From 95d1b41450e93a9af146bc836f7f3b1ad13a1f2a Mon Sep 17 00:00:00 2001 From: Simon Riggs Date: Thu, 26 Jan 2017 20:06:44 +0000 Subject: [PATCH] Reset hot standby xmin after restart Hot_standby_feedback could be reset by reload and worked correctly, but if the server was restarted rather than reloaded the xmin was not reset. Force reset always if hot_standby_feedback is enabled at startup. Ants Aasma, Craig Ringer Reported-by: Ants Aasma --- src/backend/replication/walreceiver.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-) diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c index 413ee3a5c1..e0ab112d31 100644 --- a/src/backend/replication/walreceiver.c +++ b/src/backend/replication/walreceiver.c @@ -1154,7 +1154,10 @@ XLogWalRcvSendReply(bool force, bool requestReply) * in case they don't have a watch. * * If the user disables feedback, send one final message to tell sender - * to forget about the xmin on this standby. + * to forget about the xmin on this standby. We also send this message + * on first connect because a previous connection might have set xmin + * on a replication slot. (If we're not using a slot it's harmless to + * send a feedback message explicitly setting InvalidTransactionId). */ static void XLogWalRcvSendHSFeedback(bool immed) @@ -1164,7 +1167,8 @@ XLogWalRcvSendHSFeedback(bool immed) uint32 nextEpoch; TransactionId xmin; static TimestampTz sendTime = 0; - static bool master_has_standby_xmin = false; + /* initially true so we always send at least one feedback message */ + static bool master_has_standby_xmin = true; /* * If the user doesn't want status to be reported to the master, be sure @@ -1189,14 +1193,17 @@ XLogWalRcvSendHSFeedback(bool immed) } /* - * If Hot Standby is not yet active there is nothing to send. Check this - * after the interval has expired to reduce number of calls. + * If Hot Standby is not yet accepting connections there is nothing to + * send. Check this after the interval has expired to reduce number of + * calls. + * + * Bailing out here also ensures that we don't send feedback until we've + * read our own replication slot state, so we don't tell the master to + * discard needed xmin or catalog_xmin from any slots that may exist + * on this replica. */ if (!HotStandbyActive()) - { - Assert(!master_has_standby_xmin); return; - } /* * Make the expensive call to get the oldest xmin once we are certain