[SQL] Fix incorrect field type computation for nullable structs

mihaibudiu · mihaibudiu · commit afa94c4a1c54 · 2025-11-17T22:18:29.000Z
Signed-off-by: Mihai Budiu &lt;mbudiu@feldera.com&gt;
diff --git a/sql-to-dbsp-compiler/SQL-compiler/src/main/java/org/dbsp/sqlCompiler/ir/expression/DBSPFieldExpression.java b/sql-to-dbsp-compiler/SQL-compiler/src/main/java/org/dbsp/sqlCompiler/ir/expression/DBSPFieldExpression.java
@@ -46,7 +46,8 @@ public final class DBSPFieldExpression extends DBSPExpression {
         this.expression = expression;
         this.fieldNo = fieldNo;
         Utilities.enforce(fieldNo >= 0, () -> "Negative field index " + fieldNo);
-        Utilities.enforce(!expression.getType().mayBeNull || type.mayBeNull);
+        Utilities.enforce(!expression.getType().mayBeNull || type.mayBeNull,
+                () -> "Non-nullable field from nullable struct");
     }
 
     DBSPFieldExpression(DBSPExpression expression, int fieldNo, DBSPType type) {
diff --git a/sql-to-dbsp-compiler/SQL-compiler/src/main/java/org/dbsp/sqlCompiler/ir/expression/DBSPTupleExpression.java b/sql-to-dbsp-compiler/SQL-compiler/src/main/java/org/dbsp/sqlCompiler/ir/expression/DBSPTupleExpression.java
@@ -110,8 +110,7 @@ public static DBSPTupleExpression flatten(List<DBSPExpression> expressions) {
         for (DBSPExpression expression: expressions) {
             DBSPTypeTupleBase type = expression.getType().to(DBSPTypeTupleBase.class);
             for (int i = 0; i < type.size(); i++) {
-                DBSPType fieldType = type.tupFields[i];
-                DBSPExpression field = new DBSPFieldExpression(expression.deepCopy(), i, fieldType)
+                DBSPExpression field = new DBSPFieldExpression(expression.deepCopy(), i)
                         .simplify()
                         .applyCloneIfNeeded();
                 fields.add(field);
diff --git a/sql-to-dbsp-compiler/SQL-compiler/src/test/java/org/dbsp/sqlCompiler/compiler/sql/simple/Regression1Tests.java b/sql-to-dbsp-compiler/SQL-compiler/src/test/java/org/dbsp/sqlCompiler/compiler/sql/simple/Regression1Tests.java
@@ -8,18 +8,14 @@
 import org.dbsp.sqlCompiler.compiler.sql.tools.CompilerCircuitStream;
 import org.dbsp.sqlCompiler.compiler.sql.tools.SqlIoTest;
 import org.dbsp.sqlCompiler.compiler.visitors.inner.InnerVisitor;
-import org.dbsp.sqlCompiler.compiler.visitors.outer.CSE;
 import org.dbsp.sqlCompiler.compiler.visitors.outer.CircuitVisitor;
-import org.dbsp.sqlCompiler.compiler.visitors.outer.Passes;
 import org.dbsp.sqlCompiler.ir.expression.DBSPCloneExpression;
 import org.dbsp.sqlCompiler.ir.expression.DBSPTupleExpression;
 import org.dbsp.sqlCompiler.ir.expression.DBSPZSetExpression;
 import org.dbsp.sqlCompiler.ir.expression.literal.DBSPStringLiteral;
 import org.dbsp.sqlCompiler.ir.statement.DBSPStaticItem;
 import org.dbsp.util.Linq;
-import org.dbsp.util.Logger;
 import org.junit.Assert;
-import org.junit.Ignore;
 import org.junit.Test;
 
 import java.sql.SQLException;
@@ -1381,5 +1377,40 @@ CREATE TABLE interval_tbl(
                  0  | -121| 1
                  0  | -318226680.000000| 1""");
     }
+
+    @Test
+    public void issue5120() {
+        var ccs = this.getCCS("""
+                CREATE TYPE S AS(i1 INT NOT NULL, i2 INT);
+                CREATE TABLE tbl(id INT, c1_arr S ARRAY);
+                
+                CREATE VIEW v AS SELECT
+                id,  i1_val + 1, i2_val + 1,  idx
+                FROM tbl,
+                UNNEST(c1_arr) WITH ORDINALITY AS t (i1_val, i2_val, idx);""");
+        ccs.step("""
+                INSERT INTO tbl VALUES (0, ARRAY[S(1, NULL), S(5, 6)]);
+                """, """
+                 id | i1 | i2 | idx | weight
+                -----------------------------
+                  0 | 2  |    |   1 | 1
+                  0 | 6  |  7 |   2 | 1""");
+
+        ccs = this.getCCS("""
+                CREATE TABLE tbl(id INT,
+                c1_arr ROW(i1 INT NOT NULL, i2 INT NULL)  ARRAY NOT NULL);
+                
+                CREATE VIEW v AS SELECT
+                id,  i1_val + 1, i2_val + 1,  idx
+                FROM tbl,
+                UNNEST(c1_arr) WITH ORDINALITY AS t (i1_val, i2_val, idx);""");
+        ccs.step("""
+                INSERT INTO tbl VALUES (0, ARRAY[ROW(1, NULL), ROW(5, 6)]);
+                """, """
+                 id | i1 | i2 | idx | weight
+                -----------------------------
+                  0 | 2  |    |   1 | 1
+                  0 | 6  |  7 |   2 | 1""");
+    }
 }
  

Original file line number	Diff line number	Diff line change
`@@ -46,7 +46,8 @@ public final class DBSPFieldExpression extends DBSPExpression {`
`46`	`46`	`this.expression = expression;`
`47`	`47`	`this.fieldNo = fieldNo;`
`48`	`48`	`Utilities.enforce(fieldNo >= 0, () -> "Negative field index " + fieldNo);`
`49`		`- Utilities.enforce(!expression.getType().mayBeNull \|\| type.mayBeNull);`
	`49`	`+ Utilities.enforce(!expression.getType().mayBeNull \|\| type.mayBeNull,`
	`50`	`+ () -> "Non-nullable field from nullable struct");`
`50`	`51`	`}`
`51`	`52`
`52`	`53`	`DBSPFieldExpression(DBSPExpression expression, int fieldNo, DBSPType type) {`