v6-0002-Address-some-comments-proposed-on-hackers.patch

From ad645b61dad1a8ce03ab0ad28a0c44d0a943cc3e Mon Sep 17 00:00:00 2001
From: Shlok Kyal <shlok.kyal.oss@gmail.com>
Date: Mon, 22 Jan 2024 12:42:34 +0530
Subject: [PATCH v6 2/3] Address some comments proposed on -hackers

The patch has following changes:

* Some comments reported on the thread
* Add a timeout option for the recovery option
* Reject if the target server is not a standby
* Reject when the --subscriber-conninfo specifies non-local server
* Add -u and -p options
* Check wal_level and max_replication_slot parameters
---
 doc/src/sgml/ref/pg_subscriber.sgml           |  21 +-
 src/bin/pg_basebackup/pg_subscriber.c         | 911 +++++++++++-------
 src/bin/pg_basebackup/t/040_pg_subscriber.pl  |   9 +-
 .../t/041_pg_subscriber_standby.pl            |   8 +-
 4 files changed, 600 insertions(+), 349 deletions(-)

diff --git a/doc/src/sgml/ref/pg_subscriber.sgml b/doc/src/sgml/ref/pg_subscriber.sgml
index 553185c35f..eaabfc7053 100644
--- a/doc/src/sgml/ref/pg_subscriber.sgml
+++ b/doc/src/sgml/ref/pg_subscriber.sgml
@@ -16,12 +16,18 @@ PostgreSQL documentation
 
  <refnamediv>
   <refname>pg_subscriber</refname>
-  <refpurpose>create a new logical replica from a standby server</refpurpose>
+  <refpurpose>Convert a standby replica to a logical replica</refpurpose>
  </refnamediv>
 
  <refsynopsisdiv>
   <cmdsynopsis>
    <command>pg_subscriber</command>
+   <arg choice="plain"><option>-D</option></arg>
+   <arg choice="plain"><replaceable>datadir</replaceable></arg>
+   <arg choice="plain"><option>-P</option>
+   <replaceable>publisher-conninfo</replaceable></arg>
+   <arg choice="plain"><option>-S</option></arg>
+   <arg choice="plain"><replaceable>subscriber-conninfo</replaceable></arg>
    <arg rep="repeat"><replaceable>option</replaceable></arg>
   </cmdsynopsis>
  </refsynopsisdiv>
@@ -29,17 +35,18 @@ PostgreSQL documentation
  <refsect1>
   <title>Description</title>
   <para>
-   <application>pg_subscriber</application> takes the publisher and subscriber
-   connection strings, a cluster directory from a standby server and a list of
-   database names and it sets up a new logical replica using the physical
-   recovery process.
+   pg_subscriber creates a new <link
+   linkend="logical-replication-subscription">subscriber</link> from a physical
+   standby server. This allows users to quickly set up logical replication
+   system.
   </para>
 
   <para>
-   The <application>pg_subscriber</application> should be run at the target
+   The <application>pg_subscriber</application> has to be run at the target
    server. The source server (known as publisher server) should accept logical
    replication connections from the target server (known as subscriber server).
-   The target server should accept local logical replication connection.
+   The target server should accept logical replication connection from
+   localhost.
   </para>
  </refsect1>
 
diff --git a/src/bin/pg_basebackup/pg_subscriber.c b/src/bin/pg_basebackup/pg_subscriber.c
index e998c29f9e..0dc87e919b 100644
--- a/src/bin/pg_basebackup/pg_subscriber.c
+++ b/src/bin/pg_basebackup/pg_subscriber.c
@@ -1,12 +1,12 @@
 /*-------------------------------------------------------------------------
  *
  * pg_subscriber.c
- *	  Create a new logical replica from a standby server
+ *	  Convert a standby replica to a logical replica
  *
  * Copyright (C) 2024, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *		src/bin/pg_subscriber/pg_subscriber.c
+ *		src/bin/pg_basebackup/pg_subscriber.c
  *
  *-------------------------------------------------------------------------
  */
@@ -32,81 +32,122 @@
 
 #define	PGS_OUTPUT_DIR	"pg_subscriber_output.d"
 
-typedef struct LogicalRepInfo
+typedef struct LogicalRepPerdbInfo
 {
-	Oid			oid;			/* database OID */
-	char	   *dbname;			/* database name */
-	char	   *pubconninfo;	/* publication connection string for logical
-								 * replication */
-	char	   *subconninfo;	/* subscription connection string for logical
-								 * replication */
-	char	   *pubname;		/* publication name */
-	char	   *subname;		/* subscription name (also replication slot
-								 * name) */
-
-	bool		made_replslot;	/* replication slot was created */
-	bool		made_publication;	/* publication was created */
-	bool		made_subscription;	/* subscription was created */
-} LogicalRepInfo;
+	Oid		oid;
+	char   *dbname;
+	bool	made_replslot;	/* replication slot was created */
+	bool	made_publication;	/* publication was created */
+	bool	made_subscription;	/* subscription was created */
+} LogicalRepPerdbInfo;
+
+typedef struct
+{
+	LogicalRepPerdbInfo	   *perdb;			/* array of db infos */
+	int						ndbs;			/* number of db infos */
+} LogicalRepPerdbInfoArr;
+
+typedef struct PrimaryInfo
+{
+	char   *base_conninfo;
+	uint64	sysid;
+} PrimaryInfo;
+
+typedef struct StandbyInfo
+{
+	char   *base_conninfo;
+	char   *bindir;
+	char   *pgdata;
+	char   *primary_slot_name;
+	uint64	sysid;
+} StandbyInfo;
 
 static void cleanup_objects_atexit(void);
 static void usage();
-static char *get_base_conninfo(char *conninfo, char *dbname,
-							   const char *noderole);
-static bool get_exec_path(const char *path);
+static char *get_base_conninfo(char *conninfo, char *dbname);
+static bool get_exec_base_path(const char *path);
 static bool check_data_directory(const char *datadir);
+static void store_db_names(LogicalRepPerdbInfo **perdb, int ndbs);
+static void get_sysid_for_primary(PrimaryInfo *primary, char *dbname);
+static void get_control_for_standby(StandbyInfo *standby);
 static char *concat_conninfo_dbname(const char *conninfo, const char *dbname);
-static LogicalRepInfo *store_pub_sub_info(const char *pub_base_conninfo, const char *sub_base_conninfo);
-static PGconn *connect_database(const char *conninfo);
+static PGconn *connect_database(const char *base_conninfo, const char*dbname);
 static void disconnect_database(PGconn *conn);
-static uint64 get_sysid_from_conn(const char *conninfo);
-static uint64 get_control_from_datadir(const char *datadir);
-static void modify_sysid(const char *pg_resetwal_path, const char *datadir);
-static char *use_primary_slot_name(void);
-static bool create_all_logical_replication_slots(LogicalRepInfo *dbinfo);
-static char *create_logical_replication_slot(PGconn *conn, LogicalRepInfo *dbinfo,
-											 char *slot_name);
-static void drop_replication_slot(PGconn *conn, LogicalRepInfo *dbinfo, const char *slot_name);
+static char *use_primary_slot_name(PrimaryInfo *primary, StandbyInfo *standby,
+								   LogicalRepPerdbInfo *perdb);
+static bool create_all_logical_replication_slots(PrimaryInfo *primary,
+												 LogicalRepPerdbInfoArr *dbarr);
+static char *create_logical_replication_slot(PGconn *conn, bool temporary,
+											 LogicalRepPerdbInfo *perdb);
+static void modify_sysid(const char *bindir, const char *datadir);
+static void drop_replication_slot(PGconn *conn, LogicalRepPerdbInfo *perdb,
+								  const char *slot_name);
 static void pg_ctl_status(const char *pg_ctl_cmd, int rc, int action);
-static void wait_for_end_recovery(const char *conninfo);
-static void create_publication(PGconn *conn, LogicalRepInfo *dbinfo);
-static void drop_publication(PGconn *conn, LogicalRepInfo *dbinfo);
-static void create_subscription(PGconn *conn, LogicalRepInfo *dbinfo);
-static void drop_subscription(PGconn *conn, LogicalRepInfo *dbinfo);
-static void set_replication_progress(PGconn *conn, LogicalRepInfo *dbinfo, const char *lsn);
-static void enable_subscription(PGconn *conn, LogicalRepInfo *dbinfo);
+static void wait_for_end_recovery(const char *base_conninfo,
+								  const char *dbname);
+static void create_publication(PGconn *conn, PrimaryInfo *primary,
+							   LogicalRepPerdbInfo *perdb);
+static void drop_publication(PGconn *conn, LogicalRepPerdbInfo *perdb);
+static void create_subscription(PGconn *conn, StandbyInfo *standby,
+								char *base_conninfo,
+								LogicalRepPerdbInfo *perdb);
+static void drop_subscription(PGconn *conn, LogicalRepPerdbInfo *perdb);
+static void set_replication_progress(PGconn *conn, LogicalRepPerdbInfo *perdb, const char *lsn);
+static void enable_subscription(PGconn *conn, LogicalRepPerdbInfo *perdb);
+static void start_standby_server(StandbyInfo *standby, unsigned short subport,
+								 char *server_start_log);
+static char *construct_sub_conninfo(char *username, unsigned short subport);
 
 #define	USEC_PER_SEC	1000000
-#define	WAIT_INTERVAL	1		/* 1 second */
+#define DEFAULT_WAIT	60
+#define WAITS_PER_SEC	10              /* should divide USEC_PER_SEC evenly */
+#define DEF_PGSPORT		50111
 
 /* Options */
-static const char *progname;
-
-static char *subscriber_dir = NULL;
 static char *pub_conninfo_str = NULL;
-static char *sub_conninfo_str = NULL;
 static SimpleStringList database_names = {NULL, NULL};
-static char *primary_slot_name = NULL;
+static int	wait_seconds = DEFAULT_WAIT;
+static bool retain = false;
 static bool dry_run = false;
 
 static bool success = false;
+static const char *progname;
+static LogicalRepPerdbInfoArr dbarr;
+static PrimaryInfo primary;
+static StandbyInfo standby;
 
-static char *pg_ctl_path = NULL;
-static char *pg_resetwal_path = NULL;
+enum PGSWaitPMResult
+{
+	PGS_POSTMASTER_READY,
+	PGS_POSTMASTER_STANDBY,
+	PGS_POSTMASTER_STILL_STARTING,
+	PGS_POSTMASTER_FAILED
+};
 
-static LogicalRepInfo *dbinfo;
-static int	num_dbs = 0;
 
-static char temp_replslot[NAMEDATALEN] = {0};
-static bool made_transient_replslot = false;
+/*
+ * Build the replication slot and subscription name. The name must not exceed
+ * NAMEDATALEN - 1. This current schema uses a maximum of 36 characters
+ * (14 + 10 + 1 + 10 + '\0'). System identifier is included to reduce the
+ * probability of collision. By default, subscription name is used as
+ * replication slot name.
+ */
+static inline void
+get_subscription_name(Oid oid, int pid, char *subname, Size szsub)
+{
+	snprintf(subname, szsub, "pg_subscriber_%u_%d", oid, pid);
+}
 
-enum WaitPMResult
+/*
+ * Build the publication name. The name must not exceed NAMEDATALEN -
+ * 1. This current schema uses a maximum of 35 characters (14 + 10 +
+ * '\0').
+ */
+static inline void
+get_publication_name(Oid oid, char *pubname, Size szpub)
 {
-	POSTMASTER_READY,
-	POSTMASTER_STANDBY,
-	POSTMASTER_STILL_STARTING,
-	POSTMASTER_FAILED
-};
+	snprintf(pubname, szpub, "pg_subscriber_%u", oid);
+}
 
 
 /*
@@ -125,41 +166,39 @@ cleanup_objects_atexit(void)
 	if (success)
 		return;
 
-	for (i = 0; i < num_dbs; i++)
+	for (i = 0; i < dbarr.ndbs; i++)
 	{
-		if (dbinfo[i].made_subscription)
+		LogicalRepPerdbInfo *perdb = &dbarr.perdb[i];
+
+		if (perdb->made_subscription)
 		{
-			conn = connect_database(dbinfo[i].subconninfo);
+			conn = connect_database(standby.base_conninfo, perdb->dbname);
 			if (conn != NULL)
 			{
-				drop_subscription(conn, &dbinfo[i]);
+				drop_subscription(conn, perdb);
 				disconnect_database(conn);
 			}
 		}
 
-		if (dbinfo[i].made_publication || dbinfo[i].made_replslot)
+		if (perdb->made_publication || perdb->made_replslot)
 		{
-			conn = connect_database(dbinfo[i].pubconninfo);
+			conn = connect_database(primary.base_conninfo, perdb->dbname);
 			if (conn != NULL)
 			{
-				if (dbinfo[i].made_publication)
-					drop_publication(conn, &dbinfo[i]);
-				if (dbinfo[i].made_replslot)
-					drop_replication_slot(conn, &dbinfo[i], NULL);
+				if (perdb->made_publication)
+					drop_publication(conn, perdb);
+				if (perdb->made_replslot)
+				{
+					char replslotname[NAMEDATALEN];
+
+					get_subscription_name(perdb->oid, (int) getpid(),
+										  replslotname, NAMEDATALEN);
+					drop_replication_slot(conn, perdb, replslotname);
+				}
 				disconnect_database(conn);
 			}
 		}
 	}
-
-	if (made_transient_replslot)
-	{
-		conn = connect_database(dbinfo[0].pubconninfo);
-		if (conn != NULL)
-		{
-			drop_replication_slot(conn, &dbinfo[0], temp_replslot);
-			disconnect_database(conn);
-		}
-	}
 }
 
 static void
@@ -184,17 +223,16 @@ usage(void)
 
 /*
  * Validate a connection string. Returns a base connection string that is a
- * connection string without a database name plus a fallback application name.
- * Since we might process multiple databases, each database name will be
- * appended to this base connection string to provide a final connection string.
- * If the second argument (dbname) is not null, returns dbname if the provided
- * connection string contains it. If option --database is not provided, uses
- * dbname as the only database to setup the logical replica.
- * It is the caller's responsibility to free the returned connection string and
- * dbname.
+ * connection string without a database name. Since we might process multiple
+ * databases, each database name will be appended to this base connection
+ * string to provide a final connection string. If the second argument (dbname)
+ * is not null, returns dbname if the provided connection string contains it.
+ * If option --database is not provided, uses dbname as the only database to
+ * setup the logical replica. It is the caller's responsibility to free the
+ * returned connection string and dbname.
  */
 static char *
-get_base_conninfo(char *conninfo, char *dbname, const char *noderole)
+get_base_conninfo(char *conninfo, char *dbname)
 {
 	PQExpBuffer buf = createPQExpBuffer();
 	PQconninfoOption *conn_opts = NULL;
@@ -203,7 +241,7 @@ get_base_conninfo(char *conninfo, char *dbname, const char *noderole)
 	char	   *ret;
 	int			i;
 
-	pg_log_info("validating connection string on %s", noderole);
+	pg_log_info("validating connection string on publisher");
 
 	conn_opts = PQconninfoParse(conninfo, &errmsg);
 	if (conn_opts == NULL)
@@ -231,10 +269,6 @@ get_base_conninfo(char *conninfo, char *dbname, const char *noderole)
 		}
 	}
 
-	if (i > 0)
-		appendPQExpBufferChar(buf, ' ');
-	appendPQExpBuffer(buf, "fallback_application_name=%s", progname);
-
 	ret = pg_strdup(buf->data);
 
 	destroyPQExpBuffer(buf);
@@ -244,15 +278,16 @@ get_base_conninfo(char *conninfo, char *dbname, const char *noderole)
 }
 
 /*
- * Get the absolute path from other PostgreSQL binaries (pg_ctl and
- * pg_resetwal) that is used by it.
+ * Get the absolute binary path from another PostgreSQL binary (pg_ctl) and set
+ * to StandbyInfo.
  */
 static bool
-get_exec_path(const char *path)
+get_exec_base_path(const char *path)
 {
 	int			rc;
+	char		pg_ctl_path[MAXPGPATH];
+	char	   *p;
 
-	pg_ctl_path = pg_malloc(MAXPGPATH);
 	rc = find_other_exec(path, "pg_ctl",
 						 "pg_ctl (PostgreSQL) " PG_VERSION "\n",
 						 pg_ctl_path);
@@ -277,30 +312,10 @@ get_exec_path(const char *path)
 
 	pg_log_debug("pg_ctl path is: %s", pg_ctl_path);
 
-	pg_resetwal_path = pg_malloc(MAXPGPATH);
-	rc = find_other_exec(path, "pg_resetwal",
-						 "pg_resetwal (PostgreSQL) " PG_VERSION "\n",
-						 pg_resetwal_path);
-	if (rc < 0)
-	{
-		char		full_path[MAXPGPATH];
-
-		if (find_my_exec(path, full_path) < 0)
-			strlcpy(full_path, progname, sizeof(full_path));
-		if (rc == -1)
-			pg_log_error("The program \"%s\" is needed by %s but was not found in the\n"
-						 "same directory as \"%s\".\n"
-						 "Check your installation.",
-						 "pg_resetwal", progname, full_path);
-		else
-			pg_log_error("The program \"%s\" was found by \"%s\"\n"
-						 "but was not the same version as %s.\n"
-						 "Check your installation.",
-						 "pg_resetwal", full_path, progname);
-		return false;
-	}
-
-	pg_log_debug("pg_resetwal path is: %s", pg_resetwal_path);
+	/* Extract the directory part from the path */
+	Assert(p = strrchr(pg_ctl_path, 'p'));
+	*p = '\0';
+	standby.bindir = pg_strdup(pg_ctl_path);
 
 	return true;
 }
@@ -364,49 +379,36 @@ concat_conninfo_dbname(const char *conninfo, const char *dbname)
 }
 
 /*
- * Store publication and subscription information.
+ * Initialize per-db structure and store the name of databases
  */
-static LogicalRepInfo *
-store_pub_sub_info(const char *pub_base_conninfo, const char *sub_base_conninfo)
+static void
+store_db_names(LogicalRepPerdbInfo **perdb, int ndbs)
 {
-	LogicalRepInfo *dbinfo;
 	SimpleStringListCell *cell;
 	int			i = 0;
 
-	dbinfo = (LogicalRepInfo *) pg_malloc(num_dbs * sizeof(LogicalRepInfo));
+	*perdb = (LogicalRepPerdbInfo *) pg_malloc0(sizeof(LogicalRepPerdbInfo) *
+											   ndbs);
 
 	for (cell = database_names.head; cell; cell = cell->next)
 	{
-		char	   *conninfo;
-
-		/* Publisher. */
-		conninfo = concat_conninfo_dbname(pub_base_conninfo, cell->val);
-		dbinfo[i].pubconninfo = conninfo;
-		dbinfo[i].dbname = cell->val;
-		dbinfo[i].made_replslot = false;
-		dbinfo[i].made_publication = false;
-		dbinfo[i].made_subscription = false;
-		/* other struct fields will be filled later. */
-
-		/* Subscriber. */
-		conninfo = concat_conninfo_dbname(sub_base_conninfo, cell->val);
-		dbinfo[i].subconninfo = conninfo;
-
+		(*perdb)[i].dbname = pg_strdup(cell->val);
 		i++;
 	}
-
-	return dbinfo;
 }
 
 static PGconn *
-connect_database(const char *conninfo)
+connect_database(const char *base_conninfo, const char*dbname)
 {
 	PGconn	   *conn;
 	PGresult   *res;
-	const char *rconninfo;
+
+	char	   *rconninfo;
+	char	   *concat_conninfo = concat_conninfo_dbname(base_conninfo,
+														 dbname);
 
 	/* logical replication mode */
-	rconninfo = psprintf("%s replication=database", conninfo);
+	rconninfo = psprintf("%s replication=database", concat_conninfo);
 
 	conn = PQconnectdb(rconninfo);
 	if (PQstatus(conn) != CONNECTION_OK)
@@ -424,6 +426,9 @@ connect_database(const char *conninfo)
 	}
 	PQclear(res);
 
+	pfree(rconninfo);
+	pfree(concat_conninfo);
+
 	return conn;
 }
 
@@ -436,19 +441,18 @@ disconnect_database(PGconn *conn)
 }
 
 /*
- * Obtain the system identifier using the provided connection. It will be used
- * to compare if a data directory is a clone of another one.
+ * Obtain the system identifier from the primary server. It will be used to
+ * compare if a data directory is a clone of another one.
  */
-static uint64
-get_sysid_from_conn(const char *conninfo)
+static void
+get_sysid_for_primary(PrimaryInfo *primary, char *dbname)
 {
 	PGconn	   *conn;
 	PGresult   *res;
-	uint64		sysid;
 
 	pg_log_info("getting system identifier from publisher");
 
-	conn = connect_database(conninfo);
+	conn = connect_database(primary->base_conninfo, dbname);
 	if (conn == NULL)
 		exit(1);
 
@@ -471,43 +475,39 @@ get_sysid_from_conn(const char *conninfo)
 		exit(1);
 	}
 
-	sysid = strtou64(PQgetvalue(res, 0, 0), NULL, 10);
+	primary->sysid = strtou64(PQgetvalue(res, 0, 0), NULL, 10);
 
-	pg_log_info("system identifier is %llu on publisher", (unsigned long long) sysid);
+	pg_log_info("system identifier is %llu on publisher",
+				(unsigned long long) primary->sysid);
 
 	disconnect_database(conn);
-
-	return sysid;
 }
 
 /*
- * Obtain the system identifier from control file. It will be used to compare
- * if a data directory is a clone of another one. This routine is used locally
- * and avoids a replication connection.
+ * Obtain the system identifier from a standby server. It will be used to
+ * compare if a data directory is a clone of another one. This routine is used
+ * locally and avoids a replication connection.
  */
-static uint64
-get_control_from_datadir(const char *datadir)
+static void
+get_control_for_standby(StandbyInfo *standby)
 {
 	ControlFileData *cf;
 	bool		crc_ok;
-	uint64		sysid;
 
 	pg_log_info("getting system identifier from subscriber");
 
-	cf = get_controlfile(datadir, &crc_ok);
+	cf = get_controlfile(standby->pgdata, &crc_ok);
 	if (!crc_ok)
 	{
 		pg_log_error("control file appears to be corrupt");
 		exit(1);
 	}
 
-	sysid = cf->system_identifier;
+	standby->sysid = cf->system_identifier;
 
-	pg_log_info("system identifier is %llu on subscriber", (unsigned long long) sysid);
+	pg_log_info("system identifier is %llu on subscriber", (unsigned long long) standby->sysid);
 
 	pfree(cf);
-
-	return sysid;
 }
 
 /*
@@ -516,7 +516,7 @@ get_control_from_datadir(const char *datadir)
  * files from one of the systems might be used in the other one.
  */
 static void
-modify_sysid(const char *pg_resetwal_path, const char *datadir)
+modify_sysid(const char *bindir, const char *datadir)
 {
 	ControlFileData *cf;
 	bool		crc_ok;
@@ -551,7 +551,7 @@ modify_sysid(const char *pg_resetwal_path, const char *datadir)
 
 	pg_log_info("running pg_resetwal on the subscriber");
 
-	cmd_str = psprintf("\"%s\" -D \"%s\"", pg_resetwal_path, datadir);
+	cmd_str = psprintf("\"%s/pg_resetwal\" -D \"%s\"", bindir, datadir);
 
 	pg_log_debug("command is: %s", cmd_str);
 
@@ -571,14 +571,15 @@ modify_sysid(const char *pg_resetwal_path, const char *datadir)
  * Return a palloc'd slot name if the replication is using one.
  */
 static char *
-use_primary_slot_name(void)
+use_primary_slot_name(PrimaryInfo *primary, StandbyInfo *standby,
+					  LogicalRepPerdbInfo *perdb)
 {
 	PGconn	   *conn;
 	PGresult   *res;
 	PQExpBuffer str = createPQExpBuffer();
 	char	   *slot_name;
 
-	conn = connect_database(dbinfo[0].subconninfo);
+	conn = connect_database(standby->base_conninfo, perdb->dbname);
 	if (conn == NULL)
 		exit(1);
 
@@ -604,7 +605,7 @@ use_primary_slot_name(void)
 
 	disconnect_database(conn);
 
-	conn = connect_database(dbinfo[0].pubconninfo);
+	conn = connect_database(primary->base_conninfo, perdb->dbname);
 	if (conn == NULL)
 		exit(1);
 
@@ -634,17 +635,19 @@ use_primary_slot_name(void)
 }
 
 static bool
-create_all_logical_replication_slots(LogicalRepInfo *dbinfo)
+create_all_logical_replication_slots(PrimaryInfo *primary,
+									 LogicalRepPerdbInfoArr *dbarr)
 {
 	int			i;
 
-	for (i = 0; i < num_dbs; i++)
+	for (i = 0; i < dbarr->ndbs; i++)
 	{
 		PGconn	   *conn;
 		PGresult   *res;
 		char		replslotname[NAMEDATALEN];
+		LogicalRepPerdbInfo *perdb = &dbarr->perdb[i];
 
-		conn = connect_database(dbinfo[i].pubconninfo);
+		conn = connect_database(primary->base_conninfo, perdb->dbname);
 		if (conn == NULL)
 			exit(1);
 
@@ -664,27 +667,14 @@ create_all_logical_replication_slots(LogicalRepInfo *dbinfo)
 		}
 
 		/* Remember database OID. */
-		dbinfo[i].oid = strtoul(PQgetvalue(res, 0, 0), NULL, 10);
+		perdb->oid = strtoul(PQgetvalue(res, 0, 0), NULL, 10);
 
 		PQclear(res);
 
-		/*
-		 * Build the replication slot name. The name must not exceed
-		 * NAMEDATALEN - 1. This current schema uses a maximum of 36
-		 * characters (14 + 10 + 1 + 10 + '\0'). System identifier is included
-		 * to reduce the probability of collision. By default, subscription
-		 * name is used as replication slot name.
-		 */
-		snprintf(replslotname, sizeof(replslotname),
-				 "pg_subscriber_%u_%d",
-				 dbinfo[i].oid,
-				 (int) getpid());
-		dbinfo[i].subname = pg_strdup(replslotname);
+		get_subscription_name(perdb->oid, (int) getpid(), replslotname, NAMEDATALEN);
 
 		/* Create replication slot on publisher. */
-		if (create_logical_replication_slot(conn, &dbinfo[i], replslotname) != NULL || dry_run)
-			pg_log_info("create replication slot \"%s\" on publisher", replslotname);
-		else
+		if (create_logical_replication_slot(conn, false, perdb) == NULL && !dry_run)
 			return false;
 
 		disconnect_database(conn);
@@ -701,30 +691,36 @@ create_all_logical_replication_slots(LogicalRepInfo *dbinfo)
  * result set that contains the consistent LSN.
  */
 static char *
-create_logical_replication_slot(PGconn *conn, LogicalRepInfo *dbinfo,
-								char *slot_name)
+create_logical_replication_slot(PGconn *conn, bool temporary,
+								LogicalRepPerdbInfo *perdb)
 {
 	PQExpBuffer str = createPQExpBuffer();
 	PGresult   *res = NULL;
 	char	   *lsn = NULL;
-	bool		transient_replslot = false;
+	char		slot_name[NAMEDATALEN];
 
 	Assert(conn != NULL);
 
 	/*
-	 * If no slot name is informed, it is a transient replication slot used
-	 * only for catch up purposes.
+	 * Construct a name of logical replication slot. The formatting is
+	 * different depends on its persistency.
+	 *
+	 * For persistent slots: the name must be same as the subscription.
+	 * For temporary slots: OID is not needed, but another string is added.
 	 */
-	if (slot_name[0] == '\0')
-	{
+	if (!temporary)
+		get_subscription_name(perdb->oid, (int) getpid(), slot_name, NAMEDATALEN);
+	else
 		snprintf(slot_name, NAMEDATALEN, "pg_subscriber_%d_startpoint",
 				 (int) getpid());
-		transient_replslot = true;
-	}
 
-	pg_log_info("creating the replication slot \"%s\" on database \"%s\"", slot_name, dbinfo->dbname);
+	pg_log_info("creating the replication slot \"%s\" on database \"%s\"", slot_name, perdb->dbname);
 
 	appendPQExpBuffer(str, "CREATE_REPLICATION_SLOT \"%s\"", slot_name);
+
+	if(temporary)
+		appendPQExpBufferStr(str, " TEMPORARY");
+
 	appendPQExpBufferStr(str, " LOGICAL \"pgoutput\" NOEXPORT_SNAPSHOT");
 
 	pg_log_debug("command is: %s", str->data);
@@ -734,17 +730,14 @@ create_logical_replication_slot(PGconn *conn, LogicalRepInfo *dbinfo,
 		res = PQexec(conn, str->data);
 		if (PQresultStatus(res) != PGRES_TUPLES_OK)
 		{
-			pg_log_error("could not create replication slot \"%s\" on database \"%s\": %s", slot_name, dbinfo->dbname,
-						 PQresultErrorMessage(res));
+			pg_log_error("could not create replication slot \"%s\" on database \"%s\": %s",
+						 slot_name, perdb->dbname, PQresultErrorMessage(res));
 			return lsn;
 		}
 	}
 
 	/* for cleanup purposes */
-	if (transient_replslot)
-		made_transient_replslot = true;
-	else
-		dbinfo->made_replslot = true;
+	perdb->made_replslot = true;
 
 	if (!dry_run)
 	{
@@ -758,14 +751,15 @@ create_logical_replication_slot(PGconn *conn, LogicalRepInfo *dbinfo,
 }
 
 static void
-drop_replication_slot(PGconn *conn, LogicalRepInfo *dbinfo, const char *slot_name)
+drop_replication_slot(PGconn *conn, LogicalRepPerdbInfo *perdb,
+					  const char *slot_name)
 {
 	PQExpBuffer str = createPQExpBuffer();
 	PGresult   *res;
 
 	Assert(conn != NULL);
 
-	pg_log_info("dropping the replication slot \"%s\" on database \"%s\"", slot_name, dbinfo->dbname);
+	pg_log_info("dropping the replication slot \"%s\" on database \"%s\"", slot_name, perdb->dbname);
 
 	appendPQExpBuffer(str, "DROP_REPLICATION_SLOT \"%s\"", slot_name);
 
@@ -775,7 +769,7 @@ drop_replication_slot(PGconn *conn, LogicalRepInfo *dbinfo, const char *slot_nam
 	{
 		res = PQexec(conn, str->data);
 		if (PQresultStatus(res) != PGRES_COMMAND_OK)
-			pg_log_error("could not drop replication slot \"%s\" on database \"%s\": %s", slot_name, dbinfo->dbname,
+			pg_log_error("could not drop replication slot \"%s\" on database \"%s\": %s", slot_name, perdb->dbname,
 						 PQerrorMessage(conn));
 
 		PQclear(res);
@@ -825,19 +819,22 @@ pg_ctl_status(const char *pg_ctl_cmd, int rc, int action)
  * Returns after the server finishes the recovery process.
  */
 static void
-wait_for_end_recovery(const char *conninfo)
+wait_for_end_recovery(const char *base_conninfo, const char *dbname)
 {
 	PGconn	   *conn;
 	PGresult   *res;
-	int			status = POSTMASTER_STILL_STARTING;
+	int			status = PGS_POSTMASTER_STILL_STARTING;
+	int			cnt;
+	int			rc;
+	char	   *pg_ctl_cmd;
 
 	pg_log_info("waiting the postmaster to reach the consistent state");
 
-	conn = connect_database(conninfo);
+	conn = connect_database(base_conninfo, dbname);
 	if (conn == NULL)
 		exit(1);
 
-	for (;;)
+	for (cnt = 0; cnt < wait_seconds * WAITS_PER_SEC; cnt++)
 	{
 		bool		in_recovery;
 
@@ -865,17 +862,32 @@ wait_for_end_recovery(const char *conninfo)
 		 */
 		if (!in_recovery || dry_run)
 		{
-			status = POSTMASTER_READY;
+			status = PGS_POSTMASTER_READY;
 			break;
 		}
 
 		/* Keep waiting. */
-		pg_usleep(WAIT_INTERVAL * USEC_PER_SEC);
+		pg_usleep(USEC_PER_SEC / WAITS_PER_SEC);
 	}
 
 	disconnect_database(conn);
 
-	if (status == POSTMASTER_STILL_STARTING)
+	/*
+	 * If timeout is reached exit the pg_subscriber and stop the standby node.
+	 */
+	if (cnt >= wait_seconds * WAITS_PER_SEC)
+	{
+		pg_log_error("recovery timed out");
+
+		pg_ctl_cmd = psprintf("\"%s/pg_ctl\" stop -D \"%s\" -s",
+							  standby.bindir, standby.pgdata);
+		rc = system(pg_ctl_cmd);
+		pg_ctl_status(pg_ctl_cmd, rc, 0);
+
+		exit(1);
+	}
+
+	if (status == PGS_POSTMASTER_STILL_STARTING)
 	{
 		pg_log_error("server did not end recovery");
 		exit(1);
@@ -888,17 +900,21 @@ wait_for_end_recovery(const char *conninfo)
  * Create a publication that includes all tables in the database.
  */
 static void
-create_publication(PGconn *conn, LogicalRepInfo *dbinfo)
+create_publication(PGconn *conn, PrimaryInfo *primary,
+				   LogicalRepPerdbInfo *perdb)
 {
 	PQExpBuffer str = createPQExpBuffer();
 	PGresult   *res;
+	char		pubname[NAMEDATALEN];
 
 	Assert(conn != NULL);
 
+	get_publication_name(perdb->oid, pubname, NAMEDATALEN);
+
 	/* Check if the publication needs to be created. */
 	appendPQExpBuffer(str,
 					  "SELECT puballtables FROM pg_catalog.pg_publication WHERE pubname = '%s'",
-					  dbinfo->pubname);
+					  pubname);
 	res = PQexec(conn, str->data);
 	if (PQresultStatus(res) != PGRES_TUPLES_OK)
 	{
@@ -918,7 +934,7 @@ create_publication(PGconn *conn, LogicalRepInfo *dbinfo)
 		 */
 		if (strcmp(PQgetvalue(res, 0, 0), "t") == 0)
 		{
-			pg_log_info("publication \"%s\" already exists", dbinfo->pubname);
+			pg_log_info("publication \"%s\" already exists", pubname);
 			return;
 		}
 		else
@@ -931,7 +947,7 @@ create_publication(PGconn *conn, LogicalRepInfo *dbinfo)
 			 * database oid in which puballtables is false.
 			 */
 			pg_log_error("publication \"%s\" does not replicate changes for all tables",
-						 dbinfo->pubname);
+						 pubname);
 			pg_log_error_hint("Consider renaming this publication.");
 			PQclear(res);
 			PQfinish(conn);
@@ -942,9 +958,9 @@ create_publication(PGconn *conn, LogicalRepInfo *dbinfo)
 	PQclear(res);
 	resetPQExpBuffer(str);
 
-	pg_log_info("creating publication \"%s\" on database \"%s\"", dbinfo->pubname, dbinfo->dbname);
+	pg_log_info("creating publication \"%s\" on database \"%s\"", pubname, perdb->dbname);
 
-	appendPQExpBuffer(str, "CREATE PUBLICATION %s FOR ALL TABLES", dbinfo->pubname);
+	appendPQExpBuffer(str, "CREATE PUBLICATION %s FOR ALL TABLES", pubname);
 
 	pg_log_debug("command is: %s", str->data);
 
@@ -954,14 +970,14 @@ create_publication(PGconn *conn, LogicalRepInfo *dbinfo)
 		if (PQresultStatus(res) != PGRES_COMMAND_OK)
 		{
 			pg_log_error("could not create publication \"%s\" on database \"%s\": %s",
-						 dbinfo->pubname, dbinfo->dbname, PQerrorMessage(conn));
+						 pubname, perdb->dbname, PQerrorMessage(conn));
 			PQfinish(conn);
 			exit(1);
 		}
 	}
 
 	/* for cleanup purposes */
-	dbinfo->made_publication = true;
+	perdb->made_publication = true;
 
 	if (!dry_run)
 		PQclear(res);
@@ -973,16 +989,19 @@ create_publication(PGconn *conn, LogicalRepInfo *dbinfo)
  * Remove publication if it couldn't finish all steps.
  */
 static void
-drop_publication(PGconn *conn, LogicalRepInfo *dbinfo)
+drop_publication(PGconn *conn, LogicalRepPerdbInfo *perdb)
 {
 	PQExpBuffer str = createPQExpBuffer();
 	PGresult   *res;
+	char		pubname[NAMEDATALEN];
 
 	Assert(conn != NULL);
 
-	pg_log_info("dropping publication \"%s\" on database \"%s\"", dbinfo->pubname, dbinfo->dbname);
+	get_publication_name(perdb->oid, pubname, NAMEDATALEN);
+
+	pg_log_info("dropping publication \"%s\" on database \"%s\"", pubname, perdb->dbname);
 
-	appendPQExpBuffer(str, "DROP PUBLICATION %s", dbinfo->pubname);
+	appendPQExpBuffer(str, "DROP PUBLICATION %s", pubname);
 
 	pg_log_debug("command is: %s", str->data);
 
@@ -990,7 +1009,7 @@ drop_publication(PGconn *conn, LogicalRepInfo *dbinfo)
 	{
 		res = PQexec(conn, str->data);
 		if (PQresultStatus(res) != PGRES_COMMAND_OK)
-			pg_log_error("could not drop publication \"%s\" on database \"%s\": %s", dbinfo->pubname, dbinfo->dbname, PQerrorMessage(conn));
+			pg_log_error("could not drop publication \"%s\" on database \"%s\": %s", pubname, perdb->dbname, PQerrorMessage(conn));
 
 		PQclear(res);
 	}
@@ -1011,19 +1030,27 @@ drop_publication(PGconn *conn, LogicalRepInfo *dbinfo)
  * initial location.
  */
 static void
-create_subscription(PGconn *conn, LogicalRepInfo *dbinfo)
+create_subscription(PGconn *conn, StandbyInfo *standby, char *base_conninfo,
+					LogicalRepPerdbInfo *perdb)
 {
 	PQExpBuffer str = createPQExpBuffer();
 	PGresult   *res;
+	char		subname[NAMEDATALEN];
+	char		pubname[NAMEDATALEN];
 
 	Assert(conn != NULL);
 
-	pg_log_info("creating subscription \"%s\" on database \"%s\"", dbinfo->subname, dbinfo->dbname);
+
+	get_subscription_name(perdb->oid, (int) getpid(), subname, NAMEDATALEN);
+	get_publication_name(perdb->oid, pubname, NAMEDATALEN);
+
+	pg_log_info("creating subscription \"%s\" on database \"%s\"", subname,
+				perdb->dbname);
 
 	appendPQExpBuffer(str,
 					  "CREATE SUBSCRIPTION %s CONNECTION '%s' PUBLICATION %s "
 					  "WITH (create_slot = false, copy_data = false, enabled = false)",
-					  dbinfo->subname, dbinfo->pubconninfo, dbinfo->pubname);
+					  subname, concat_conninfo_dbname(base_conninfo, perdb->dbname), pubname);
 
 	pg_log_debug("command is: %s", str->data);
 
@@ -1033,14 +1060,14 @@ create_subscription(PGconn *conn, LogicalRepInfo *dbinfo)
 		if (PQresultStatus(res) != PGRES_COMMAND_OK)
 		{
 			pg_log_error("could not create subscription \"%s\" on database \"%s\": %s",
-						 dbinfo->subname, dbinfo->dbname, PQerrorMessage(conn));
+						 subname, perdb->dbname, PQerrorMessage(conn));
 			PQfinish(conn);
 			exit(1);
 		}
 	}
 
 	/* for cleanup purposes */
-	dbinfo->made_subscription = true;
+	perdb->made_subscription = true;
 
 	if (!dry_run)
 		PQclear(res);
@@ -1052,16 +1079,19 @@ create_subscription(PGconn *conn, LogicalRepInfo *dbinfo)
  * Remove subscription if it couldn't finish all steps.
  */
 static void
-drop_subscription(PGconn *conn, LogicalRepInfo *dbinfo)
+drop_subscription(PGconn *conn, LogicalRepPerdbInfo *perdb)
 {
 	PQExpBuffer str = createPQExpBuffer();
 	PGresult   *res;
+	char		subname[NAMEDATALEN];
 
 	Assert(conn != NULL);
 
-	pg_log_info("dropping subscription \"%s\" on database \"%s\"", dbinfo->subname, dbinfo->dbname);
+	get_subscription_name(perdb->oid, (int) getpid(), subname, NAMEDATALEN);
 
-	appendPQExpBuffer(str, "DROP SUBSCRIPTION %s", dbinfo->subname);
+	pg_log_info("dropping subscription \"%s\" on database \"%s\"", subname, perdb->dbname);
+
+	appendPQExpBuffer(str, "DROP SUBSCRIPTION %s", subname);
 
 	pg_log_debug("command is: %s", str->data);
 
@@ -1069,7 +1099,7 @@ drop_subscription(PGconn *conn, LogicalRepInfo *dbinfo)
 	{
 		res = PQexec(conn, str->data);
 		if (PQresultStatus(res) != PGRES_COMMAND_OK)
-			pg_log_error("could not drop subscription \"%s\" on database \"%s\": %s", dbinfo->subname, dbinfo->dbname, PQerrorMessage(conn));
+			pg_log_error("could not drop subscription \"%s\" on database \"%s\": %s", subname, perdb->dbname, PQerrorMessage(conn));
 
 		PQclear(res);
 	}
@@ -1088,18 +1118,21 @@ drop_subscription(PGconn *conn, LogicalRepInfo *dbinfo)
  * printing purposes.
  */
 static void
-set_replication_progress(PGconn *conn, LogicalRepInfo *dbinfo, const char *lsn)
+set_replication_progress(PGconn *conn, LogicalRepPerdbInfo *perdb, const char *lsn)
 {
 	PQExpBuffer str = createPQExpBuffer();
 	PGresult   *res;
 	Oid			suboid;
 	char		originname[NAMEDATALEN];
 	char		lsnstr[17 + 1]; /* MAXPG_LSNLEN = 17 */
+	char		subname[NAMEDATALEN];
 
 	Assert(conn != NULL);
 
+	get_subscription_name(perdb->oid, (int) getpid(), subname, NAMEDATALEN);
+
 	appendPQExpBuffer(str,
-					  "SELECT oid FROM pg_catalog.pg_subscription WHERE subname = '%s'", dbinfo->subname);
+					  "SELECT oid FROM pg_catalog.pg_subscription WHERE subname = '%s'", subname);
 
 	res = PQexec(conn, str->data);
 	if (PQresultStatus(res) != PGRES_TUPLES_OK)
@@ -1140,7 +1173,7 @@ set_replication_progress(PGconn *conn, LogicalRepInfo *dbinfo, const char *lsn)
 	PQclear(res);
 
 	pg_log_info("setting the replication progress (node name \"%s\" ; LSN %s) on database \"%s\"",
-				originname, lsnstr, dbinfo->dbname);
+				originname, lsnstr, perdb->dbname);
 
 	resetPQExpBuffer(str);
 	appendPQExpBuffer(str,
@@ -1154,7 +1187,7 @@ set_replication_progress(PGconn *conn, LogicalRepInfo *dbinfo, const char *lsn)
 		if (PQresultStatus(res) != PGRES_TUPLES_OK)
 		{
 			pg_log_error("could not set replication progress for the subscription \"%s\": %s",
-						 dbinfo->subname, PQresultErrorMessage(res));
+						 subname, PQresultErrorMessage(res));
 			PQfinish(conn);
 			exit(1);
 		}
@@ -1173,16 +1206,20 @@ set_replication_progress(PGconn *conn, LogicalRepInfo *dbinfo, const char *lsn)
  * of this setup.
  */
 static void
-enable_subscription(PGconn *conn, LogicalRepInfo *dbinfo)
+enable_subscription(PGconn *conn, LogicalRepPerdbInfo *perdb)
 {
 	PQExpBuffer str = createPQExpBuffer();
 	PGresult   *res;
+	char		subname[NAMEDATALEN];
 
 	Assert(conn != NULL);
 
-	pg_log_info("enabling subscription \"%s\" on database \"%s\"", dbinfo->subname, dbinfo->dbname);
+	get_subscription_name(perdb->oid, (int) getpid(), subname, NAMEDATALEN);
 
-	appendPQExpBuffer(str, "ALTER SUBSCRIPTION %s ENABLE", dbinfo->subname);
+	pg_log_info("enabling subscription \"%s\" on database \"%s\"", subname,
+				perdb->dbname);
+
+	appendPQExpBuffer(str, "ALTER SUBSCRIPTION %s ENABLE", subname);
 
 	pg_log_debug("command is: %s", str->data);
 
@@ -1191,7 +1228,7 @@ enable_subscription(PGconn *conn, LogicalRepInfo *dbinfo)
 		res = PQexec(conn, str->data);
 		if (PQresultStatus(res) != PGRES_COMMAND_OK)
 		{
-			pg_log_error("could not enable subscription \"%s\": %s", dbinfo->subname,
+			pg_log_error("could not enable subscription \"%s\": %s", subname,
 						 PQerrorMessage(conn));
 			PQfinish(conn);
 			exit(1);
@@ -1203,6 +1240,61 @@ enable_subscription(PGconn *conn, LogicalRepInfo *dbinfo)
 	destroyPQExpBuffer(str);
 }
 
+static void
+start_standby_server(StandbyInfo *standby, unsigned short subport,
+					 char *server_start_log)
+{
+	char		timebuf[128];
+	struct timeval time;
+	time_t		tt;
+	int			len;
+	int			rc;
+	char	   *pg_ctl_cmd;
+
+	if (server_start_log[0] == '\0')
+	{
+		/* append timestamp with ISO 8601 format. */
+		gettimeofday(&time, NULL);
+		tt = (time_t) time.tv_sec;
+		strftime(timebuf, sizeof(timebuf), "%Y%m%dT%H%M%S", localtime(&tt));
+		snprintf(timebuf + strlen(timebuf), sizeof(timebuf) - strlen(timebuf),
+				 ".%03d", (int) (time.tv_usec / 1000));
+
+		len = snprintf(server_start_log, MAXPGPATH,
+					   "%s/%s/server_start_%s.log", standby->pgdata,
+					   PGS_OUTPUT_DIR, timebuf);
+		if (len >= MAXPGPATH)
+		{
+			pg_log_error("log file path is too long");
+			exit(1);
+		}
+	}
+	pg_ctl_cmd = psprintf("\"%s/pg_ctl\" start -D \"%s\" -s -o \"-p %d\" -l \"%s\"",
+						  standby->bindir,
+						  standby->pgdata, subport, server_start_log);
+	rc = system(pg_ctl_cmd);
+	pg_ctl_status(pg_ctl_cmd, rc, 1);
+}
+
+static char *
+construct_sub_conninfo(char *username, unsigned short subport)
+{
+	PQExpBuffer buf = createPQExpBuffer();
+	char	   *ret;
+
+	if (username)
+		appendPQExpBuffer(buf, "user=%s ", username);
+
+	appendPQExpBuffer(buf, "port=%d fallback_application_name=%s",
+					  subport, progname);
+
+	ret = pg_strdup(buf->data);
+
+	destroyPQExpBuffer(buf);
+
+	return ret;
+}
+
 int
 main(int argc, char **argv)
 {
@@ -1214,6 +1306,10 @@ main(int argc, char **argv)
 		{"publisher-conninfo", required_argument, NULL, 'P'},
 		{"subscriber-conninfo", required_argument, NULL, 'S'},
 		{"database", required_argument, NULL, 'd'},
+		{"timeout", required_argument, NULL, 't'},
+		{"username", required_argument, NULL, 'u'},
+		{"port", required_argument, NULL, 'p'},
+		{"retain", no_argument, NULL, 'r'},
 		{"dry-run", no_argument, NULL, 'n'},
 		{"verbose", no_argument, NULL, 'v'},
 		{NULL, 0, NULL, 0}
@@ -1225,20 +1321,15 @@ main(int argc, char **argv)
 
 	char	   *pg_ctl_cmd;
 
-	char	   *base_dir;
-	char	   *server_start_log;
-
-	char		timebuf[128];
-	struct timeval time;
-	time_t		tt;
+	char		base_dir[MAXPGPATH];
+	char		server_start_log[MAXPGPATH] = {0};
 	int			len;
 
-	char	   *pub_base_conninfo = NULL;
-	char	   *sub_base_conninfo = NULL;
 	char	   *dbname_conninfo = NULL;
 
-	uint64		pub_sysid;
-	uint64		sub_sysid;
+	unsigned short subport = DEF_PGSPORT;
+	char	   *username = NULL;
+
 	struct stat statbuf;
 
 	PGconn	   *conn;
@@ -1250,6 +1341,13 @@ main(int argc, char **argv)
 
 	int			i;
 
+	PGresult   *res;
+
+	char	   *wal_level;
+	int			max_replication_slots;
+	int			nslots_old;
+	int			nslots_new;
+
 	pg_logging_init(argv[0]);
 	pg_logging_set_level(PG_LOG_WARNING);
 	progname = get_progname(argv[0]);
@@ -1286,28 +1384,40 @@ main(int argc, char **argv)
 	}
 #endif
 
-	while ((c = getopt_long(argc, argv, "D:P:S:d:nv",
+	while ((c = getopt_long(argc, argv, "D:P:S:d:t:u:p:rnv",
 							long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
 			case 'D':
-				subscriber_dir = pg_strdup(optarg);
+				standby.pgdata = pg_strdup(optarg);
+				canonicalize_path(standby.pgdata);
 				break;
 			case 'P':
 				pub_conninfo_str = pg_strdup(optarg);
 				break;
-			case 'S':
-				sub_conninfo_str = pg_strdup(optarg);
-				break;
 			case 'd':
 				/* Ignore duplicated database names. */
 				if (!simple_string_list_member(&database_names, optarg))
 				{
 					simple_string_list_append(&database_names, optarg);
-					num_dbs++;
+					dbarr.ndbs++;
 				}
 				break;
+			case 't':
+				wait_seconds = atoi(optarg);
+				break;
+			case 'u':
+				pfree(username);
+				username = pg_strdup(optarg);
+				break;
+			case 'p':
+				if ((subport = atoi(optarg)) <= 0)
+					pg_fatal("invalid old port number");
+				break;
+			case 'r':
+				retain = true;
+				break;
 			case 'n':
 				dry_run = true;
 				break;
@@ -1335,7 +1445,7 @@ main(int argc, char **argv)
 	/*
 	 * Required arguments
 	 */
-	if (subscriber_dir == NULL)
+	if (standby.pgdata == NULL)
 	{
 		pg_log_error("no subscriber data directory specified");
 		pg_log_error_hint("Try \"%s --help\" for more information.", progname);
@@ -1358,21 +1468,14 @@ main(int argc, char **argv)
 		pg_log_error_hint("Try \"%s --help\" for more information.", progname);
 		exit(1);
 	}
-	pub_base_conninfo = get_base_conninfo(pub_conninfo_str, dbname_conninfo,
-										  "publisher");
-	if (pub_base_conninfo == NULL)
-		exit(1);
 
-	if (sub_conninfo_str == NULL)
-	{
-		pg_log_error("no subscriber connection string specified");
-		pg_log_error_hint("Try \"%s --help\" for more information.", progname);
-		exit(1);
-	}
-	sub_base_conninfo = get_base_conninfo(sub_conninfo_str, NULL, "subscriber");
-	if (sub_base_conninfo == NULL)
+	primary.base_conninfo = get_base_conninfo(pub_conninfo_str,
+											  dbname_conninfo);
+	if (primary.base_conninfo == NULL)
 		exit(1);
 
+	standby.base_conninfo = construct_sub_conninfo(username, subport);
+
 	if (database_names.head == NULL)
 	{
 		pg_log_info("no database was specified");
@@ -1385,7 +1488,7 @@ main(int argc, char **argv)
 		if (dbname_conninfo)
 		{
 			simple_string_list_append(&database_names, dbname_conninfo);
-			num_dbs++;
+			dbarr.ndbs++;
 
 			pg_log_info("database \"%s\" was extracted from the publisher connection string",
 						dbname_conninfo);
@@ -1399,25 +1502,25 @@ main(int argc, char **argv)
 	}
 
 	/*
-	 * Get the absolute path of pg_ctl and pg_resetwal on the subscriber.
+	 * Get the absolute path of binaries on the subscriber.
 	 */
-	if (!get_exec_path(argv[0]))
+	if (!get_exec_base_path(argv[0]))
 		exit(1);
 
 	/* rudimentary check for a data directory. */
-	if (!check_data_directory(subscriber_dir))
+	if (!check_data_directory(standby.pgdata))
 		exit(1);
 
-	/* Store database information for publisher and subscriber. */
-	dbinfo = store_pub_sub_info(pub_base_conninfo, sub_base_conninfo);
+	/* Store database information to dbarr */
+	store_db_names(&dbarr.perdb, dbarr.ndbs);
 
 	/*
 	 * Check if the subscriber data directory has the same system identifier
 	 * than the publisher data directory.
 	 */
-	pub_sysid = get_sysid_from_conn(dbinfo[0].pubconninfo);
-	sub_sysid = get_control_from_datadir(subscriber_dir);
-	if (pub_sysid != sub_sysid)
+	get_sysid_for_primary(&primary, dbarr.perdb[0].dbname);
+	get_control_for_standby(&standby);
+	if (primary.sysid != standby.sysid)
 	{
 		pg_log_error("subscriber data directory is not a copy of the source database cluster");
 		exit(1);
@@ -1426,8 +1529,8 @@ main(int argc, char **argv)
 	/*
 	 * Create the output directory to store any data generated by this tool.
 	 */
-	base_dir = (char *) pg_malloc0(MAXPGPATH);
-	len = snprintf(base_dir, MAXPGPATH, "%s/%s", subscriber_dir, PGS_OUTPUT_DIR);
+	len = snprintf(base_dir, MAXPGPATH, "%s/%s",
+				   standby.pgdata, PGS_OUTPUT_DIR);
 	if (len >= MAXPGPATH)
 	{
 		pg_log_error("directory path for subscriber is too long");
@@ -1441,7 +1544,153 @@ main(int argc, char **argv)
 	}
 
 	/* subscriber PID file. */
-	snprintf(pidfile, MAXPGPATH, "%s/postmaster.pid", subscriber_dir);
+	snprintf(pidfile, MAXPGPATH, "%s/postmaster.pid",
+			  standby.pgdata);
+
+	/* Start the standby server anyway */
+	start_standby_server(&standby, subport, server_start_log);
+
+	/*
+	 * Check wal_level in publisher and the max_replication_slots of publisher
+	 */
+	conn = connect_database(primary.base_conninfo, dbarr.perdb[0].dbname);
+	if (conn == NULL)
+		exit(1);
+
+	res = PQexec(conn, "SELECT count(*) from pg_replication_slots;");
+
+	if (PQresultStatus(res) != PGRES_TUPLES_OK)
+	{
+		pg_log_error("could not obtain number of replication slots");
+		exit(1);
+	}
+
+	if (PQntuples(res) != 1)
+	{
+		pg_log_error("could not determine parameter settings on publisher");
+		exit(1);
+	}
+
+	nslots_old = atoi(PQgetvalue(res, 0, 0));
+	PQclear(res);
+
+	res = PQexec(conn, "SELECT setting FROM pg_settings "
+				 "WHERE name IN ('wal_level', 'max_replication_slots') "
+				 "ORDER BY name DESC;");
+
+	if (PQresultStatus(res) != PGRES_TUPLES_OK)
+	{
+		pg_log_error("could not obtain guc parameters on publisher");
+		exit(1);
+	}
+
+	if (PQntuples(res) != 2)
+	{
+		pg_log_error("could not determine parameter settings on publisher");
+		exit(1);
+	}
+
+	wal_level = PQgetvalue(res, 0, 0);
+
+	if (strcmp(wal_level, "logical") != 0)
+	{
+		pg_log_error("wal_level must be \"logical\", but is set to \"%s\"", wal_level);
+		exit(1);
+	}
+
+	max_replication_slots = atoi(PQgetvalue(res, 1, 0));
+	nslots_new = nslots_old + dbarr.ndbs + 1;
+
+	if (nslots_new > max_replication_slots)
+	{
+		pg_log_error("max_replication_slots (%d) must be greater than or equal to "
+					 "the number of replication slots required (%d)", max_replication_slots, nslots_new);
+		exit(1);
+	}
+
+	PQclear(res);
+	disconnect_database(conn);
+
+	conn = connect_database(standby.base_conninfo, dbarr.perdb[0].dbname);
+	if (conn == NULL)
+		exit(1);
+
+	/*
+	 * Check the max_replication_slots in subscriber
+	 */
+	res = PQexec(conn, "SELECT count(*) from pg_replication_slots;");
+
+	if (PQresultStatus(res) != PGRES_TUPLES_OK)
+	{
+		pg_log_error("could not obtain number of replication slots on subscriber");
+		exit(1);
+	}
+
+	if (PQntuples(res) != 1)
+	{
+		pg_log_error("could not determine parameter settings on subscriber");
+		exit(1);
+	}
+
+	nslots_old = atoi(PQgetvalue(res, 0, 0));
+	PQclear(res);
+
+	res = PQexec(conn, "SELECT setting FROM pg_settings "
+				 "WHERE name = 'max_replication_slots';");
+
+	if (PQresultStatus(res) != PGRES_TUPLES_OK)
+	{
+		pg_log_error("could not obtain guc parameters");
+		exit(1);
+	}
+
+	if (PQntuples(res) != 1)
+	{
+		pg_log_error("could not determine parameter settings on publisher");
+		exit(1);
+	}
+
+	max_replication_slots = atoi(PQgetvalue(res, 0, 0));
+	nslots_new = nslots_old + dbarr.ndbs;
+
+	if (nslots_new > max_replication_slots)
+	{
+		pg_log_error("max_replication_slots (%d) must be greater than or equal to "
+					 "the number of replication slots required (%d)", max_replication_slots, nslots_new);
+		exit(1);
+	}
+
+	PQclear(res);
+
+	/*
+	 * Exit the pg_subscriber if the node is not a standby server.
+	 */
+	res = PQexec(conn, "SELECT pg_catalog.pg_is_in_recovery()");
+
+	if (PQresultStatus(res) != PGRES_TUPLES_OK)
+	{
+		pg_log_error("could not obtain recovery progress");
+		exit(1);
+	}
+
+	if (PQntuples(res) != 1)
+	{
+		pg_log_error("unexpected result from pg_is_in_recovery function");
+		exit(1);
+	}
+
+	/* Check if the server is in recovery */
+	if (strcmp(PQgetvalue(res, 0, 0), "t") != 0)
+	{
+		pg_log_error("pg_subscriber is supported only on standby server");
+		exit(1);
+	}
+
+	PQclear(res);
+	disconnect_database(conn);
+
+	/* subscriber PID file. */
+	snprintf(pidfile, MAXPGPATH, "%s/postmaster.pid", standby.pgdata);
 
 	/*
 	 * Stop the subscriber if it is a standby server. Before executing the
@@ -1457,14 +1706,18 @@ main(int argc, char **argv)
 		 * replication slot has no use after the transformation, hence, it
 		 * will be removed at the end of this process.
 		 */
-		primary_slot_name = use_primary_slot_name();
-		if (primary_slot_name != NULL)
-			pg_log_info("primary has replication slot \"%s\"", primary_slot_name);
+		standby.primary_slot_name = use_primary_slot_name(&primary,
+														   &standby,
+														   &dbarr.perdb[0]);
+		if (standby.primary_slot_name != NULL)
+			pg_log_info("primary has replication slot \"%s\"",
+						standby.primary_slot_name);
 
 		pg_log_info("subscriber is up and running");
 		pg_log_info("stopping the server to start the transformation steps");
 
-		pg_ctl_cmd = psprintf("\"%s\" stop -D \"%s\" -s", pg_ctl_path, subscriber_dir);
+		pg_ctl_cmd = psprintf("\"%s/pg_ctl\" stop -D \"%s\" -s",
+							  standby.bindir, standby.pgdata);
 		rc = system(pg_ctl_cmd);
 		pg_ctl_status(pg_ctl_cmd, rc, 0);
 	}
@@ -1472,7 +1725,7 @@ main(int argc, char **argv)
 	/*
 	 * Create a replication slot for each database on the publisher.
 	 */
-	if (!create_all_logical_replication_slots(dbinfo))
+	if (!create_all_logical_replication_slots(&primary, &dbarr))
 		exit(1);
 
 	/*
@@ -1492,11 +1745,11 @@ main(int argc, char **argv)
 	 * replication connection open (depending when base backup was taken, the
 	 * connection should be open for a few hours).
 	 */
-	conn = connect_database(dbinfo[0].pubconninfo);
+	conn = connect_database(primary.base_conninfo, dbarr.perdb[0].dbname);
 	if (conn == NULL)
 		exit(1);
-	consistent_lsn = create_logical_replication_slot(conn, &dbinfo[0],
-													 temp_replslot);
+	consistent_lsn = create_logical_replication_slot(conn, true,
+													 &dbarr.perdb[0]);
 
 	/*
 	 * Write recovery parameters.
@@ -1522,7 +1775,7 @@ main(int argc, char **argv)
 	{
 		appendPQExpBuffer(recoveryconfcontents, "recovery_target_lsn = '%s'\n",
 						  consistent_lsn);
-		WriteRecoveryConfig(conn, subscriber_dir, recoveryconfcontents);
+		WriteRecoveryConfig(conn, standby.pgdata, recoveryconfcontents);
 	}
 	disconnect_database(conn);
 
@@ -1532,54 +1785,29 @@ main(int argc, char **argv)
 	 * Start subscriber and wait until accepting connections.
 	 */
 	pg_log_info("starting the subscriber");
-
-	/* append timestamp with ISO 8601 format. */
-	gettimeofday(&time, NULL);
-	tt = (time_t) time.tv_sec;
-	strftime(timebuf, sizeof(timebuf), "%Y%m%dT%H%M%S", localtime(&tt));
-	snprintf(timebuf + strlen(timebuf), sizeof(timebuf) - strlen(timebuf),
-			 ".%03d", (int) (time.tv_usec / 1000));
-
-	server_start_log = (char *) pg_malloc0(MAXPGPATH);
-	len = snprintf(server_start_log, MAXPGPATH, "%s/%s/server_start_%s.log", subscriber_dir, PGS_OUTPUT_DIR, timebuf);
-	if (len >= MAXPGPATH)
-	{
-		pg_log_error("log file path is too long");
-		exit(1);
-	}
-
-	pg_ctl_cmd = psprintf("\"%s\" start -D \"%s\" -s -l \"%s\"", pg_ctl_path, subscriber_dir, server_start_log);
-	rc = system(pg_ctl_cmd);
-	pg_ctl_status(pg_ctl_cmd, rc, 1);
+	start_standby_server(&standby, subport, server_start_log);
 
 	/*
 	 * Waiting the subscriber to be promoted.
 	 */
-	wait_for_end_recovery(dbinfo[0].subconninfo);
+	wait_for_end_recovery(standby.base_conninfo, dbarr.perdb[0].dbname);
 
 	/*
 	 * Create a publication for each database. This step should be executed
 	 * after promoting the subscriber to avoid replicating unnecessary
 	 * objects.
 	 */
-	for (i = 0; i < num_dbs; i++)
+	for (i = 0; i < dbarr.ndbs; i++)
 	{
-		char		pubname[NAMEDATALEN];
+		LogicalRepPerdbInfo *perdb = &dbarr.perdb[i];
 
 		/* Connect to publisher. */
-		conn = connect_database(dbinfo[i].pubconninfo);
+		conn = connect_database(primary.base_conninfo, perdb->dbname);
 		if (conn == NULL)
 			exit(1);
 
-		/*
-		 * Build the publication name. The name must not exceed NAMEDATALEN -
-		 * 1. This current schema uses a maximum of 35 characters (14 + 10 +
-		 * '\0').
-		 */
-		snprintf(pubname, sizeof(pubname), "pg_subscriber_%u", dbinfo[i].oid);
-		dbinfo[i].pubname = pg_strdup(pubname);
-
-		create_publication(conn, &dbinfo[i]);
+		/* Also create a publication */
+		create_publication(conn, &primary, perdb);
 
 		disconnect_database(conn);
 	}
@@ -1587,20 +1815,25 @@ main(int argc, char **argv)
 	/*
 	 * Create a subscription for each database.
 	 */
-	for (i = 0; i < num_dbs; i++)
+	for (i = 0; i < dbarr.ndbs; i++)
 	{
+		LogicalRepPerdbInfo *perdb = &dbarr.perdb[i];
+
 		/* Connect to subscriber. */
-		conn = connect_database(dbinfo[i].subconninfo);
+		conn = connect_database(standby.base_conninfo, perdb->dbname);
+
 		if (conn == NULL)
 			exit(1);
 
-		create_subscription(conn, &dbinfo[i]);
+		create_subscription(conn, &standby, primary.base_conninfo, perdb);
 
 		/* Set the replication progress to the correct LSN. */
-		set_replication_progress(conn, &dbinfo[i], consistent_lsn);
+		set_replication_progress(conn, perdb, consistent_lsn);
 
 		/* Enable subscription. */
-		enable_subscription(conn, &dbinfo[i]);
+		enable_subscription(conn, perdb);
+
+		drop_publication(conn, perdb);
 
 		disconnect_database(conn);
 	}
@@ -1613,19 +1846,21 @@ main(int argc, char **argv)
 	 * XXX we might not fail here. Instead, we provide a warning so the user
 	 * eventually drops the replication slot later.
 	 */
-	conn = connect_database(dbinfo[0].pubconninfo);
+	conn = connect_database(primary.base_conninfo, dbarr.perdb[0].dbname);
 	if (conn == NULL)
 	{
-		pg_log_warning("could not drop transient replication slot \"%s\" on publisher", temp_replslot);
-		pg_log_warning_hint("Drop this replication slot soon to avoid retention of WAL files.");
+		char *primary_slot_name = standby.primary_slot_name;
+
 		if (primary_slot_name != NULL)
 			pg_log_warning("could not drop replication slot \"%s\" on primary", primary_slot_name);
 	}
 	else
 	{
-		drop_replication_slot(conn, &dbinfo[0], temp_replslot);
+		LogicalRepPerdbInfo *perdb = &dbarr.perdb[0];
+		char *primary_slot_name = standby.primary_slot_name;
+
 		if (primary_slot_name != NULL)
-			drop_replication_slot(conn, &dbinfo[0], primary_slot_name);
+			drop_replication_slot(conn, perdb, primary_slot_name);
 		disconnect_database(conn);
 	}
 
@@ -1634,20 +1869,22 @@ main(int argc, char **argv)
 	 */
 	pg_log_info("stopping the subscriber");
 
-	pg_ctl_cmd = psprintf("\"%s\" stop -D \"%s\" -s", pg_ctl_path, subscriber_dir);
+	pg_ctl_cmd = psprintf("\"%s/pg_ctl\" stop -D \"%s\" -s",
+						  standby.bindir, standby.pgdata);
 	rc = system(pg_ctl_cmd);
 	pg_ctl_status(pg_ctl_cmd, rc, 0);
 
 	/*
 	 * Change system identifier.
 	 */
-	modify_sysid(pg_resetwal_path, subscriber_dir);
+	modify_sysid(standby.bindir, standby.pgdata);
 
 	/*
 	 * Remove log file generated by this tool, if it runs successfully.
 	 * Otherwise, file is kept that may provide useful debugging information.
 	 */
-	unlink(server_start_log);
+	if (!retain)
+		unlink(server_start_log);
 
 	success = true;
 
diff --git a/src/bin/pg_basebackup/t/040_pg_subscriber.pl b/src/bin/pg_basebackup/t/040_pg_subscriber.pl
index 4ebff76b2d..9915b8cb3c 100644
--- a/src/bin/pg_basebackup/t/040_pg_subscriber.pl
+++ b/src/bin/pg_basebackup/t/040_pg_subscriber.pl
@@ -37,8 +37,13 @@ command_fails(
 		'--verbose',
 		'--pgdata', $datadir,
 		'--publisher-conninfo', 'dbname=postgres',
-		'--subscriber-conninfo', 'dbname=postgres'
 	],
 	'no database name specified');
-
+command_fails(
+	[
+		'pg_subscriber', '--verbose',
+		'--pgdata', $datadir,
+		'--publisher-conninfo', 'dbname=postgres',
+	],
+	'subscriber connection string specnfied non-local server');
 done_testing();
diff --git a/src/bin/pg_basebackup/t/041_pg_subscriber_standby.pl b/src/bin/pg_basebackup/t/041_pg_subscriber_standby.pl
index fbcd0fc82b..4e26607611 100644
--- a/src/bin/pg_basebackup/t/041_pg_subscriber_standby.pl
+++ b/src/bin/pg_basebackup/t/041_pg_subscriber_standby.pl
@@ -51,25 +51,27 @@ $node_s->start;
 $node_p->safe_psql('pg1', "INSERT INTO tbl1 VALUES('second row')");
 $node_p->wait_for_replay_catchup($node_s);
 
+$node_f->stop;
+
 # Run pg_subscriber on about-to-fail node F
 command_fails(
 	[
 		'pg_subscriber', '--verbose',
 		'--pgdata', $node_f->data_dir,
 		'--publisher-conninfo', $node_p->connstr('pg1'),
-		'--subscriber-conninfo', $node_f->connstr('pg1'),
 		'--database', 'pg1',
 		'--database', 'pg2'
 	],
 	'subscriber data directory is not a copy of the source database cluster');
 
+$node_s->stop;
+
 # dry run mode on node S
 command_ok(
 	[
 		'pg_subscriber', '--verbose', '--dry-run',
 		'--pgdata', $node_s->data_dir,
 		'--publisher-conninfo', $node_p->connstr('pg1'),
-		'--subscriber-conninfo', $node_s->connstr('pg1'),
 		'--database', 'pg1',
 		'--database', 'pg2'
 	],
@@ -82,6 +84,7 @@ $node_s->start;
 # Check if node S is still a standby
 is($node_s->safe_psql('postgres', 'SELECT pg_is_in_recovery()'),
 	't', 'standby is in recovery');
+$node_s->stop;
 
 # Run pg_subscriber on node S
 command_ok(
@@ -89,7 +92,6 @@ command_ok(
 		'pg_subscriber', '--verbose',
 		'--pgdata', $node_s->data_dir,
 		'--publisher-conninfo', $node_p->connstr('pg1'),
-		'--subscriber-conninfo', $node_s->connstr('pg1'),
 		'--database', 'pg1',
 		'--database', 'pg2'
 	],
-- 
2.34.1