From 9affb4075aa2a24c764ad56ff19c695c9d89a668 Mon Sep 17 00:00:00 2001
From: Sakthivel Subramanian <sakthipvmj@gmail.com>
Date: Fri, 27 Feb 2026 16:00:55 +0530
Subject: [PATCH] fix: Fix Column Type Name for PostgreSQL ARRAY types

---
 .../spanner/jdbc/JdbcResultSetMetaData.java   | 11 +++++++-
 .../jdbc/JdbcResultSetMetaDataTest.java       | 25 +++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/src/main/java/com/google/cloud/spanner/jdbc/JdbcResultSetMetaData.java b/src/main/java/com/google/cloud/spanner/jdbc/JdbcResultSetMetaData.java
index f582ce45e..c549ee27d 100644
--- a/src/main/java/com/google/cloud/spanner/jdbc/JdbcResultSetMetaData.java
+++ b/src/main/java/com/google/cloud/spanner/jdbc/JdbcResultSetMetaData.java
@@ -16,7 +16,9 @@
 
 package com.google.cloud.spanner.jdbc;
 
+import com.google.cloud.spanner.Dialect;
 import com.google.cloud.spanner.ResultSet;
+import com.google.cloud.spanner.Type;
 import com.google.cloud.spanner.connection.ConnectionProperties;
 import com.google.common.base.Preconditions;
 import java.sql.Connection;
@@ -192,7 +194,14 @@ public int getColumnType(int column) {
 
   @Override
   public String getColumnTypeName(int column) {
-    return spannerResultSet.getColumnType(column - 1).getCode().name();
+    Type columnType = spannerResultSet.getColumnType(column - 1);
+    if (columnType.getCode() == Type.Code.ARRAY && statement instanceof JdbcStatement) {
+      Dialect dialect = ((JdbcStatement) statement).getConnection().getDialect();
+      if (dialect == Dialect.POSTGRESQL) {
+        return "_" + columnType.getArrayElementType().getSpannerTypeName(dialect);
+      }
+    }
+    return columnType.getCode().name();
   }
 
   @Override
diff --git a/src/test/java/com/google/cloud/spanner/jdbc/JdbcResultSetMetaDataTest.java b/src/test/java/com/google/cloud/spanner/jdbc/JdbcResultSetMetaDataTest.java
index 36996c801..3fdbf374c 100644
--- a/src/test/java/com/google/cloud/spanner/jdbc/JdbcResultSetMetaDataTest.java
+++ b/src/test/java/com/google/cloud/spanner/jdbc/JdbcResultSetMetaDataTest.java
@@ -23,6 +23,7 @@
 import static org.mockito.Mockito.when;
 
 import com.google.cloud.ByteArray;
+import com.google.cloud.spanner.Dialect;
 import com.google.cloud.spanner.ResultSet;
 import com.google.cloud.spanner.ResultSets;
 import com.google.cloud.spanner.Struct;
@@ -540,6 +541,30 @@ public void getColumnTypeName() {
     }
   }
 
+  @Test
+  public void getColumnTypeNameForPostgreSQL() throws SQLException {
+    JdbcConnection connection = mock(JdbcConnection.class);
+    JdbcStatement statement = mock(JdbcStatement.class);
+    JdbcResultSet resultSet = getFooTestResultSet(statement);
+    when(connection.getSchema()).thenReturn("");
+    when(connection.getCatalog()).thenReturn("test-database");
+    when(statement.getConnection()).then(new Returns(connection));
+    when(connection.getDialect()).thenReturn(Dialect.POSTGRESQL);
+
+    JdbcResultSetMetaData sub = resultSet.getMetaData();
+
+    int index = 1;
+    for (TestColumn col : TEST_COLUMNS) {
+      if (col.type.getCode() == Type.Code.ARRAY
+          && col.type.getSpannerTypeName(Dialect.POSTGRESQL).contains("bool")) {
+        assertEquals("_boolean", sub.getColumnTypeName(index));
+      } else if (col.type.getCode() != Type.Code.ARRAY) {
+        assertEquals(col.type.getCode().name(), sub.getColumnTypeName(index));
+      }
+      index++;
+    }
+  }
+
   @Test
   public void testIsReadOnly() {
     for (int i = 0; i < TEST_COLUMNS.size(); i++) {