Tweak pg_promote() to report failures on kill() or postmaster failures

michaelpq · michaelpq · commit f593c5517d14 · 2023-08-29T08:45:04.000+09:00
Since its introduction in 1007465, pg_promote() has been returning a false status in three cases: - SIGUSR1 not sent to the postmaster process. - Postmaster death during standby promotion. - Standby not promoted within the specified wait time. An application calling this function will have a hard time understanding what a false state returned actually means. Per discussion, this switches the two first states to fail rather than return a "false" status, making the second case more consistent with the existing CHECK_FOR_INTERRUPTS in the wait loop. False is only returned when the promotion is not completed within the specified time (60s by default). Author: Ashutosh Sharma Reviewed-by: Fujii Masao, Laurenz Albe, Michael Paquier Discussion: https://postgr.es/m/CAE9k0P=QTrwptL0t4J0fuBRDDjgsT-0PVKd-ikd96i1hyL7Bcg@mail.gmail.com
diff --git a/src/backend/access/transam/xlogfuncs.c b/src/backend/access/transam/xlogfuncs.c
@@ -711,10 +711,10 @@ pg_promote(PG_FUNCTION_ARGS)
 	/* signal the postmaster */
 	if (kill(PostmasterPid, SIGUSR1) != 0)
 	{
-		ereport(WARNING,
-				(errmsg("failed to send signal to postmaster: %m")));
 		(void) unlink(PROMOTE_SIGNAL_FILE);
-		PG_RETURN_BOOL(false);
+		ereport(ERROR,
+				(errcode(ERRCODE_SYSTEM_ERROR),
+				 errmsg("failed to send signal to postmaster: %m")));
 	}
 
 	/* return immediately if waiting was not requested */
@@ -744,7 +744,10 @@ pg_promote(PG_FUNCTION_ARGS)
 		 * necessity for manual cleanup of all postmaster children.
 		 */
 		if (rc & WL_POSTMASTER_DEATH)
-			PG_RETURN_BOOL(false);
+			ereport(FATAL,
+					(errcode(ERRCODE_ADMIN_SHUTDOWN),
+					 errmsg("terminating connection due to unexpected postmaster exit"),
+					 errcontext("while waiting on promotion")));
 	}
 
 	ereport(WARNING,
