Improve connection denied error message during recovery.

MasaoFujii · MasaoFujii · commit df9384492b89 · 2021-03-25T10:41:28.000+09:00
Previously when an archive recovery or a standby was starting and reached the consistent recovery state but hot_standby was configured to off, the error message when a client connectted was "the database system is starting up", which was needless confusing and not really all that accurate either. This commit improves the connection denied error message during recovery, as follows, so that the users immediately know that their servers are configured to deny those connections. - If hot_standby is disabled, the error message "the database system is not accepting connections" and the detail message "Hot standby mode is disabled." are output when clients connect while an archive recovery or a standby is running. - If hot_standby is enabled, the error message "the database system is not yet accepting connections" and the detail message "Consistent recovery state has not been yet reached." are output when clients connect until the consistent recovery state is reached and postmaster starts accepting read only connections. This commit doesn't change the connection denied error message of "the database system is starting up" during normal server startup and crash recovery. Because it's still suitable for those situations. Author: James Coleman Reviewed-by: Alvaro Herrera, Andres Freund, David Zhang, Tom Lane, Fujii Masao Discussion: https://postgr.es/m/CAAaqYe8h5ES_B=F_zDT+Nj9XU7YEwNhKhHA2RE4CFhAQ93hfig@mail.gmail.com
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
@@ -2294,6 +2294,18 @@ ProcessStartupPacket(Port *port, bool ssl_done, bool gss_done)
 					(errcode(ERRCODE_CANNOT_CONNECT_NOW),
 					 errmsg("the database system is starting up")));
 			break;
+		case CAC_NOTCONSISTENT:
+			if (EnableHotStandby)
+				ereport(FATAL,
+						(errcode(ERRCODE_CANNOT_CONNECT_NOW),
+						 errmsg("the database system is not yet accepting connections"),
+						 errdetail("Consistent recovery state has not been yet reached.")));
+			else
+				ereport(FATAL,
+						(errcode(ERRCODE_CANNOT_CONNECT_NOW),
+						 errmsg("the database system is not accepting connections"),
+						 errdetail("Hot standby mode is disabled.")));
+			break;
 		case CAC_SHUTDOWN:
 			ereport(FATAL,
 					(errcode(ERRCODE_CANNOT_CONNECT_NOW),
@@ -2435,10 +2447,11 @@ canAcceptConnections(int backend_type)
 	{
 		if (Shutdown > NoShutdown)
 			return CAC_SHUTDOWN;	/* shutdown is pending */
-		else if (!FatalError &&
-				 (pmState == PM_STARTUP ||
-				  pmState == PM_RECOVERY))
+		else if (!FatalError && pmState == PM_STARTUP)
 			return CAC_STARTUP; /* normal startup */
+		else if (!FatalError && pmState == PM_RECOVERY)
+			return CAC_NOTCONSISTENT;	/* not yet at consistent recovery
+										 * state */
 		else
 			return CAC_RECOVERY;	/* else must be crash recovery */
 	}
diff --git a/src/include/libpq/libpq-be.h b/src/include/libpq/libpq-be.h
@@ -70,7 +70,12 @@ typedef struct
 
 typedef enum CAC_state
 {
-	CAC_OK, CAC_STARTUP, CAC_SHUTDOWN, CAC_RECOVERY, CAC_TOOMANY,
+	CAC_OK,
+	CAC_STARTUP,
+	CAC_SHUTDOWN,
+	CAC_RECOVERY,
+	CAC_NOTCONSISTENT,
+	CAC_TOOMANY,
 	CAC_SUPERUSER
 } CAC_state;
 
