
assertTrue(r.next());
String plan = r.getString(1);
// Fails here. It actually casts to a BIGINT NOT NULL whereas the actual resuls contains a NULL.
assertTrue(plan.contains("[CAST($t0):BIGINT]"));
}
}
}
} {code}
The least restrictive type is _nullable BIGINT._ Looks ok. However, _StandardConvertletTable#convertCast(...)_ produces a _CAST_ to a {_}NOT NULLABLE{_}.
Regarding my research, the nullability is lost somewhere around
{code:java}
class AbstractTypeCoercion
RelDataType syncAttributes(
RelDataType fromType,
RelDataType toType) {
RelDataType syncedType = toType;
if (fromType != null) {
syncedType = factory.createTypeWithNullability(syncedType, fromType.isNullable());
...
}{code}
It doesn't take in account {_}toType.isNullable(){_}.
And also in
{code:java}
class SqlCastFunction
private static RelDataType createTypeWithNullabilityFromExpr(RelDataTypeFactory typeFactory,
RelDataType expressionType, RelDataType targetType, boolean safe) {
boolean isNullable = expressionType.isNullable() || safe;
...
} {code}
The same: _targetType.isNullable()_ is ignored.
> Row type of UNION may ignore a column's nullability
> ---------------------------------------------------
>
> Key: CALCITE-7062
> URL: https://issues.apache.org/jira/browse/CALCITE-7062
> Project: Calcite
> Issue Type: Bug
> Affects Versions: 1.39.0, 1.40.0
> Reporter: Vladimir Steshin
> Priority: Minor
>
> I'm not sure this is a problem. Is that ok? I found it by one of our type casting tests.
> Consider:
> {code:java}
> package org.apache.calcite.test;
> class ServerTest {
> @Test void testNullableCoercionInUnion() throws Exception {
> try (Connection c = connect(); Statement s = c.createStatement()) {
> s.execute("create table t1 (i smallint not null)");
> s.execute("create table t2 (i bigint)");
> s.executeUpdate("insert into t1 values (1)");
> s.executeUpdate("insert into t2 values (10), (null)");
> try (ResultSet r = s.executeQuery("select i from t1 union all select i from t2")) {
> assertTrue(r.next());
> assertThat(r.getLong("i"), is(1L));
> assertTrue(r.next());
> assertThat(r.getLong("i"), is(10L));
> assertTrue(r.next());
> // The result has a null value. It is ok.
> assertNull(r.getObject("i"));
> }
> // The plan.
> try (ResultSet r = s.executeQuery("explain plan for select i from t1 union all select i from t2")) {
> assertTrue(r.next());
> String plan = r.getString(1);
> // Fails here. It actually casts to a BIGINT NOT NULL whereas the actual resuls contains a NULL.
> assertTrue(plan.contains("[CAST($t0):BIGINT]"));
> }
> }
> }
> } {code}
>
> The least restrictive type is _nullable BIGINT._ Looks ok. However, _StandardConvertletTable#convertCast(...)_ produces a _CAST_ to a {_}NOT NULLABLE{_}.
> Regarding my research, the nullability is lost somewhere around
> {code:java}
> class AbstractTypeCoercion
> RelDataType syncAttributes(
> RelDataType fromType,
> RelDataType toType) {
> RelDataType syncedType = toType;
> if (fromType != null) {
> syncedType = factory.createTypeWithNullability(syncedType, fromType.isNullable());
> ...
> }{code}
>
> It doesn't take in account {_}toType.isNullable(){_}.
> And also in
>
> {code:java}
> class SqlCastFunction
> private static RelDataType createTypeWithNullabilityFromExpr(RelDataTypeFactory typeFactory,
> RelDataType expressionType, RelDataType targetType, boolean safe) {
> boolean isNullable = expressionType.isNullable() || safe;
> ...
> } {code}
>
> The same: _targetType.isNullable()_ is ignored.
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