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https://issues.apache.org/jira/browse/CALCITE-7062?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18009950#comment-18009950
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Zhen Chen commented on CALCITE-7062:
------------------------------------
Fixed in
https://github.com/apache/calcite/commit/3719447e125982aaa47f0a7b2564f94b9900539e
Thanks for contribution [~alex_pl]
Thanks for reviews [~mbudiu] [~julianhyde] [~xuzifu666] [~nobigo]
> Row type of SetOp 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
> Assignee: Aleksey Plekhanov
> Priority: Minor
> Labels: pull-request-available
>
> Reproducer:
> {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 t(a DATE)");
> try (ResultSet r = s.executeQuery("SELECT a FROM t UNION ALL select
> CURRENT_TIMESTAMP")) {
> assertTrue(r.next());
> assertFalse(r.next());
> }
> }
> }
> // Or
> @Test void test2() throws Exception {
> try (Connection c = connect(); Statement s = c.createStatement()) {
> s.execute("create table t1(id int not null, test TIMESTAMP NOT NULL)");
> s.execute("create table t2(id int not null, test VARCHAR)");
> s.execute("insert into t1 values (1, SYSTIMESTAMP)");
> s.execute("insert into t2 values (1, CAST(SYSDATE AS VARCHAR))");
> String query = "SELECT cast(test as date) as test FROM t2 " +
> "UNION ALL " +
> "select test from t1";
> s.execute(query);
> }
> }{code}
> Failure:
> {code:java}
> Conversion to relational algebra failed to preserve datatypes:
> validated type:
> RecordType(TIMESTAMP(0) NOT NULL A) NOT NULL
> converted type:
> RecordType(TIMESTAMP(0) A) NOT NULL
> rel:
> LogicalUnion(all=[true])
> LogicalProject(A=[CAST($0):TIMESTAMP(0)])
> LogicalTableScan(table=[[T]])
> LogicalProject(CURRENT_TIMESTAMP=[CURRENT_TIMESTAMP])
> LogicalValues(tuples=[[{ 0 }]])
> at
> org.apache.calcite.sql2rel.SqlToRelConverter.checkConvertedType(SqlToRelConverter.java:524)
> at
> org.apache.calcite.sql2rel.SqlToRelConverter.convertQuery(SqlToRelConverter.java:643)
> at org.apache.calcite.prepare.Prepare.prepareSql(Prepare.java:258) at
> org.apache.calcite.prepare.Prepare.prepareSql(Prepare.java:221) at
> org.apache.calcite.prepare.CalcitePrepareImpl.prepare2_(CalcitePrepareImpl.java:673)
> at
> org.apache.calcite.prepare.CalcitePrepareImpl.prepare_(CalcitePrepareImpl.java:524)
> at
> org.apache.calcite.prepare.CalcitePrepareImpl.prepareSql(CalcitePrepareImpl.java:492)
> at
> org.apache.calcite.jdbc.CalciteConnectionImpl.parseQuery(CalciteConnectionImpl.java:246)
> at
> org.apache.calcite.jdbc.CalciteMetaImpl.prepareAndExecute(CalciteMetaImpl.java:654){code}
> 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(){_}.
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