Message-ID: <gh-pgjdbc-pgjdbc-3941@github.com>
From: "findepi (@findepi)" <noreply+findepi@github.com>
To: "pgjdbc/pgjdbc" <noreply+pgjdbc-pgjdbc@github.com>
Date: Mon, 16 Feb 2026 16:32:26 +0000
Subject: [pgjdbc/pgjdbc] issue #3941: `ResultSetMetaData.getColumnClassName` returns incorrect class for NUMBER type
List-Id: <gh-pgjdbc-pgjdbc.github.com>
X-GitHub-Author-Id: 144328
X-GitHub-Author-Login: findepi
X-GitHub-Issue: 3941
X-GitHub-Repo: pgjdbc/pgjdbc
X-GitHub-State: open
X-GitHub-Type: issue
X-GitHub-Url: https://github.com/pgjdbc/pgjdbc/issues/3941
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**Describe the issue**

`java.sql.ResultSetMetaData.getColumnClassName` / `java.sql.ResultSet.getObject`  inconsistency.




**Driver Version?** 

42.7.10

**Java Version?**

25

**OS Version?**

MacOS 15.7.3 

**PostgreSQL Version?**

18

**To Reproduce**

```java
try (var container = new org.testcontainers.postgresql.PostgreSQLContainer("postgres:18")) {
    container.start();
    try (Connection connection = DriverManager.getConnection(container.getJdbcUrl(), container.getUsername(), container.getPassword());
            Statement statement = connection.createStatement()) {
        try (ResultSet resultSet = statement.executeQuery("SELECT '+Infinity'::decimal AS a")) {
            Class<?> clazz = Class.forName(resultSet.getMetaData().getColumnClassName(1));
            verify(resultSet.next());
            assertThat(resultSet.getObject(1)).isInstanceOf(clazz);
        }
    }
}
```


**Expected behaviour**

The contract for `getColumnClassName` is the following:

> Returns the fully-qualified name of the Java class whose instances are manufactured if the method ResultSet.getObject is called to retrieve a value from the column. ResultSet.getObject may return a subclass of the class returned by this method.

For NUMBER type, `getColumnClassName` returns `java.math.BigDecimal`.
However, `ResultSet.getObject` may sometimes return `java.lang.Double`, which obviously is not subclass of `java.math.BigDecimal`.

**proposed solution** return ``java.lang.Number`` from `getColumnClassName`


**Logs**

N/A