From e1c021cb684743fcbf2033591562790cb2d1cdf4 Mon Sep 17 00:00:00 2001 From: Craig Ringer Date: Mon, 5 Sep 2016 16:23:57 +0800 Subject: [PATCH 10/21] Send catalog_xmin separately in hot_standby_feedback messages Now that the protocol supports reporting catalog_xmin separately and GetOldestXmin() allows us to exclude the catalog_xmin from the calculated xmin, actually send a separate catalog_xmin to the master. This change is necessary, but not sufficient, to allow logical decoding on a standby. --- src/backend/replication/walreceiver.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c index 80cc482..318d8ce 100644 --- a/src/backend/replication/walreceiver.c +++ b/src/backend/replication/walreceiver.c @@ -1206,11 +1206,21 @@ XLogWalRcvSendHSFeedback(bool immed) * everything else has been checked. */ if (hot_standby_feedback) - xmin = GetOldestXmin(NULL, false, NULL); + { + /* + * Usually GetOldestXmin() would include the catalog_xmin in its + * calculations, but we don't want to hold upstream back from vacuuming + * normal user table tuples just because they're within the + * catalog_xmin horizon of logical replication slots on this standby. + * Instead we report the catalog_xmin to the upstream separately. + */ + xmin = GetOldestXmin(NULL, false, &catalog_xmin); + } else + { xmin = InvalidTransactionId; - - catalog_xmin = InvalidTransactionId; + catalog_xmin = InvalidTransactionId; + } /* * Get epoch and adjust if nextXid and oldestXmin are different sides of @@ -1235,7 +1245,7 @@ XLogWalRcvSendHSFeedback(bool immed) pq_sendint(&reply_message, catalog_xmin, 4); pq_sendint(&reply_message, catalog_xmin_epoch, 4); walrcv_send(reply_message.data, reply_message.len); - if (TransactionIdIsValid(xmin)) + if (TransactionIdIsValid(xmin) || TransactionIdIsValid(catalog_xmin)) master_has_standby_xmin = true; else master_has_standby_xmin = false; -- 2.5.5