ProxySQL fails to keep idle connection open for PostgreSQL databases

[PGGB]

Hi,
I'm having an issue where database queries via ProxySQL to a PostgreSQL database fail after a period of inactivity. The following errors appear in the logs

2026-07-30 07:40:32 PgSQL_Connection.cpp:1240:fetch_result_cont(): [ERROR] Failed to consume input. [P0001] server closed the connection unexpectedly
        This probably means the server terminated abnormally
        before or while processing the request.
2026-07-30 07:40:32 PgSQL_Connection.cpp:1284:flush(): [ERROR] Failed to flush data to backend. [P0001] server closed the connection unexpectedly
        This probably means the server terminated abnormally
        before or while processing the request.
2026-07-30 07:40:32 PgSQL_Session.cpp:2862:handler_minus1_ClientLibraryError(): [ERROR] Detected a broken connection while running query on (0,server.loc,5433,0) , FD (Conn:72 , MyDS:72) , user admin , last_used 46342ms ago : P0001, Failed to synchronize connection

pgsql-ping_interval_server_msec is set to 2 minutes, but I don't see any connections to the database during idle.

Looking at the code it seems like the handler in the async_ping function has been commented out:

proxysql/lib/PgSQL_Connection.cpp

Lines 1599 to 1602 in b3dd57d

	default:
	//handler(event);
	async_state_machine = ASYNC_PING_SUCCESSFUL;
	break;

ProxySQL version 3.0.9-618-g7ddb3dc
OS Version SUSE Linux Enterprise Server 15 SP7

proxysql.log

[coderabbitai]

🔗 Related PRs

#5093 - Avoid usage of deleted connection [merged]
#5301 - Fix: Close Statement flood exceeds threshold before backend operation deadlock [merged]
#5344 - Fix wrong index in connection cleanup loops (MySQL and PgSQL) [merged]
#5360 - fix: crash on macOS/FreeBSD when running PostgreSQL queries [merged]
#5421 - Harden PostgreSQL connection handling against unstable backends and error scenarios - P1 [merged]

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