From a3f17b9c315512e9c116dbc243056aad8b372e18 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@gmx.net>
Date: Tue, 25 Apr 2017 14:40:33 -0400
Subject: [PATCH] Wake up launcher when enabling a subscription

Otherwise one would have to wait up to DEFAULT_NAPTIME_PER_CYCLE until
the subscription worker is considered for starting.

There is a small race condition:  If one enables a subscription right
after disabling it, the launcher might not have registered the stopping
when receiving the wakeup signal for the re-enabling.  The start will
then not happen right away but after the full cycle time.

Author: Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>
---
 src/backend/commands/subscriptioncmds.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index c29a57ed52d..6a404bbe1e3 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -644,6 +644,9 @@ AlterSubscription(AlterSubscriptionStmt *stmt)
 					BoolGetDatum(enabled);
 				replaces[Anum_pg_subscription_subenabled - 1] = true;
 
+				if (enabled)
+					ApplyLauncherWakeupAtCommit();
+
 				update_tuple = true;
 				break;
 			}
-- 
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