Adding upstream version 14.5.upstream/14.5upstream

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

1 files changed, 1621 insertions, 0 deletions

diff --git a/src/backend/commands/foreigncmds.c b/src/backend/commands/foreigncmds.c
new file mode 100644
index 0000000..901b8bc
--- /dev/null
+++ b/src/backend/commands/foreigncmds.c
@@ -0,0 +1,1621 @@
+/*-------------------------------------------------------------------------
+ *
+ * foreigncmds.c
+ *	  foreign-data wrapper/server creation/manipulation commands
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/commands/foreigncmds.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/htup_details.h"
+#include "access/reloptions.h"
+#include "access/table.h"
+#include "access/xact.h"
+#include "catalog/catalog.h"
+#include "catalog/dependency.h"
+#include "catalog/indexing.h"
+#include "catalog/objectaccess.h"
+#include "catalog/pg_foreign_data_wrapper.h"
+#include "catalog/pg_foreign_server.h"
+#include "catalog/pg_foreign_table.h"
+#include "catalog/pg_proc.h"
+#include "catalog/pg_type.h"
+#include "catalog/pg_user_mapping.h"
+#include "commands/defrem.h"
+#include "foreign/fdwapi.h"
+#include "foreign/foreign.h"
+#include "miscadmin.h"
+#include "parser/parse_func.h"
+#include "tcop/utility.h"
+#include "utils/acl.h"
+#include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+#include "utils/syscache.h"
+
+
+typedef struct
+{
+	char	   *tablename;
+	char	   *cmd;
+} import_error_callback_arg;
+
+/* Internal functions */
+static void import_error_callback(void *arg);
+
+
+/*
+ * Convert a DefElem list to the text array format that is used in
+ * pg_foreign_data_wrapper, pg_foreign_server, pg_user_mapping, and
+ * pg_foreign_table.
+ *
+ * Returns the array in the form of a Datum, or PointerGetDatum(NULL)
+ * if the list is empty.
+ *
+ * Note: The array is usually stored to database without further
+ * processing, hence any validation should be done before this
+ * conversion.
+ */
+static Datum
+optionListToArray(List *options)
+{
+	ArrayBuildState *astate = NULL;
+	ListCell   *cell;
+
+	foreach(cell, options)
+	{
+		DefElem    *def = lfirst(cell);
+		const char *value;
+		Size		len;
+		text	   *t;
+
+		value = defGetString(def);
+		len = VARHDRSZ + strlen(def->defname) + 1 + strlen(value);
+		t = palloc(len + 1);
+		SET_VARSIZE(t, len);
+		sprintf(VARDATA(t), "%s=%s", def->defname, value);
+
+		astate = accumArrayResult(astate, PointerGetDatum(t),
+								  false, TEXTOID,
+								  CurrentMemoryContext);
+	}
+
+	if (astate)
+		return makeArrayResult(astate, CurrentMemoryContext);
+
+	return PointerGetDatum(NULL);
+}
+
+
+/*
+ * Transform a list of DefElem into text array format.  This is substantially
+ * the same thing as optionListToArray(), except we recognize SET/ADD/DROP
+ * actions for modifying an existing list of options, which is passed in
+ * Datum form as oldOptions.  Also, if fdwvalidator isn't InvalidOid
+ * it specifies a validator function to call on the result.
+ *
+ * Returns the array in the form of a Datum, or PointerGetDatum(NULL)
+ * if the list is empty.
+ *
+ * This is used by CREATE/ALTER of FOREIGN DATA WRAPPER/SERVER/USER MAPPING/
+ * FOREIGN TABLE.
+ */
+Datum
+transformGenericOptions(Oid catalogId,
+						Datum oldOptions,
+						List *options,
+						Oid fdwvalidator)
+{
+	List	   *resultOptions = untransformRelOptions(oldOptions);
+	ListCell   *optcell;
+	Datum		result;
+
+	foreach(optcell, options)
+	{
+		DefElem    *od = lfirst(optcell);
+		ListCell   *cell;
+
+		/*
+		 * Find the element in resultOptions.  We need this for validation in
+		 * all cases.
+		 */
+		foreach(cell, resultOptions)
+		{
+			DefElem    *def = lfirst(cell);
+
+			if (strcmp(def->defname, od->defname) == 0)
+				break;
+		}
+
+		/*
+		 * It is possible to perform multiple SET/DROP actions on the same
+		 * option.  The standard permits this, as long as the options to be
+		 * added are unique.  Note that an unspecified action is taken to be
+		 * ADD.
+		 */
+		switch (od->defaction)
+		{
+			case DEFELEM_DROP:
+				if (!cell)
+					ereport(ERROR,
+							(errcode(ERRCODE_UNDEFINED_OBJECT),
+							 errmsg("option \"%s\" not found",
+									od->defname)));
+				resultOptions = list_delete_cell(resultOptions, cell);
+				break;
+
+			case DEFELEM_SET:
+				if (!cell)
+					ereport(ERROR,
+							(errcode(ERRCODE_UNDEFINED_OBJECT),
+							 errmsg("option \"%s\" not found",
+									od->defname)));
+				lfirst(cell) = od;
+				break;
+
+			case DEFELEM_ADD:
+			case DEFELEM_UNSPEC:
+				if (cell)
+					ereport(ERROR,
+							(errcode(ERRCODE_DUPLICATE_OBJECT),
+							 errmsg("option \"%s\" provided more than once",
+									od->defname)));
+				resultOptions = lappend(resultOptions, od);
+				break;
+
+			default:
+				elog(ERROR, "unrecognized action %d on option \"%s\"",
+					 (int) od->defaction, od->defname);
+				break;
+		}
+	}
+
+	result = optionListToArray(resultOptions);
+
+	if (OidIsValid(fdwvalidator))
+	{
+		Datum		valarg = result;
+
+		/*
+		 * Pass a null options list as an empty array, so that validators
+		 * don't have to be declared non-strict to handle the case.
+		 */
+		if (DatumGetPointer(valarg) == NULL)
+			valarg = PointerGetDatum(construct_empty_array(TEXTOID));
+		OidFunctionCall2(fdwvalidator, valarg, ObjectIdGetDatum(catalogId));
+	}
+
+	return result;
+}
+
+
+/*
+ * Internal workhorse for changing a data wrapper's owner.
+ *
+ * Allow this only for superusers; also the new owner must be a
+ * superuser.
+ */
+static void
+AlterForeignDataWrapperOwner_internal(Relation rel, HeapTuple tup, Oid newOwnerId)
+{
+	Form_pg_foreign_data_wrapper form;
+	Datum		repl_val[Natts_pg_foreign_data_wrapper];
+	bool		repl_null[Natts_pg_foreign_data_wrapper];
+	bool		repl_repl[Natts_pg_foreign_data_wrapper];
+	Acl		   *newAcl;
+	Datum		aclDatum;
+	bool		isNull;
+
+	form = (Form_pg_foreign_data_wrapper) GETSTRUCT(tup);
+
+	/* Must be a superuser to change a FDW owner */
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("permission denied to change owner of foreign-data wrapper \"%s\"",
+						NameStr(form->fdwname)),
+				 errhint("Must be superuser to change owner of a foreign-data wrapper.")));
+
+	/* New owner must also be a superuser */
+	if (!superuser_arg(newOwnerId))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("permission denied to change owner of foreign-data wrapper \"%s\"",
+						NameStr(form->fdwname)),
+				 errhint("The owner of a foreign-data wrapper must be a superuser.")));
+
+	if (form->fdwowner != newOwnerId)
+	{
+		memset(repl_null, false, sizeof(repl_null));
+		memset(repl_repl, false, sizeof(repl_repl));
+
+		repl_repl[Anum_pg_foreign_data_wrapper_fdwowner - 1] = true;
+		repl_val[Anum_pg_foreign_data_wrapper_fdwowner - 1] = ObjectIdGetDatum(newOwnerId);
+
+		aclDatum = heap_getattr(tup,
+								Anum_pg_foreign_data_wrapper_fdwacl,
+								RelationGetDescr(rel),
+								&isNull);
+		/* Null ACLs do not require changes */
+		if (!isNull)
+		{
+			newAcl = aclnewowner(DatumGetAclP(aclDatum),
+								 form->fdwowner, newOwnerId);
+			repl_repl[Anum_pg_foreign_data_wrapper_fdwacl - 1] = true;
+			repl_val[Anum_pg_foreign_data_wrapper_fdwacl - 1] = PointerGetDatum(newAcl);
+		}
+
+		tup = heap_modify_tuple(tup, RelationGetDescr(rel), repl_val, repl_null,
+								repl_repl);
+
+		CatalogTupleUpdate(rel, &tup->t_self, tup);
+
+		/* Update owner dependency reference */
+		changeDependencyOnOwner(ForeignDataWrapperRelationId,
+								form->oid,
+								newOwnerId);
+	}
+
+	InvokeObjectPostAlterHook(ForeignDataWrapperRelationId,
+							  form->oid, 0);
+}
+
+/*
+ * Change foreign-data wrapper owner -- by name
+ *
+ * Note restrictions in the "_internal" function, above.
+ */
+ObjectAddress
+AlterForeignDataWrapperOwner(const char *name, Oid newOwnerId)
+{
+	Oid			fdwId;
+	HeapTuple	tup;
+	Relation	rel;
+	ObjectAddress address;
+	Form_pg_foreign_data_wrapper form;
+
+
+	rel = table_open(ForeignDataWrapperRelationId, RowExclusiveLock);
+
+	tup = SearchSysCacheCopy1(FOREIGNDATAWRAPPERNAME, CStringGetDatum(name));
+
+	if (!HeapTupleIsValid(tup))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("foreign-data wrapper \"%s\" does not exist", name)));
+
+	form = (Form_pg_foreign_data_wrapper) GETSTRUCT(tup);
+	fdwId = form->oid;
+
+	AlterForeignDataWrapperOwner_internal(rel, tup, newOwnerId);
+
+	ObjectAddressSet(address, ForeignDataWrapperRelationId, fdwId);
+
+	heap_freetuple(tup);
+
+	table_close(rel, RowExclusiveLock);
+
+	return address;
+}
+
+/*
+ * Change foreign-data wrapper owner -- by OID
+ *
+ * Note restrictions in the "_internal" function, above.
+ */
+void
+AlterForeignDataWrapperOwner_oid(Oid fwdId, Oid newOwnerId)
+{
+	HeapTuple	tup;
+	Relation	rel;
+
+	rel = table_open(ForeignDataWrapperRelationId, RowExclusiveLock);
+
+	tup = SearchSysCacheCopy1(FOREIGNDATAWRAPPEROID, ObjectIdGetDatum(fwdId));
+
+	if (!HeapTupleIsValid(tup))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("foreign-data wrapper with OID %u does not exist", fwdId)));
+
+	AlterForeignDataWrapperOwner_internal(rel, tup, newOwnerId);
+
+	heap_freetuple(tup);
+
+	table_close(rel, RowExclusiveLock);
+}
+
+/*
+ * Internal workhorse for changing a foreign server's owner
+ */
+static void
+AlterForeignServerOwner_internal(Relation rel, HeapTuple tup, Oid newOwnerId)
+{
+	Form_pg_foreign_server form;
+	Datum		repl_val[Natts_pg_foreign_server];
+	bool		repl_null[Natts_pg_foreign_server];
+	bool		repl_repl[Natts_pg_foreign_server];
+	Acl		   *newAcl;
+	Datum		aclDatum;
+	bool		isNull;
+
+	form = (Form_pg_foreign_server) GETSTRUCT(tup);
+
+	if (form->srvowner != newOwnerId)
+	{
+		/* Superusers can always do it */
+		if (!superuser())
+		{
+			Oid			srvId;
+			AclResult	aclresult;
+
+			srvId = form->oid;
+
+			/* Must be owner */
+			if (!pg_foreign_server_ownercheck(srvId, GetUserId()))
+				aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_FOREIGN_SERVER,
+							   NameStr(form->srvname));
+
+			/* Must be able to become new owner */
+			check_is_member_of_role(GetUserId(), newOwnerId);
+
+			/* New owner must have USAGE privilege on foreign-data wrapper */
+			aclresult = pg_foreign_data_wrapper_aclcheck(form->srvfdw, newOwnerId, ACL_USAGE);
+			if (aclresult != ACLCHECK_OK)
+			{
+				ForeignDataWrapper *fdw = GetForeignDataWrapper(form->srvfdw);
+
+				aclcheck_error(aclresult, OBJECT_FDW, fdw->fdwname);
+			}
+		}
+
+		memset(repl_null, false, sizeof(repl_null));
+		memset(repl_repl, false, sizeof(repl_repl));
+
+		repl_repl[Anum_pg_foreign_server_srvowner - 1] = true;
+		repl_val[Anum_pg_foreign_server_srvowner - 1] = ObjectIdGetDatum(newOwnerId);
+
+		aclDatum = heap_getattr(tup,
+								Anum_pg_foreign_server_srvacl,
+								RelationGetDescr(rel),
+								&isNull);
+		/* Null ACLs do not require changes */
+		if (!isNull)
+		{
+			newAcl = aclnewowner(DatumGetAclP(aclDatum),
+								 form->srvowner, newOwnerId);
+			repl_repl[Anum_pg_foreign_server_srvacl - 1] = true;
+			repl_val[Anum_pg_foreign_server_srvacl - 1] = PointerGetDatum(newAcl);
+		}
+
+		tup = heap_modify_tuple(tup, RelationGetDescr(rel), repl_val, repl_null,
+								repl_repl);
+
+		CatalogTupleUpdate(rel, &tup->t_self, tup);
+
+		/* Update owner dependency reference */
+		changeDependencyOnOwner(ForeignServerRelationId, form->oid,
+								newOwnerId);
+	}
+
+	InvokeObjectPostAlterHook(ForeignServerRelationId,
+							  form->oid, 0);
+}
+
+/*
+ * Change foreign server owner -- by name
+ */
+ObjectAddress
+AlterForeignServerOwner(const char *name, Oid newOwnerId)
+{
+	Oid			servOid;
+	HeapTuple	tup;
+	Relation	rel;
+	ObjectAddress address;
+	Form_pg_foreign_server form;
+
+	rel = table_open(ForeignServerRelationId, RowExclusiveLock);
+
+	tup = SearchSysCacheCopy1(FOREIGNSERVERNAME, CStringGetDatum(name));
+
+	if (!HeapTupleIsValid(tup))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("server \"%s\" does not exist", name)));
+
+	form = (Form_pg_foreign_server) GETSTRUCT(tup);
+	servOid = form->oid;
+
+	AlterForeignServerOwner_internal(rel, tup, newOwnerId);
+
+	ObjectAddressSet(address, ForeignServerRelationId, servOid);
+
+	heap_freetuple(tup);
+
+	table_close(rel, RowExclusiveLock);
+
+	return address;
+}
+
+/*
+ * Change foreign server owner -- by OID
+ */
+void
+AlterForeignServerOwner_oid(Oid srvId, Oid newOwnerId)
+{
+	HeapTuple	tup;
+	Relation	rel;
+
+	rel = table_open(ForeignServerRelationId, RowExclusiveLock);
+
+	tup = SearchSysCacheCopy1(FOREIGNSERVEROID, ObjectIdGetDatum(srvId));
+
+	if (!HeapTupleIsValid(tup))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("foreign server with OID %u does not exist", srvId)));
+
+	AlterForeignServerOwner_internal(rel, tup, newOwnerId);
+
+	heap_freetuple(tup);
+
+	table_close(rel, RowExclusiveLock);
+}
+
+/*
+ * Convert a handler function name passed from the parser to an Oid.
+ */
+static Oid
+lookup_fdw_handler_func(DefElem *handler)
+{
+	Oid			handlerOid;
+
+	if (handler == NULL || handler->arg == NULL)
+		return InvalidOid;
+
+	/* handlers have no arguments */
+	handlerOid = LookupFuncName((List *) handler->arg, 0, NULL, false);
+
+	/* check that handler has correct return type */
+	if (get_func_rettype(handlerOid) != FDW_HANDLEROID)
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("function %s must return type %s",
+						NameListToString((List *) handler->arg), "fdw_handler")));
+
+	return handlerOid;
+}
+
+/*
+ * Convert a validator function name passed from the parser to an Oid.
+ */
+static Oid
+lookup_fdw_validator_func(DefElem *validator)
+{
+	Oid			funcargtypes[2];
+
+	if (validator == NULL || validator->arg == NULL)
+		return InvalidOid;
+
+	/* validators take text[], oid */
+	funcargtypes[0] = TEXTARRAYOID;
+	funcargtypes[1] = OIDOID;
+
+	return LookupFuncName((List *) validator->arg, 2, funcargtypes, false);
+	/* validator's return value is ignored, so we don't check the type */
+}
+
+/*
+ * Process function options of CREATE/ALTER FDW
+ */
+static void
+parse_func_options(List *func_options,
+				   bool *handler_given, Oid *fdwhandler,
+				   bool *validator_given, Oid *fdwvalidator)
+{
+	ListCell   *cell;
+
+	*handler_given = false;
+	*validator_given = false;
+	/* return InvalidOid if not given */
+	*fdwhandler = InvalidOid;
+	*fdwvalidator = InvalidOid;
+
+	foreach(cell, func_options)
+	{
+		DefElem    *def = (DefElem *) lfirst(cell);
+
+		if (strcmp(def->defname, "handler") == 0)
+		{
+			if (*handler_given)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			*handler_given = true;
+			*fdwhandler = lookup_fdw_handler_func(def);
+		}
+		else if (strcmp(def->defname, "validator") == 0)
+		{
+			if (*validator_given)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			*validator_given = true;
+			*fdwvalidator = lookup_fdw_validator_func(def);
+		}
+		else
+			elog(ERROR, "option \"%s\" not recognized",
+				 def->defname);
+	}
+}
+
+/*
+ * Create a foreign-data wrapper
+ */
+ObjectAddress
+CreateForeignDataWrapper(CreateFdwStmt *stmt)
+{
+	Relation	rel;
+	Datum		values[Natts_pg_foreign_data_wrapper];
+	bool		nulls[Natts_pg_foreign_data_wrapper];
+	HeapTuple	tuple;
+	Oid			fdwId;
+	bool		handler_given;
+	bool		validator_given;
+	Oid			fdwhandler;
+	Oid			fdwvalidator;
+	Datum		fdwoptions;
+	Oid			ownerId;
+	ObjectAddress myself;
+	ObjectAddress referenced;
+
+	rel = table_open(ForeignDataWrapperRelationId, RowExclusiveLock);
+
+	/* Must be super user */
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("permission denied to create foreign-data wrapper \"%s\"",
+						stmt->fdwname),
+				 errhint("Must be superuser to create a foreign-data wrapper.")));
+
+	/* For now the owner cannot be specified on create. Use effective user ID. */
+	ownerId = GetUserId();
+
+	/*
+	 * Check that there is no other foreign-data wrapper by this name.
+	 */
+	if (GetForeignDataWrapperByName(stmt->fdwname, true) != NULL)
+		ereport(ERROR,
+				(errcode(ERRCODE_DUPLICATE_OBJECT),
+				 errmsg("foreign-data wrapper \"%s\" already exists",
+						stmt->fdwname)));
+
+	/*
+	 * Insert tuple into pg_foreign_data_wrapper.
+	 */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+
+	fdwId = GetNewOidWithIndex(rel, ForeignDataWrapperOidIndexId,
+							   Anum_pg_foreign_data_wrapper_oid);
+	values[Anum_pg_foreign_data_wrapper_oid - 1] = ObjectIdGetDatum(fdwId);
+	values[Anum_pg_foreign_data_wrapper_fdwname - 1] =
+		DirectFunctionCall1(namein, CStringGetDatum(stmt->fdwname));
+	values[Anum_pg_foreign_data_wrapper_fdwowner - 1] = ObjectIdGetDatum(ownerId);
+
+	/* Lookup handler and validator functions, if given */
+	parse_func_options(stmt->func_options,
+					   &handler_given, &fdwhandler,
+					   &validator_given, &fdwvalidator);
+
+	values[Anum_pg_foreign_data_wrapper_fdwhandler - 1] = ObjectIdGetDatum(fdwhandler);
+	values[Anum_pg_foreign_data_wrapper_fdwvalidator - 1] = ObjectIdGetDatum(fdwvalidator);
+
+	nulls[Anum_pg_foreign_data_wrapper_fdwacl - 1] = true;
+
+	fdwoptions = transformGenericOptions(ForeignDataWrapperRelationId,
+										 PointerGetDatum(NULL),
+										 stmt->options,
+										 fdwvalidator);
+
+	if (PointerIsValid(DatumGetPointer(fdwoptions)))
+		values[Anum_pg_foreign_data_wrapper_fdwoptions - 1] = fdwoptions;
+	else
+		nulls[Anum_pg_foreign_data_wrapper_fdwoptions - 1] = true;
+
+	tuple = heap_form_tuple(rel->rd_att, values, nulls);
+
+	CatalogTupleInsert(rel, tuple);
+
+	heap_freetuple(tuple);
+
+	/* record dependencies */
+	myself.classId = ForeignDataWrapperRelationId;
+	myself.objectId = fdwId;
+	myself.objectSubId = 0;
+
+	if (OidIsValid(fdwhandler))
+	{
+		referenced.classId = ProcedureRelationId;
+		referenced.objectId = fdwhandler;
+		referenced.objectSubId = 0;
+		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	}
+
+	if (OidIsValid(fdwvalidator))
+	{
+		referenced.classId = ProcedureRelationId;
+		referenced.objectId = fdwvalidator;
+		referenced.objectSubId = 0;
+		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	}
+
+	recordDependencyOnOwner(ForeignDataWrapperRelationId, fdwId, ownerId);
+
+	/* dependency on extension */
+	recordDependencyOnCurrentExtension(&myself, false);
+
+	/* Post creation hook for new foreign data wrapper */
+	InvokeObjectPostCreateHook(ForeignDataWrapperRelationId, fdwId, 0);
+
+	table_close(rel, RowExclusiveLock);
+
+	return myself;
+}
+
+
+/*
+ * Alter foreign-data wrapper
+ */
+ObjectAddress
+AlterForeignDataWrapper(AlterFdwStmt *stmt)
+{
+	Relation	rel;
+	HeapTuple	tp;
+	Form_pg_foreign_data_wrapper fdwForm;
+	Datum		repl_val[Natts_pg_foreign_data_wrapper];
+	bool		repl_null[Natts_pg_foreign_data_wrapper];
+	bool		repl_repl[Natts_pg_foreign_data_wrapper];
+	Oid			fdwId;
+	bool		isnull;
+	Datum		datum;
+	bool		handler_given;
+	bool		validator_given;
+	Oid			fdwhandler;
+	Oid			fdwvalidator;
+	ObjectAddress myself;
+
+	rel = table_open(ForeignDataWrapperRelationId, RowExclusiveLock);
+
+	/* Must be super user */
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("permission denied to alter foreign-data wrapper \"%s\"",
+						stmt->fdwname),
+				 errhint("Must be superuser to alter a foreign-data wrapper.")));
+
+	tp = SearchSysCacheCopy1(FOREIGNDATAWRAPPERNAME,
+							 CStringGetDatum(stmt->fdwname));
+
+	if (!HeapTupleIsValid(tp))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("foreign-data wrapper \"%s\" does not exist", stmt->fdwname)));
+
+	fdwForm = (Form_pg_foreign_data_wrapper) GETSTRUCT(tp);
+	fdwId = fdwForm->oid;
+
+	memset(repl_val, 0, sizeof(repl_val));
+	memset(repl_null, false, sizeof(repl_null));
+	memset(repl_repl, false, sizeof(repl_repl));
+
+	parse_func_options(stmt->func_options,
+					   &handler_given, &fdwhandler,
+					   &validator_given, &fdwvalidator);
+
+	if (handler_given)
+	{
+		repl_val[Anum_pg_foreign_data_wrapper_fdwhandler - 1] = ObjectIdGetDatum(fdwhandler);
+		repl_repl[Anum_pg_foreign_data_wrapper_fdwhandler - 1] = true;
+
+		/*
+		 * It could be that the behavior of accessing foreign table changes
+		 * with the new handler.  Warn about this.
+		 */
+		ereport(WARNING,
+				(errmsg("changing the foreign-data wrapper handler can change behavior of existing foreign tables")));
+	}
+
+	if (validator_given)
+	{
+		repl_val[Anum_pg_foreign_data_wrapper_fdwvalidator - 1] = ObjectIdGetDatum(fdwvalidator);
+		repl_repl[Anum_pg_foreign_data_wrapper_fdwvalidator - 1] = true;
+
+		/*
+		 * It could be that existing options for the FDW or dependent SERVER,
+		 * USER MAPPING or FOREIGN TABLE objects are no longer valid according
+		 * to the new validator.  Warn about this.
+		 */
+		if (OidIsValid(fdwvalidator))
+			ereport(WARNING,
+					(errmsg("changing the foreign-data wrapper validator can cause "
+							"the options for dependent objects to become invalid")));
+	}
+	else
+	{
+		/*
+		 * Validator is not changed, but we need it for validating options.
+		 */
+		fdwvalidator = fdwForm->fdwvalidator;
+	}
+
+	/*
+	 * If options specified, validate and update.
+	 */
+	if (stmt->options)
+	{
+		/* Extract the current options */
+		datum = SysCacheGetAttr(FOREIGNDATAWRAPPEROID,
+								tp,
+								Anum_pg_foreign_data_wrapper_fdwoptions,
+								&isnull);
+		if (isnull)
+			datum = PointerGetDatum(NULL);
+
+		/* Transform the options */
+		datum = transformGenericOptions(ForeignDataWrapperRelationId,
+										datum,
+										stmt->options,
+										fdwvalidator);
+
+		if (PointerIsValid(DatumGetPointer(datum)))
+			repl_val[Anum_pg_foreign_data_wrapper_fdwoptions - 1] = datum;
+		else
+			repl_null[Anum_pg_foreign_data_wrapper_fdwoptions - 1] = true;
+
+		repl_repl[Anum_pg_foreign_data_wrapper_fdwoptions - 1] = true;
+	}
+
+	/* Everything looks good - update the tuple */
+	tp = heap_modify_tuple(tp, RelationGetDescr(rel),
+						   repl_val, repl_null, repl_repl);
+
+	CatalogTupleUpdate(rel, &tp->t_self, tp);
+
+	heap_freetuple(tp);
+
+	ObjectAddressSet(myself, ForeignDataWrapperRelationId, fdwId);
+
+	/* Update function dependencies if we changed them */
+	if (handler_given || validator_given)
+	{
+		ObjectAddress referenced;
+
+		/*
+		 * Flush all existing dependency records of this FDW on functions; we
+		 * assume there can be none other than the ones we are fixing.
+		 */
+		deleteDependencyRecordsForClass(ForeignDataWrapperRelationId,
+										fdwId,
+										ProcedureRelationId,
+										DEPENDENCY_NORMAL);
+
+		/* And build new ones. */
+
+		if (OidIsValid(fdwhandler))
+		{
+			referenced.classId = ProcedureRelationId;
+			referenced.objectId = fdwhandler;
+			referenced.objectSubId = 0;
+			recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+		}
+
+		if (OidIsValid(fdwvalidator))
+		{
+			referenced.classId = ProcedureRelationId;
+			referenced.objectId = fdwvalidator;
+			referenced.objectSubId = 0;
+			recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+		}
+	}
+
+	InvokeObjectPostAlterHook(ForeignDataWrapperRelationId, fdwId, 0);
+
+	table_close(rel, RowExclusiveLock);
+
+	return myself;
+}
+
+
+/*
+ * Create a foreign server
+ */
+ObjectAddress
+CreateForeignServer(CreateForeignServerStmt *stmt)
+{
+	Relation	rel;
+	Datum		srvoptions;
+	Datum		values[Natts_pg_foreign_server];
+	bool		nulls[Natts_pg_foreign_server];
+	HeapTuple	tuple;
+	Oid			srvId;
+	Oid			ownerId;
+	AclResult	aclresult;
+	ObjectAddress myself;
+	ObjectAddress referenced;
+	ForeignDataWrapper *fdw;
+
+	rel = table_open(ForeignServerRelationId, RowExclusiveLock);
+
+	/* For now the owner cannot be specified on create. Use effective user ID. */
+	ownerId = GetUserId();
+
+	/*
+	 * Check that there is no other foreign server by this name.  If there is
+	 * one, do nothing if IF NOT EXISTS was specified.
+	 */
+	srvId = get_foreign_server_oid(stmt->servername, true);
+	if (OidIsValid(srvId))
+	{
+		if (stmt->if_not_exists)
+		{
+			/*
+			 * If we are in an extension script, insist that the pre-existing
+			 * object be a member of the extension, to avoid security risks.
+			 */
+			ObjectAddressSet(myself, ForeignServerRelationId, srvId);
+			checkMembershipInCurrentExtension(&myself);
+
+			/* OK to skip */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_OBJECT),
+					 errmsg("server \"%s\" already exists, skipping",
+							stmt->servername)));
+			table_close(rel, RowExclusiveLock);
+			return InvalidObjectAddress;
+		}
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_OBJECT),
+					 errmsg("server \"%s\" already exists",
+							stmt->servername)));
+	}
+
+	/*
+	 * Check that the FDW exists and that we have USAGE on it. Also get the
+	 * actual FDW for option validation etc.
+	 */
+	fdw = GetForeignDataWrapperByName(stmt->fdwname, false);
+
+	aclresult = pg_foreign_data_wrapper_aclcheck(fdw->fdwid, ownerId, ACL_USAGE);
+	if (aclresult != ACLCHECK_OK)
+		aclcheck_error(aclresult, OBJECT_FDW, fdw->fdwname);
+
+	/*
+	 * Insert tuple into pg_foreign_server.
+	 */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+
+	srvId = GetNewOidWithIndex(rel, ForeignServerOidIndexId,
+							   Anum_pg_foreign_server_oid);
+	values[Anum_pg_foreign_server_oid - 1] = ObjectIdGetDatum(srvId);
+	values[Anum_pg_foreign_server_srvname - 1] =
+		DirectFunctionCall1(namein, CStringGetDatum(stmt->servername));
+	values[Anum_pg_foreign_server_srvowner - 1] = ObjectIdGetDatum(ownerId);
+	values[Anum_pg_foreign_server_srvfdw - 1] = ObjectIdGetDatum(fdw->fdwid);
+
+	/* Add server type if supplied */
+	if (stmt->servertype)
+		values[Anum_pg_foreign_server_srvtype - 1] =
+			CStringGetTextDatum(stmt->servertype);
+	else
+		nulls[Anum_pg_foreign_server_srvtype - 1] = true;
+
+	/* Add server version if supplied */
+	if (stmt->version)
+		values[Anum_pg_foreign_server_srvversion - 1] =
+			CStringGetTextDatum(stmt->version);
+	else
+		nulls[Anum_pg_foreign_server_srvversion - 1] = true;
+
+	/* Start with a blank acl */
+	nulls[Anum_pg_foreign_server_srvacl - 1] = true;
+
+	/* Add server options */
+	srvoptions = transformGenericOptions(ForeignServerRelationId,
+										 PointerGetDatum(NULL),
+										 stmt->options,
+										 fdw->fdwvalidator);
+
+	if (PointerIsValid(DatumGetPointer(srvoptions)))
+		values[Anum_pg_foreign_server_srvoptions - 1] = srvoptions;
+	else
+		nulls[Anum_pg_foreign_server_srvoptions - 1] = true;
+
+	tuple = heap_form_tuple(rel->rd_att, values, nulls);
+
+	CatalogTupleInsert(rel, tuple);
+
+	heap_freetuple(tuple);
+
+	/* record dependencies */
+	myself.classId = ForeignServerRelationId;
+	myself.objectId = srvId;
+	myself.objectSubId = 0;
+
+	referenced.classId = ForeignDataWrapperRelationId;
+	referenced.objectId = fdw->fdwid;
+	referenced.objectSubId = 0;
+	recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+
+	recordDependencyOnOwner(ForeignServerRelationId, srvId, ownerId);
+
+	/* dependency on extension */
+	recordDependencyOnCurrentExtension(&myself, false);
+
+	/* Post creation hook for new foreign server */
+	InvokeObjectPostCreateHook(ForeignServerRelationId, srvId, 0);
+
+	table_close(rel, RowExclusiveLock);
+
+	return myself;
+}
+
+
+/*
+ * Alter foreign server
+ */
+ObjectAddress
+AlterForeignServer(AlterForeignServerStmt *stmt)
+{
+	Relation	rel;
+	HeapTuple	tp;
+	Datum		repl_val[Natts_pg_foreign_server];
+	bool		repl_null[Natts_pg_foreign_server];
+	bool		repl_repl[Natts_pg_foreign_server];
+	Oid			srvId;
+	Form_pg_foreign_server srvForm;
+	ObjectAddress address;
+
+	rel = table_open(ForeignServerRelationId, RowExclusiveLock);
+
+	tp = SearchSysCacheCopy1(FOREIGNSERVERNAME,
+							 CStringGetDatum(stmt->servername));
+
+	if (!HeapTupleIsValid(tp))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("server \"%s\" does not exist", stmt->servername)));
+
+	srvForm = (Form_pg_foreign_server) GETSTRUCT(tp);
+	srvId = srvForm->oid;
+
+	/*
+	 * Only owner or a superuser can ALTER a SERVER.
+	 */
+	if (!pg_foreign_server_ownercheck(srvId, GetUserId()))
+		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_FOREIGN_SERVER,
+					   stmt->servername);
+
+	memset(repl_val, 0, sizeof(repl_val));
+	memset(repl_null, false, sizeof(repl_null));
+	memset(repl_repl, false, sizeof(repl_repl));
+
+	if (stmt->has_version)
+	{
+		/*
+		 * Change the server VERSION string.
+		 */
+		if (stmt->version)
+			repl_val[Anum_pg_foreign_server_srvversion - 1] =
+				CStringGetTextDatum(stmt->version);
+		else
+			repl_null[Anum_pg_foreign_server_srvversion - 1] = true;
+
+		repl_repl[Anum_pg_foreign_server_srvversion - 1] = true;
+	}
+
+	if (stmt->options)
+	{
+		ForeignDataWrapper *fdw = GetForeignDataWrapper(srvForm->srvfdw);
+		Datum		datum;
+		bool		isnull;
+
+		/* Extract the current srvoptions */
+		datum = SysCacheGetAttr(FOREIGNSERVEROID,
+								tp,
+								Anum_pg_foreign_server_srvoptions,
+								&isnull);
+		if (isnull)
+			datum = PointerGetDatum(NULL);
+
+		/* Prepare the options array */
+		datum = transformGenericOptions(ForeignServerRelationId,
+										datum,
+										stmt->options,
+										fdw->fdwvalidator);
+
+		if (PointerIsValid(DatumGetPointer(datum)))
+			repl_val[Anum_pg_foreign_server_srvoptions - 1] = datum;
+		else
+			repl_null[Anum_pg_foreign_server_srvoptions - 1] = true;
+
+		repl_repl[Anum_pg_foreign_server_srvoptions - 1] = true;
+	}
+
+	/* Everything looks good - update the tuple */
+	tp = heap_modify_tuple(tp, RelationGetDescr(rel),
+						   repl_val, repl_null, repl_repl);
+
+	CatalogTupleUpdate(rel, &tp->t_self, tp);
+
+	InvokeObjectPostAlterHook(ForeignServerRelationId, srvId, 0);
+
+	ObjectAddressSet(address, ForeignServerRelationId, srvId);
+
+	heap_freetuple(tp);
+
+	table_close(rel, RowExclusiveLock);
+
+	return address;
+}
+
+
+/*
+ * Common routine to check permission for user-mapping-related DDL
+ * commands.  We allow server owners to operate on any mapping, and
+ * users to operate on their own mapping.
+ */
+static void
+user_mapping_ddl_aclcheck(Oid umuserid, Oid serverid, const char *servername)
+{
+	Oid			curuserid = GetUserId();
+
+	if (!pg_foreign_server_ownercheck(serverid, curuserid))
+	{
+		if (umuserid == curuserid)
+		{
+			AclResult	aclresult;
+
+			aclresult = pg_foreign_server_aclcheck(serverid, curuserid, ACL_USAGE);
+			if (aclresult != ACLCHECK_OK)
+				aclcheck_error(aclresult, OBJECT_FOREIGN_SERVER, servername);
+		}
+		else
+			aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_FOREIGN_SERVER,
+						   servername);
+	}
+}
+
+
+/*
+ * Create user mapping
+ */
+ObjectAddress
+CreateUserMapping(CreateUserMappingStmt *stmt)
+{
+	Relation	rel;
+	Datum		useoptions;
+	Datum		values[Natts_pg_user_mapping];
+	bool		nulls[Natts_pg_user_mapping];
+	HeapTuple	tuple;
+	Oid			useId;
+	Oid			umId;
+	ObjectAddress myself;
+	ObjectAddress referenced;
+	ForeignServer *srv;
+	ForeignDataWrapper *fdw;
+	RoleSpec   *role = (RoleSpec *) stmt->user;
+
+	rel = table_open(UserMappingRelationId, RowExclusiveLock);
+
+	if (role->roletype == ROLESPEC_PUBLIC)
+		useId = ACL_ID_PUBLIC;
+	else
+		useId = get_rolespec_oid(stmt->user, false);
+
+	/* Check that the server exists. */
+	srv = GetForeignServerByName(stmt->servername, false);
+
+	user_mapping_ddl_aclcheck(useId, srv->serverid, stmt->servername);
+
+	/*
+	 * Check that the user mapping is unique within server.
+	 */
+	umId = GetSysCacheOid2(USERMAPPINGUSERSERVER, Anum_pg_user_mapping_oid,
+						   ObjectIdGetDatum(useId),
+						   ObjectIdGetDatum(srv->serverid));
+
+	if (OidIsValid(umId))
+	{
+		if (stmt->if_not_exists)
+		{
+			/*
+			 * Since user mappings aren't members of extensions (see comments
+			 * below), no need for checkMembershipInCurrentExtension here.
+			 */
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_OBJECT),
+					 errmsg("user mapping for \"%s\" already exists for server \"%s\", skipping",
+							MappingUserName(useId),
+							stmt->servername)));
+
+			table_close(rel, RowExclusiveLock);
+			return InvalidObjectAddress;
+		}
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_OBJECT),
+					 errmsg("user mapping for \"%s\" already exists for server \"%s\"",
+							MappingUserName(useId),
+							stmt->servername)));
+	}
+
+	fdw = GetForeignDataWrapper(srv->fdwid);
+
+	/*
+	 * Insert tuple into pg_user_mapping.
+	 */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+
+	umId = GetNewOidWithIndex(rel, UserMappingOidIndexId,
+							  Anum_pg_user_mapping_oid);
+	values[Anum_pg_user_mapping_oid - 1] = ObjectIdGetDatum(umId);
+	values[Anum_pg_user_mapping_umuser - 1] = ObjectIdGetDatum(useId);
+	values[Anum_pg_user_mapping_umserver - 1] = ObjectIdGetDatum(srv->serverid);
+
+	/* Add user options */
+	useoptions = transformGenericOptions(UserMappingRelationId,
+										 PointerGetDatum(NULL),
+										 stmt->options,
+										 fdw->fdwvalidator);
+
+	if (PointerIsValid(DatumGetPointer(useoptions)))
+		values[Anum_pg_user_mapping_umoptions - 1] = useoptions;
+	else
+		nulls[Anum_pg_user_mapping_umoptions - 1] = true;
+
+	tuple = heap_form_tuple(rel->rd_att, values, nulls);
+
+	CatalogTupleInsert(rel, tuple);
+
+	heap_freetuple(tuple);
+
+	/* Add dependency on the server */
+	myself.classId = UserMappingRelationId;
+	myself.objectId = umId;
+	myself.objectSubId = 0;
+
+	referenced.classId = ForeignServerRelationId;
+	referenced.objectId = srv->serverid;
+	referenced.objectSubId = 0;
+	recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+
+	if (OidIsValid(useId))
+	{
+		/* Record the mapped user dependency */
+		recordDependencyOnOwner(UserMappingRelationId, umId, useId);
+	}
+
+	/*
+	 * Perhaps someday there should be a recordDependencyOnCurrentExtension
+	 * call here; but since roles aren't members of extensions, it seems like
+	 * user mappings shouldn't be either.  Note that the grammar and pg_dump
+	 * would need to be extended too if we change this.
+	 */
+
+	/* Post creation hook for new user mapping */
+	InvokeObjectPostCreateHook(UserMappingRelationId, umId, 0);
+
+	table_close(rel, RowExclusiveLock);
+
+	return myself;
+}
+
+
+/*
+ * Alter user mapping
+ */
+ObjectAddress
+AlterUserMapping(AlterUserMappingStmt *stmt)
+{
+	Relation	rel;
+	HeapTuple	tp;
+	Datum		repl_val[Natts_pg_user_mapping];
+	bool		repl_null[Natts_pg_user_mapping];
+	bool		repl_repl[Natts_pg_user_mapping];
+	Oid			useId;
+	Oid			umId;
+	ForeignServer *srv;
+	ObjectAddress address;
+	RoleSpec   *role = (RoleSpec *) stmt->user;
+
+	rel = table_open(UserMappingRelationId, RowExclusiveLock);
+
+	if (role->roletype == ROLESPEC_PUBLIC)
+		useId = ACL_ID_PUBLIC;
+	else
+		useId = get_rolespec_oid(stmt->user, false);
+
+	srv = GetForeignServerByName(stmt->servername, false);
+
+	umId = GetSysCacheOid2(USERMAPPINGUSERSERVER, Anum_pg_user_mapping_oid,
+						   ObjectIdGetDatum(useId),
+						   ObjectIdGetDatum(srv->serverid));
+	if (!OidIsValid(umId))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("user mapping for \"%s\" does not exist for server \"%s\"",
+						MappingUserName(useId), stmt->servername)));
+
+	user_mapping_ddl_aclcheck(useId, srv->serverid, stmt->servername);
+
+	tp = SearchSysCacheCopy1(USERMAPPINGOID, ObjectIdGetDatum(umId));
+
+	if (!HeapTupleIsValid(tp))
+		elog(ERROR, "cache lookup failed for user mapping %u", umId);
+
+	memset(repl_val, 0, sizeof(repl_val));
+	memset(repl_null, false, sizeof(repl_null));
+	memset(repl_repl, false, sizeof(repl_repl));
+
+	if (stmt->options)
+	{
+		ForeignDataWrapper *fdw;
+		Datum		datum;
+		bool		isnull;
+
+		/*
+		 * Process the options.
+		 */
+
+		fdw = GetForeignDataWrapper(srv->fdwid);
+
+		datum = SysCacheGetAttr(USERMAPPINGUSERSERVER,
+								tp,
+								Anum_pg_user_mapping_umoptions,
+								&isnull);
+		if (isnull)
+			datum = PointerGetDatum(NULL);
+
+		/* Prepare the options array */
+		datum = transformGenericOptions(UserMappingRelationId,
+										datum,
+										stmt->options,
+										fdw->fdwvalidator);
+
+		if (PointerIsValid(DatumGetPointer(datum)))
+			repl_val[Anum_pg_user_mapping_umoptions - 1] = datum;
+		else
+			repl_null[Anum_pg_user_mapping_umoptions - 1] = true;
+
+		repl_repl[Anum_pg_user_mapping_umoptions - 1] = true;
+	}
+
+	/* Everything looks good - update the tuple */
+	tp = heap_modify_tuple(tp, RelationGetDescr(rel),
+						   repl_val, repl_null, repl_repl);
+
+	CatalogTupleUpdate(rel, &tp->t_self, tp);
+
+	InvokeObjectPostAlterHook(UserMappingRelationId,
+							  umId, 0);
+
+	ObjectAddressSet(address, UserMappingRelationId, umId);
+
+	heap_freetuple(tp);
+
+	table_close(rel, RowExclusiveLock);
+
+	return address;
+}
+
+
+/*
+ * Drop user mapping
+ */
+Oid
+RemoveUserMapping(DropUserMappingStmt *stmt)
+{
+	ObjectAddress object;
+	Oid			useId;
+	Oid			umId;
+	ForeignServer *srv;
+	RoleSpec   *role = (RoleSpec *) stmt->user;
+
+	if (role->roletype == ROLESPEC_PUBLIC)
+		useId = ACL_ID_PUBLIC;
+	else
+	{
+		useId = get_rolespec_oid(stmt->user, stmt->missing_ok);
+		if (!OidIsValid(useId))
+		{
+			/*
+			 * IF EXISTS specified, role not found and not public. Notice this
+			 * and leave.
+			 */
+			elog(NOTICE, "role \"%s\" does not exist, skipping",
+				 role->rolename);
+			return InvalidOid;
+		}
+	}
+
+	srv = GetForeignServerByName(stmt->servername, true);
+
+	if (!srv)
+	{
+		if (!stmt->missing_ok)
+			ereport(ERROR,
+					(errcode(ERRCODE_UNDEFINED_OBJECT),
+					 errmsg("server \"%s\" does not exist",
+							stmt->servername)));
+		/* IF EXISTS, just note it */
+		ereport(NOTICE,
+				(errmsg("server \"%s\" does not exist, skipping",
+						stmt->servername)));
+		return InvalidOid;
+	}
+
+	umId = GetSysCacheOid2(USERMAPPINGUSERSERVER, Anum_pg_user_mapping_oid,
+						   ObjectIdGetDatum(useId),
+						   ObjectIdGetDatum(srv->serverid));
+
+	if (!OidIsValid(umId))
+	{
+		if (!stmt->missing_ok)
+			ereport(ERROR,
+					(errcode(ERRCODE_UNDEFINED_OBJECT),
+					 errmsg("user mapping for \"%s\" does not exist for server \"%s\"",
+							MappingUserName(useId), stmt->servername)));
+
+		/* IF EXISTS specified, just note it */
+		ereport(NOTICE,
+				(errmsg("user mapping for \"%s\" does not exist for server \"%s\", skipping",
+						MappingUserName(useId), stmt->servername)));
+		return InvalidOid;
+	}
+
+	user_mapping_ddl_aclcheck(useId, srv->serverid, srv->servername);
+
+	/*
+	 * Do the deletion
+	 */
+	object.classId = UserMappingRelationId;
+	object.objectId = umId;
+	object.objectSubId = 0;
+
+	performDeletion(&object, DROP_CASCADE, 0);
+
+	return umId;
+}
+
+
+/*
+ * Create a foreign table
+ * call after DefineRelation().
+ */
+void
+CreateForeignTable(CreateForeignTableStmt *stmt, Oid relid)
+{
+	Relation	ftrel;
+	Datum		ftoptions;
+	Datum		values[Natts_pg_foreign_table];
+	bool		nulls[Natts_pg_foreign_table];
+	HeapTuple	tuple;
+	AclResult	aclresult;
+	ObjectAddress myself;
+	ObjectAddress referenced;
+	Oid			ownerId;
+	ForeignDataWrapper *fdw;
+	ForeignServer *server;
+
+	/*
+	 * Advance command counter to ensure the pg_attribute tuple is visible;
+	 * the tuple might be updated to add constraints in previous step.
+	 */
+	CommandCounterIncrement();
+
+	ftrel = table_open(ForeignTableRelationId, RowExclusiveLock);
+
+	/*
+	 * For now the owner cannot be specified on create. Use effective user ID.
+	 */
+	ownerId = GetUserId();
+
+	/*
+	 * Check that the foreign server exists and that we have USAGE on it. Also
+	 * get the actual FDW for option validation etc.
+	 */
+	server = GetForeignServerByName(stmt->servername, false);
+	aclresult = pg_foreign_server_aclcheck(server->serverid, ownerId, ACL_USAGE);
+	if (aclresult != ACLCHECK_OK)
+		aclcheck_error(aclresult, OBJECT_FOREIGN_SERVER, server->servername);
+
+	fdw = GetForeignDataWrapper(server->fdwid);
+
+	/*
+	 * Insert tuple into pg_foreign_table.
+	 */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+
+	values[Anum_pg_foreign_table_ftrelid - 1] = ObjectIdGetDatum(relid);
+	values[Anum_pg_foreign_table_ftserver - 1] = ObjectIdGetDatum(server->serverid);
+	/* Add table generic options */
+	ftoptions = transformGenericOptions(ForeignTableRelationId,
+										PointerGetDatum(NULL),
+										stmt->options,
+										fdw->fdwvalidator);
+
+	if (PointerIsValid(DatumGetPointer(ftoptions)))
+		values[Anum_pg_foreign_table_ftoptions - 1] = ftoptions;
+	else
+		nulls[Anum_pg_foreign_table_ftoptions - 1] = true;
+
+	tuple = heap_form_tuple(ftrel->rd_att, values, nulls);
+
+	CatalogTupleInsert(ftrel, tuple);
+
+	heap_freetuple(tuple);
+
+	/* Add pg_class dependency on the server */
+	myself.classId = RelationRelationId;
+	myself.objectId = relid;
+	myself.objectSubId = 0;
+
+	referenced.classId = ForeignServerRelationId;
+	referenced.objectId = server->serverid;
+	referenced.objectSubId = 0;
+	recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+
+	table_close(ftrel, RowExclusiveLock);
+}
+
+/*
+ * Import a foreign schema
+ */
+void
+ImportForeignSchema(ImportForeignSchemaStmt *stmt)
+{
+	ForeignServer *server;
+	ForeignDataWrapper *fdw;
+	FdwRoutine *fdw_routine;
+	AclResult	aclresult;
+	List	   *cmd_list;
+	ListCell   *lc;
+
+	/* Check that the foreign server exists and that we have USAGE on it */
+	server = GetForeignServerByName(stmt->server_name, false);
+	aclresult = pg_foreign_server_aclcheck(server->serverid, GetUserId(), ACL_USAGE);
+	if (aclresult != ACLCHECK_OK)
+		aclcheck_error(aclresult, OBJECT_FOREIGN_SERVER, server->servername);
+
+	/* Check that the schema exists and we have CREATE permissions on it */
+	(void) LookupCreationNamespace(stmt->local_schema);
+
+	/* Get the FDW and check it supports IMPORT */
+	fdw = GetForeignDataWrapper(server->fdwid);
+	if (!OidIsValid(fdw->fdwhandler))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("foreign-data wrapper \"%s\" has no handler",
+						fdw->fdwname)));
+	fdw_routine = GetFdwRoutine(fdw->fdwhandler);
+	if (fdw_routine->ImportForeignSchema == NULL)
+		ereport(ERROR,
+				(errcode(ERRCODE_FDW_NO_SCHEMAS),
+				 errmsg("foreign-data wrapper \"%s\" does not support IMPORT FOREIGN SCHEMA",
+						fdw->fdwname)));
+
+	/* Call FDW to get a list of commands */
+	cmd_list = fdw_routine->ImportForeignSchema(stmt, server->serverid);
+
+	/* Parse and execute each command */
+	foreach(lc, cmd_list)
+	{
+		char	   *cmd = (char *) lfirst(lc);
+		import_error_callback_arg callback_arg;
+		ErrorContextCallback sqlerrcontext;
+		List	   *raw_parsetree_list;
+		ListCell   *lc2;
+
+		/*
+		 * Setup error traceback support for ereport().  This is so that any
+		 * error in the generated SQL will be displayed nicely.
+		 */
+		callback_arg.tablename = NULL;	/* not known yet */
+		callback_arg.cmd = cmd;
+		sqlerrcontext.callback = import_error_callback;
+		sqlerrcontext.arg = (void *) &callback_arg;
+		sqlerrcontext.previous = error_context_stack;
+		error_context_stack = &sqlerrcontext;
+
+		/*
+		 * Parse the SQL string into a list of raw parse trees.
+		 */
+		raw_parsetree_list = pg_parse_query(cmd);
+
+		/*
+		 * Process each parse tree (we allow the FDW to put more than one
+		 * command per string, though this isn't really advised).
+		 */
+		foreach(lc2, raw_parsetree_list)
+		{
+			RawStmt    *rs = lfirst_node(RawStmt, lc2);
+			CreateForeignTableStmt *cstmt = (CreateForeignTableStmt *) rs->stmt;
+			PlannedStmt *pstmt;
+
+			/*
+			 * Because we only allow CreateForeignTableStmt, we can skip parse
+			 * analysis, rewrite, and planning steps here.
+			 */
+			if (!IsA(cstmt, CreateForeignTableStmt))
+				elog(ERROR,
+					 "foreign-data wrapper \"%s\" returned incorrect statement type %d",
+					 fdw->fdwname, (int) nodeTag(cstmt));
+
+			/* Ignore commands for tables excluded by filter options */
+			if (!IsImportableForeignTable(cstmt->base.relation->relname, stmt))
+				continue;
+
+			/* Enable reporting of current table's name on error */
+			callback_arg.tablename = cstmt->base.relation->relname;
+
+			/* Ensure creation schema is the one given in IMPORT statement */
+			cstmt->base.relation->schemaname = pstrdup(stmt->local_schema);
+
+			/* No planning needed, just make a wrapper PlannedStmt */
+			pstmt = makeNode(PlannedStmt);
+			pstmt->commandType = CMD_UTILITY;
+			pstmt->canSetTag = false;
+			pstmt->utilityStmt = (Node *) cstmt;
+			pstmt->stmt_location = rs->stmt_location;
+			pstmt->stmt_len = rs->stmt_len;
+
+			/* Execute statement */
+			ProcessUtility(pstmt, cmd, false,
+						   PROCESS_UTILITY_SUBCOMMAND, NULL, NULL,
+						   None_Receiver, NULL);
+
+			/* Be sure to advance the command counter between subcommands */
+			CommandCounterIncrement();
+
+			callback_arg.tablename = NULL;
+		}
+
+		error_context_stack = sqlerrcontext.previous;
+	}
+}
+
+/*
+ * error context callback to let us supply the failing SQL statement's text
+ */
+static void
+import_error_callback(void *arg)
+{
+	import_error_callback_arg *callback_arg = (import_error_callback_arg *) arg;
+	int			syntaxerrposition;
+
+	/* If it's a syntax error, convert to internal syntax error report */
+	syntaxerrposition = geterrposition();
+	if (syntaxerrposition > 0)
+	{
+		errposition(0);
+		internalerrposition(syntaxerrposition);
+		internalerrquery(callback_arg->cmd);
+	}
+
+	if (callback_arg->tablename)
+		errcontext("importing foreign table \"%s\"",
+				   callback_arg->tablename);
+}