Adding upstream version 14.5.upstream/14.5upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1683 insertions, 0 deletions

diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
new file mode 100644
index 0000000..1719f04
--- /dev/null
+++ b/src/backend/commands/subscriptioncmds.c
@@ -0,0 +1,1683 @@
+/*-------------------------------------------------------------------------
+ *
+ * subscriptioncmds.c
+ *		subscription catalog manipulation functions
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ *		subscriptioncmds.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/htup_details.h"
+#include "access/table.h"
+#include "access/xact.h"
+#include "catalog/catalog.h"
+#include "catalog/dependency.h"
+#include "catalog/indexing.h"
+#include "catalog/namespace.h"
+#include "catalog/objectaccess.h"
+#include "catalog/objectaddress.h"
+#include "catalog/pg_subscription.h"
+#include "catalog/pg_subscription_rel.h"
+#include "catalog/pg_type.h"
+#include "commands/defrem.h"
+#include "commands/event_trigger.h"
+#include "commands/subscriptioncmds.h"
+#include "executor/executor.h"
+#include "miscadmin.h"
+#include "nodes/makefuncs.h"
+#include "replication/logicallauncher.h"
+#include "replication/origin.h"
+#include "replication/slot.h"
+#include "replication/walreceiver.h"
+#include "replication/walsender.h"
+#include "replication/worker_internal.h"
+#include "storage/lmgr.h"
+#include "utils/acl.h"
+#include "utils/builtins.h"
+#include "utils/guc.h"
+#include "utils/lsyscache.h"
+#include "utils/memutils.h"
+#include "utils/syscache.h"
+
+static List *fetch_table_list(WalReceiverConn *wrconn, List *publications);
+static void check_duplicates_in_publist(List *publist, Datum *datums);
+static List *merge_publications(List *oldpublist, List *newpublist, bool addpub, const char *subname);
+static void ReportSlotConnectionError(List *rstates, Oid subid, char *slotname, char *err);
+
+
+/*
+ * Common option parsing function for CREATE and ALTER SUBSCRIPTION commands.
+ *
+ * Since not all options can be specified in both commands, this function
+ * will report an error on options if the target output pointer is NULL to
+ * accommodate that.
+ */
+static void
+parse_subscription_options(List *options,
+						   bool *connect,
+						   bool *enabled_given, bool *enabled,
+						   bool *create_slot,
+						   bool *slot_name_given, char **slot_name,
+						   bool *copy_data,
+						   char **synchronous_commit,
+						   bool *refresh,
+						   bool *binary_given, bool *binary,
+						   bool *streaming_given, bool *streaming)
+{
+	ListCell   *lc;
+	bool		connect_given = false;
+	bool		create_slot_given = false;
+	bool		copy_data_given = false;
+	bool		refresh_given = false;
+
+	/* If connect is specified, the others also need to be. */
+	Assert(!connect || (enabled && create_slot && copy_data));
+
+	if (connect)
+		*connect = true;
+	if (enabled)
+	{
+		*enabled_given = false;
+		*enabled = true;
+	}
+	if (create_slot)
+		*create_slot = true;
+	if (slot_name)
+	{
+		*slot_name_given = false;
+		*slot_name = NULL;
+	}
+	if (copy_data)
+		*copy_data = true;
+	if (synchronous_commit)
+		*synchronous_commit = NULL;
+	if (refresh)
+		*refresh = true;
+	if (binary)
+	{
+		*binary_given = false;
+		*binary = false;
+	}
+	if (streaming)
+	{
+		*streaming_given = false;
+		*streaming = false;
+	}
+
+	/* Parse options */
+	foreach(lc, options)
+	{
+		DefElem    *defel = (DefElem *) lfirst(lc);
+
+		if (strcmp(defel->defname, "connect") == 0 && connect)
+		{
+			if (connect_given)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+
+			connect_given = true;
+			*connect = defGetBoolean(defel);
+		}
+		else if (strcmp(defel->defname, "enabled") == 0 && enabled)
+		{
+			if (*enabled_given)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+
+			*enabled_given = true;
+			*enabled = defGetBoolean(defel);
+		}
+		else if (strcmp(defel->defname, "create_slot") == 0 && create_slot)
+		{
+			if (create_slot_given)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+
+			create_slot_given = true;
+			*create_slot = defGetBoolean(defel);
+		}
+		else if (strcmp(defel->defname, "slot_name") == 0 && slot_name)
+		{
+			if (*slot_name_given)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+
+			*slot_name_given = true;
+			*slot_name = defGetString(defel);
+
+			/* Setting slot_name = NONE is treated as no slot name. */
+			if (strcmp(*slot_name, "none") == 0)
+				*slot_name = NULL;
+			else
+				ReplicationSlotValidateName(*slot_name, ERROR);
+		}
+		else if (strcmp(defel->defname, "copy_data") == 0 && copy_data)
+		{
+			if (copy_data_given)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+
+			copy_data_given = true;
+			*copy_data = defGetBoolean(defel);
+		}
+		else if (strcmp(defel->defname, "synchronous_commit") == 0 &&
+				 synchronous_commit)
+		{
+			if (*synchronous_commit)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+
+			*synchronous_commit = defGetString(defel);
+
+			/* Test if the given value is valid for synchronous_commit GUC. */
+			(void) set_config_option("synchronous_commit", *synchronous_commit,
+									 PGC_BACKEND, PGC_S_TEST, GUC_ACTION_SET,
+									 false, 0, false);
+		}
+		else if (strcmp(defel->defname, "refresh") == 0 && refresh)
+		{
+			if (refresh_given)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+
+			refresh_given = true;
+			*refresh = defGetBoolean(defel);
+		}
+		else if (strcmp(defel->defname, "binary") == 0 && binary)
+		{
+			if (*binary_given)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+
+			*binary_given = true;
+			*binary = defGetBoolean(defel);
+		}
+		else if (strcmp(defel->defname, "streaming") == 0 && streaming)
+		{
+			if (*streaming_given)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+
+			*streaming_given = true;
+			*streaming = defGetBoolean(defel);
+		}
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("unrecognized subscription parameter: \"%s\"", defel->defname)));
+	}
+
+	/*
+	 * We've been explicitly asked to not connect, that requires some
+	 * additional processing.
+	 */
+	if (connect && !*connect)
+	{
+		/* Check for incompatible options from the user. */
+		if (enabled && *enabled_given && *enabled)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+			/*- translator: both %s are strings of the form "option = value" */
+					 errmsg("%s and %s are mutually exclusive options",
+							"connect = false", "enabled = true")));
+
+		if (create_slot && create_slot_given && *create_slot)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("%s and %s are mutually exclusive options",
+							"connect = false", "create_slot = true")));
+
+		if (copy_data && copy_data_given && *copy_data)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("%s and %s are mutually exclusive options",
+							"connect = false", "copy_data = true")));
+
+		/* Change the defaults of other options. */
+		*enabled = false;
+		*create_slot = false;
+		*copy_data = false;
+	}
+
+	/*
+	 * Do additional checking for disallowed combination when slot_name = NONE
+	 * was used.
+	 */
+	if (slot_name && *slot_name_given && !*slot_name)
+	{
+		if (enabled && *enabled_given && *enabled)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+			/*- translator: both %s are strings of the form "option = value" */
+					 errmsg("%s and %s are mutually exclusive options",
+							"slot_name = NONE", "enabled = true")));
+
+		if (create_slot && create_slot_given && *create_slot)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("%s and %s are mutually exclusive options",
+							"slot_name = NONE", "create_slot = true")));
+
+		if (enabled && !*enabled_given && *enabled)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+			/*- translator: both %s are strings of the form "option = value" */
+					 errmsg("subscription with %s must also set %s",
+							"slot_name = NONE", "enabled = false")));
+
+		if (create_slot && !create_slot_given && *create_slot)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("subscription with %s must also set %s",
+							"slot_name = NONE", "create_slot = false")));
+	}
+}
+
+/*
+ * Auxiliary function to build a text array out of a list of String nodes.
+ */
+static Datum
+publicationListToArray(List *publist)
+{
+	ArrayType  *arr;
+	Datum	   *datums;
+	MemoryContext memcxt;
+	MemoryContext oldcxt;
+
+	/* Create memory context for temporary allocations. */
+	memcxt = AllocSetContextCreate(CurrentMemoryContext,
+								   "publicationListToArray to array",
+								   ALLOCSET_DEFAULT_SIZES);
+	oldcxt = MemoryContextSwitchTo(memcxt);
+
+	datums = (Datum *) palloc(sizeof(Datum) * list_length(publist));
+
+	check_duplicates_in_publist(publist, datums);
+
+	MemoryContextSwitchTo(oldcxt);
+
+	arr = construct_array(datums, list_length(publist),
+						  TEXTOID, -1, false, TYPALIGN_INT);
+
+	MemoryContextDelete(memcxt);
+
+	return PointerGetDatum(arr);
+}
+
+/*
+ * Create new subscription.
+ */
+ObjectAddress
+CreateSubscription(CreateSubscriptionStmt *stmt, bool isTopLevel)
+{
+	Relation	rel;
+	ObjectAddress myself;
+	Oid			subid;
+	bool		nulls[Natts_pg_subscription];
+	Datum		values[Natts_pg_subscription];
+	Oid			owner = GetUserId();
+	HeapTuple	tup;
+	bool		connect;
+	bool		enabled_given;
+	bool		enabled;
+	bool		copy_data;
+	bool		streaming;
+	bool		streaming_given;
+	char	   *synchronous_commit;
+	char	   *conninfo;
+	char	   *slotname;
+	bool		slotname_given;
+	bool		binary;
+	bool		binary_given;
+	char		originname[NAMEDATALEN];
+	bool		create_slot;
+	List	   *publications;
+
+	/*
+	 * Parse and check options.
+	 *
+	 * Connection and publication should not be specified here.
+	 */
+	parse_subscription_options(stmt->options,
+							   &connect,
+							   &enabled_given, &enabled,
+							   &create_slot,
+							   &slotname_given, &slotname,
+							   &copy_data,
+							   &synchronous_commit,
+							   NULL,	/* no "refresh" */
+							   &binary_given, &binary,
+							   &streaming_given, &streaming);
+
+	/*
+	 * Since creating a replication slot is not transactional, rolling back
+	 * the transaction leaves the created replication slot.  So we cannot run
+	 * CREATE SUBSCRIPTION inside a transaction block if creating a
+	 * replication slot.
+	 */
+	if (create_slot)
+		PreventInTransactionBlock(isTopLevel, "CREATE SUBSCRIPTION ... WITH (create_slot = true)");
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to create subscriptions")));
+
+	/*
+	 * If built with appropriate switch, whine when regression-testing
+	 * conventions for subscription names are violated.
+	 */
+#ifdef ENFORCE_REGRESSION_TEST_NAME_RESTRICTIONS
+	if (strncmp(stmt->subname, "regress_", 8) != 0)
+		elog(WARNING, "subscriptions created by regression test cases should have names starting with \"regress_\"");
+#endif
+
+	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
+
+	/* Check if name is used */
+	subid = GetSysCacheOid2(SUBSCRIPTIONNAME, Anum_pg_subscription_oid,
+							MyDatabaseId, CStringGetDatum(stmt->subname));
+	if (OidIsValid(subid))
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_DUPLICATE_OBJECT),
+				 errmsg("subscription \"%s\" already exists",
+						stmt->subname)));
+	}
+
+	if (!slotname_given && slotname == NULL)
+		slotname = stmt->subname;
+
+	/* The default for synchronous_commit of subscriptions is off. */
+	if (synchronous_commit == NULL)
+		synchronous_commit = "off";
+
+	conninfo = stmt->conninfo;
+	publications = stmt->publication;
+
+	/* Load the library providing us libpq calls. */
+	load_file("libpqwalreceiver", false);
+
+	/* Check the connection info string. */
+	walrcv_check_conninfo(conninfo);
+
+	/* Everything ok, form a new tuple. */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+
+	subid = GetNewOidWithIndex(rel, SubscriptionObjectIndexId,
+							   Anum_pg_subscription_oid);
+	values[Anum_pg_subscription_oid - 1] = ObjectIdGetDatum(subid);
+	values[Anum_pg_subscription_subdbid - 1] = ObjectIdGetDatum(MyDatabaseId);
+	values[Anum_pg_subscription_subname - 1] =
+		DirectFunctionCall1(namein, CStringGetDatum(stmt->subname));
+	values[Anum_pg_subscription_subowner - 1] = ObjectIdGetDatum(owner);
+	values[Anum_pg_subscription_subenabled - 1] = BoolGetDatum(enabled);
+	values[Anum_pg_subscription_subbinary - 1] = BoolGetDatum(binary);
+	values[Anum_pg_subscription_substream - 1] = BoolGetDatum(streaming);
+	values[Anum_pg_subscription_subconninfo - 1] =
+		CStringGetTextDatum(conninfo);
+	if (slotname)
+		values[Anum_pg_subscription_subslotname - 1] =
+			DirectFunctionCall1(namein, CStringGetDatum(slotname));
+	else
+		nulls[Anum_pg_subscription_subslotname - 1] = true;
+	values[Anum_pg_subscription_subsynccommit - 1] =
+		CStringGetTextDatum(synchronous_commit);
+	values[Anum_pg_subscription_subpublications - 1] =
+		publicationListToArray(publications);
+
+	tup = heap_form_tuple(RelationGetDescr(rel), values, nulls);
+
+	/* Insert tuple into catalog. */
+	CatalogTupleInsert(rel, tup);
+	heap_freetuple(tup);
+
+	recordDependencyOnOwner(SubscriptionRelationId, subid, owner);
+
+	snprintf(originname, sizeof(originname), "pg_%u", subid);
+	replorigin_create(originname);
+
+	/*
+	 * Connect to remote side to execute requested commands and fetch table
+	 * info.
+	 */
+	if (connect)
+	{
+		char	   *err;
+		WalReceiverConn *wrconn;
+		List	   *tables;
+		ListCell   *lc;
+		char		table_state;
+
+		/* Try to connect to the publisher. */
+		wrconn = walrcv_connect(conninfo, true, stmt->subname, &err);
+		if (!wrconn)
+			ereport(ERROR,
+					(errcode(ERRCODE_CONNECTION_FAILURE),
+					 errmsg("could not connect to the publisher: %s", err)));
+
+		PG_TRY();
+		{
+			/*
+			 * Set sync state based on if we were asked to do data copy or
+			 * not.
+			 */
+			table_state = copy_data ? SUBREL_STATE_INIT : SUBREL_STATE_READY;
+
+			/*
+			 * Get the table list from publisher and build local table status
+			 * info.
+			 */
+			tables = fetch_table_list(wrconn, publications);
+			foreach(lc, tables)
+			{
+				RangeVar   *rv = (RangeVar *) lfirst(lc);
+				Oid			relid;
+
+				relid = RangeVarGetRelid(rv, AccessShareLock, false);
+
+				/* Check for supported relkind. */
+				CheckSubscriptionRelkind(get_rel_relkind(relid),
+										 rv->schemaname, rv->relname);
+
+				AddSubscriptionRelState(subid, relid, table_state,
+										InvalidXLogRecPtr);
+			}
+
+			/*
+			 * If requested, create permanent slot for the subscription. We
+			 * won't use the initial snapshot for anything, so no need to
+			 * export it.
+			 */
+			if (create_slot)
+			{
+				Assert(slotname);
+
+				walrcv_create_slot(wrconn, slotname, false,
+								   CRS_NOEXPORT_SNAPSHOT, NULL);
+				ereport(NOTICE,
+						(errmsg("created replication slot \"%s\" on publisher",
+								slotname)));
+			}
+		}
+		PG_FINALLY();
+		{
+			walrcv_disconnect(wrconn);
+		}
+		PG_END_TRY();
+	}
+	else
+		ereport(WARNING,
+		/* translator: %s is an SQL ALTER statement */
+				(errmsg("tables were not subscribed, you will have to run %s to subscribe the tables",
+						"ALTER SUBSCRIPTION ... REFRESH PUBLICATION")));
+
+	table_close(rel, RowExclusiveLock);
+
+	if (enabled)
+		ApplyLauncherWakeupAtCommit();
+
+	ObjectAddressSet(myself, SubscriptionRelationId, subid);
+
+	InvokeObjectPostCreateHook(SubscriptionRelationId, subid, 0);
+
+	return myself;
+}
+
+static void
+AlterSubscription_refresh(Subscription *sub, bool copy_data)
+{
+	char	   *err;
+	List	   *pubrel_names;
+	List	   *subrel_states;
+	Oid		   *subrel_local_oids;
+	Oid		   *pubrel_local_oids;
+	ListCell   *lc;
+	int			off;
+	int			remove_rel_len;
+	Relation	rel = NULL;
+	typedef struct SubRemoveRels
+	{
+		Oid			relid;
+		char		state;
+	} SubRemoveRels;
+	SubRemoveRels *sub_remove_rels;
+	WalReceiverConn *wrconn;
+
+	/* Load the library providing us libpq calls. */
+	load_file("libpqwalreceiver", false);
+
+	/* Try to connect to the publisher. */
+	wrconn = walrcv_connect(sub->conninfo, true, sub->name, &err);
+	if (!wrconn)
+		ereport(ERROR,
+				(errcode(ERRCODE_CONNECTION_FAILURE),
+				 errmsg("could not connect to the publisher: %s", err)));
+
+	PG_TRY();
+	{
+		/* Get the table list from publisher. */
+		pubrel_names = fetch_table_list(wrconn, sub->publications);
+
+		/* Get local table list. */
+		subrel_states = GetSubscriptionRelations(sub->oid);
+
+		/*
+		 * Build qsorted array of local table oids for faster lookup. This can
+		 * potentially contain all tables in the database so speed of lookup
+		 * is important.
+		 */
+		subrel_local_oids = palloc(list_length(subrel_states) * sizeof(Oid));
+		off = 0;
+		foreach(lc, subrel_states)
+		{
+			SubscriptionRelState *relstate = (SubscriptionRelState *) lfirst(lc);
+
+			subrel_local_oids[off++] = relstate->relid;
+		}
+		qsort(subrel_local_oids, list_length(subrel_states),
+			  sizeof(Oid), oid_cmp);
+
+		/*
+		 * Rels that we want to remove from subscription and drop any slots
+		 * and origins corresponding to them.
+		 */
+		sub_remove_rels = palloc(list_length(subrel_states) * sizeof(SubRemoveRels));
+
+		/*
+		 * Walk over the remote tables and try to match them to locally known
+		 * tables. If the table is not known locally create a new state for
+		 * it.
+		 *
+		 * Also builds array of local oids of remote tables for the next step.
+		 */
+		off = 0;
+		pubrel_local_oids = palloc(list_length(pubrel_names) * sizeof(Oid));
+
+		foreach(lc, pubrel_names)
+		{
+			RangeVar   *rv = (RangeVar *) lfirst(lc);
+			Oid			relid;
+
+			relid = RangeVarGetRelid(rv, AccessShareLock, false);
+
+			/* Check for supported relkind. */
+			CheckSubscriptionRelkind(get_rel_relkind(relid),
+									 rv->schemaname, rv->relname);
+
+			pubrel_local_oids[off++] = relid;
+
+			if (!bsearch(&relid, subrel_local_oids,
+						 list_length(subrel_states), sizeof(Oid), oid_cmp))
+			{
+				AddSubscriptionRelState(sub->oid, relid,
+										copy_data ? SUBREL_STATE_INIT : SUBREL_STATE_READY,
+										InvalidXLogRecPtr);
+				ereport(DEBUG1,
+						(errmsg_internal("table \"%s.%s\" added to subscription \"%s\"",
+										 rv->schemaname, rv->relname, sub->name)));
+			}
+		}
+
+		/*
+		 * Next remove state for tables we should not care about anymore using
+		 * the data we collected above
+		 */
+		qsort(pubrel_local_oids, list_length(pubrel_names),
+			  sizeof(Oid), oid_cmp);
+
+		remove_rel_len = 0;
+		for (off = 0; off < list_length(subrel_states); off++)
+		{
+			Oid			relid = subrel_local_oids[off];
+
+			if (!bsearch(&relid, pubrel_local_oids,
+						 list_length(pubrel_names), sizeof(Oid), oid_cmp))
+			{
+				char		state;
+				XLogRecPtr	statelsn;
+
+				/*
+				 * Lock pg_subscription_rel with AccessExclusiveLock to
+				 * prevent any race conditions with the apply worker
+				 * re-launching workers at the same time this code is trying
+				 * to remove those tables.
+				 *
+				 * Even if new worker for this particular rel is restarted it
+				 * won't be able to make any progress as we hold exclusive
+				 * lock on subscription_rel till the transaction end. It will
+				 * simply exit as there is no corresponding rel entry.
+				 *
+				 * This locking also ensures that the state of rels won't
+				 * change till we are done with this refresh operation.
+				 */
+				if (!rel)
+					rel = table_open(SubscriptionRelRelationId, AccessExclusiveLock);
+
+				/* Last known rel state. */
+				state = GetSubscriptionRelState(sub->oid, relid, &statelsn);
+
+				sub_remove_rels[remove_rel_len].relid = relid;
+				sub_remove_rels[remove_rel_len++].state = state;
+
+				RemoveSubscriptionRel(sub->oid, relid);
+
+				logicalrep_worker_stop(sub->oid, relid);
+
+				/*
+				 * For READY state, we would have already dropped the
+				 * tablesync origin.
+				 */
+				if (state != SUBREL_STATE_READY)
+				{
+					char		originname[NAMEDATALEN];
+
+					/*
+					 * Drop the tablesync's origin tracking if exists.
+					 *
+					 * It is possible that the origin is not yet created for
+					 * tablesync worker, this can happen for the states before
+					 * SUBREL_STATE_FINISHEDCOPY. The apply worker can also
+					 * concurrently try to drop the origin and by this time
+					 * the origin might be already removed. For these reasons,
+					 * passing missing_ok = true.
+					 */
+					ReplicationOriginNameForTablesync(sub->oid, relid, originname,
+													  sizeof(originname));
+					replorigin_drop_by_name(originname, true, false);
+				}
+
+				ereport(DEBUG1,
+						(errmsg_internal("table \"%s.%s\" removed from subscription \"%s\"",
+										 get_namespace_name(get_rel_namespace(relid)),
+										 get_rel_name(relid),
+										 sub->name)));
+			}
+		}
+
+		/*
+		 * Drop the tablesync slots associated with removed tables. This has
+		 * to be at the end because otherwise if there is an error while doing
+		 * the database operations we won't be able to rollback dropped slots.
+		 */
+		for (off = 0; off < remove_rel_len; off++)
+		{
+			if (sub_remove_rels[off].state != SUBREL_STATE_READY &&
+				sub_remove_rels[off].state != SUBREL_STATE_SYNCDONE)
+			{
+				char		syncslotname[NAMEDATALEN] = {0};
+
+				/*
+				 * For READY/SYNCDONE states we know the tablesync slot has
+				 * already been dropped by the tablesync worker.
+				 *
+				 * For other states, there is no certainty, maybe the slot
+				 * does not exist yet. Also, if we fail after removing some of
+				 * the slots, next time, it will again try to drop already
+				 * dropped slots and fail. For these reasons, we allow
+				 * missing_ok = true for the drop.
+				 */
+				ReplicationSlotNameForTablesync(sub->oid, sub_remove_rels[off].relid,
+												syncslotname, sizeof(syncslotname));
+				ReplicationSlotDropAtPubNode(wrconn, syncslotname, true);
+			}
+		}
+	}
+	PG_FINALLY();
+	{
+		walrcv_disconnect(wrconn);
+	}
+	PG_END_TRY();
+
+	if (rel)
+		table_close(rel, NoLock);
+}
+
+/*
+ * Alter the existing subscription.
+ */
+ObjectAddress
+AlterSubscription(AlterSubscriptionStmt *stmt, bool isTopLevel)
+{
+	Relation	rel;
+	ObjectAddress myself;
+	bool		nulls[Natts_pg_subscription];
+	bool		replaces[Natts_pg_subscription];
+	Datum		values[Natts_pg_subscription];
+	HeapTuple	tup;
+	Oid			subid;
+	bool		update_tuple = false;
+	Subscription *sub;
+	Form_pg_subscription form;
+
+	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
+
+	/* Fetch the existing tuple. */
+	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, MyDatabaseId,
+							  CStringGetDatum(stmt->subname));
+
+	if (!HeapTupleIsValid(tup))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("subscription \"%s\" does not exist",
+						stmt->subname)));
+
+	form = (Form_pg_subscription) GETSTRUCT(tup);
+	subid = form->oid;
+
+	/* must be owner */
+	if (!pg_subscription_ownercheck(subid, GetUserId()))
+		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+					   stmt->subname);
+
+	sub = GetSubscription(subid, false);
+
+	/* Lock the subscription so nobody else can do anything with it. */
+	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+
+	/* Form a new tuple. */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	memset(replaces, false, sizeof(replaces));
+
+	switch (stmt->kind)
+	{
+		case ALTER_SUBSCRIPTION_OPTIONS:
+			{
+				char	   *slotname;
+				bool		slotname_given;
+				char	   *synchronous_commit;
+				bool		binary_given;
+				bool		binary;
+				bool		streaming_given;
+				bool		streaming;
+
+				parse_subscription_options(stmt->options,
+										   NULL,	/* no "connect" */
+										   NULL, NULL,	/* no "enabled" */
+										   NULL,	/* no "create_slot" */
+										   &slotname_given, &slotname,
+										   NULL,	/* no "copy_data" */
+										   &synchronous_commit,
+										   NULL,	/* no "refresh" */
+										   &binary_given, &binary,
+										   &streaming_given, &streaming);
+
+				if (slotname_given)
+				{
+					if (sub->enabled && !slotname)
+						ereport(ERROR,
+								(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+								 errmsg("cannot set %s for enabled subscription",
+										"slot_name = NONE")));
+
+					if (slotname)
+						values[Anum_pg_subscription_subslotname - 1] =
+							DirectFunctionCall1(namein, CStringGetDatum(slotname));
+					else
+						nulls[Anum_pg_subscription_subslotname - 1] = true;
+					replaces[Anum_pg_subscription_subslotname - 1] = true;
+				}
+
+				if (synchronous_commit)
+				{
+					values[Anum_pg_subscription_subsynccommit - 1] =
+						CStringGetTextDatum(synchronous_commit);
+					replaces[Anum_pg_subscription_subsynccommit - 1] = true;
+				}
+
+				if (binary_given)
+				{
+					values[Anum_pg_subscription_subbinary - 1] =
+						BoolGetDatum(binary);
+					replaces[Anum_pg_subscription_subbinary - 1] = true;
+				}
+
+				if (streaming_given)
+				{
+					values[Anum_pg_subscription_substream - 1] =
+						BoolGetDatum(streaming);
+					replaces[Anum_pg_subscription_substream - 1] = true;
+				}
+
+				update_tuple = true;
+				break;
+			}
+
+		case ALTER_SUBSCRIPTION_ENABLED:
+			{
+				bool		enabled,
+							enabled_given;
+
+				parse_subscription_options(stmt->options,
+										   NULL,	/* no "connect" */
+										   &enabled_given, &enabled,
+										   NULL,	/* no "create_slot" */
+										   NULL, NULL,	/* no "slot_name" */
+										   NULL,	/* no "copy_data" */
+										   NULL,	/* no "synchronous_commit" */
+										   NULL,	/* no "refresh" */
+										   NULL, NULL,	/* no "binary" */
+										   NULL, NULL); /* no streaming */
+				Assert(enabled_given);
+
+				if (!sub->slotname && enabled)
+					ereport(ERROR,
+							(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+							 errmsg("cannot enable subscription that does not have a slot name")));
+
+				values[Anum_pg_subscription_subenabled - 1] =
+					BoolGetDatum(enabled);
+				replaces[Anum_pg_subscription_subenabled - 1] = true;
+
+				if (enabled)
+					ApplyLauncherWakeupAtCommit();
+
+				update_tuple = true;
+				break;
+			}
+
+		case ALTER_SUBSCRIPTION_CONNECTION:
+			/* Load the library providing us libpq calls. */
+			load_file("libpqwalreceiver", false);
+			/* Check the connection info string. */
+			walrcv_check_conninfo(stmt->conninfo);
+
+			values[Anum_pg_subscription_subconninfo - 1] =
+				CStringGetTextDatum(stmt->conninfo);
+			replaces[Anum_pg_subscription_subconninfo - 1] = true;
+			update_tuple = true;
+			break;
+
+		case ALTER_SUBSCRIPTION_SET_PUBLICATION:
+			{
+				bool		copy_data;
+				bool		refresh;
+
+				parse_subscription_options(stmt->options,
+										   NULL,	/* no "connect" */
+										   NULL, NULL,	/* no "enabled" */
+										   NULL,	/* no "create_slot" */
+										   NULL, NULL,	/* no "slot_name" */
+										   &copy_data,
+										   NULL,	/* no "synchronous_commit" */
+										   &refresh,
+										   NULL, NULL,	/* no "binary" */
+										   NULL, NULL); /* no "streaming" */
+				values[Anum_pg_subscription_subpublications - 1] =
+					publicationListToArray(stmt->publication);
+				replaces[Anum_pg_subscription_subpublications - 1] = true;
+
+				update_tuple = true;
+
+				/* Refresh if user asked us to. */
+				if (refresh)
+				{
+					if (!sub->enabled)
+						ereport(ERROR,
+								(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+								 errmsg("ALTER SUBSCRIPTION with refresh is not allowed for disabled subscriptions"),
+								 errhint("Use ALTER SUBSCRIPTION ... SET PUBLICATION ... WITH (refresh = false).")));
+
+					PreventInTransactionBlock(isTopLevel, "ALTER SUBSCRIPTION with refresh");
+
+					/* Make sure refresh sees the new list of publications. */
+					sub->publications = stmt->publication;
+
+					AlterSubscription_refresh(sub, copy_data);
+				}
+
+				break;
+			}
+
+		case ALTER_SUBSCRIPTION_ADD_PUBLICATION:
+		case ALTER_SUBSCRIPTION_DROP_PUBLICATION:
+			{
+				bool		isadd = stmt->kind == ALTER_SUBSCRIPTION_ADD_PUBLICATION;
+				bool		copy_data = false;
+				bool		refresh;
+				List	   *publist;
+
+				parse_subscription_options(stmt->options,
+										   NULL,	/* no "connect" */
+										   NULL, NULL,	/* no "enabled" */
+										   NULL,	/* no "create_slot" */
+										   NULL, NULL,	/* no "slot_name" */
+										   &copy_data,
+										   NULL,	/* no "synchronous_commit" */
+										   &refresh,
+										   NULL, NULL,	/* no "binary" */
+										   NULL, NULL); /* no "streaming" */
+
+				publist = merge_publications(sub->publications, stmt->publication, isadd, stmt->subname);
+
+				values[Anum_pg_subscription_subpublications - 1] =
+					publicationListToArray(publist);
+				replaces[Anum_pg_subscription_subpublications - 1] = true;
+
+				update_tuple = true;
+
+				/* Refresh if user asked us to. */
+				if (refresh)
+				{
+					if (!sub->enabled)
+						ereport(ERROR,
+								(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+								 errmsg("ALTER SUBSCRIPTION with refresh is not allowed for disabled subscriptions"),
+								 errhint("Use ALTER SUBSCRIPTION ... SET PUBLICATION ... WITH (refresh = false).")));
+
+					PreventInTransactionBlock(isTopLevel, "ALTER SUBSCRIPTION with refresh");
+
+					/* Refresh the new list of publications. */
+					sub->publications = publist;
+
+					AlterSubscription_refresh(sub, copy_data);
+				}
+
+				break;
+			}
+
+		case ALTER_SUBSCRIPTION_REFRESH:
+			{
+				bool		copy_data;
+
+				if (!sub->enabled)
+					ereport(ERROR,
+							(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+							 errmsg("ALTER SUBSCRIPTION ... REFRESH is not allowed for disabled subscriptions")));
+
+				parse_subscription_options(stmt->options,
+										   NULL,	/* no "connect" */
+										   NULL, NULL,	/* no "enabled" */
+										   NULL,	/* no "create_slot" */
+										   NULL, NULL,	/* no "slot_name" */
+										   &copy_data,
+										   NULL,	/* no "synchronous_commit" */
+										   NULL,	/* no "refresh" */
+										   NULL, NULL,	/* no "binary" */
+										   NULL, NULL); /* no "streaming" */
+
+				PreventInTransactionBlock(isTopLevel, "ALTER SUBSCRIPTION ... REFRESH");
+
+				AlterSubscription_refresh(sub, copy_data);
+
+				break;
+			}
+
+		default:
+			elog(ERROR, "unrecognized ALTER SUBSCRIPTION kind %d",
+				 stmt->kind);
+	}
+
+	/* Update the catalog if needed. */
+	if (update_tuple)
+	{
+		tup = heap_modify_tuple(tup, RelationGetDescr(rel), values, nulls,
+								replaces);
+
+		CatalogTupleUpdate(rel, &tup->t_self, tup);
+
+		heap_freetuple(tup);
+	}
+
+	table_close(rel, RowExclusiveLock);
+
+	ObjectAddressSet(myself, SubscriptionRelationId, subid);
+
+	InvokeObjectPostAlterHook(SubscriptionRelationId, subid, 0);
+
+	return myself;
+}
+
+/*
+ * Drop a subscription
+ */
+void
+DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
+{
+	Relation	rel;
+	ObjectAddress myself;
+	HeapTuple	tup;
+	Oid			subid;
+	Datum		datum;
+	bool		isnull;
+	char	   *subname;
+	char	   *conninfo;
+	char	   *slotname;
+	List	   *subworkers;
+	ListCell   *lc;
+	char		originname[NAMEDATALEN];
+	char	   *err = NULL;
+	WalReceiverConn *wrconn;
+	Form_pg_subscription form;
+	List	   *rstates;
+
+	/*
+	 * Lock pg_subscription with AccessExclusiveLock to ensure that the
+	 * launcher doesn't restart new worker during dropping the subscription
+	 */
+	rel = table_open(SubscriptionRelationId, AccessExclusiveLock);
+
+	tup = SearchSysCache2(SUBSCRIPTIONNAME, MyDatabaseId,
+						  CStringGetDatum(stmt->subname));
+
+	if (!HeapTupleIsValid(tup))
+	{
+		table_close(rel, NoLock);
+
+		if (!stmt->missing_ok)
+			ereport(ERROR,
+					(errcode(ERRCODE_UNDEFINED_OBJECT),
+					 errmsg("subscription \"%s\" does not exist",
+							stmt->subname)));
+		else
+			ereport(NOTICE,
+					(errmsg("subscription \"%s\" does not exist, skipping",
+							stmt->subname)));
+
+		return;
+	}
+
+	form = (Form_pg_subscription) GETSTRUCT(tup);
+	subid = form->oid;
+
+	/* must be owner */
+	if (!pg_subscription_ownercheck(subid, GetUserId()))
+		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+					   stmt->subname);
+
+	/* DROP hook for the subscription being removed */
+	InvokeObjectDropHook(SubscriptionRelationId, subid, 0);
+
+	/*
+	 * Lock the subscription so nobody else can do anything with it (including
+	 * the replication workers).
+	 */
+	LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+
+	/* Get subname */
+	datum = SysCacheGetAttr(SUBSCRIPTIONOID, tup,
+							Anum_pg_subscription_subname, &isnull);
+	Assert(!isnull);
+	subname = pstrdup(NameStr(*DatumGetName(datum)));
+
+	/* Get conninfo */
+	datum = SysCacheGetAttr(SUBSCRIPTIONOID, tup,
+							Anum_pg_subscription_subconninfo, &isnull);
+	Assert(!isnull);
+	conninfo = TextDatumGetCString(datum);
+
+	/* Get slotname */
+	datum = SysCacheGetAttr(SUBSCRIPTIONOID, tup,
+							Anum_pg_subscription_subslotname, &isnull);
+	if (!isnull)
+		slotname = pstrdup(NameStr(*DatumGetName(datum)));
+	else
+		slotname = NULL;
+
+	/*
+	 * Since dropping a replication slot is not transactional, the replication
+	 * slot stays dropped even if the transaction rolls back.  So we cannot
+	 * run DROP SUBSCRIPTION inside a transaction block if dropping the
+	 * replication slot.
+	 *
+	 * XXX The command name should really be something like "DROP SUBSCRIPTION
+	 * of a subscription that is associated with a replication slot", but we
+	 * don't have the proper facilities for that.
+	 */
+	if (slotname)
+		PreventInTransactionBlock(isTopLevel, "DROP SUBSCRIPTION");
+
+	ObjectAddressSet(myself, SubscriptionRelationId, subid);
+	EventTriggerSQLDropAddObject(&myself, true, true);
+
+	/* Remove the tuple from catalog. */
+	CatalogTupleDelete(rel, &tup->t_self);
+
+	ReleaseSysCache(tup);
+
+	/*
+	 * Stop all the subscription workers immediately.
+	 *
+	 * This is necessary if we are dropping the replication slot, so that the
+	 * slot becomes accessible.
+	 *
+	 * It is also necessary if the subscription is disabled and was disabled
+	 * in the same transaction.  Then the workers haven't seen the disabling
+	 * yet and will still be running, leading to hangs later when we want to
+	 * drop the replication origin.  If the subscription was disabled before
+	 * this transaction, then there shouldn't be any workers left, so this
+	 * won't make a difference.
+	 *
+	 * New workers won't be started because we hold an exclusive lock on the
+	 * subscription till the end of the transaction.
+	 */
+	LWLockAcquire(LogicalRepWorkerLock, LW_SHARED);
+	subworkers = logicalrep_workers_find(subid, false);
+	LWLockRelease(LogicalRepWorkerLock);
+	foreach(lc, subworkers)
+	{
+		LogicalRepWorker *w = (LogicalRepWorker *) lfirst(lc);
+
+		logicalrep_worker_stop(w->subid, w->relid);
+	}
+	list_free(subworkers);
+
+	/*
+	 * Cleanup of tablesync replication origins.
+	 *
+	 * Any READY-state relations would already have dealt with clean-ups.
+	 *
+	 * Note that the state can't change because we have already stopped both
+	 * the apply and tablesync workers and they can't restart because of
+	 * exclusive lock on the subscription.
+	 */
+	rstates = GetSubscriptionNotReadyRelations(subid);
+	foreach(lc, rstates)
+	{
+		SubscriptionRelState *rstate = (SubscriptionRelState *) lfirst(lc);
+		Oid			relid = rstate->relid;
+
+		/* Only cleanup resources of tablesync workers */
+		if (!OidIsValid(relid))
+			continue;
+
+		/*
+		 * Drop the tablesync's origin tracking if exists.
+		 *
+		 * It is possible that the origin is not yet created for tablesync
+		 * worker so passing missing_ok = true. This can happen for the states
+		 * before SUBREL_STATE_FINISHEDCOPY.
+		 */
+		ReplicationOriginNameForTablesync(subid, relid, originname,
+										  sizeof(originname));
+		replorigin_drop_by_name(originname, true, false);
+	}
+
+	/* Clean up dependencies */
+	deleteSharedDependencyRecordsFor(SubscriptionRelationId, subid, 0);
+
+	/* Remove any associated relation synchronization states. */
+	RemoveSubscriptionRel(subid, InvalidOid);
+
+	/* Remove the origin tracking if exists. */
+	snprintf(originname, sizeof(originname), "pg_%u", subid);
+	replorigin_drop_by_name(originname, true, false);
+
+	/*
+	 * If there is no slot associated with the subscription, we can finish
+	 * here.
+	 */
+	if (!slotname && rstates == NIL)
+	{
+		table_close(rel, NoLock);
+		return;
+	}
+
+	/*
+	 * Try to acquire the connection necessary for dropping slots.
+	 *
+	 * Note: If the slotname is NONE/NULL then we allow the command to finish
+	 * and users need to manually cleanup the apply and tablesync worker slots
+	 * later.
+	 *
+	 * This has to be at the end because otherwise if there is an error while
+	 * doing the database operations we won't be able to rollback dropped
+	 * slot.
+	 */
+	load_file("libpqwalreceiver", false);
+
+	wrconn = walrcv_connect(conninfo, true, subname, &err);
+	if (wrconn == NULL)
+	{
+		if (!slotname)
+		{
+			/* be tidy */
+			list_free(rstates);
+			table_close(rel, NoLock);
+			return;
+		}
+		else
+		{
+			ReportSlotConnectionError(rstates, subid, slotname, err);
+		}
+	}
+
+	PG_TRY();
+	{
+		foreach(lc, rstates)
+		{
+			SubscriptionRelState *rstate = (SubscriptionRelState *) lfirst(lc);
+			Oid			relid = rstate->relid;
+
+			/* Only cleanup resources of tablesync workers */
+			if (!OidIsValid(relid))
+				continue;
+
+			/*
+			 * Drop the tablesync slots associated with removed tables.
+			 *
+			 * For SYNCDONE/READY states, the tablesync slot is known to have
+			 * already been dropped by the tablesync worker.
+			 *
+			 * For other states, there is no certainty, maybe the slot does
+			 * not exist yet. Also, if we fail after removing some of the
+			 * slots, next time, it will again try to drop already dropped
+			 * slots and fail. For these reasons, we allow missing_ok = true
+			 * for the drop.
+			 */
+			if (rstate->state != SUBREL_STATE_SYNCDONE)
+			{
+				char		syncslotname[NAMEDATALEN] = {0};
+
+				ReplicationSlotNameForTablesync(subid, relid, syncslotname,
+												sizeof(syncslotname));
+				ReplicationSlotDropAtPubNode(wrconn, syncslotname, true);
+			}
+		}
+
+		list_free(rstates);
+
+		/*
+		 * If there is a slot associated with the subscription, then drop the
+		 * replication slot at the publisher.
+		 */
+		if (slotname)
+			ReplicationSlotDropAtPubNode(wrconn, slotname, false);
+
+	}
+	PG_FINALLY();
+	{
+		walrcv_disconnect(wrconn);
+	}
+	PG_END_TRY();
+
+	table_close(rel, NoLock);
+}
+
+/*
+ * Drop the replication slot at the publisher node using the replication
+ * connection.
+ *
+ * missing_ok - if true then only issue a LOG message if the slot doesn't
+ * exist.
+ */
+void
+ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname, bool missing_ok)
+{
+	StringInfoData cmd;
+
+	Assert(wrconn);
+
+	load_file("libpqwalreceiver", false);
+
+	initStringInfo(&cmd);
+	appendStringInfo(&cmd, "DROP_REPLICATION_SLOT %s WAIT", quote_identifier(slotname));
+
+	PG_TRY();
+	{
+		WalRcvExecResult *res;
+
+		res = walrcv_exec(wrconn, cmd.data, 0, NULL);
+
+		if (res->status == WALRCV_OK_COMMAND)
+		{
+			/* NOTICE. Success. */
+			ereport(NOTICE,
+					(errmsg("dropped replication slot \"%s\" on publisher",
+							slotname)));
+		}
+		else if (res->status == WALRCV_ERROR &&
+				 missing_ok &&
+				 res->sqlstate == ERRCODE_UNDEFINED_OBJECT)
+		{
+			/* LOG. Error, but missing_ok = true. */
+			ereport(LOG,
+					(errmsg("could not drop replication slot \"%s\" on publisher: %s",
+							slotname, res->err)));
+		}
+		else
+		{
+			/* ERROR. */
+			ereport(ERROR,
+					(errcode(ERRCODE_CONNECTION_FAILURE),
+					 errmsg("could not drop replication slot \"%s\" on publisher: %s",
+							slotname, res->err)));
+		}
+
+		walrcv_clear_result(res);
+	}
+	PG_FINALLY();
+	{
+		pfree(cmd.data);
+	}
+	PG_END_TRY();
+}
+
+/*
+ * Internal workhorse for changing a subscription owner
+ */
+static void
+AlterSubscriptionOwner_internal(Relation rel, HeapTuple tup, Oid newOwnerId)
+{
+	Form_pg_subscription form;
+
+	form = (Form_pg_subscription) GETSTRUCT(tup);
+
+	if (form->subowner == newOwnerId)
+		return;
+
+	if (!pg_subscription_ownercheck(form->oid, GetUserId()))
+		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SUBSCRIPTION,
+					   NameStr(form->subname));
+
+	/* New owner must be a superuser */
+	if (!superuser_arg(newOwnerId))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("permission denied to change owner of subscription \"%s\"",
+						NameStr(form->subname)),
+				 errhint("The owner of a subscription must be a superuser.")));
+
+	form->subowner = newOwnerId;
+	CatalogTupleUpdate(rel, &tup->t_self, tup);
+
+	/* Update owner dependency reference */
+	changeDependencyOnOwner(SubscriptionRelationId,
+							form->oid,
+							newOwnerId);
+
+	InvokeObjectPostAlterHook(SubscriptionRelationId,
+							  form->oid, 0);
+}
+
+/*
+ * Change subscription owner -- by name
+ */
+ObjectAddress
+AlterSubscriptionOwner(const char *name, Oid newOwnerId)
+{
+	Oid			subid;
+	HeapTuple	tup;
+	Relation	rel;
+	ObjectAddress address;
+	Form_pg_subscription form;
+
+	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
+
+	tup = SearchSysCacheCopy2(SUBSCRIPTIONNAME, MyDatabaseId,
+							  CStringGetDatum(name));
+
+	if (!HeapTupleIsValid(tup))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("subscription \"%s\" does not exist", name)));
+
+	form = (Form_pg_subscription) GETSTRUCT(tup);
+	subid = form->oid;
+
+	AlterSubscriptionOwner_internal(rel, tup, newOwnerId);
+
+	ObjectAddressSet(address, SubscriptionRelationId, subid);
+
+	heap_freetuple(tup);
+
+	table_close(rel, RowExclusiveLock);
+
+	return address;
+}
+
+/*
+ * Change subscription owner -- by OID
+ */
+void
+AlterSubscriptionOwner_oid(Oid subid, Oid newOwnerId)
+{
+	HeapTuple	tup;
+	Relation	rel;
+
+	rel = table_open(SubscriptionRelationId, RowExclusiveLock);
+
+	tup = SearchSysCacheCopy1(SUBSCRIPTIONOID, ObjectIdGetDatum(subid));
+
+	if (!HeapTupleIsValid(tup))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("subscription with OID %u does not exist", subid)));
+
+	AlterSubscriptionOwner_internal(rel, tup, newOwnerId);
+
+	heap_freetuple(tup);
+
+	table_close(rel, RowExclusiveLock);
+}
+
+/*
+ * Get the list of tables which belong to specified publications on the
+ * publisher connection.
+ */
+static List *
+fetch_table_list(WalReceiverConn *wrconn, List *publications)
+{
+	WalRcvExecResult *res;
+	StringInfoData cmd;
+	TupleTableSlot *slot;
+	Oid			tableRow[2] = {TEXTOID, TEXTOID};
+	ListCell   *lc;
+	bool		first;
+	List	   *tablelist = NIL;
+
+	Assert(list_length(publications) > 0);
+
+	initStringInfo(&cmd);
+	appendStringInfoString(&cmd, "SELECT DISTINCT t.schemaname, t.tablename\n"
+						   "  FROM pg_catalog.pg_publication_tables t\n"
+						   " WHERE t.pubname IN (");
+	first = true;
+	foreach(lc, publications)
+	{
+		char	   *pubname = strVal(lfirst(lc));
+
+		if (first)
+			first = false;
+		else
+			appendStringInfoString(&cmd, ", ");
+
+		appendStringInfoString(&cmd, quote_literal_cstr(pubname));
+	}
+	appendStringInfoChar(&cmd, ')');
+
+	res = walrcv_exec(wrconn, cmd.data, 2, tableRow);
+	pfree(cmd.data);
+
+	if (res->status != WALRCV_OK_TUPLES)
+		ereport(ERROR,
+				(errcode(ERRCODE_CONNECTION_FAILURE),
+				 errmsg("could not receive list of replicated tables from the publisher: %s",
+						res->err)));
+
+	/* Process tables. */
+	slot = MakeSingleTupleTableSlot(res->tupledesc, &TTSOpsMinimalTuple);
+	while (tuplestore_gettupleslot(res->tuplestore, true, false, slot))
+	{
+		char	   *nspname;
+		char	   *relname;
+		bool		isnull;
+		RangeVar   *rv;
+
+		nspname = TextDatumGetCString(slot_getattr(slot, 1, &isnull));
+		Assert(!isnull);
+		relname = TextDatumGetCString(slot_getattr(slot, 2, &isnull));
+		Assert(!isnull);
+
+		rv = makeRangeVar(nspname, relname, -1);
+		tablelist = lappend(tablelist, rv);
+
+		ExecClearTuple(slot);
+	}
+	ExecDropSingleTupleTableSlot(slot);
+
+	walrcv_clear_result(res);
+
+	return tablelist;
+}
+
+/*
+ * This is to report the connection failure while dropping replication slots.
+ * Here, we report the WARNING for all tablesync slots so that user can drop
+ * them manually, if required.
+ */
+static void
+ReportSlotConnectionError(List *rstates, Oid subid, char *slotname, char *err)
+{
+	ListCell   *lc;
+
+	foreach(lc, rstates)
+	{
+		SubscriptionRelState *rstate = (SubscriptionRelState *) lfirst(lc);
+		Oid			relid = rstate->relid;
+
+		/* Only cleanup resources of tablesync workers */
+		if (!OidIsValid(relid))
+			continue;
+
+		/*
+		 * Caller needs to ensure that relstate doesn't change underneath us.
+		 * See DropSubscription where we get the relstates.
+		 */
+		if (rstate->state != SUBREL_STATE_SYNCDONE)
+		{
+			char		syncslotname[NAMEDATALEN] = {0};
+
+			ReplicationSlotNameForTablesync(subid, relid, syncslotname,
+											sizeof(syncslotname));
+			elog(WARNING, "could not drop tablesync replication slot \"%s\"",
+				 syncslotname);
+		}
+	}
+
+	ereport(ERROR,
+			(errcode(ERRCODE_CONNECTION_FAILURE),
+			 errmsg("could not connect to publisher when attempting to "
+					"drop replication slot \"%s\": %s", slotname, err),
+	/* translator: %s is an SQL ALTER command */
+			 errhint("Use %s to disassociate the subscription from the slot.",
+					 "ALTER SUBSCRIPTION ... SET (slot_name = NONE)")));
+}
+
+/*
+ * Check for duplicates in the given list of publications and error out if
+ * found one.  Add publications to datums as text datums, if datums is not
+ * NULL.
+ */
+static void
+check_duplicates_in_publist(List *publist, Datum *datums)
+{
+	ListCell   *cell;
+	int			j = 0;
+
+	foreach(cell, publist)
+	{
+		char	   *name = strVal(lfirst(cell));
+		ListCell   *pcell;
+
+		foreach(pcell, publist)
+		{
+			char	   *pname = strVal(lfirst(pcell));
+
+			if (pcell == cell)
+				break;
+
+			if (strcmp(name, pname) == 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_DUPLICATE_OBJECT),
+						 errmsg("publication name \"%s\" used more than once",
+								pname)));
+		}
+
+		if (datums)
+			datums[j++] = CStringGetTextDatum(name);
+	}
+}
+
+/*
+ * Merge current subscription's publications and user-specified publications
+ * from ADD/DROP PUBLICATIONS.
+ *
+ * If addpub is true, we will add the list of publications into oldpublist.
+ * Otherwise, we will delete the list of publications from oldpublist.  The
+ * returned list is a copy, oldpublist itself is not changed.
+ *
+ * subname is the subscription name, for error messages.
+ */
+static List *
+merge_publications(List *oldpublist, List *newpublist, bool addpub, const char *subname)
+{
+	ListCell   *lc;
+
+	oldpublist = list_copy(oldpublist);
+
+	check_duplicates_in_publist(newpublist, NULL);
+
+	foreach(lc, newpublist)
+	{
+		char	   *name = strVal(lfirst(lc));
+		ListCell   *lc2;
+		bool		found = false;
+
+		foreach(lc2, oldpublist)
+		{
+			char	   *pubname = strVal(lfirst(lc2));
+
+			if (strcmp(name, pubname) == 0)
+			{
+				found = true;
+				if (addpub)
+					ereport(ERROR,
+							(errcode(ERRCODE_DUPLICATE_OBJECT),
+							 errmsg("publication \"%s\" is already in subscription \"%s\"",
+									name, subname)));
+				else
+					oldpublist = foreach_delete_current(oldpublist, lc2);
+
+				break;
+			}
+		}
+
+		if (addpub && !found)
+			oldpublist = lappend(oldpublist, makeString(name));
+		else if (!addpub && !found)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
+					 errmsg("publication \"%s\" is not in subscription \"%s\"",
+							name, subname)));
+	}
+
+	/*
+	 * XXX Probably no strong reason for this, but for now it's to make ALTER
+	 * SUBSCRIPTION ... DROP PUBLICATION consistent with SET PUBLICATION.
+	 */
+	if (!oldpublist)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
+				 errmsg("cannot drop all the publications from a subscription")));
+
+	return oldpublist;
+}