Message-ID: <gh-pgjdbc-pgjdbc-3107-c3051715469@github.com>
From: "vlsi (@vlsi)" <noreply+vlsi@github.com>
To: "pgjdbc/pgjdbc" <noreply+pgjdbc-pgjdbc@github.com>
Date: Wed, 09 Jul 2025 08:40:46 +0000
Subject: Re: [pgjdbc/pgjdbc] issue #3107: JDBC driver sends "SAVEPOINT" query without finishing extended query protocol cycle
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Here's the discussion thread on hackers:
* https://www.postgresql.org/message-id/20240130.082257.800729082723903188.t-ishii%40sranhm.sra.co.jp

Note that pgjdbc can't use extended protocol for `savepoint pgjdbc_autosave` since we can't allow "prepared statement doe snot exist" for autosave queries (it defeats the purpose of `autosave`): https://www.postgresql.org/message-id/CAB%3DJe-HqHHqryuebk8MZGLpginRATRXHbP5_XvGG1arKtCWe0g%40mail.gmail.com

At the same time, currently, the error message is pgpool2-specific only. PostgreSQL does not throw such errors yet: https://www.postgresql.org/message-id/CAB%3DJe-HQ0Zwy1QWo2OpRcu3d41XW_o35ZV%3D12cS94%3D4DP6fw1A%40mail.gmail.com

The fix could probably be sending extra sync message before sending a simple query, however:
1) The error is pgpool2-specific only
2) Probably we should inject `sync` messages if we send a simple query before sending an extended one: https://www.postgresql.org/message-id/20240228.210532.1955389974353647116.t-ishii%40sranhm.sra.co.jp
3) We probably need to account for transaction safety as it looks like extra `sync` might close the currently active transaction: https://www.postgresql.org/message-id/CAGECzQSEeZMR%2Bhc9%2BtM%2BiGeOxWEx53VB0WKLyx1EOjt_y%3DNAKg%40mail.gmail.com