diff --git a/contrib/postgres_fdw/connection.c b/contrib/postgres_fdw/connection.c
index 0c6c3cee30..6e664b0213 100644
--- a/contrib/postgres_fdw/connection.c
+++ b/contrib/postgres_fdw/connection.c
@@ -24,9 +24,11 @@
 /*
  * Connection cache hash table entry
  *
- * The lookup key in this hash table is the foreign server OID plus the user
- * mapping OID.  (We use just one connection per user per foreign server,
- * so that we can ensure all scans use the same snapshot during a query.)
+ * The lookup key in this hash table is the user mapping OID. We use just one
+ * connection per user mapping ID, which ensures that all the scans use the
+ * same snapshot during a query.  Using the user mapping OID rather than
+ * the foreign server OID + user OID avoids creating multiple connections when
+ * the public user mapping applies to all user OIDs.
  *
  * The "conn" pointer can be NULL if we don't currently have a live connection.
  * When we do have a connection, xact_depth tracks the current depth of
@@ -35,11 +37,7 @@
  * ourselves, so that rolling back a subtransaction will kill the right
  * queries and not the wrong ones.
  */
-typedef struct ConnCacheKey
-{
-	Oid			serverid;		/* OID of foreign server */
-	Oid			userid;			/* OID of local user whose mapping we use */
-} ConnCacheKey;
+typedef Oid ConnCacheKey;
 
 typedef struct ConnCacheEntry
 {
@@ -94,8 +92,7 @@ static void pgfdw_subxact_callback(SubXactEvent event,
  * mid-transaction anyway.
  */
 PGconn *
-GetConnection(ForeignServer *server, UserMapping *user,
-			  bool will_prep_stmt)
+GetConnection(UserMapping *user, bool will_prep_stmt)
 {
 	bool		found;
 	ConnCacheEntry *entry;
@@ -127,8 +124,7 @@ GetConnection(ForeignServer *server, UserMapping *user,
 	xact_got_connection = true;
 
 	/* Create hash key for the entry.  Assume no pad bytes in key struct */
-	key.serverid = server->serverid;
-	key.userid = user->userid;
+	key = user->umid;
 
 	/*
 	 * Find or create cached entry for requested connection.
@@ -156,12 +152,15 @@ GetConnection(ForeignServer *server, UserMapping *user,
 	 */
 	if (entry->conn == NULL)
 	{
+		ForeignServer *server = GetForeignServer(user->serverid);
+
 		entry->xact_depth = 0;	/* just to be sure */
 		entry->have_prep_stmt = false;
 		entry->have_error = false;
 		entry->conn = connect_pg_server(server, user);
-		elog(DEBUG3, "new postgres_fdw connection %p for server \"%s\"",
-			 entry->conn, server->servername);
+
+		elog(DEBUG3, "new postgres_fdw connection %p for server \"%s\ (user mapping oid %d, userid %d)",
+			 entry->conn, server->servername, user->umid, user->userid);
 	}
 
 	/*
diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index 374faf5a25..a237e152c0 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -1101,7 +1101,6 @@ postgresBeginForeignScan(ForeignScanState *node, int eflags)
 	RangeTblEntry *rte;
 	Oid			userid;
 	ForeignTable *table;
-	ForeignServer *server;
 	UserMapping *user;
 	int			numParams;
 	int			i;
@@ -1129,14 +1128,13 @@ postgresBeginForeignScan(ForeignScanState *node, int eflags)
 	/* Get info about foreign table. */
 	fsstate->rel = node->ss.ss_currentRelation;
 	table = GetForeignTable(RelationGetRelid(fsstate->rel));
-	server = GetForeignServer(table->serverid);
-	user = GetUserMapping(userid, server->serverid);
+	user = GetUserMapping(userid, table->serverid);
 
 	/*
 	 * Get connection to the foreign server.  Connection manager will
 	 * establish new connection if necessary.
 	 */
-	fsstate->conn = GetConnection(server, user, false);
+	fsstate->conn = GetConnection(user, false);
 
 	/* Assign a unique ID for my cursor */
 	fsstate->cursor_number = GetCursorNumber(fsstate->conn);
@@ -1503,7 +1501,6 @@ postgresBeginForeignModify(ModifyTableState *mtstate,
 	RangeTblEntry *rte;
 	Oid			userid;
 	ForeignTable *table;
-	ForeignServer *server;
 	UserMapping *user;
 	AttrNumber	n_params;
 	Oid			typefnoid;
@@ -1530,11 +1527,10 @@ postgresBeginForeignModify(ModifyTableState *mtstate,
 
 	/* Get info about foreign table. */
 	table = GetForeignTable(RelationGetRelid(rel));
-	server = GetForeignServer(table->serverid);
-	user = GetUserMapping(userid, server->serverid);
+	user = GetUserMapping(userid, table->serverid);
 
 	/* Open connection; report that we'll create a prepared statement. */
-	fmstate->conn = GetConnection(server, user, true);
+	fmstate->conn = GetConnection(user, true);
 	fmstate->p_name = NULL;		/* prepared statement not made yet */
 
 	/* Deconstruct fdw_private data. */
@@ -1988,7 +1984,7 @@ estimate_path_cost_size(PlannerInfo *root,
 			appendOrderByClause(&sql, root, baserel, pathkeys);
 
 		/* Get the remote estimate */
-		conn = GetConnection(fpinfo->server, fpinfo->user, false);
+		conn = GetConnection(fpinfo->user, false);
 		get_remote_estimate(sql.data, conn, &rows, &width,
 							&startup_cost, &total_cost);
 		ReleaseConnection(conn);
@@ -2544,7 +2540,6 @@ postgresAnalyzeForeignTable(Relation relation,
 							BlockNumber *totalpages)
 {
 	ForeignTable *table;
-	ForeignServer *server;
 	UserMapping *user;
 	PGconn	   *conn;
 	StringInfoData sql;
@@ -2565,9 +2560,8 @@ postgresAnalyzeForeignTable(Relation relation,
 	 * owner, even if the ANALYZE was started by some other user.
 	 */
 	table = GetForeignTable(RelationGetRelid(relation));
-	server = GetForeignServer(table->serverid);
-	user = GetUserMapping(relation->rd_rel->relowner, server->serverid);
-	conn = GetConnection(server, user, false);
+	user = GetUserMapping(relation->rd_rel->relowner, table->serverid);
+	conn = GetConnection(user, false);
 
 	/*
 	 * Construct command to get page count for relation.
@@ -2626,7 +2620,6 @@ postgresAcquireSampleRowsFunc(Relation relation, int elevel,
 {
 	PgFdwAnalyzeState astate;
 	ForeignTable *table;
-	ForeignServer *server;
 	UserMapping *user;
 	PGconn	   *conn;
 	unsigned int cursor_number;
@@ -2657,9 +2650,8 @@ postgresAcquireSampleRowsFunc(Relation relation, int elevel,
 	 * owner, even if the ANALYZE was started by some other user.
 	 */
 	table = GetForeignTable(RelationGetRelid(relation));
-	server = GetForeignServer(table->serverid);
-	user = GetUserMapping(relation->rd_rel->relowner, server->serverid);
-	conn = GetConnection(server, user, false);
+	user = GetUserMapping(relation->rd_rel->relowner, table->serverid);
+	conn = GetConnection(user, false);
 
 	/*
 	 * Construct cursor that retrieves whole rows from remote.
@@ -2860,7 +2852,7 @@ postgresImportForeignSchema(ImportForeignSchemaStmt *stmt, Oid serverOid)
 	 */
 	server = GetForeignServer(serverOid);
 	mapping = GetUserMapping(GetUserId(), server->serverid);
-	conn = GetConnection(server, mapping, false);
+	conn = GetConnection(mapping, false);
 
 	/* Don't attempt to import collation if remote server hasn't got it */
 	if (PQserverVersion(conn) < 90100)
diff --git a/contrib/postgres_fdw/postgres_fdw.h b/contrib/postgres_fdw/postgres_fdw.h
index 8553536047..59e9f60c04 100644
--- a/contrib/postgres_fdw/postgres_fdw.h
+++ b/contrib/postgres_fdw/postgres_fdw.h
@@ -60,8 +60,7 @@ extern int	set_transmission_modes(void);
 extern void reset_transmission_modes(int nestlevel);
 
 /* in connection.c */
-extern PGconn *GetConnection(ForeignServer *server, UserMapping *user,
-			  bool will_prep_stmt);
+extern PGconn *GetConnection(UserMapping *user, bool will_prep_stmt);
 extern void ReleaseConnection(PGconn *conn);
 extern unsigned int GetCursorNumber(PGconn *conn);
 extern unsigned int GetPrepStmtNumber(PGconn *conn);
diff --git a/src/backend/foreign/foreign.c b/src/backend/foreign/foreign.c
index 14e082b5b8..c24b11b685 100644
--- a/src/backend/foreign/foreign.c
+++ b/src/backend/foreign/foreign.c
@@ -193,6 +193,7 @@ GetUserMapping(Oid userid, Oid serverid)
 						MappingUserName(userid))));
 
 	um = (UserMapping *) palloc(sizeof(UserMapping));
+	um->umid = HeapTupleGetOid(tp);
 	um->userid = userid;
 	um->serverid = serverid;
 
diff --git a/src/include/foreign/foreign.h b/src/include/foreign/foreign.h
index 2c1ada1b12..5dc2c90f3c 100644
--- a/src/include/foreign/foreign.h
+++ b/src/include/foreign/foreign.h
@@ -55,6 +55,7 @@ typedef struct ForeignServer
 
 typedef struct UserMapping
 {
+	Oid			umid;			/* Oid of user mapping */
 	Oid			userid;			/* local user Oid */
 	Oid			serverid;		/* server Oid */
 	List	   *options;		/* useoptions as DefElem list */