Message-ID: <gh-pgjdbc-pgjdbc-3870@github.com>
From: "helloJosh (@helloJosh)" <noreply+helloJosh@github.com>
To: "pgjdbc/pgjdbc" <noreply+pgjdbc-pgjdbc@github.com>
Date: Mon, 24 Nov 2025 15:51:40 +0000
Subject: [pgjdbc/pgjdbc] PR #3870: feat: Add INFO log when fetchSize is ignored under autocommit=true
List-Id: <gh-pgjdbc-pgjdbc.github.com>
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X-GitHub-Issue: 3870
X-GitHub-Repo: pgjdbc/pgjdbc
X-GitHub-State: closed
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X-GitHub-Url: https://github.com/pgjdbc/pgjdbc/pull/3870
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First of all, Thank you for maintaining pgjdbc. As someone who relies on PostgreSQL heavily, I really appreciate the effort that goes into this project

If it's not too much trouble, I would like to get feedback on whether adding this log message is acceptable.

### Motivation
While using Spring Batch with JdbcCursorItemReader, our application repeatedly hit OOM because fetchSize was silently ignored when the connection ran with autocommit=true. Although the documentation notes that server-side cursors require autocommit=false, this detail becomes easy to miss when multiple application are involved.
I initially considered implementing a WITH HOLD cursor, but the complexity was non-trivial. So, I am proposing to surface this behavior through an INFO-level log.

### Why INFO
- Users typically set fetchSize because the result set is large.
- Many users expect streaming behavior even when autocommit is true(or may not realize autocommit is enabled).
- This log appears only when fetchSize > 0 and autocommit=true, so it does not introduce noisy logging in unrelated cases.

### What is changed
- Add an INFO-level log in PgStatement.executeInternal when:
  - fetchSize > 0
  - autocommit = true
  - when driver connot use a server-side cursor
- No behavior change
  - cursor flags untouched
- No new test
  - tests passed locally