Message-ID: <gh-pgjdbc-pgjdbc-3527@github.com>
From: "kneth (@kneth)" <noreply+kneth@github.com>
To: "pgjdbc/pgjdbc" <noreply+pgjdbc-pgjdbc@github.com>
Date: Tue, 18 Feb 2025 16:10:11 +0000
Subject: [pgjdbc/pgjdbc] issue #3527: Improve compatibility with non-Postgres databases
List-Id: <gh-pgjdbc-pgjdbc.github.com>
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X-GitHub-Issue: 3527
X-GitHub-Repo: pgjdbc/pgjdbc
X-GitHub-State: closed
X-GitHub-Type: issue
X-GitHub-Url: https://github.com/pgjdbc/pgjdbc/issues/3527
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Postgres compatible databases like https://github.com/crate/crate can use PG JDBC as driver. Often the PG JDBC driver is used by a tool or integration (JetBrains DataGrip to name one). As CrateDB isn't fully PG compatible, and hopefully the PG JDBC can offer a more robust support. The issue has also been reported as https://github.com/crate/crate/issues/17393.

A patch to work around the differences between the two databases can be found in https://github.com/pgjdbc/pgjdbc/pull/3526.

**Describe the issue**

As far as I can see, a query as `SELECT current_database()` will return a different column name. For Postgres, the column name will be `current_database` while for CrateDB, the column name will be the name of the current database. The PG JDBC driver will try to access the column `current_database` - which does not exist in the CrateDB case (leading to an error or exception).

It means that https://github.com/pgjdbc/pgjdbc/blob/master/pgjdbc/src/main/java/org/postgresql/jdbc/PgDatabaseMetaData.java#L1273 will fail as the column name is not specified in https://github.com/pgjdbc/pgjdbc/blob/master/pgjdbc/src/main/java/org/postgresql/jdbc/PgDatabaseMetaData.java#L1253 .

**Driver Version?** 

42.7.5

**Java Version?**

**OS Version?**

**PostgreSQL Version?**


**To Reproduce**

Any query with `current_database()` with the minimal case `SELECT current_database()`.

**Expected behaviour**

The driver should not throw an exception.

**Logs**

The following two screenshots show the difference between Postgres and CrateDB.

![Image](https://github.com/user-attachments/assets/910c468f-3bec-4ada-8e60-0f3041ba6f28)

![Image](https://github.com/user-attachments/assets/ddc71437-23c1-4ad5-a188-1f4829fac85e)