From 444cef5aa420e421b6ab2621709fc97e8506716d Mon Sep 17 00:00:00 2001 From: Euler Taveira Date: Wed, 6 Mar 2024 17:50:01 -0300 Subject: [PATCH v27 2/4] Use latest replication slot position as replication start point Instead of using a temporary replication slot, use the latest replication slot position (LSN). --- src/bin/pg_basebackup/pg_createsubscriber.c | 60 ++++++++++----------- 1 file changed, 29 insertions(+), 31 deletions(-) diff --git a/src/bin/pg_basebackup/pg_createsubscriber.c b/src/bin/pg_basebackup/pg_createsubscriber.c index 3ccf3348a2..d9797ed8f4 100644 --- a/src/bin/pg_basebackup/pg_createsubscriber.c +++ b/src/bin/pg_basebackup/pg_createsubscriber.c @@ -74,11 +74,12 @@ static void modify_subscriber_sysid(const char *pg_resetwal_path, struct CreateSubscriberOptions *opt); static bool server_is_in_recovery(PGconn *conn); static void check_publisher(struct LogicalRepInfo *dbinfo); -static void setup_publisher(struct LogicalRepInfo *dbinfo); +static char *setup_publisher(struct LogicalRepInfo *dbinfo); static void check_subscriber(struct LogicalRepInfo *dbinfo); static void setup_subscriber(struct LogicalRepInfo *dbinfo, const char *consistent_lsn); -static char *setup_recovery(struct LogicalRepInfo *dbinfo, char *datadir); +static void setup_recovery(struct LogicalRepInfo *dbinfo, char *datadir, + char *lsn); static void drop_primary_replication_slot(struct LogicalRepInfo *dbinfo, char *slotname); static char *create_logical_replication_slot(PGconn *conn, @@ -574,11 +575,15 @@ modify_subscriber_sysid(const char *pg_resetwal_path, struct CreateSubscriberOpt /* * Create the publications and replication slots in preparation for logical - * replication. + * replication. Returns the LSN from latest replication slot. It will be the + * replication start point that is used to adjust the subscriptions (see + * set_replication_progress). */ -static void +static char * setup_publisher(struct LogicalRepInfo *dbinfo) { + char *lsn = NULL; + for (int i = 0; i < num_dbs; i++) { PGconn *conn; @@ -641,8 +646,10 @@ setup_publisher(struct LogicalRepInfo *dbinfo) dbinfo[i].subname = pg_strdup(replslotname); /* Create replication slot on publisher */ - if (create_logical_replication_slot(conn, &dbinfo[i], false) != NULL || - dry_run) + if (lsn) + pg_free(lsn); + lsn = create_logical_replication_slot(conn, &dbinfo[i], false); + if (lsn != NULL || dry_run) pg_log_info("create replication slot \"%s\" on publisher", replslotname); else @@ -650,6 +657,8 @@ setup_publisher(struct LogicalRepInfo *dbinfo) disconnect_database(conn, false); } + + return lsn; } /* @@ -995,14 +1004,11 @@ setup_subscriber(struct LogicalRepInfo *dbinfo, const char *consistent_lsn) } /* - * Get a replication start location and write the required recovery parameters - * into the configuration file. Returns the replication start location that is - * used to adjust the subscriptions (see set_replication_progress). + * Write the required recovery parameters. */ -static char * -setup_recovery(struct LogicalRepInfo *dbinfo, char *datadir) +static void +setup_recovery(struct LogicalRepInfo *dbinfo, char *datadir, char *lsn) { - char *consistent_lsn; PGconn *conn; PQExpBuffer recoveryconfcontents; @@ -1016,15 +1022,12 @@ setup_recovery(struct LogicalRepInfo *dbinfo, char *datadir) /* * Write recovery parameters. * - * Despite of the recovery parameters will be written to the subscriber, - * use a publisher connection for the following recovery functions. The - * connection is only used to check the current server version (physical - * replica, same server version). The subscriber is not running yet. In - * dry run mode, the recovery parameters *won't* be written. An invalid - * LSN is used for printing purposes. Additional recovery parameters are - * added here. It avoids unexpected behavior such as end of recovery as - * soon as a consistent state is reached (recovery_target) and failure due - * to multiple recovery targets (name, time, xid, LSN). + * The subscriber is not running yet. In dry run mode, the recovery + * parameters *won't* be written. An invalid LSN is used for printing + * purposes. Additional recovery parameters are added here. It avoids + * unexpected behavior such as end of recovery as soon as a consistent + * state is reached (recovery_target) and failure due to multiple recovery + * targets (name, time, xid, LSN). */ recoveryconfcontents = GenerateRecoveryConfig(conn, NULL); appendPQExpBuffer(recoveryconfcontents, "recovery_target = ''\n"); @@ -1048,14 +1051,12 @@ setup_recovery(struct LogicalRepInfo *dbinfo, char *datadir) else { appendPQExpBuffer(recoveryconfcontents, "recovery_target_lsn = '%s'\n", - consistent_lsn); + lsn); WriteRecoveryConfig(conn, datadir, recoveryconfcontents); } disconnect_database(conn, false); pg_log_debug("recovery parameters:\n%s", recoveryconfcontents->data); - - return consistent_lsn; } /* @@ -1988,13 +1989,10 @@ main(int argc, char **argv) * primary slot is in use. We could use an extra connection for it but it * doesn't seem worth. */ - setup_publisher(dbinfo); + consistent_lsn = setup_publisher(dbinfo); - /* - * Get the replication start point and write the required recovery - * parameters into the configuration file. - */ - consistent_lsn = setup_recovery(dbinfo, opt.subscriber_dir); + /* Write the required recovery parameters */ + setup_recovery(dbinfo, opt.subscriber_dir, consistent_lsn); /* * Restart subscriber so the recovery parameters will take effect. Wait @@ -2010,7 +2008,7 @@ main(int argc, char **argv) /* * Create the subscription for each database on subscriber. It does not * enable it immediately because it needs to adjust the replication start - * point to the LSN reported by setup_recovery(). It also cleans up + * point to the LSN reported by setup_publisher(). It also cleans up * publications created by this tool and replication to the standby. */ setup_subscriber(dbinfo, consistent_lsn); -- 2.34.1