From e724e64f352ba5852a5b507d425a730cca9b2ca1 Mon Sep 17 00:00:00 2001
From: Aastha Agrrawal <aagrrawal@linkedin.com>
Date: Wed, 12 Apr 2023 15:45:37 -0700
Subject: [PATCH] Backport [CALCITE-4145]: Select nested field from aliased
 subquery (#86)

* Backport [CALCITE-4145] select nested field from subquery

* modify UT
---
 .../org/apache/calcite/sql/type/SqlTypeUtil.java     |  8 ++++++++
 .../apache/calcite/test/SqlToRelConverterTest.java   | 11 +++++++++++
 .../apache/calcite/test/SqlToRelConverterTest.xml    | 12 ++++++++++++
 3 files changed, 31 insertions(+)

diff --git a/core/src/main/java/org/apache/calcite/sql/type/SqlTypeUtil.java b/core/src/main/java/org/apache/calcite/sql/type/SqlTypeUtil.java
index dcfcdd107..e184b9685 100644
--- a/core/src/main/java/org/apache/calcite/sql/type/SqlTypeUtil.java
+++ b/core/src/main/java/org/apache/calcite/sql/type/SqlTypeUtil.java
@@ -1209,6 +1209,10 @@ public static boolean equalAsStructSansNullability(
    * Returns the ordinal of a given field in a record type, or -1 if the field
    * is not found.
    *
+   * <p>The {@code fieldName} is always simple, if the field is nested within a record field,
+   * returns index of the outer field instead. i.g. for row type
+   * (a int, b (b1 bigint, b2 varchar(20) not null)), returns 1 for both simple name "b1" and "b2".
+   *
    * @param type      Record type
    * @param fieldName Name of field
    * @return Ordinal of field
@@ -1220,6 +1224,10 @@ public static int findField(RelDataType type, String fieldName) {
       if (field.getName().equals(fieldName)) {
         return i;
       }
+      final RelDataType fieldType = field.getType();
+      if (fieldType.isStruct() && findField(fieldType, fieldName) != -1) {
+        return i;
+      }
     }
     return -1;
   }
diff --git a/core/src/test/java/org/apache/calcite/test/SqlToRelConverterTest.java b/core/src/test/java/org/apache/calcite/test/SqlToRelConverterTest.java
index ad05e88ff..3d03bd1ab 100644
--- a/core/src/test/java/org/apache/calcite/test/SqlToRelConverterTest.java
+++ b/core/src/test/java/org/apache/calcite/test/SqlToRelConverterTest.java
@@ -3554,6 +3554,17 @@ private Tester getExtendedTester() {
     sql(sql).ok();
   }
 
+  /**
+   * Test case for
+   * <a href="https://issues.apache.org/jira/browse/CALCITE-4145">[CALCITE-4145]
+   * Exception when nested field queried from subquery</a>.
+   */
+  @Test public void testSelectNestedFromSubquery() {
+    final String sql = "select tmp.nested.\"EXPR$0\" as id from ("
+        + "  select (1, 2) as nested) tmp";
+    sql(sql).ok();
+  }
+
   /**
    * Visitor that checks that every {@link RelNode} in a tree is valid.
    *
diff --git a/core/src/test/resources/org/apache/calcite/test/SqlToRelConverterTest.xml b/core/src/test/resources/org/apache/calcite/test/SqlToRelConverterTest.xml
index a473e637b..5acf7be75 100644
--- a/core/src/test/resources/org/apache/calcite/test/SqlToRelConverterTest.xml
+++ b/core/src/test/resources/org/apache/calcite/test/SqlToRelConverterTest.xml
@@ -6269,6 +6269,18 @@ from emp window w as (order by empno)]]>
             <![CDATA[
 LogicalProject(EXPR$0=[IGNORE NULLS(LEAD($5, 4))], EXPR$1=[LEAD($5, 4) OVER (ORDER BY $0 RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)])
   LogicalTableScan(table=[[CATALOG, SALES, EMP]])
+]]>
+        </Resource>
+    </TestCase>
+    <TestCase name="testSelectNestedFromSubquery">
+        <Resource name="sql">
+            <![CDATA[SELECT tmp.nested."EXPR$0" AS if FROM
+(SELECT (1, 2) AS nested) tmp]]>
+        </Resource>
+        <Resource name="plan">
+            <![CDATA[
+LogicalProject(ID=[ROW(1, 2).EXPR$0])
+  LogicalValues(tuples=[[{ 0 }]])
 ]]>
         </Resource>
     </TestCase>